[BZ #4745]

[glibc.git] / malloc / malloc.c

/* Malloc implementation for multiple threads without lock contention.
   Copyright (C) 1996-2006, 2007 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Wolfram Gloger <wg@malloc.de>
   and Doug Lea <dl@cs.oswego.edu>, 2001.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public License as
   published by the Free Software Foundation; either version 2.1 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/*
  This is a version (aka ptmalloc2) of malloc/free/realloc written by
  Doug Lea and adapted to multiple threads/arenas by Wolfram Gloger.

* Version ptmalloc2-20011215
  based on:
  VERSION 2.7.0 Sun Mar 11 14:14:06 2001  Doug Lea  (dl at gee)

* Quickstart

  In order to compile this implementation, a Makefile is provided with
  the ptmalloc2 distribution, which has pre-defined targets for some
  popular systems (e.g. "make posix" for Posix threads).  All that is
  typically required with regard to compiler flags is the selection of
  the thread package via defining one out of USE_PTHREADS, USE_THR or
  USE_SPROC.  Check the thread-m.h file for what effects this has.
  Many/most systems will additionally require USE_TSD_DATA_HACK to be
  defined, so this is the default for "make posix".

* Why use this malloc?

  This is not the fastest, most space-conserving, most portable, or
  most tunable malloc ever written. However it is among the fastest
  while also being among the most space-conserving, portable and tunable.
  Consistent balance across these factors results in a good general-purpose
  allocator for malloc-intensive programs.

  The main properties of the algorithms are:
  * For large (>= 512 bytes) requests, it is a pure best-fit allocator,
    with ties normally decided via FIFO (i.e. least recently used).
  * For small (<= 64 bytes by default) requests, it is a caching
    allocator, that maintains pools of quickly recycled chunks.
  * In between, and for combinations of large and small requests, it does
    the best it can trying to meet both goals at once.
  * For very large requests (>= 128KB by default), it relies on system
    memory mapping facilities, if supported.

  For a longer but slightly out of date high-level description, see
     http://gee.cs.oswego.edu/dl/html/malloc.html

  You may already by default be using a C library containing a malloc
  that is  based on some version of this malloc (for example in
  linux). You might still want to use the one in this file in order to
  customize settings or to avoid overheads associated with library
  versions.

* Contents, described in more detail in "description of public routines" below.

  Standard (ANSI/SVID/...)  functions:
    malloc(size_t n);
    calloc(size_t n_elements, size_t element_size);
    free(Void_t* p);
    realloc(Void_t* p, size_t n);
    memalign(size_t alignment, size_t n);
    valloc(size_t n);
    mallinfo()
    mallopt(int parameter_number, int parameter_value)

  Additional functions:
    independent_calloc(size_t n_elements, size_t size, Void_t* chunks[]);
    independent_comalloc(size_t n_elements, size_t sizes[], Void_t* chunks[]);
    pvalloc(size_t n);
    cfree(Void_t* p);
    malloc_trim(size_t pad);
    malloc_usable_size(Void_t* p);
    malloc_stats();

* Vital statistics:

  Supported pointer representation:       4 or 8 bytes
  Supported size_t  representation:       4 or 8 bytes
       Note that size_t is allowed to be 4 bytes even if pointers are 8.
       You can adjust this by defining INTERNAL_SIZE_T

  Alignment:                              2 * sizeof(size_t) (default)
       (i.e., 8 byte alignment with 4byte size_t). This suffices for
       nearly all current machines and C compilers. However, you can
       define MALLOC_ALIGNMENT to be wider than this if necessary.

  Minimum overhead per allocated chunk:   4 or 8 bytes
       Each malloced chunk has a hidden word of overhead holding size
       and status information.

  Minimum allocated size: 4-byte ptrs:  16 bytes    (including 4 overhead)
                          8-byte ptrs:  24/32 bytes (including, 4/8 overhead)

       When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
       ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
       needed; 4 (8) for a trailing size field and 8 (16) bytes for
       free list pointers. Thus, the minimum allocatable size is
       16/24/32 bytes.

       Even a request for zero bytes (i.e., malloc(0)) returns a
       pointer to something of the minimum allocatable size.

       The maximum overhead wastage (i.e., number of extra bytes
       allocated than were requested in malloc) is less than or equal
       to the minimum size, except for requests >= mmap_threshold that
       are serviced via mmap(), where the worst case wastage is 2 *
       sizeof(size_t) bytes plus the remainder from a system page (the
       minimal mmap unit); typically 4096 or 8192 bytes.

  Maximum allocated size:  4-byte size_t: 2^32 minus about two pages
                           8-byte size_t: 2^64 minus about two pages

       It is assumed that (possibly signed) size_t values suffice to
       represent chunk sizes. `Possibly signed' is due to the fact
       that `size_t' may be defined on a system as either a signed or
       an unsigned type. The ISO C standard says that it must be
       unsigned, but a few systems are known not to adhere to this.
       Additionally, even when size_t is unsigned, sbrk (which is by
       default used to obtain memory from system) accepts signed
       arguments, and may not be able to handle size_t-wide arguments
       with negative sign bit.  Generally, values that would
       appear as negative after accounting for overhead and alignment
       are supported only via mmap(), which does not have this
       limitation.

       Requests for sizes outside the allowed range will perform an optional
       failure action and then return null. (Requests may also
       also fail because a system is out of memory.)

  Thread-safety: thread-safe unless NO_THREADS is defined

  Compliance: I believe it is compliant with the 1997 Single Unix Specification
       (See http://www.opennc.org). Also SVID/XPG, ANSI C, and probably
       others as well.

* Synopsis of compile-time options:

    People have reported using previous versions of this malloc on all
    versions of Unix, sometimes by tweaking some of the defines
    below. It has been tested most extensively on Solaris and
    Linux. It is also reported to work on WIN32 platforms.
    People also report using it in stand-alone embedded systems.

    The implementation is in straight, hand-tuned ANSI C.  It is not
    at all modular. (Sorry!)  It uses a lot of macros.  To be at all
    usable, this code should be compiled using an optimizing compiler
    (for example gcc -O3) that can simplify expressions and control
    paths. (FAQ: some macros import variables as arguments rather than
    declare locals because people reported that some debuggers
    otherwise get confused.)

    OPTION                     DEFAULT VALUE

    Compilation Environment options:

    __STD_C                    derived from C compiler defines
    WIN32                      NOT defined
    HAVE_MEMCPY                defined
    USE_MEMCPY                 1 if HAVE_MEMCPY is defined
    HAVE_MMAP                  defined as 1
    MMAP_CLEARS                1
    HAVE_MREMAP                0 unless linux defined
    USE_ARENAS                 the same as HAVE_MMAP
    malloc_getpagesize         derived from system #includes, or 4096 if not
    HAVE_USR_INCLUDE_MALLOC_H  NOT defined
    LACKS_UNISTD_H             NOT defined unless WIN32
    LACKS_SYS_PARAM_H          NOT defined unless WIN32
    LACKS_SYS_MMAN_H           NOT defined unless WIN32

    Changing default word sizes:

    INTERNAL_SIZE_T            size_t
    MALLOC_ALIGNMENT           MAX (2 * sizeof(INTERNAL_SIZE_T),
                                    __alignof__ (long double))

    Configuration and functionality options:

    USE_DL_PREFIX              NOT defined
    USE_PUBLIC_MALLOC_WRAPPERS NOT defined
    USE_MALLOC_LOCK            NOT defined
    MALLOC_DEBUG               NOT defined
    REALLOC_ZERO_BYTES_FREES   1
    MALLOC_FAILURE_ACTION      errno = ENOMEM, if __STD_C defined, else no-op
    TRIM_FASTBINS              0

    Options for customizing MORECORE:

    MORECORE                   sbrk
    MORECORE_FAILURE           -1
    MORECORE_CONTIGUOUS        1
    MORECORE_CANNOT_TRIM       NOT defined
    MORECORE_CLEARS            1
    MMAP_AS_MORECORE_SIZE      (1024 * 1024)

    Tuning options that are also dynamically changeable via mallopt:

    DEFAULT_MXFAST             64
    DEFAULT_TRIM_THRESHOLD     128 * 1024
    DEFAULT_TOP_PAD            0
    DEFAULT_MMAP_THRESHOLD     128 * 1024
    DEFAULT_MMAP_MAX           65536

    There are several other #defined constants and macros that you
    probably don't want to touch unless you are extending or adapting malloc.  */

/*
  __STD_C should be nonzero if using ANSI-standard C compiler, a C++
  compiler, or a C compiler sufficiently close to ANSI to get away
  with it.
*/

#ifndef __STD_C
#if defined(__STDC__) || defined(__cplusplus)
#define __STD_C     1
#else
#define __STD_C     0
#endif
#endif /*__STD_C*/


/*
  Void_t* is the pointer type that malloc should say it returns
*/

#ifndef Void_t
#if (__STD_C || defined(WIN32))
#define Void_t      void
#else
#define Void_t      char
#endif
#endif /*Void_t*/

#if __STD_C
#include <stddef.h>   /* for size_t */
#include <stdlib.h>   /* for getenv(), abort() */
#else
#include <sys/types.h>
#endif

#include <malloc-machine.h>

#ifdef _LIBC
#include <stdio-common/_itoa.h>
#include <bits/wordsize.h>
#endif

#ifdef __cplusplus
extern "C" {
#endif

/* define LACKS_UNISTD_H if your system does not have a <unistd.h>. */

/* #define  LACKS_UNISTD_H */

#ifndef LACKS_UNISTD_H
#include <unistd.h>
#endif

/* define LACKS_SYS_PARAM_H if your system does not have a <sys/param.h>. */

/* #define  LACKS_SYS_PARAM_H */


#include <stdio.h>    /* needed for malloc_stats */
#include <errno.h>    /* needed for optional MALLOC_FAILURE_ACTION */

/* For uintptr_t.  */
#include <stdint.h>

/* For va_arg, va_start, va_end.  */
#include <stdarg.h>

/* For writev and struct iovec.  */
#include <sys/uio.h>
/* For syslog.  */
#include <sys/syslog.h>

/* For various dynamic linking things.  */
#include <dlfcn.h>


/*
  Debugging:

  Because freed chunks may be overwritten with bookkeeping fields, this
  malloc will often die when freed memory is overwritten by user
  programs.  This can be very effective (albeit in an annoying way)
  in helping track down dangling pointers.

  If you compile with -DMALLOC_DEBUG, a number of assertion checks are
  enabled that will catch more memory errors. You probably won't be
  able to make much sense of the actual assertion errors, but they
  should help you locate incorrectly overwritten memory.  The checking
  is fairly extensive, and will slow down execution
  noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set
  will attempt to check every non-mmapped allocated and free chunk in
  the course of computing the summmaries. (By nature, mmapped regions
  cannot be checked very much automatically.)

  Setting MALLOC_DEBUG may also be helpful if you are trying to modify
  this code. The assertions in the check routines spell out in more
  detail the assumptions and invariants underlying the algorithms.

  Setting MALLOC_DEBUG does NOT provide an automated mechanism for
  checking that all accesses to malloced memory stay within their
  bounds. However, there are several add-ons and adaptations of this
  or other mallocs available that do this.
*/

#if MALLOC_DEBUG
#include <assert.h>
#else
#undef  assert
#define assert(x) ((void)0)
#endif


/*
  INTERNAL_SIZE_T is the word-size used for internal bookkeeping
  of chunk sizes.

  The default version is the same as size_t.

  While not strictly necessary, it is best to define this as an
  unsigned type, even if size_t is a signed type. This may avoid some
  artificial size limitations on some systems.

  On a 64-bit machine, you may be able to reduce malloc overhead by
  defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' at the
  expense of not being able to handle more than 2^32 of malloced
  space. If this limitation is acceptable, you are encouraged to set
  this unless you are on a platform requiring 16byte alignments. In
  this case the alignment requirements turn out to negate any
  potential advantages of decreasing size_t word size.

  Implementors: Beware of the possible combinations of:
     - INTERNAL_SIZE_T might be signed or unsigned, might be 32 or 64 bits,
       and might be the same width as int or as long
     - size_t might have different width and signedness as INTERNAL_SIZE_T
     - int and long might be 32 or 64 bits, and might be the same width
  To deal with this, most comparisons and difference computations
  among INTERNAL_SIZE_Ts should cast them to unsigned long, being
  aware of the fact that casting an unsigned int to a wider long does
  not sign-extend. (This also makes checking for negative numbers
  awkward.) Some of these casts result in harmless compiler warnings
  on some systems.
*/

#ifndef INTERNAL_SIZE_T
#define INTERNAL_SIZE_T size_t
#endif

/* The corresponding word size */
#define SIZE_SZ                (sizeof(INTERNAL_SIZE_T))


/*
  MALLOC_ALIGNMENT is the minimum alignment for malloc'ed chunks.
  It must be a power of two at least 2 * SIZE_SZ, even on machines
  for which smaller alignments would suffice. It may be defined as
  larger than this though. Note however that code and data structures
  are optimized for the case of 8-byte alignment.
*/


#ifndef MALLOC_ALIGNMENT
/* XXX This is the correct definition.  It differs from 2*SIZE_SZ only on
   powerpc32.  For the time being, changing this is causing more
   compatibility problems due to malloc_get_state/malloc_set_state than
   will returning blocks not adequately aligned for long double objects
   under -mlong-double-128.

#define MALLOC_ALIGNMENT       (2 * SIZE_SZ < __alignof__ (long double) \
                                ? __alignof__ (long double) : 2 * SIZE_SZ)
*/
#define MALLOC_ALIGNMENT       (2 * SIZE_SZ)
#endif

/* The corresponding bit mask value */
#define MALLOC_ALIGN_MASK      (MALLOC_ALIGNMENT - 1)



/*
  REALLOC_ZERO_BYTES_FREES should be set if a call to
  realloc with zero bytes should be the same as a call to free.
  This is required by the C standard. Otherwise, since this malloc
  returns a unique pointer for malloc(0), so does realloc(p, 0).
*/

#ifndef REALLOC_ZERO_BYTES_FREES
#define REALLOC_ZERO_BYTES_FREES 1
#endif

/*
  TRIM_FASTBINS controls whether free() of a very small chunk can
  immediately lead to trimming. Setting to true (1) can reduce memory
  footprint, but will almost always slow down programs that use a lot
  of small chunks.

  Define this only if you are willing to give up some speed to more
  aggressively reduce system-level memory footprint when releasing
  memory in programs that use many small chunks.  You can get
  essentially the same effect by setting MXFAST to 0, but this can
  lead to even greater slowdowns in programs using many small chunks.
  TRIM_FASTBINS is an in-between compile-time option, that disables
  only those chunks bordering topmost memory from being placed in
  fastbins.
*/

#ifndef TRIM_FASTBINS
#define TRIM_FASTBINS  0
#endif


/*
  USE_DL_PREFIX will prefix all public routines with the string 'dl'.
  This is necessary when you only want to use this malloc in one part
  of a program, using your regular system malloc elsewhere.
*/

/* #define USE_DL_PREFIX */


/*
   Two-phase name translation.
   All of the actual routines are given mangled names.
   When wrappers are used, they become the public callable versions.
   When DL_PREFIX is used, the callable names are prefixed.
*/

#ifdef USE_DL_PREFIX
#define public_cALLOc    dlcalloc
#define public_fREe      dlfree
#define public_cFREe     dlcfree
#define public_mALLOc    dlmalloc
#define public_mEMALIGn  dlmemalign
#define public_rEALLOc   dlrealloc
#define public_vALLOc    dlvalloc
#define public_pVALLOc   dlpvalloc
#define public_mALLINFo  dlmallinfo
#define public_mALLOPt   dlmallopt
#define public_mTRIm     dlmalloc_trim
#define public_mSTATs    dlmalloc_stats
#define public_mUSABLe   dlmalloc_usable_size
#define public_iCALLOc   dlindependent_calloc
#define public_iCOMALLOc dlindependent_comalloc
#define public_gET_STATe dlget_state
#define public_sET_STATe dlset_state
#else /* USE_DL_PREFIX */
#ifdef _LIBC

/* Special defines for the GNU C library.  */
#define public_cALLOc    __libc_calloc
#define public_fREe      __libc_free
#define public_cFREe     __libc_cfree
#define public_mALLOc    __libc_malloc
#define public_mEMALIGn  __libc_memalign
#define public_rEALLOc   __libc_realloc
#define public_vALLOc    __libc_valloc
#define public_pVALLOc   __libc_pvalloc
#define public_mALLINFo  __libc_mallinfo
#define public_mALLOPt   __libc_mallopt
#define public_mTRIm     __malloc_trim
#define public_mSTATs    __malloc_stats
#define public_mUSABLe   __malloc_usable_size
#define public_iCALLOc   __libc_independent_calloc
#define public_iCOMALLOc __libc_independent_comalloc
#define public_gET_STATe __malloc_get_state
#define public_sET_STATe __malloc_set_state
#define malloc_getpagesize __getpagesize()
#define open             __open
#define mmap             __mmap
#define munmap           __munmap
#define mremap           __mremap
#define mprotect         __mprotect
#define MORECORE         (*__morecore)
#define MORECORE_FAILURE 0

Void_t * __default_morecore (ptrdiff_t);
Void_t *(*__morecore)(ptrdiff_t) = __default_morecore;

#else /* !_LIBC */
#define public_cALLOc    calloc
#define public_fREe      free
#define public_cFREe     cfree
#define public_mALLOc    malloc
#define public_mEMALIGn  memalign
#define public_rEALLOc   realloc
#define public_vALLOc    valloc
#define public_pVALLOc   pvalloc
#define public_mALLINFo  mallinfo
#define public_mALLOPt   mallopt
#define public_mTRIm     malloc_trim
#define public_mSTATs    malloc_stats
#define public_mUSABLe   malloc_usable_size
#define public_iCALLOc   independent_calloc
#define public_iCOMALLOc independent_comalloc
#define public_gET_STATe malloc_get_state
#define public_sET_STATe malloc_set_state
#endif /* _LIBC */
#endif /* USE_DL_PREFIX */

#ifndef _LIBC
#define __builtin_expect(expr, val)     (expr)

#define fwrite(buf, size, count, fp) _IO_fwrite (buf, size, count, fp)
#endif

/*
  HAVE_MEMCPY should be defined if you are not otherwise using
  ANSI STD C, but still have memcpy and memset in your C library
  and want to use them in calloc and realloc. Otherwise simple
  macro versions are defined below.

  USE_MEMCPY should be defined as 1 if you actually want to
  have memset and memcpy called. People report that the macro
  versions are faster than libc versions on some systems.

  Even if USE_MEMCPY is set to 1, loops to copy/clear small chunks
  (of <= 36 bytes) are manually unrolled in realloc and calloc.
*/

#define HAVE_MEMCPY

#ifndef USE_MEMCPY
#ifdef HAVE_MEMCPY
#define USE_MEMCPY 1
#else
#define USE_MEMCPY 0
#endif
#endif


#if (__STD_C || defined(HAVE_MEMCPY))

#ifdef _LIBC
# include <string.h>
#else
#ifdef WIN32
/* On Win32 memset and memcpy are already declared in windows.h */
#else
#if __STD_C
void* memset(void*, int, size_t);
void* memcpy(void*, const void*, size_t);
#else
Void_t* memset();
Void_t* memcpy();
#endif
#endif
#endif
#endif

/*
  MALLOC_FAILURE_ACTION is the action to take before "return 0" when
  malloc fails to be able to return memory, either because memory is
  exhausted or because of illegal arguments.

  By default, sets errno if running on STD_C platform, else does nothing.
*/

#ifndef MALLOC_FAILURE_ACTION
#if __STD_C
#define MALLOC_FAILURE_ACTION \
   errno = ENOMEM;

#else
#define MALLOC_FAILURE_ACTION
#endif
#endif

/*
  MORECORE-related declarations. By default, rely on sbrk
*/


#ifdef LACKS_UNISTD_H
#if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__NetBSD__)
#if __STD_C
extern Void_t*     sbrk(ptrdiff_t);
#else
extern Void_t*     sbrk();
#endif
#endif
#endif

/*
  MORECORE is the name of the routine to call to obtain more memory
  from the system.  See below for general guidance on writing
  alternative MORECORE functions, as well as a version for WIN32 and a
  sample version for pre-OSX macos.
*/

#ifndef MORECORE
#define MORECORE sbrk
#endif

/*
  MORECORE_FAILURE is the value returned upon failure of MORECORE
  as well as mmap. Since it cannot be an otherwise valid memory address,
  and must reflect values of standard sys calls, you probably ought not
  try to redefine it.
*/

#ifndef MORECORE_FAILURE
#define MORECORE_FAILURE (-1)
#endif

/*
  If MORECORE_CONTIGUOUS is true, take advantage of fact that
  consecutive calls to MORECORE with positive arguments always return
  contiguous increasing addresses.  This is true of unix sbrk.  Even
  if not defined, when regions happen to be contiguous, malloc will
  permit allocations spanning regions obtained from different
  calls. But defining this when applicable enables some stronger
  consistency checks and space efficiencies.
*/

#ifndef MORECORE_CONTIGUOUS
#define MORECORE_CONTIGUOUS 1
#endif

/*
  Define MORECORE_CANNOT_TRIM if your version of MORECORE
  cannot release space back to the system when given negative
  arguments. This is generally necessary only if you are using
  a hand-crafted MORECORE function that cannot handle negative arguments.
*/

/* #define MORECORE_CANNOT_TRIM */

/*  MORECORE_CLEARS           (default 1)
     The degree to which the routine mapped to MORECORE zeroes out
     memory: never (0), only for newly allocated space (1) or always
     (2).  The distinction between (1) and (2) is necessary because on
     some systems, if the application first decrements and then
     increments the break value, the contents of the reallocated space
     are unspecified.
*/

#ifndef MORECORE_CLEARS
#define MORECORE_CLEARS 1
#endif


/*
  Define HAVE_MMAP as true to optionally make malloc() use mmap() to
  allocate very large blocks.  These will be returned to the
  operating system immediately after a free(). Also, if mmap
  is available, it is used as a backup strategy in cases where
  MORECORE fails to provide space from system.

  This malloc is best tuned to work with mmap for large requests.
  If you do not have mmap, operations involving very large chunks (1MB
  or so) may be slower than you'd like.
*/

#ifndef HAVE_MMAP
#define HAVE_MMAP 1

/*
   Standard unix mmap using /dev/zero clears memory so calloc doesn't
   need to.
*/

#ifndef MMAP_CLEARS
#define MMAP_CLEARS 1
#endif

#else /* no mmap */
#ifndef MMAP_CLEARS
#define MMAP_CLEARS 0
#endif
#endif


/*
   MMAP_AS_MORECORE_SIZE is the minimum mmap size argument to use if
   sbrk fails, and mmap is used as a backup (which is done only if
   HAVE_MMAP).  The value must be a multiple of page size.  This
   backup strategy generally applies only when systems have "holes" in
   address space, so sbrk cannot perform contiguous expansion, but
   there is still space available on system.  On systems for which
   this is known to be useful (i.e. most linux kernels), this occurs
   only when programs allocate huge amounts of memory.  Between this,
   and the fact that mmap regions tend to be limited, the size should
   be large, to avoid too many mmap calls and thus avoid running out
   of kernel resources.
*/

#ifndef MMAP_AS_MORECORE_SIZE
#define MMAP_AS_MORECORE_SIZE (1024 * 1024)
#endif

/*
  Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
  large blocks.  This is currently only possible on Linux with
  kernel versions newer than 1.3.77.
*/

#ifndef HAVE_MREMAP
#ifdef linux
#define HAVE_MREMAP 1
#else
#define HAVE_MREMAP 0
#endif

#endif /* HAVE_MMAP */

/* Define USE_ARENAS to enable support for multiple `arenas'.  These
   are allocated using mmap(), are necessary for threads and
   occasionally useful to overcome address space limitations affecting
   sbrk(). */

#ifndef USE_ARENAS
#define USE_ARENAS HAVE_MMAP
#endif


/*
  The system page size. To the extent possible, this malloc manages
  memory from the system in page-size units.  Note that this value is
  cached during initialization into a field of malloc_state. So even
  if malloc_getpagesize is a function, it is only called once.

  The following mechanics for getpagesize were adapted from bsd/gnu
  getpagesize.h. If none of the system-probes here apply, a value of
  4096 is used, which should be OK: If they don't apply, then using
  the actual value probably doesn't impact performance.
*/


#ifndef malloc_getpagesize

#ifndef LACKS_UNISTD_H
#  include <unistd.h>
#endif

#  ifdef _SC_PAGESIZE         /* some SVR4 systems omit an underscore */
#    ifndef _SC_PAGE_SIZE
#      define _SC_PAGE_SIZE _SC_PAGESIZE
#    endif
#  endif

#  ifdef _SC_PAGE_SIZE
#    define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
#  else
#    if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
       extern size_t getpagesize();
#      define malloc_getpagesize getpagesize()
#    else
#      ifdef WIN32 /* use supplied emulation of getpagesize */
#        define malloc_getpagesize getpagesize()
#      else
#        ifndef LACKS_SYS_PARAM_H
#          include <sys/param.h>
#        endif
#        ifdef EXEC_PAGESIZE
#          define malloc_getpagesize EXEC_PAGESIZE
#        else
#          ifdef NBPG
#            ifndef CLSIZE
#              define malloc_getpagesize NBPG
#            else
#              define malloc_getpagesize (NBPG * CLSIZE)
#            endif
#          else
#            ifdef NBPC
#              define malloc_getpagesize NBPC
#            else
#              ifdef PAGESIZE
#                define malloc_getpagesize PAGESIZE
#              else /* just guess */
#                define malloc_getpagesize (4096)
#              endif
#            endif
#          endif
#        endif
#      endif
#    endif
#  endif
#endif

/*
  This version of malloc supports the standard SVID/XPG mallinfo
  routine that returns a struct containing usage properties and
  statistics. It should work on any SVID/XPG compliant system that has
  a /usr/include/malloc.h defining struct mallinfo. (If you'd like to
  install such a thing yourself, cut out the preliminary declarations
  as described above and below and save them in a malloc.h file. But
  there's no compelling reason to bother to do this.)

  The main declaration needed is the mallinfo struct that is returned
  (by-copy) by mallinfo().  The SVID/XPG malloinfo struct contains a
  bunch of fields that are not even meaningful in this version of
  malloc.  These fields are are instead filled by mallinfo() with
  other numbers that might be of interest.

  HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
  /usr/include/malloc.h file that includes a declaration of struct
  mallinfo.  If so, it is included; else an SVID2/XPG2 compliant
  version is declared below.  These must be precisely the same for
  mallinfo() to work.  The original SVID version of this struct,
  defined on most systems with mallinfo, declares all fields as
  ints. But some others define as unsigned long. If your system
  defines the fields using a type of different width than listed here,
  you must #include your system version and #define
  HAVE_USR_INCLUDE_MALLOC_H.
*/

/* #define HAVE_USR_INCLUDE_MALLOC_H */

#ifdef HAVE_USR_INCLUDE_MALLOC_H
#include "/usr/include/malloc.h"
#endif


/* ---------- description of public routines ------------ */

/*
  malloc(size_t n)
  Returns a pointer to a newly allocated chunk of at least n bytes, or null
  if no space is available. Additionally, on failure, errno is
  set to ENOMEM on ANSI C systems.

  If n is zero, malloc returns a minumum-sized chunk. (The minimum
  size is 16 bytes on most 32bit systems, and 24 or 32 bytes on 64bit
  systems.)  On most systems, size_t is an unsigned type, so calls
  with negative arguments are interpreted as requests for huge amounts
  of space, which will often fail. The maximum supported value of n
  differs across systems, but is in all cases less than the maximum
  representable value of a size_t.
*/
#if __STD_C
Void_t*  public_mALLOc(size_t);
#else
Void_t*  public_mALLOc();
#endif
#ifdef libc_hidden_proto
libc_hidden_proto (public_mALLOc)
#endif

/*
  free(Void_t* p)
  Releases the chunk of memory pointed to by p, that had been previously
  allocated using malloc or a related routine such as realloc.
  It has no effect if p is null. It can have arbitrary (i.e., bad!)
  effects if p has already been freed.

  Unless disabled (using mallopt), freeing very large spaces will
  when possible, automatically trigger operations that give
  back unused memory to the system, thus reducing program footprint.
*/
#if __STD_C
void     public_fREe(Void_t*);
#else
void     public_fREe();
#endif
#ifdef libc_hidden_proto
libc_hidden_proto (public_fREe)
#endif

/*
  calloc(size_t n_elements, size_t element_size);
  Returns a pointer to n_elements * element_size bytes, with all locations
  set to zero.
*/
#if __STD_C
Void_t*  public_cALLOc(size_t, size_t);
#else
Void_t*  public_cALLOc();
#endif

/*
  realloc(Void_t* p, size_t n)
  Returns a pointer to a chunk of size n that contains the same data
  as does chunk p up to the minimum of (n, p's size) bytes, or null
  if no space is available.

  The returned pointer may or may not be the same as p. The algorithm
  prefers extending p when possible, otherwise it employs the
  equivalent of a malloc-copy-free sequence.

  If p is null, realloc is equivalent to malloc.

  If space is not available, realloc returns null, errno is set (if on
  ANSI) and p is NOT freed.

  if n is for fewer bytes than already held by p, the newly unused
  space is lopped off and freed if possible.  Unless the #define
  REALLOC_ZERO_BYTES_FREES is set, realloc with a size argument of
  zero (re)allocates a minimum-sized chunk.

  Large chunks that were internally obtained via mmap will always
  be reallocated using malloc-copy-free sequences unless
  the system supports MREMAP (currently only linux).

  The old unix realloc convention of allowing the last-free'd chunk
  to be used as an argument to realloc is not supported.
*/
#if __STD_C
Void_t*  public_rEALLOc(Void_t*, size_t);
#else
Void_t*  public_rEALLOc();
#endif
#ifdef libc_hidden_proto
libc_hidden_proto (public_rEALLOc)
#endif

/*
  memalign(size_t alignment, size_t n);
  Returns a pointer to a newly allocated chunk of n bytes, aligned
  in accord with the alignment argument.

  The alignment argument should be a power of two. If the argument is
  not a power of two, the nearest greater power is used.
  8-byte alignment is guaranteed by normal malloc calls, so don't
  bother calling memalign with an argument of 8 or less.

  Overreliance on memalign is a sure way to fragment space.
*/
#if __STD_C
Void_t*  public_mEMALIGn(size_t, size_t);
#else
Void_t*  public_mEMALIGn();
#endif
#ifdef libc_hidden_proto
libc_hidden_proto (public_mEMALIGn)
#endif

/*
  valloc(size_t n);
  Equivalent to memalign(pagesize, n), where pagesize is the page
  size of the system. If the pagesize is unknown, 4096 is used.
*/
#if __STD_C
Void_t*  public_vALLOc(size_t);
#else
Void_t*  public_vALLOc();
#endif



/*
  mallopt(int parameter_number, int parameter_value)
  Sets tunable parameters The format is to provide a
  (parameter-number, parameter-value) pair.  mallopt then sets the
  corresponding parameter to the argument value if it can (i.e., so
  long as the value is meaningful), and returns 1 if successful else
  0.  SVID/XPG/ANSI defines four standard param numbers for mallopt,
  normally defined in malloc.h.  Only one of these (M_MXFAST) is used
  in this malloc. The others (M_NLBLKS, M_GRAIN, M_KEEP) don't apply,
  so setting them has no effect. But this malloc also supports four
  other options in mallopt. See below for details.  Briefly, supported
  parameters are as follows (listed defaults are for "typical"
  configurations).

  Symbol            param #   default    allowed param values
  M_MXFAST          1         64         0-80  (0 disables fastbins)
  M_TRIM_THRESHOLD -1         128*1024   any   (-1U disables trimming)
  M_TOP_PAD        -2         0          any
  M_MMAP_THRESHOLD -3         128*1024   any   (or 0 if no MMAP support)
  M_MMAP_MAX       -4         65536      any   (0 disables use of mmap)
*/
#if __STD_C
int      public_mALLOPt(int, int);
#else
int      public_mALLOPt();
#endif


/*
  mallinfo()
  Returns (by copy) a struct containing various summary statistics:

  arena:     current total non-mmapped bytes allocated from system
  ordblks:   the number of free chunks
  smblks:    the number of fastbin blocks (i.e., small chunks that
               have been freed but not use resused or consolidated)
  hblks:     current number of mmapped regions
  hblkhd:    total bytes held in mmapped regions
  usmblks:   the maximum total allocated space. This will be greater
                than current total if trimming has occurred.
  fsmblks:   total bytes held in fastbin blocks
  uordblks:  current total allocated space (normal or mmapped)
  fordblks:  total free space
  keepcost:  the maximum number of bytes that could ideally be released
               back to system via malloc_trim. ("ideally" means that
               it ignores page restrictions etc.)

  Because these fields are ints, but internal bookkeeping may
  be kept as longs, the reported values may wrap around zero and
  thus be inaccurate.
*/
#if __STD_C
struct mallinfo public_mALLINFo(void);
#else
struct mallinfo public_mALLINFo();
#endif

#ifndef _LIBC
/*
  independent_calloc(size_t n_elements, size_t element_size, Void_t* chunks[]);

  independent_calloc is similar to calloc, but instead of returning a
  single cleared space, it returns an array of pointers to n_elements
  independent elements that can hold contents of size elem_size, each
  of which starts out cleared, and can be independently freed,
  realloc'ed etc. The elements are guaranteed to be adjacently
  allocated (this is not guaranteed to occur with multiple callocs or
  mallocs), which may also improve cache locality in some
  applications.

  The "chunks" argument is optional (i.e., may be null, which is
  probably the most typical usage). If it is null, the returned array
  is itself dynamically allocated and should also be freed when it is
  no longer needed. Otherwise, the chunks array must be of at least
  n_elements in length. It is filled in with the pointers to the
  chunks.

  In either case, independent_calloc returns this pointer array, or
  null if the allocation failed.  If n_elements is zero and "chunks"
  is null, it returns a chunk representing an array with zero elements
  (which should be freed if not wanted).

  Each element must be individually freed when it is no longer
  needed. If you'd like to instead be able to free all at once, you
  should instead use regular calloc and assign pointers into this
  space to represent elements.  (In this case though, you cannot
  independently free elements.)

  independent_calloc simplifies and speeds up implementations of many
  kinds of pools.  It may also be useful when constructing large data
  structures that initially have a fixed number of fixed-sized nodes,
  but the number is not known at compile time, and some of the nodes
  may later need to be freed. For example:

  struct Node { int item; struct Node* next; };

  struct Node* build_list() {
    struct Node** pool;
    int n = read_number_of_nodes_needed();
    if (n <= 0) return 0;
    pool = (struct Node**)(independent_calloc(n, sizeof(struct Node), 0);
    if (pool == 0) die();
    // organize into a linked list...
    struct Node* first = pool[0];
    for (i = 0; i < n-1; ++i)
      pool[i]->next = pool[i+1];
    free(pool);     // Can now free the array (or not, if it is needed later)
    return first;
  }
*/
#if __STD_C
Void_t** public_iCALLOc(size_t, size_t, Void_t**);
#else
Void_t** public_iCALLOc();
#endif

/*
  independent_comalloc(size_t n_elements, size_t sizes[], Void_t* chunks[]);

  independent_comalloc allocates, all at once, a set of n_elements
  chunks with sizes indicated in the "sizes" array.    It returns
  an array of pointers to these elements, each of which can be
  independently freed, realloc'ed etc. The elements are guaranteed to
  be adjacently allocated (this is not guaranteed to occur with
  multiple callocs or mallocs), which may also improve cache locality
  in some applications.

  The "chunks" argument is optional (i.e., may be null). If it is null
  the returned array is itself dynamically allocated and should also
  be freed when it is no longer needed. Otherwise, the chunks array
  must be of at least n_elements in length. It is filled in with the
  pointers to the chunks.

  In either case, independent_comalloc returns this pointer array, or
  null if the allocation failed.  If n_elements is zero and chunks is
  null, it returns a chunk representing an array with zero elements
  (which should be freed if not wanted).

  Each element must be individually freed when it is no longer
  needed. If you'd like to instead be able to free all at once, you
  should instead use a single regular malloc, and assign pointers at
  particular offsets in the aggregate space. (In this case though, you
  cannot independently free elements.)

  independent_comallac differs from independent_calloc in that each
  element may have a different size, and also that it does not
  automatically clear elements.

  independent_comalloc can be used to speed up allocation in cases
  where several structs or objects must always be allocated at the
  same time.  For example:

  struct Head { ... }
  struct Foot { ... }

  void send_message(char* msg) {
    int msglen = strlen(msg);
    size_t sizes[3] = { sizeof(struct Head), msglen, sizeof(struct Foot) };
    void* chunks[3];
    if (independent_comalloc(3, sizes, chunks) == 0)
      die();
    struct Head* head = (struct Head*)(chunks[0]);
    char*        body = (char*)(chunks[1]);
    struct Foot* foot = (struct Foot*)(chunks[2]);
    // ...
  }

  In general though, independent_comalloc is worth using only for
  larger values of n_elements. For small values, you probably won't
  detect enough difference from series of malloc calls to bother.

  Overuse of independent_comalloc can increase overall memory usage,
  since it cannot reuse existing noncontiguous small chunks that
  might be available for some of the elements.
*/
#if __STD_C
Void_t** public_iCOMALLOc(size_t, size_t*, Void_t**);
#else
Void_t** public_iCOMALLOc();
#endif

#endif /* _LIBC */


/*
  pvalloc(size_t n);
  Equivalent to valloc(minimum-page-that-holds(n)), that is,
  round up n to nearest pagesize.
 */
#if __STD_C
Void_t*  public_pVALLOc(size_t);
#else
Void_t*  public_pVALLOc();
#endif

/*
  cfree(Void_t* p);
  Equivalent to free(p).

  cfree is needed/defined on some systems that pair it with calloc,
  for odd historical reasons (such as: cfree is used in example
  code in the first edition of K&R).
*/
#if __STD_C
void     public_cFREe(Void_t*);
#else
void     public_cFREe();
#endif

/*
  malloc_trim(size_t pad);

  If possible, gives memory back to the system (via negative
  arguments to sbrk) if there is unused memory at the `high' end of
  the malloc pool. You can call this after freeing large blocks of
  memory to potentially reduce the system-level memory requirements
  of a program. However, it cannot guarantee to reduce memory. Under
  some allocation patterns, some large free blocks of memory will be
  locked between two used chunks, so they cannot be given back to
  the system.

  The `pad' argument to malloc_trim represents the amount of free
  trailing space to leave untrimmed. If this argument is zero,
  only the minimum amount of memory to maintain internal data
  structures will be left (one page or less). Non-zero arguments
  can be supplied to maintain enough trailing space to service
  future expected allocations without having to re-obtain memory
  from the system.

  Malloc_trim returns 1 if it actually released any memory, else 0.
  On systems that do not support "negative sbrks", it will always
  rreturn 0.
*/
#if __STD_C
int      public_mTRIm(size_t);
#else
int      public_mTRIm();
#endif

/*
  malloc_usable_size(Void_t* p);

  Returns the number of bytes you can actually use in
  an allocated chunk, which may be more than you requested (although
  often not) due to alignment and minimum size constraints.
  You can use this many bytes without worrying about
  overwriting other allocated objects. This is not a particularly great
  programming practice. malloc_usable_size can be more useful in
  debugging and assertions, for example:

  p = malloc(n);
  assert(malloc_usable_size(p) >= 256);

*/
#if __STD_C
size_t   public_mUSABLe(Void_t*);
#else
size_t   public_mUSABLe();
#endif

/*
  malloc_stats();
  Prints on stderr the amount of space obtained from the system (both
  via sbrk and mmap), the maximum amount (which may be more than
  current if malloc_trim and/or munmap got called), and the current
  number of bytes allocated via malloc (or realloc, etc) but not yet
  freed. Note that this is the number of bytes allocated, not the
  number requested. It will be larger than the number requested
  because of alignment and bookkeeping overhead. Because it includes
  alignment wastage as being in use, this figure may be greater than
  zero even when no user-level chunks are allocated.

  The reported current and maximum system memory can be inaccurate if
  a program makes other calls to system memory allocation functions
  (normally sbrk) outside of malloc.

  malloc_stats prints only the most commonly interesting statistics.
  More information can be obtained by calling mallinfo.

*/
#if __STD_C
void     public_mSTATs(void);
#else
void     public_mSTATs();
#endif

/*
  malloc_get_state(void);

  Returns the state of all malloc variables in an opaque data
  structure.
*/
#if __STD_C
Void_t*  public_gET_STATe(void);
#else
Void_t*  public_gET_STATe();
#endif

/*
  malloc_set_state(Void_t* state);

  Restore the state of all malloc variables from data obtained with
  malloc_get_state().
*/
#if __STD_C
int      public_sET_STATe(Void_t*);
#else
int      public_sET_STATe();
#endif

#ifdef _LIBC
/*
  posix_memalign(void **memptr, size_t alignment, size_t size);

  POSIX wrapper like memalign(), checking for validity of size.
*/
int      __posix_memalign(void **, size_t, size_t);
#endif

/* mallopt tuning options */

/*
  M_MXFAST is the maximum request size used for "fastbins", special bins
  that hold returned chunks without consolidating their spaces. This
  enables future requests for chunks of the same size to be handled
  very quickly, but can increase fragmentation, and thus increase the
  overall memory footprint of a program.

  This malloc manages fastbins very conservatively yet still
  efficiently, so fragmentation is rarely a problem for values less
  than or equal to the default.  The maximum supported value of MXFAST
  is 80. You wouldn't want it any higher than this anyway.  Fastbins
  are designed especially for use with many small structs, objects or
  strings -- the default handles structs/objects/arrays with sizes up
  to 8 4byte fields, or small strings representing words, tokens,
  etc. Using fastbins for larger objects normally worsens
  fragmentation without improving speed.

  M_MXFAST is set in REQUEST size units. It is internally used in
  chunksize units, which adds padding and alignment.  You can reduce
  M_MXFAST to 0 to disable all use of fastbins.  This causes the malloc
  algorithm to be a closer approximation of fifo-best-fit in all cases,
  not just for larger requests, but will generally cause it to be
  slower.
*/


/* M_MXFAST is a standard SVID/XPG tuning option, usually listed in malloc.h */
#ifndef M_MXFAST
#define M_MXFAST            1
#endif

#ifndef DEFAULT_MXFAST
#define DEFAULT_MXFAST     64
#endif


/*
  M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
  to keep before releasing via malloc_trim in free().

  Automatic trimming is mainly useful in long-lived programs.
  Because trimming via sbrk can be slow on some systems, and can
  sometimes be wasteful (in cases where programs immediately
  afterward allocate more large chunks) the value should be high
  enough so that your overall system performance would improve by
  releasing this much memory.

  The trim threshold and the mmap control parameters (see below)
  can be traded off with one another. Trimming and mmapping are
  two different ways of releasing unused memory back to the
  system. Between these two, it is often possible to keep
  system-level demands of a long-lived program down to a bare
  minimum. For example, in one test suite of sessions measuring
  the XF86 X server on Linux, using a trim threshold of 128K and a
  mmap threshold of 192K led to near-minimal long term resource
  consumption.

  If you are using this malloc in a long-lived program, it should
  pay to experiment with these values.  As a rough guide, you
  might set to a value close to the average size of a process
  (program) running on your system.  Releasing this much memory
  would allow such a process to run in memory.  Generally, it's
  worth it to tune for trimming rather tham memory mapping when a
  program undergoes phases where several large chunks are
  allocated and released in ways that can reuse each other's
  storage, perhaps mixed with phases where there are no such
  chunks at all.  And in well-behaved long-lived programs,
  controlling release of large blocks via trimming versus mapping
  is usually faster.

  However, in most programs, these parameters serve mainly as
  protection against the system-level effects of carrying around
  massive amounts of unneeded memory. Since frequent calls to
  sbrk, mmap, and munmap otherwise degrade performance, the default
  parameters are set to relatively high values that serve only as
  safeguards.

  The trim value It must be greater than page size to have any useful
  effect.  To disable trimming completely, you can set to
  (unsigned long)(-1)

  Trim settings interact with fastbin (MXFAST) settings: Unless
  TRIM_FASTBINS is defined, automatic trimming never takes place upon
  freeing a chunk with size less than or equal to MXFAST. Trimming is
  instead delayed until subsequent freeing of larger chunks. However,
  you can still force an attempted trim by calling malloc_trim.

  Also, trimming is not generally possible in cases where
  the main arena is obtained via mmap.

  Note that the trick some people use of mallocing a huge space and
  then freeing it at program startup, in an attempt to reserve system
  memory, doesn't have the intended effect under automatic trimming,
  since that memory will immediately be returned to the system.
*/

#define M_TRIM_THRESHOLD       -1

#ifndef DEFAULT_TRIM_THRESHOLD
#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
#endif

/*
  M_TOP_PAD is the amount of extra `padding' space to allocate or
  retain whenever sbrk is called. It is used in two ways internally:

  * When sbrk is called to extend the top of the arena to satisfy
  a new malloc request, this much padding is added to the sbrk
  request.

  * When malloc_trim is called automatically from free(),
  it is used as the `pad' argument.

  In both cases, the actual amount of padding is rounded
  so that the end of the arena is always a system page boundary.

  The main reason for using padding is to avoid calling sbrk so
  often. Having even a small pad greatly reduces the likelihood
  that nearly every malloc request during program start-up (or
  after trimming) will invoke sbrk, which needlessly wastes
  time.

  Automatic rounding-up to page-size units is normally sufficient
  to avoid measurable overhead, so the default is 0.  However, in
  systems where sbrk is relatively slow, it can pay to increase
  this value, at the expense of carrying around more memory than
  the program needs.
*/

#define M_TOP_PAD              -2

#ifndef DEFAULT_TOP_PAD
#define DEFAULT_TOP_PAD        (0)
#endif

/*
  MMAP_THRESHOLD_MAX and _MIN are the bounds on the dynamically
  adjusted MMAP_THRESHOLD.
*/

#ifndef DEFAULT_MMAP_THRESHOLD_MIN
#define DEFAULT_MMAP_THRESHOLD_MIN (128 * 1024)
#endif

#ifndef DEFAULT_MMAP_THRESHOLD_MAX
  /* For 32-bit platforms we cannot increase the maximum mmap
     threshold much because it is also the minimum value for the
     maximum heap size and its alignment.  Going above 512k (i.e., 1M
     for new heaps) wastes too much address space.  */
# if __WORDSIZE == 32
#  define DEFAULT_MMAP_THRESHOLD_MAX (512 * 1024)
# else
#  define DEFAULT_MMAP_THRESHOLD_MAX (4 * 1024 * 1024 * sizeof(long))
# endif
#endif

/*
  M_MMAP_THRESHOLD is the request size threshold for using mmap()
  to service a request. Requests of at least this size that cannot
  be allocated using already-existing space will be serviced via mmap.
  (If enough normal freed space already exists it is used instead.)

  Using mmap segregates relatively large chunks of memory so that
  they can be individually obtained and released from the host
  system. A request serviced through mmap is never reused by any
  other request (at least not directly; the system may just so
  happen to remap successive requests to the same locations).

  Segregating space in this way has the benefits that:

   1. Mmapped space can ALWAYS be individually released back
      to the system, which helps keep the system level memory
      demands of a long-lived program low.
   2. Mapped memory can never become `locked' between
      other chunks, as can happen with normally allocated chunks, which
      means that even trimming via malloc_trim would not release them.
   3. On some systems with "holes" in address spaces, mmap can obtain
      memory that sbrk cannot.

  However, it has the disadvantages that:

   1. The space cannot be reclaimed, consolidated, and then
      used to service later requests, as happens with normal chunks.
   2. It can lead to more wastage because of mmap page alignment
      requirements
   3. It causes malloc performance to be more dependent on host
      system memory management support routines which may vary in
      implementation quality and may impose arbitrary
      limitations. Generally, servicing a request via normal
      malloc steps is faster than going through a system's mmap.

  The advantages of mmap nearly always outweigh disadvantages for
  "large" chunks, but the value of "large" varies across systems.  The
  default is an empirically derived value that works well in most
  systems.


  Update in 2006:
  The above was written in 2001. Since then the world has changed a lot.
  Memory got bigger. Applications got bigger. The virtual address space
  layout in 32 bit linux changed.

  In the new situation, brk() and mmap space is shared and there are no
  artificial limits on brk size imposed by the kernel. What is more,
  applications have started using transient allocations larger than the
  128Kb as was imagined in 2001.

  The price for mmap is also high now; each time glibc mmaps from the
  kernel, the kernel is forced to zero out the memory it gives to the
  application. Zeroing memory is expensive and eats a lot of cache and
  memory bandwidth. This has nothing to do with the efficiency of the
  virtual memory system, by doing mmap the kernel just has no choice but
  to zero.

  In 2001, the kernel had a maximum size for brk() which was about 800
  megabytes on 32 bit x86, at that point brk() would hit the first
  mmaped shared libaries and couldn't expand anymore. With current 2.6
  kernels, the VA space layout is different and brk() and mmap
  both can span the entire heap at will.

  Rather than using a static threshold for the brk/mmap tradeoff,
  we are now using a simple dynamic one. The goal is still to avoid
  fragmentation. The old goals we kept are
  1) try to get the long lived large allocations to use mmap()
  2) really large allocations should always use mmap()
  and we're adding now:
  3) transient allocations should use brk() to avoid forcing the kernel
     having to zero memory over and over again

  The implementation works with a sliding threshold, which is by default
  limited to go between 128Kb and 32Mb (64Mb for 64 bitmachines) and starts
  out at 128Kb as per the 2001 default.

  This allows us to satisfy requirement 1) under the assumption that long
  lived allocations are made early in the process' lifespan, before it has
  started doing dynamic allocations of the same size (which will
  increase the threshold).

  The upperbound on the threshold satisfies requirement 2)

  The threshold goes up in value when the application frees memory that was
  allocated with the mmap allocator. The idea is that once the application
  starts freeing memory of a certain size, it's highly probable that this is
  a size the application uses for transient allocations. This estimator
  is there to satisfy the new third requirement.

*/

#define M_MMAP_THRESHOLD      -3

#ifndef DEFAULT_MMAP_THRESHOLD
#define DEFAULT_MMAP_THRESHOLD DEFAULT_MMAP_THRESHOLD_MIN
#endif

/*
  M_MMAP_MAX is the maximum number of requests to simultaneously
  service using mmap. This parameter exists because
  some systems have a limited number of internal tables for
  use by mmap, and using more than a few of them may degrade
  performance.

  The default is set to a value that serves only as a safeguard.
  Setting to 0 disables use of mmap for servicing large requests.  If
  HAVE_MMAP is not set, the default value is 0, and attempts to set it
  to non-zero values in mallopt will fail.
*/

#define M_MMAP_MAX             -4

#ifndef DEFAULT_MMAP_MAX
#if HAVE_MMAP
#define DEFAULT_MMAP_MAX       (65536)
#else
#define DEFAULT_MMAP_MAX       (0)
#endif
#endif

#ifdef __cplusplus
} /* end of extern "C" */
#endif

#include <malloc.h>

#ifndef BOUNDED_N
#define BOUNDED_N(ptr, sz) (ptr)
#endif
#ifndef RETURN_ADDRESS
#define RETURN_ADDRESS(X_) (NULL)
#endif

/* On some platforms we can compile internal, not exported functions better.
   Let the environment provide a macro and define it to be empty if it
   is not available.  */
#ifndef internal_function
# define internal_function
#endif

/* Forward declarations.  */
struct malloc_chunk;
typedef struct malloc_chunk* mchunkptr;

/* Internal routines.  */

#if __STD_C

Void_t*         _int_malloc(mstate, size_t);
void            _int_free(mstate, Void_t*);
Void_t*         _int_realloc(mstate, Void_t*, size_t);
Void_t*         _int_memalign(mstate, size_t, size_t);
Void_t*         _int_valloc(mstate, size_t);
static Void_t*  _int_pvalloc(mstate, size_t);
/*static Void_t*  cALLOc(size_t, size_t);*/
#ifndef _LIBC
static Void_t** _int_icalloc(mstate, size_t, size_t, Void_t**);
static Void_t** _int_icomalloc(mstate, size_t, size_t*, Void_t**);
#endif
static int      mTRIm(size_t);
static size_t   mUSABLe(Void_t*);
static void     mSTATs(void);
static int      mALLOPt(int, int);
static struct mallinfo mALLINFo(mstate);
static void malloc_printerr(int action, const char *str, void *ptr);

static Void_t* internal_function mem2mem_check(Void_t *p, size_t sz);
static int internal_function top_check(void);
static void internal_function munmap_chunk(mchunkptr p);
#if HAVE_MREMAP
static mchunkptr internal_function mremap_chunk(mchunkptr p, size_t new_size);
#endif

static Void_t*   malloc_check(size_t sz, const Void_t *caller);
static void      free_check(Void_t* mem, const Void_t *caller);
static Void_t*   realloc_check(Void_t* oldmem, size_t bytes,
                               const Void_t *caller);
static Void_t*   memalign_check(size_t alignment, size_t bytes,
                                const Void_t *caller);
#ifndef NO_THREADS
# ifdef _LIBC
#  if USE___THREAD || !defined SHARED
    /* These routines are never needed in this configuration.  */
#   define NO_STARTER
#  endif
# endif
# ifdef NO_STARTER
#  undef NO_STARTER
# else
static Void_t*   malloc_starter(size_t sz, const Void_t *caller);
static Void_t*   memalign_starter(size_t aln, size_t sz, const Void_t *caller);
static void      free_starter(Void_t* mem, const Void_t *caller);
# endif
static Void_t*   malloc_atfork(size_t sz, const Void_t *caller);
static void      free_atfork(Void_t* mem, const Void_t *caller);
#endif

#else

Void_t*         _int_malloc();
void            _int_free();
Void_t*         _int_realloc();
Void_t*         _int_memalign();
Void_t*         _int_valloc();
Void_t*         _int_pvalloc();
/*static Void_t*  cALLOc();*/
static Void_t** _int_icalloc();
static Void_t** _int_icomalloc();
static int      mTRIm();
static size_t   mUSABLe();
static void     mSTATs();
static int      mALLOPt();
static struct mallinfo mALLINFo();

#endif




/* ------------- Optional versions of memcopy ---------------- */


#if USE_MEMCPY

/*
  Note: memcpy is ONLY invoked with non-overlapping regions,
  so the (usually slower) memmove is not needed.
*/

#define MALLOC_COPY(dest, src, nbytes)  memcpy(dest, src, nbytes)
#define MALLOC_ZERO(dest, nbytes)       memset(dest, 0,   nbytes)

#else /* !USE_MEMCPY */

/* Use Duff's device for good zeroing/copying performance. */

#define MALLOC_ZERO(charp, nbytes)                                            \
do {                                                                          \
  INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp);                           \
  unsigned long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T);                     \
  long mcn;                                                                   \
  if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
  switch (mctmp) {                                                            \
    case 0: for(;;) { *mzp++ = 0;                                             \
    case 7:           *mzp++ = 0;                                             \
    case 6:           *mzp++ = 0;                                             \
    case 5:           *mzp++ = 0;                                             \
    case 4:           *mzp++ = 0;                                             \
    case 3:           *mzp++ = 0;                                             \
    case 2:           *mzp++ = 0;                                             \
    case 1:           *mzp++ = 0; if(mcn <= 0) break; mcn--; }                \
  }                                                                           \
} while(0)

#define MALLOC_COPY(dest,src,nbytes)                                          \
do {                                                                          \
  INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src;                            \
  INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest;                           \
  unsigned long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T);                     \
  long mcn;                                                                   \
  if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
  switch (mctmp) {                                                            \
    case 0: for(;;) { *mcdst++ = *mcsrc++;                                    \
    case 7:           *mcdst++ = *mcsrc++;                                    \
    case 6:           *mcdst++ = *mcsrc++;                                    \
    case 5:           *mcdst++ = *mcsrc++;                                    \
    case 4:           *mcdst++ = *mcsrc++;                                    \
    case 3:           *mcdst++ = *mcsrc++;                                    \
    case 2:           *mcdst++ = *mcsrc++;                                    \
    case 1:           *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; }       \
  }                                                                           \
} while(0)

#endif

/* ------------------ MMAP support ------------------  */


#if HAVE_MMAP

#include <fcntl.h>
#ifndef LACKS_SYS_MMAN_H
#include <sys/mman.h>
#endif

#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
# define MAP_ANONYMOUS MAP_ANON
#endif
#if !defined(MAP_FAILED)
# define MAP_FAILED ((char*)-1)
#endif

#ifndef MAP_NORESERVE
# ifdef MAP_AUTORESRV
#  define MAP_NORESERVE MAP_AUTORESRV
# else
#  define MAP_NORESERVE 0
# endif
#endif

/*
   Nearly all versions of mmap support MAP_ANONYMOUS,
   so the following is unlikely to be needed, but is
   supplied just in case.
*/

#ifndef MAP_ANONYMOUS

static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */

#define MMAP(addr, size, prot, flags) ((dev_zero_fd < 0) ? \
 (dev_zero_fd = open("/dev/zero", O_RDWR), \
  mmap((addr), (size), (prot), (flags), dev_zero_fd, 0)) : \
   mmap((addr), (size), (prot), (flags), dev_zero_fd, 0))

#else

#define MMAP(addr, size, prot, flags) \
 (mmap((addr), (size), (prot), (flags)|MAP_ANONYMOUS, -1, 0))

#endif


#endif /* HAVE_MMAP */


/*
  -----------------------  Chunk representations -----------------------
*/


/*
  This struct declaration is misleading (but accurate and necessary).
  It declares a "view" into memory allowing access to necessary
  fields at known offsets from a given base. See explanation below.
*/

struct malloc_chunk {

  INTERNAL_SIZE_T      prev_size;  /* Size of previous chunk (if free).  */
  INTERNAL_SIZE_T      size;       /* Size in bytes, including overhead. */

  struct malloc_chunk* fd;         /* double links -- used only if free. */
  struct malloc_chunk* bk;

  /* Only used for large blocks: pointer to next larger size.  */
  struct malloc_chunk* fd_nextsize; /* double links -- used only if free. */
  struct malloc_chunk* bk_nextsize;
};


/*
   malloc_chunk details:

    (The following includes lightly edited explanations by Colin Plumb.)

    Chunks of memory are maintained using a `boundary tag' method as
    described in e.g., Knuth or Standish.  (See the paper by Paul
    Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
    survey of such techniques.)  Sizes of free chunks are stored both
    in the front of each chunk and at the end.  This makes
    consolidating fragmented chunks into bigger chunks very fast.  The
    size fields also hold bits representing whether chunks are free or
    in use.

    An allocated chunk looks like this:


    chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |             Size of previous chunk, if allocated            | |
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |             Size of chunk, in bytes                       |M|P|
      mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |             User data starts here...                          .
            .                                                               .
            .             (malloc_usable_size() bytes)                      .
            .                                                               |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |             Size of chunk                                     |
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


    Where "chunk" is the front of the chunk for the purpose of most of
    the malloc code, but "mem" is the pointer that is returned to the
    user.  "Nextchunk" is the beginning of the next contiguous chunk.

    Chunks always begin on even word boundries, so the mem portion
    (which is returned to the user) is also on an even word boundary, and
    thus at least double-word aligned.

    Free chunks are stored in circular doubly-linked lists, and look like this:

    chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |             Size of previous chunk                            |
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    `head:' |             Size of chunk, in bytes                         |P|
      mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |             Forward pointer to next chunk in list             |
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |             Back pointer to previous chunk in list            |
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |             Unused space (may be 0 bytes long)                .
            .                                                               .
            .                                                               |
nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    `foot:' |             Size of chunk, in bytes                           |
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    The P (PREV_INUSE) bit, stored in the unused low-order bit of the
    chunk size (which is always a multiple of two words), is an in-use
    bit for the *previous* chunk.  If that bit is *clear*, then the
    word before the current chunk size contains the previous chunk
    size, and can be used to find the front of the previous chunk.
    The very first chunk allocated always has this bit set,
    preventing access to non-existent (or non-owned) memory. If
    prev_inuse is set for any given chunk, then you CANNOT determine
    the size of the previous chunk, and might even get a memory
    addressing fault when trying to do so.

    Note that the `foot' of the current chunk is actually represented
    as the prev_size of the NEXT chunk. This makes it easier to
    deal with alignments etc but can be very confusing when trying
    to extend or adapt this code.

    The two exceptions to all this are

     1. The special chunk `top' doesn't bother using the
        trailing size field since there is no next contiguous chunk
        that would have to index off it. After initialization, `top'
        is forced to always exist.  If it would become less than
        MINSIZE bytes long, it is replenished.

     2. Chunks allocated via mmap, which have the second-lowest-order
        bit M (IS_MMAPPED) set in their size fields.  Because they are
        allocated one-by-one, each must contain its own trailing size field.

*/

/*
  ---------- Size and alignment checks and conversions ----------
*/

/* conversion from malloc headers to user pointers, and back */

#define chunk2mem(p)   ((Void_t*)((char*)(p) + 2*SIZE_SZ))
#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))

/* The smallest possible chunk */
#define MIN_CHUNK_SIZE        (offsetof(struct malloc_chunk, fd_nextsize))

/* The smallest size we can malloc is an aligned minimal chunk */

#define MINSIZE  \
  (unsigned long)(((MIN_CHUNK_SIZE+MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK))

/* Check if m has acceptable alignment */

#define aligned_OK(m)  (((unsigned long)(m) & MALLOC_ALIGN_MASK) == 0)

#define misaligned_chunk(p) \
  ((uintptr_t)(MALLOC_ALIGNMENT == 2 * SIZE_SZ ? (p) : chunk2mem (p)) \
   & MALLOC_ALIGN_MASK)


/*
   Check if a request is so large that it would wrap around zero when
   padded and aligned. To simplify some other code, the bound is made
   low enough so that adding MINSIZE will also not wrap around zero.
*/

#define REQUEST_OUT_OF_RANGE(req)                                 \
  ((unsigned long)(req) >=                                        \
   (unsigned long)(INTERNAL_SIZE_T)(-2 * MINSIZE))

/* pad request bytes into a usable size -- internal version */

#define request2size(req)                                         \
  (((req) + SIZE_SZ + MALLOC_ALIGN_MASK < MINSIZE)  ?             \
   MINSIZE :                                                      \
   ((req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK)

/*  Same, except also perform argument check */

#define checked_request2size(req, sz)                             \
  if (REQUEST_OUT_OF_RANGE(req)) {                                \
    MALLOC_FAILURE_ACTION;                                        \
    return 0;                                                     \
  }                                                               \
  (sz) = request2size(req);

/*
  --------------- Physical chunk operations ---------------
*/


/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
#define PREV_INUSE 0x1

/* extract inuse bit of previous chunk */
#define prev_inuse(p)       ((p)->size & PREV_INUSE)


/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
#define IS_MMAPPED 0x2

/* check for mmap()'ed chunk */
#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)


/* size field is or'ed with NON_MAIN_ARENA if the chunk was obtained
   from a non-main arena.  This is only set immediately before handing
   the chunk to the user, if necessary.  */
#define NON_MAIN_ARENA 0x4

/* check for chunk from non-main arena */
#define chunk_non_main_arena(p) ((p)->size & NON_MAIN_ARENA)


/*
  Bits to mask off when extracting size

  Note: IS_MMAPPED is intentionally not masked off from size field in
  macros for which mmapped chunks should never be seen. This should
  cause helpful core dumps to occur if it is tried by accident by
  people extending or adapting this malloc.
*/
#define SIZE_BITS (PREV_INUSE|IS_MMAPPED|NON_MAIN_ARENA)

/* Get size, ignoring use bits */
#define chunksize(p)         ((p)->size & ~(SIZE_BITS))


/* Ptr to next physical malloc_chunk. */
#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~SIZE_BITS) ))

/* Ptr to previous physical malloc_chunk */
#define prev_chunk(p) ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))

/* Treat space at ptr + offset as a chunk */
#define chunk_at_offset(p, s)  ((mchunkptr)(((char*)(p)) + (s)))

/* extract p's inuse bit */
#define inuse(p)\
((((mchunkptr)(((char*)(p))+((p)->size & ~SIZE_BITS)))->size) & PREV_INUSE)

/* set/clear chunk as being inuse without otherwise disturbing */
#define set_inuse(p)\
((mchunkptr)(((char*)(p)) + ((p)->size & ~SIZE_BITS)))->size |= PREV_INUSE

#define clear_inuse(p)\
((mchunkptr)(((char*)(p)) + ((p)->size & ~SIZE_BITS)))->size &= ~(PREV_INUSE)


/* check/set/clear inuse bits in known places */
#define inuse_bit_at_offset(p, s)\
 (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)

#define set_inuse_bit_at_offset(p, s)\
 (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)

#define clear_inuse_bit_at_offset(p, s)\
 (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))


/* Set size at head, without disturbing its use bit */
#define set_head_size(p, s)  ((p)->size = (((p)->size & SIZE_BITS) | (s)))

/* Set size/use field */
#define set_head(p, s)       ((p)->size = (s))

/* Set size at footer (only when chunk is not in use) */
#define set_foot(p, s)       (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))


/*
  -------------------- Internal data structures --------------------

   All internal state is held in an instance of malloc_state defined
   below. There are no other static variables, except in two optional
   cases:
   * If USE_MALLOC_LOCK is defined, the mALLOC_MUTEx declared above.
   * If HAVE_MMAP is true, but mmap doesn't support
     MAP_ANONYMOUS, a dummy file descriptor for mmap.

   Beware of lots of tricks that minimize the total bookkeeping space
   requirements. The result is a little over 1K bytes (for 4byte
   pointers and size_t.)
*/

/*
  Bins

    An array of bin headers for free chunks. Each bin is doubly
    linked.  The bins are approximately proportionally (log) spaced.
    There are a lot of these bins (128). This may look excessive, but
    works very well in practice.  Most bins hold sizes that are
    unusual as malloc request sizes, but are more usual for fragments
    and consolidated sets of chunks, which is what these bins hold, so
    they can be found quickly.  All procedures maintain the invariant
    that no consolidated chunk physically borders another one, so each
    chunk in a list is known to be preceeded and followed by either
    inuse chunks or the ends of memory.

    Chunks in bins are kept in size order, with ties going to the
    approximately least recently used chunk. Ordering isn't needed
    for the small bins, which all contain the same-sized chunks, but
    facilitates best-fit allocation for larger chunks. These lists
    are just sequential. Keeping them in order almost never requires
    enough traversal to warrant using fancier ordered data
    structures.

    Chunks of the same size are linked with the most
    recently freed at the front, and allocations are taken from the
    back.  This results in LRU (FIFO) allocation order, which tends
    to give each chunk an equal opportunity to be consolidated with
    adjacent freed chunks, resulting in larger free chunks and less
    fragmentation.

    To simplify use in double-linked lists, each bin header acts
    as a malloc_chunk. This avoids special-casing for headers.
    But to conserve space and improve locality, we allocate
    only the fd/bk pointers of bins, and then use repositioning tricks
    to treat these as the fields of a malloc_chunk*.
*/

typedef struct malloc_chunk* mbinptr;

/* addressing -- note that bin_at(0) does not exist */
#define bin_at(m, i) \
  (mbinptr) (((char *) &((m)->bins[((i) - 1) * 2]))                           \
             - offsetof (struct malloc_chunk, fd))

/* analog of ++bin */
#define next_bin(b)  ((mbinptr)((char*)(b) + (sizeof(mchunkptr)<<1)))

/* Reminders about list directionality within bins */
#define first(b)     ((b)->fd)
#define last(b)      ((b)->bk)

/* Take a chunk off a bin list */
#define unlink(P, BK, FD) {                                            \
  FD = P->fd;                                                          \
  BK = P->bk;                                                          \
  if (__builtin_expect (FD->bk != P || BK->fd != P, 0))                \
    malloc_printerr (check_action, "corrupted double-linked list", P); \
  else {                                                               \
    FD->bk = BK;                                                       \
    BK->fd = FD;                                                       \
    if (!in_smallbin_range (P->size)                                   \
        && __builtin_expect (P->fd_nextsize != NULL, 0)) {             \
      assert (P->fd_nextsize->bk_nextsize == P);                       \
      assert (P->bk_nextsize->fd_nextsize == P);                       \
      if (FD->fd_nextsize == NULL) {                                   \
        if (P->fd_nextsize == P)                                       \
          FD->fd_nextsize = FD->bk_nextsize = FD;                      \
        else {                                                         \
          FD->fd_nextsize = P->fd_nextsize;                            \
          FD->bk_nextsize = P->bk_nextsize;                            \
          P->fd_nextsize->bk_nextsize = FD;                            \
          P->bk_nextsize->fd_nextsize = FD;                            \
        }                                                              \
      } else {                                                         \
        P->fd_nextsize->bk_nextsize = P->bk_nextsize;                  \
        P->bk_nextsize->fd_nextsize = P->fd_nextsize;                  \
      }                                                                \
    }                                                                  \
  }                                                                    \
}

/*
  Indexing

    Bins for sizes < 512 bytes contain chunks of all the same size, spaced
    8 bytes apart. Larger bins are approximately logarithmically spaced:

    64 bins of size       8
    32 bins of size      64
    16 bins of size     512
     8 bins of size    4096
     4 bins of size   32768
     2 bins of size  262144
     1 bin  of size what's left

    There is actually a little bit of slop in the numbers in bin_index
    for the sake of speed. This makes no difference elsewhere.

    The bins top out around 1MB because we expect to service large
    requests via mmap.
*/

#define NBINS             128
#define NSMALLBINS         64
#define SMALLBIN_WIDTH    MALLOC_ALIGNMENT
#define MIN_LARGE_SIZE    (NSMALLBINS * SMALLBIN_WIDTH)

#define in_smallbin_range(sz)  \
  ((unsigned long)(sz) < (unsigned long)MIN_LARGE_SIZE)

#define smallbin_index(sz) \
  (SMALLBIN_WIDTH == 16 ? (((unsigned)(sz)) >> 4) : (((unsigned)(sz)) >> 3))

#define largebin_index_32(sz)                                                \
(((((unsigned long)(sz)) >>  6) <= 38)?  56 + (((unsigned long)(sz)) >>  6): \
 ((((unsigned long)(sz)) >>  9) <= 20)?  91 + (((unsigned long)(sz)) >>  9): \
 ((((unsigned long)(sz)) >> 12) <= 10)? 110 + (((unsigned long)(sz)) >> 12): \
 ((((unsigned long)(sz)) >> 15) <=  4)? 119 + (((unsigned long)(sz)) >> 15): \
 ((((unsigned long)(sz)) >> 18) <=  2)? 124 + (((unsigned long)(sz)) >> 18): \
                                        126)

// XXX It remains to be seen whether it is good to keep the widths of
// XXX the buckets the same or whether it should be scaled by a factor
// XXX of two as well.
#define largebin_index_64(sz)                                                \
(((((unsigned long)(sz)) >>  6) <= 48)?  48 + (((unsigned long)(sz)) >>  6): \
 ((((unsigned long)(sz)) >>  9) <= 20)?  91 + (((unsigned long)(sz)) >>  9): \
 ((((unsigned long)(sz)) >> 12) <= 10)? 110 + (((unsigned long)(sz)) >> 12): \
 ((((unsigned long)(sz)) >> 15) <=  4)? 119 + (((unsigned long)(sz)) >> 15): \
 ((((unsigned long)(sz)) >> 18) <=  2)? 124 + (((unsigned long)(sz)) >> 18): \
                                        126)

#define largebin_index(sz) \
  (SIZE_SZ == 8 ? largebin_index_64 (sz) : largebin_index_32 (sz))

#define bin_index(sz) \
 ((in_smallbin_range(sz)) ? smallbin_index(sz) : largebin_index(sz))


/*
  Unsorted chunks

    All remainders from chunk splits, as well as all returned chunks,
    are first placed in the "unsorted" bin. They are then placed
    in regular bins after malloc gives them ONE chance to be used before
    binning. So, basically, the unsorted_chunks list acts as a queue,
    with chunks being placed on it in free (and malloc_consolidate),
    and taken off (to be either used or placed in bins) in malloc.

    The NON_MAIN_ARENA flag is never set for unsorted chunks, so it
    does not have to be taken into account in size comparisons.
*/

/* The otherwise unindexable 1-bin is used to hold unsorted chunks. */
#define unsorted_chunks(M)          (bin_at(M, 1))

/*
  Top

    The top-most available chunk (i.e., the one bordering the end of
    available memory) is treated specially. It is never included in
    any bin, is used only if no other chunk is available, and is
    released back to the system if it is very large (see
    M_TRIM_THRESHOLD).  Because top initially
    points to its own bin with initial zero size, thus forcing
    extension on the first malloc request, we avoid having any special
    code in malloc to check whether it even exists yet. But we still
    need to do so when getting memory from system, so we make
    initial_top treat the bin as a legal but unusable chunk during the
    interval between initialization and the first call to
    sYSMALLOc. (This is somewhat delicate, since it relies on
    the 2 preceding words to be zero during this interval as well.)
*/

/* Conveniently, the unsorted bin can be used as dummy top on first call */
#define initial_top(M)              (unsorted_chunks(M))

/*
  Binmap

    To help compensate for the large number of bins, a one-level index
    structure is used for bin-by-bin searching.  `binmap' is a
    bitvector recording whether bins are definitely empty so they can
    be skipped over during during traversals.  The bits are NOT always
    cleared as soon as bins are empty, but instead only
    when they are noticed to be empty during traversal in malloc.
*/

/* Conservatively use 32 bits per map word, even if on 64bit system */
#define BINMAPSHIFT      5
#define BITSPERMAP       (1U << BINMAPSHIFT)
#define BINMAPSIZE       (NBINS / BITSPERMAP)

#define idx2block(i)     ((i) >> BINMAPSHIFT)
#define idx2bit(i)       ((1U << ((i) & ((1U << BINMAPSHIFT)-1))))

#define mark_bin(m,i)    ((m)->binmap[idx2block(i)] |=  idx2bit(i))
#define unmark_bin(m,i)  ((m)->binmap[idx2block(i)] &= ~(idx2bit(i)))
#define get_binmap(m,i)  ((m)->binmap[idx2block(i)] &   idx2bit(i))

/*
  Fastbins

    An array of lists holding recently freed small chunks.  Fastbins
    are not doubly linked.  It is faster to single-link them, and
    since chunks are never removed from the middles of these lists,
    double linking is not necessary. Also, unlike regular bins, they
    are not even processed in FIFO order (they use faster LIFO) since
    ordering doesn't much matter in the transient contexts in which
    fastbins are normally used.

    Chunks in fastbins keep their inuse bit set, so they cannot
    be consolidated with other free chunks. malloc_consolidate
    releases all chunks in fastbins and consolidates them with
    other free chunks.
*/

typedef struct malloc_chunk* mfastbinptr;

/* offset 2 to use otherwise unindexable first 2 bins */
#define fastbin_index(sz)        ((((unsigned int)(sz)) >> 3) - 2)

/* The maximum fastbin request size we support */
#define MAX_FAST_SIZE     80

#define NFASTBINS  (fastbin_index(request2size(MAX_FAST_SIZE))+1)

/*
  FASTBIN_CONSOLIDATION_THRESHOLD is the size of a chunk in free()
  that triggers automatic consolidation of possibly-surrounding
  fastbin chunks. This is a heuristic, so the exact value should not
  matter too much. It is defined at half the default trim threshold as a
  compromise heuristic to only attempt consolidation if it is likely
  to lead to trimming. However, it is not dynamically tunable, since
  consolidation reduces fragmentation surrounding large chunks even
  if trimming is not used.
*/

#define FASTBIN_CONSOLIDATION_THRESHOLD  (65536UL)

/*
  Since the lowest 2 bits in max_fast don't matter in size comparisons,
  they are used as flags.
*/

/*
  FASTCHUNKS_BIT held in max_fast indicates that there are probably
  some fastbin chunks. It is set true on entering a chunk into any
  fastbin, and cleared only in malloc_consolidate.

  The truth value is inverted so that have_fastchunks will be true
  upon startup (since statics are zero-filled), simplifying
  initialization checks.
*/

#define FASTCHUNKS_BIT        (1U)

#define have_fastchunks(M)     (((M)->flags &  FASTCHUNKS_BIT) == 0)
#define clear_fastchunks(M)    ((M)->flags |=  FASTCHUNKS_BIT)
#define set_fastchunks(M)      ((M)->flags &= ~FASTCHUNKS_BIT)

/*
  NONCONTIGUOUS_BIT indicates that MORECORE does not return contiguous
  regions.  Otherwise, contiguity is exploited in merging together,
  when possible, results from consecutive MORECORE calls.

  The initial value comes from MORECORE_CONTIGUOUS, but is
  changed dynamically if mmap is ever used as an sbrk substitute.
*/

#define NONCONTIGUOUS_BIT     (2U)

#define contiguous(M)          (((M)->flags &  NONCONTIGUOUS_BIT) == 0)
#define noncontiguous(M)       (((M)->flags &  NONCONTIGUOUS_BIT) != 0)
#define set_noncontiguous(M)   ((M)->flags |=  NONCONTIGUOUS_BIT)
#define set_contiguous(M)      ((M)->flags &= ~NONCONTIGUOUS_BIT)

/*
   Set value of max_fast.
   Use impossibly small value if 0.
   Precondition: there are no existing fastbin chunks.
   Setting the value clears fastchunk bit but preserves noncontiguous bit.
*/

#define set_max_fast(s) \
  global_max_fast = ((s) == 0)? SMALLBIN_WIDTH: request2size(s)
#define get_max_fast() global_max_fast


/*
   ----------- Internal state representation and initialization -----------
*/

struct malloc_state {
  /* Serialize access.  */
  mutex_t mutex;

  /* Flags (formerly in max_fast).  */
  int flags;

#if THREAD_STATS
  /* Statistics for locking.  Only used if THREAD_STATS is defined.  */
  long stat_lock_direct, stat_lock_loop, stat_lock_wait;
#endif

  /* Fastbins */
  mfastbinptr      fastbins[NFASTBINS];

  /* Base of the topmost chunk -- not otherwise kept in a bin */
  mchunkptr        top;

  /* The remainder from the most recent split of a small request */
  mchunkptr        last_remainder;

  /* Normal bins packed as described above */
  mchunkptr        bins[NBINS * 2 - 2];

  /* Bitmap of bins */
  unsigned int     binmap[BINMAPSIZE];

  /* Linked list */
  struct malloc_state *next;

  /* Memory allocated from the system in this arena.  */
  INTERNAL_SIZE_T system_mem;
  INTERNAL_SIZE_T max_system_mem;
};

struct malloc_par {
  /* Tunable parameters */
  unsigned long    trim_threshold;
  INTERNAL_SIZE_T  top_pad;
  INTERNAL_SIZE_T  mmap_threshold;

  /* Memory map support */
  int              n_mmaps;
  int              n_mmaps_max;
  int              max_n_mmaps;
  /* the mmap_threshold is dynamic, until the user sets
     it manually, at which point we need to disable any
     dynamic behavior. */
  int              no_dyn_threshold;

  /* Cache malloc_getpagesize */
  unsigned int     pagesize;

  /* Statistics */
  INTERNAL_SIZE_T  mmapped_mem;
  /*INTERNAL_SIZE_T  sbrked_mem;*/
  /*INTERNAL_SIZE_T  max_sbrked_mem;*/
  INTERNAL_SIZE_T  max_mmapped_mem;
  INTERNAL_SIZE_T  max_total_mem; /* only kept for NO_THREADS */

  /* First address handed out by MORECORE/sbrk.  */
  char*            sbrk_base;
};

/* There are several instances of this struct ("arenas") in this
   malloc.  If you are adapting this malloc in a way that does NOT use
   a static or mmapped malloc_state, you MUST explicitly zero-fill it
   before using. This malloc relies on the property that malloc_state
   is initialized to all zeroes (as is true of C statics).  */

static struct malloc_state main_arena;

/* There is only one instance of the malloc parameters.  */

static struct malloc_par mp_;


/* Maximum size of memory handled in fastbins.  */
static INTERNAL_SIZE_T global_max_fast;

/*
  Initialize a malloc_state struct.

  This is called only from within malloc_consolidate, which needs
  be called in the same contexts anyway.  It is never called directly
  outside of malloc_consolidate because some optimizing compilers try
  to inline it at all call points, which turns out not to be an
  optimization at all. (Inlining it in malloc_consolidate is fine though.)
*/

#if __STD_C
static void malloc_init_state(mstate av)
#else
static void malloc_init_state(av) mstate av;
#endif
{
  int     i;
  mbinptr bin;

  /* Establish circular links for normal bins */
  for (i = 1; i < NBINS; ++i) {
    bin = bin_at(av,i);
    bin->fd = bin->bk = bin;
  }

#if MORECORE_CONTIGUOUS
  if (av != &main_arena)
#endif
    set_noncontiguous(av);
  if (av == &main_arena)
    set_max_fast(DEFAULT_MXFAST);
  av->flags |= FASTCHUNKS_BIT;

  av->top            = initial_top(av);
}

/*
   Other internal utilities operating on mstates
*/

#if __STD_C
static Void_t*  sYSMALLOc(INTERNAL_SIZE_T, mstate);
static int      sYSTRIm(size_t, mstate);
static void     malloc_consolidate(mstate);
#ifndef _LIBC
static Void_t** iALLOc(mstate, size_t, size_t*, int, Void_t**);
#endif
#else
static Void_t*  sYSMALLOc();
static int      sYSTRIm();
static void     malloc_consolidate();
static Void_t** iALLOc();
#endif


/* -------------- Early definitions for debugging hooks ---------------- */

/* Define and initialize the hook variables.  These weak definitions must
   appear before any use of the variables in a function (arena.c uses one).  */
#ifndef weak_variable
#ifndef _LIBC
#define weak_variable /**/
#else
/* In GNU libc we want the hook variables to be weak definitions to
   avoid a problem with Emacs.  */
#define weak_variable weak_function
#endif
#endif

/* Forward declarations.  */
static Void_t* malloc_hook_ini __MALLOC_P ((size_t sz,
                                            const __malloc_ptr_t caller));
static Void_t* realloc_hook_ini __MALLOC_P ((Void_t* ptr, size_t sz,
                                             const __malloc_ptr_t caller));
static Void_t* memalign_hook_ini __MALLOC_P ((size_t alignment, size_t sz,
                                              const __malloc_ptr_t caller));

void weak_variable (*__malloc_initialize_hook) (void) = NULL;
void weak_variable (*__free_hook) (__malloc_ptr_t __ptr,
                                   const __malloc_ptr_t) = NULL;
__malloc_ptr_t weak_variable (*__malloc_hook)
     (size_t __size, const __malloc_ptr_t) = malloc_hook_ini;
__malloc_ptr_t weak_variable (*__realloc_hook)
     (__malloc_ptr_t __ptr, size_t __size, const __malloc_ptr_t)
     = realloc_hook_ini;
__malloc_ptr_t weak_variable (*__memalign_hook)
     (size_t __alignment, size_t __size, const __malloc_ptr_t)
     = memalign_hook_ini;
void weak_variable (*__after_morecore_hook) (void) = NULL;


/* ---------------- Error behavior ------------------------------------ */

#ifndef DEFAULT_CHECK_ACTION
#define DEFAULT_CHECK_ACTION 3
#endif

static int check_action = DEFAULT_CHECK_ACTION;


/* ------------------ Testing support ----------------------------------*/

static int perturb_byte;

#define alloc_perturb(p, n) memset (p, (perturb_byte ^ 0xff) & 0xff, n)
#define free_perturb(p, n) memset (p, perturb_byte & 0xff, n)


/* ------------------- Support for multiple arenas -------------------- */
#include "arena.c"

/*
  Debugging support

  These routines make a number of assertions about the states
  of data structures that should be true at all times. If any
  are not true, it's very likely that a user program has somehow
  trashed memory. (It's also possible that there is a coding error
  in malloc. In which case, please report it!)
*/

#if ! MALLOC_DEBUG

#define check_chunk(A,P)
#define check_free_chunk(A,P)
#define check_inuse_chunk(A,P)
#define check_remalloced_chunk(A,P,N)
#define check_malloced_chunk(A,P,N)
#define check_malloc_state(A)

#else

#define check_chunk(A,P)              do_check_chunk(A,P)
#define check_free_chunk(A,P)         do_check_free_chunk(A,P)
#define check_inuse_chunk(A,P)        do_check_inuse_chunk(A,P)
#define check_remalloced_chunk(A,P,N) do_check_remalloced_chunk(A,P,N)
#define check_malloced_chunk(A,P,N)   do_check_malloced_chunk(A,P,N)
#define check_malloc_state(A)         do_check_malloc_state(A)

/*
  Properties of all chunks
*/

#if __STD_C
static void do_check_chunk(mstate av, mchunkptr p)
#else
static void do_check_chunk(av, p) mstate av; mchunkptr p;
#endif
{
  unsigned long sz = chunksize(p);
  /* min and max possible addresses assuming contiguous allocation */
  char* max_address = (char*)(av->top) + chunksize(av->top);
  char* min_address = max_address - av->system_mem;

  if (!chunk_is_mmapped(p)) {

    /* Has legal address ... */
    if (p != av->top) {
      if (contiguous(av)) {
        assert(((char*)p) >= min_address);
        assert(((char*)p + sz) <= ((char*)(av->top)));
      }
    }
    else {
      /* top size is always at least MINSIZE */
      assert((unsigned long)(sz) >= MINSIZE);
      /* top predecessor always marked inuse */
      assert(prev_inuse(p));
    }

  }
  else {
#if HAVE_MMAP
    /* address is outside main heap  */
    if (contiguous(av) && av->top != initial_top(av)) {
      assert(((char*)p) < min_address || ((char*)p) >= max_address);
    }
    /* chunk is page-aligned */
    assert(((p->prev_size + sz) & (mp_.pagesize-1)) == 0);
    /* mem is aligned */
    assert(aligned_OK(chunk2mem(p)));
#else
    /* force an appropriate assert violation if debug set */
    assert(!chunk_is_mmapped(p));
#endif
  }
}

/*
  Properties of free chunks
*/

#if __STD_C
static void do_check_free_chunk(mstate av, mchunkptr p)
#else
static void do_check_free_chunk(av, p) mstate av; mchunkptr p;
#endif
{
  INTERNAL_SIZE_T sz = p->size & ~(PREV_INUSE|NON_MAIN_ARENA);
  mchunkptr next = chunk_at_offset(p, sz);

  do_check_chunk(av, p);

  /* Chunk must claim to be free ... */
  assert(!inuse(p));
  assert (!chunk_is_mmapped(p));

  /* Unless a special marker, must have OK fields */
  if ((unsigned long)(sz) >= MINSIZE)
  {
    assert((sz & MALLOC_ALIGN_MASK) == 0);
    assert(aligned_OK(chunk2mem(p)));
    /* ... matching footer field */
    assert(next->prev_size == sz);
    /* ... and is fully consolidated */
    assert(prev_inuse(p));
    assert (next == av->top || inuse(next));

    /* ... and has minimally sane links */
    assert(p->fd->bk == p);
    assert(p->bk->fd == p);
  }
  else /* markers are always of size SIZE_SZ */
    assert(sz == SIZE_SZ);
}

/*
  Properties of inuse chunks
*/

#if __STD_C
static void do_check_inuse_chunk(mstate av, mchunkptr p)
#else
static void do_check_inuse_chunk(av, p) mstate av; mchunkptr p;
#endif
{
  mchunkptr next;

  do_check_chunk(av, p);

  if (chunk_is_mmapped(p))
    return; /* mmapped chunks have no next/prev */

  /* Check whether it claims to be in use ... */
  assert(inuse(p));

  next = next_chunk(p);

  /* ... and is surrounded by OK chunks.
    Since more things can be checked with free chunks than inuse ones,
    if an inuse chunk borders them and debug is on, it's worth doing them.
  */
  if (!prev_inuse(p))  {
    /* Note that we cannot even look at prev unless it is not inuse */
    mchunkptr prv = prev_chunk(p);
    assert(next_chunk(prv) == p);
    do_check_free_chunk(av, prv);
  }

  if (next == av->top) {
    assert(prev_inuse(next));
    assert(chunksize(next) >= MINSIZE);
  }
  else if (!inuse(next))
    do_check_free_chunk(av, next);
}

/*
  Properties of chunks recycled from fastbins
*/

#if __STD_C
static void do_check_remalloced_chunk(mstate av, mchunkptr p, INTERNAL_SIZE_T s)
#else
static void do_check_remalloced_chunk(av, p, s)
mstate av; mchunkptr p; INTERNAL_SIZE_T s;
#endif
{
  INTERNAL_SIZE_T sz = p->size & ~(PREV_INUSE|NON_MAIN_ARENA);

  if (!chunk_is_mmapped(p)) {
    assert(av == arena_for_chunk(p));
    if (chunk_non_main_arena(p))
      assert(av != &main_arena);
    else
      assert(av == &main_arena);
  }

  do_check_inuse_chunk(av, p);

  /* Legal size ... */
  assert((sz & MALLOC_ALIGN_MASK) == 0);
  assert((unsigned long)(sz) >= MINSIZE);
  /* ... and alignment */
  assert(aligned_OK(chunk2mem(p)));
  /* chunk is less than MINSIZE more than request */
  assert((long)(sz) - (long)(s) >= 0);
  assert((long)(sz) - (long)(s + MINSIZE) < 0);
}

/*
  Properties of nonrecycled chunks at the point they are malloced
*/

#if __STD_C
static void do_check_malloced_chunk(mstate av, mchunkptr p, INTERNAL_SIZE_T s)
#else
static void do_check_malloced_chunk(av, p, s)
mstate av; mchunkptr p; INTERNAL_SIZE_T s;
#endif
{
  /* same as recycled case ... */
  do_check_remalloced_chunk(av, p, s);

  /*
    ... plus,  must obey implementation invariant that prev_inuse is
    always true of any allocated chunk; i.e., that each allocated
    chunk borders either a previously allocated and still in-use
    chunk, or the base of its memory arena. This is ensured
    by making all allocations from the the `lowest' part of any found
    chunk.  This does not necessarily hold however for chunks
    recycled via fastbins.
  */

  assert(prev_inuse(p));
}


/*
  Properties of malloc_state.

  This may be useful for debugging malloc, as well as detecting user
  programmer errors that somehow write into malloc_state.

  If you are extending or experimenting with this malloc, you can
  probably figure out how to hack this routine to print out or
  display chunk addresses, sizes, bins, and other instrumentation.
*/

static void do_check_malloc_state(mstate av)
{
  int i;
  mchunkptr p;
  mchunkptr q;
  mbinptr b;
  unsigned int binbit;
  int empty;
  unsigned int idx;
  INTERNAL_SIZE_T size;
  unsigned long total = 0;
  int max_fast_bin;

  /* internal size_t must be no wider than pointer type */
  assert(sizeof(INTERNAL_SIZE_T) <= sizeof(char*));

  /* alignment is a power of 2 */
  assert((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT-1)) == 0);

  /* cannot run remaining checks until fully initialized */
  if (av->top == 0 || av->top == initial_top(av))
    return;

  /* pagesize is a power of 2 */
  assert((mp_.pagesize & (mp_.pagesize-1)) == 0);

  /* A contiguous main_arena is consistent with sbrk_base.  */
  if (av == &main_arena && contiguous(av))
    assert((char*)mp_.sbrk_base + av->system_mem ==
           (char*)av->top + chunksize(av->top));

  /* properties of fastbins */

  /* max_fast is in allowed range */
  assert((get_max_fast () & ~1) <= request2size(MAX_FAST_SIZE));

  max_fast_bin = fastbin_index(get_max_fast ());

  for (i = 0; i < NFASTBINS; ++i) {
    p = av->fastbins[i];

    /* The following test can only be performed for the main arena.
       While mallopt calls malloc_consolidate to get rid of all fast
       bins (especially those larger than the new maximum) this does
       only happen for the main arena.  Trying to do this for any
       other arena would mean those arenas have to be locked and
       malloc_consolidate be called for them.  This is excessive.  And
       even if this is acceptable to somebody it still cannot solve
       the problem completely since if the arena is locked a
       concurrent malloc call might create a new arena which then
       could use the newly invalid fast bins.  */

    /* all bins past max_fast are empty */
    if (av == &main_arena && i > max_fast_bin)
      assert(p == 0);

    while (p != 0) {
      /* each chunk claims to be inuse */
      do_check_inuse_chunk(av, p);
      total += chunksize(p);
      /* chunk belongs in this bin */
      assert(fastbin_index(chunksize(p)) == i);
      p = p->fd;
    }
  }

  if (total != 0)
    assert(have_fastchunks(av));
  else if (!have_fastchunks(av))
    assert(total == 0);

  /* check normal bins */
  for (i = 1; i < NBINS; ++i) {
    b = bin_at(av,i);

    /* binmap is accurate (except for bin 1 == unsorted_chunks) */
    if (i >= 2) {
      binbit = get_binmap(av,i);
      empty = last(b) == b;
      if (!binbit)
        assert(empty);
      else if (!empty)
        assert(binbit);
    }

    for (p = last(b); p != b; p = p->bk) {
      /* each chunk claims to be free */
      do_check_free_chunk(av, p);
      size = chunksize(p);
      total += size;
      if (i >= 2) {
        /* chunk belongs in bin */
        idx = bin_index(size);
        assert(idx == i);
        /* lists are sorted */
        assert(p->bk == b ||
               (unsigned long)chunksize(p->bk) >= (unsigned long)chunksize(p));

        if (!in_smallbin_range(size))
          {
            if (p->fd_nextsize != NULL)
              {
                if (p->fd_nextsize == p)
                  assert (p->bk_nextsize == p);
                else
                  {
                    if (p->fd_nextsize == first (b))
                      assert (chunksize (p) < chunksize (p->fd_nextsize));
                    else
                      assert (chunksize (p) > chunksize (p->fd_nextsize));

                    if (p == first (b))
                      assert (chunksize (p) > chunksize (p->bk_nextsize));
                    else
                      assert (chunksize (p) < chunksize (p->bk_nextsize));
                  }
              }
            else
              assert (p->bk_nextsize == NULL);
          }
      } else if (!in_smallbin_range(size))
        assert (p->fd_nextsize == NULL && p->bk_nextsize == NULL);
      /* chunk is followed by a legal chain of inuse chunks */
      for (q = next_chunk(p);
           (q != av->top && inuse(q) &&
             (unsigned long)(chunksize(q)) >= MINSIZE);
           q = next_chunk(q))
        do_check_inuse_chunk(av, q);
    }
  }

  /* top chunk is OK */
  check_chunk(av, av->top);

  /* sanity checks for statistics */

#ifdef NO_THREADS
  assert(total <= (unsigned long)(mp_.max_total_mem));
  assert(mp_.n_mmaps >= 0);
#endif
  assert(mp_.n_mmaps <= mp_.max_n_mmaps);

  assert((unsigned long)(av->system_mem) <=
         (unsigned long)(av->max_system_mem));

  assert((unsigned long)(mp_.mmapped_mem) <=
         (unsigned long)(mp_.max_mmapped_mem));

#ifdef NO_THREADS
  assert((unsigned long)(mp_.max_total_mem) >=
         (unsigned long)(mp_.mmapped_mem) + (unsigned long)(av->system_mem));
#endif
}
#endif


/* ----------------- Support for debugging hooks -------------------- */
#include "hooks.c"


/* ----------- Routines dealing with system allocation -------------- */

/*
  sysmalloc handles malloc cases requiring more memory from the system.
  On entry, it is assumed that av->top does not have enough
  space to service request for nb bytes, thus requiring that av->top
  be extended or replaced.
*/

#if __STD_C
static Void_t* sYSMALLOc(INTERNAL_SIZE_T nb, mstate av)
#else
static Void_t* sYSMALLOc(nb, av) INTERNAL_SIZE_T nb; mstate av;
#endif
{
  mchunkptr       old_top;        /* incoming value of av->top */
  INTERNAL_SIZE_T old_size;       /* its size */
  char*           old_end;        /* its end address */

  long            size;           /* arg to first MORECORE or mmap call */
  char*           brk;            /* return value from MORECORE */

  long            correction;     /* arg to 2nd MORECORE call */
  char*           snd_brk;        /* 2nd return val */

  INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of new space */
  INTERNAL_SIZE_T end_misalign;   /* partial page left at end of new space */
  char*           aligned_brk;    /* aligned offset into brk */

  mchunkptr       p;              /* the allocated/returned chunk */
  mchunkptr       remainder;      /* remainder from allocation */
  unsigned long   remainder_size; /* its size */

  unsigned long   sum;            /* for updating stats */

  size_t          pagemask  = mp_.pagesize - 1;
  bool            tried_mmap = false;


#if HAVE_MMAP

  /*
    If have mmap, and the request size meets the mmap threshold, and
    the system supports mmap, and there are few enough currently
    allocated mmapped regions, try to directly map this request
    rather than expanding top.
  */

  if ((unsigned long)(nb) >= (unsigned long)(mp_.mmap_threshold) &&
      (mp_.n_mmaps < mp_.n_mmaps_max)) {

    char* mm;             /* return value from mmap call*/

  try_mmap:
    /*
      Round up size to nearest page.  For mmapped chunks, the overhead
      is one SIZE_SZ unit larger than for normal chunks, because there
      is no following chunk whose prev_size field could be used.
    */
#if 1
    /* See the front_misalign handling below, for glibc there is no
       need for further alignments.  */
    size = (nb + SIZE_SZ + pagemask) & ~pagemask;
#else
    size = (nb + SIZE_SZ + MALLOC_ALIGN_MASK + pagemask) & ~pagemask;
#endif
    tried_mmap = true;

    /* Don't try if size wraps around 0 */
    if ((unsigned long)(size) > (unsigned long)(nb)) {

      mm = (char*)(MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE));

      if (mm != MAP_FAILED) {

        /*
          The offset to the start of the mmapped region is stored
          in the prev_size field of the chunk. This allows us to adjust
          returned start address to meet alignment requirements here
          and in memalign(), and still be able to compute proper
          address argument for later munmap in free() and realloc().
        */

#if 1
        /* For glibc, chunk2mem increases the address by 2*SIZE_SZ and
           MALLOC_ALIGN_MASK is 2*SIZE_SZ-1.  Each mmap'ed area is page
           aligned and therefore definitely MALLOC_ALIGN_MASK-aligned.  */
        assert (((INTERNAL_SIZE_T)chunk2mem(mm) & MALLOC_ALIGN_MASK) == 0);
#else
        front_misalign = (INTERNAL_SIZE_T)chunk2mem(mm) & MALLOC_ALIGN_MASK;
        if (front_misalign > 0) {
          correction = MALLOC_ALIGNMENT - front_misalign;
          p = (mchunkptr)(mm + correction);
          p->prev_size = correction;
          set_head(p, (size - correction) |IS_MMAPPED);
        }
        else
#endif
          {
            p = (mchunkptr)mm;
            set_head(p, size|IS_MMAPPED);
          }

        /* update statistics */

        if (++mp_.n_mmaps > mp_.max_n_mmaps)
          mp_.max_n_mmaps = mp_.n_mmaps;

        sum = mp_.mmapped_mem += size;
        if (sum > (unsigned long)(mp_.max_mmapped_mem))
          mp_.max_mmapped_mem = sum;
#ifdef NO_THREADS
        sum += av->system_mem;
        if (sum > (unsigned long)(mp_.max_total_mem))
          mp_.max_total_mem = sum;
#endif

        check_chunk(av, p);

        return chunk2mem(p);
      }
    }
  }
#endif

  /* Record incoming configuration of top */

  old_top  = av->top;
  old_size = chunksize(old_top);
  old_end  = (char*)(chunk_at_offset(old_top, old_size));

  brk = snd_brk = (char*)(MORECORE_FAILURE);

  /*
     If not the first time through, we require old_size to be
     at least MINSIZE and to have prev_inuse set.
  */

  assert((old_top == initial_top(av) && old_size == 0) ||
         ((unsigned long) (old_size) >= MINSIZE &&
          prev_inuse(old_top) &&
          ((unsigned long)old_end & pagemask) == 0));

  /* Precondition: not enough current space to satisfy nb request */
  assert((unsigned long)(old_size) < (unsigned long)(nb + MINSIZE));

  /* Precondition: all fastbins are consolidated */
  assert(!have_fastchunks(av));


  if (av != &main_arena) {

    heap_info *old_heap, *heap;
    size_t old_heap_size;

    /* First try to extend the current heap. */
    old_heap = heap_for_ptr(old_top);
    old_heap_size = old_heap->size;
    if ((long) (MINSIZE + nb - old_size) > 0
        && grow_heap(old_heap, MINSIZE + nb - old_size) == 0) {
      av->system_mem += old_heap->size - old_heap_size;
      arena_mem += old_heap->size - old_heap_size;
#if 0
      if(mmapped_mem + arena_mem + sbrked_mem > max_total_mem)
        max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
#endif
      set_head(old_top, (((char *)old_heap + old_heap->size) - (char *)old_top)
               | PREV_INUSE);
    }
    else if ((heap = new_heap(nb + (MINSIZE + sizeof(*heap)), mp_.top_pad))) {
      /* Use a newly allocated heap.  */
      heap->ar_ptr = av;
      heap->prev = old_heap;
      av->system_mem += heap->size;
      arena_mem += heap->size;
#if 0
      if((unsigned long)(mmapped_mem + arena_mem + sbrked_mem) > max_total_mem)
        max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
#endif
      /* Set up the new top.  */
      top(av) = chunk_at_offset(heap, sizeof(*heap));
      set_head(top(av), (heap->size - sizeof(*heap)) | PREV_INUSE);

      /* Setup fencepost and free the old top chunk. */
      /* The fencepost takes at least MINSIZE bytes, because it might
         become the top chunk again later.  Note that a footer is set
         up, too, although the chunk is marked in use. */
      old_size -= MINSIZE;
      set_head(chunk_at_offset(old_top, old_size + 2*SIZE_SZ), 0|PREV_INUSE);
      if (old_size >= MINSIZE) {
        set_head(chunk_at_offset(old_top, old_size), (2*SIZE_SZ)|PREV_INUSE);
        set_foot(chunk_at_offset(old_top, old_size), (2*SIZE_SZ));
        set_head(old_top, old_size|PREV_INUSE|NON_MAIN_ARENA);
        _int_free(av, chunk2mem(old_top));
      } else {
        set_head(old_top, (old_size + 2*SIZE_SZ)|PREV_INUSE);
        set_foot(old_top, (old_size + 2*SIZE_SZ));
      }
    }
    else if (!tried_mmap)
      /* We can at least try to use to mmap memory.  */
      goto try_mmap;

  } else { /* av == main_arena */


  /* Request enough space for nb + pad + overhead */

  size = nb + mp_.top_pad + MINSIZE;

  /*
    If contiguous, we can subtract out existing space that we hope to
    combine with new space. We add it back later only if
    we don't actually get contiguous space.
  */

  if (contiguous(av))
    size -= old_size;

  /*
    Round to a multiple of page size.
    If MORECORE is not contiguous, this ensures that we only call it
    with whole-page arguments.  And if MORECORE is contiguous and
    this is not first time through, this preserves page-alignment of
    previous calls. Otherwise, we correct to page-align below.
  */

  size = (size + pagemask) & ~pagemask;

  /*
    Don't try to call MORECORE if argument is so big as to appear
    negative. Note that since mmap takes size_t arg, it may succeed
    below even if we cannot call MORECORE.
  */

  if (size > 0)
    brk = (char*)(MORECORE(size));

  if (brk != (char*)(MORECORE_FAILURE)) {
    /* Call the `morecore' hook if necessary.  */
    if (__after_morecore_hook)
      (*__after_morecore_hook) ();
  } else {
  /*
    If have mmap, try using it as a backup when MORECORE fails or
    cannot be used. This is worth doing on systems that have "holes" in
    address space, so sbrk cannot extend to give contiguous space, but
    space is available elsewhere.  Note that we ignore mmap max count
    and threshold limits, since the space will not be used as a
    segregated mmap region.
  */

#if HAVE_MMAP
    /* Cannot merge with old top, so add its size back in */
    if (contiguous(av))
      size = (size + old_size + pagemask) & ~pagemask;

    /* If we are relying on mmap as backup, then use larger units */
    if ((unsigned long)(size) < (unsigned long)(MMAP_AS_MORECORE_SIZE))
      size = MMAP_AS_MORECORE_SIZE;

    /* Don't try if size wraps around 0 */
    if ((unsigned long)(size) > (unsigned long)(nb)) {

      char *mbrk = (char*)(MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE));

      if (mbrk != MAP_FAILED) {

        /* We do not need, and cannot use, another sbrk call to find end */
        brk = mbrk;
        snd_brk = brk + size;

        /*
           Record that we no longer have a contiguous sbrk region.
           After the first time mmap is used as backup, we do not
           ever rely on contiguous space since this could incorrectly
           bridge regions.
        */
        set_noncontiguous(av);
      }
    }
#endif
  }

  if (brk != (char*)(MORECORE_FAILURE)) {
    if (mp_.sbrk_base == 0)
      mp_.sbrk_base = brk;
    av->system_mem += size;

    /*
      If MORECORE extends previous space, we can likewise extend top size.
    */

    if (brk == old_end && snd_brk == (char*)(MORECORE_FAILURE))
      set_head(old_top, (size + old_size) | PREV_INUSE);

    else if (contiguous(av) && old_size && brk < old_end) {
      /* Oops!  Someone else killed our space..  Can't touch anything.  */
      assert(0);
    }

    /*
      Otherwise, make adjustments:

      * If the first time through or noncontiguous, we need to call sbrk
        just to find out where the end of memory lies.

      * We need to ensure that all returned chunks from malloc will meet
        MALLOC_ALIGNMENT

      * If there was an intervening foreign sbrk, we need to adjust sbrk
        request size to account for fact that we will not be able to
        combine new space with existing space in old_top.

      * Almost all systems internally allocate whole pages at a time, in
        which case we might as well use the whole last page of request.
        So we allocate enough more memory to hit a page boundary now,
        which in turn causes future contiguous calls to page-align.
    */

    else {
      front_misalign = 0;
      end_misalign = 0;
      correction = 0;
      aligned_brk = brk;

      /* handle contiguous cases */
      if (contiguous(av)) {

        /* Count foreign sbrk as system_mem.  */
        if (old_size)
          av->system_mem += brk - old_end;

        /* Guarantee alignment of first new chunk made from this space */

        front_misalign = (INTERNAL_SIZE_T)chunk2mem(brk) & MALLOC_ALIGN_MASK;
        if (front_misalign > 0) {

          /*
            Skip over some bytes to arrive at an aligned position.
            We don't need to specially mark these wasted front bytes.
            They will never be accessed anyway because
            prev_inuse of av->top (and any chunk created from its start)
            is always true after initialization.
          */

          correction = MALLOC_ALIGNMENT - front_misalign;
          aligned_brk += correction;
        }

        /*
          If this isn't adjacent to existing space, then we will not
          be able to merge with old_top space, so must add to 2nd request.
        */

        correction += old_size;

        /* Extend the end address to hit a page boundary */
        end_misalign = (INTERNAL_SIZE_T)(brk + size + correction);
        correction += ((end_misalign + pagemask) & ~pagemask) - end_misalign;

        assert(correction >= 0);
        snd_brk = (char*)(MORECORE(correction));

        /*
          If can't allocate correction, try to at least find out current
          brk.  It might be enough to proceed without failing.

          Note that if second sbrk did NOT fail, we assume that space
          is contiguous with first sbrk. This is a safe assumption unless
          program is multithreaded but doesn't use locks and a foreign sbrk
          occurred between our first and second calls.
        */

        if (snd_brk == (char*)(MORECORE_FAILURE)) {
          correction = 0;
          snd_brk = (char*)(MORECORE(0));
        } else
          /* Call the `morecore' hook if necessary.  */
          if (__after_morecore_hook)
            (*__after_morecore_hook) ();
      }

      /* handle non-contiguous cases */
      else {
        /* MORECORE/mmap must correctly align */
        assert(((unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK) == 0);

        /* Find out current end of memory */
        if (snd_brk == (char*)(MORECORE_FAILURE)) {
          snd_brk = (char*)(MORECORE(0));
        }
      }

      /* Adjust top based on results of second sbrk */
      if (snd_brk != (char*)(MORECORE_FAILURE)) {
        av->top = (mchunkptr)aligned_brk;
        set_head(av->top, (snd_brk - aligned_brk + correction) | PREV_INUSE);
        av->system_mem += correction;

        /*
          If not the first time through, we either have a
          gap due to foreign sbrk or a non-contiguous region.  Insert a
          double fencepost at old_top to prevent consolidation with space
          we don't own. These fenceposts are artificial chunks that are
          marked as inuse and are in any case too small to use.  We need
          two to make sizes and alignments work out.
        */

        if (old_size != 0) {
          /*
             Shrink old_top to insert fenceposts, keeping size a
             multiple of MALLOC_ALIGNMENT. We know there is at least
             enough space in old_top to do this.
          */
          old_size = (old_size - 4*SIZE_SZ) & ~MALLOC_ALIGN_MASK;
          set_head(old_top, old_size | PREV_INUSE);

          /*
            Note that the following assignments completely overwrite
            old_top when old_size was previously MINSIZE.  This is
            intentional. We need the fencepost, even if old_top otherwise gets
            lost.
          */
          chunk_at_offset(old_top, old_size            )->size =
            (2*SIZE_SZ)|PREV_INUSE;

          chunk_at_offset(old_top, old_size + 2*SIZE_SZ)->size =
            (2*SIZE_SZ)|PREV_INUSE;

          /* If possible, release the rest. */
          if (old_size >= MINSIZE) {
            _int_free(av, chunk2mem(old_top));
          }

        }
      }
    }

    /* Update statistics */
#ifdef NO_THREADS
    sum = av->system_mem + mp_.mmapped_mem;
    if (sum > (unsigned long)(mp_.max_total_mem))
      mp_.max_total_mem = sum;
#endif

  }

  } /* if (av !=  &main_arena) */

  if ((unsigned long)av->system_mem > (unsigned long)(av->max_system_mem))
    av->max_system_mem = av->system_mem;
  check_malloc_state(av);

  /* finally, do the allocation */
  p = av->top;
  size = chunksize(p);

  /* check that one of the above allocation paths succeeded */
  if ((unsigned long)(size) >= (unsigned long)(nb + MINSIZE)) {
    remainder_size = size - nb;
    remainder = chunk_at_offset(p, nb);
    av->top = remainder;
    set_head(p, nb | PREV_INUSE | (av != &main_arena ? NON_MAIN_ARENA : 0));
    set_head(remainder, remainder_size | PREV_INUSE);
    check_malloced_chunk(av, p, nb);
    return chunk2mem(p);
  }

  /* catch all failure paths */
  MALLOC_FAILURE_ACTION;
  return 0;
}


/*
  sYSTRIm is an inverse of sorts to sYSMALLOc.  It gives memory back
  to the system (via negative arguments to sbrk) if there is unused
  memory at the `high' end of the malloc pool. It is called
  automatically by free() when top space exceeds the trim
  threshold. It is also called by the public malloc_trim routine.  It
  returns 1 if it actually released any memory, else 0.
*/

#if __STD_C
static int sYSTRIm(size_t pad, mstate av)
#else
static int sYSTRIm(pad, av) size_t pad; mstate av;
#endif
{
  long  top_size;        /* Amount of top-most memory */
  long  extra;           /* Amount to release */
  long  released;        /* Amount actually released */
  char* current_brk;     /* address returned by pre-check sbrk call */
  char* new_brk;         /* address returned by post-check sbrk call */
  size_t pagesz;

  pagesz = mp_.pagesize;
  top_size = chunksize(av->top);

  /* Release in pagesize units, keeping at least one page */
  extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;

  if (extra > 0) {

    /*
      Only proceed if end of memory is where we last set it.
      This avoids problems if there were foreign sbrk calls.
    */
    current_brk = (char*)(MORECORE(0));
    if (current_brk == (char*)(av->top) + top_size) {

      /*
        Attempt to release memory. We ignore MORECORE return value,
        and instead call again to find out where new end of memory is.
        This avoids problems if first call releases less than we asked,
        of if failure somehow altered brk value. (We could still
        encounter problems if it altered brk in some very bad way,
        but the only thing we can do is adjust anyway, which will cause
        some downstream failure.)
      */

      MORECORE(-extra);
      /* Call the `morecore' hook if necessary.  */
      if (__after_morecore_hook)
        (*__after_morecore_hook) ();
      new_brk = (char*)(MORECORE(0));

      if (new_brk != (char*)MORECORE_FAILURE) {
        released = (long)(current_brk - new_brk);

        if (released != 0) {
          /* Success. Adjust top. */
          av->system_mem -= released;
          set_head(av->top, (top_size - released) | PREV_INUSE);
          check_malloc_state(av);
          return 1;
        }
      }
    }
  }
  return 0;
}

#ifdef HAVE_MMAP

static void
internal_function
#if __STD_C
munmap_chunk(mchunkptr p)
#else
munmap_chunk(p) mchunkptr p;
#endif
{
  INTERNAL_SIZE_T size = chunksize(p);

  assert (chunk_is_mmapped(p));
#if 0
  assert(! ((char*)p >= mp_.sbrk_base && (char*)p < mp_.sbrk_base + mp_.sbrked_mem));
  assert((mp_.n_mmaps > 0));
#endif

  uintptr_t block = (uintptr_t) p - p->prev_size;
  size_t total_size = p->prev_size + size;
  /* Unfortunately we have to do the compilers job by hand here.  Normally
     we would test BLOCK and TOTAL-SIZE separately for compliance with the
     page size.  But gcc does not recognize the optimization possibility
     (in the moment at least) so we combine the two values into one before
     the bit test.  */
  if (__builtin_expect (((block | total_size) & (mp_.pagesize - 1)) != 0, 0))
    {
      malloc_printerr (check_action, "munmap_chunk(): invalid pointer",
                       chunk2mem (p));
      return;
    }

  mp_.n_mmaps--;
  mp_.mmapped_mem -= total_size;

  int ret __attribute__ ((unused)) = munmap((char *)block, total_size);

  /* munmap returns non-zero on failure */
  assert(ret == 0);
}

#if HAVE_MREMAP

static mchunkptr
internal_function
#if __STD_C
mremap_chunk(mchunkptr p, size_t new_size)
#else
mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
#endif
{
  size_t page_mask = mp_.pagesize - 1;
  INTERNAL_SIZE_T offset = p->prev_size;
  INTERNAL_SIZE_T size = chunksize(p);
  char *cp;

  assert (chunk_is_mmapped(p));
#if 0
  assert(! ((char*)p >= mp_.sbrk_base && (char*)p < mp_.sbrk_base + mp_.sbrked_mem));
  assert((mp_.n_mmaps > 0));
#endif
  assert(((size + offset) & (mp_.pagesize-1)) == 0);

  /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
  new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;

  cp = (char *)mremap((char *)p - offset, size + offset, new_size,
                      MREMAP_MAYMOVE);

  if (cp == MAP_FAILED) return 0;

  p = (mchunkptr)(cp + offset);

  assert(aligned_OK(chunk2mem(p)));

  assert((p->prev_size == offset));
  set_head(p, (new_size - offset)|IS_MMAPPED);

  mp_.mmapped_mem -= size + offset;
  mp_.mmapped_mem += new_size;
  if ((unsigned long)mp_.mmapped_mem > (unsigned long)mp_.max_mmapped_mem)
    mp_.max_mmapped_mem = mp_.mmapped_mem;
#ifdef NO_THREADS
  if ((unsigned long)(mp_.mmapped_mem + arena_mem + main_arena.system_mem) >
      mp_.max_total_mem)
    mp_.max_total_mem = mp_.mmapped_mem + arena_mem + main_arena.system_mem;
#endif
  return p;
}

#endif /* HAVE_MREMAP */

#endif /* HAVE_MMAP */

/*------------------------ Public wrappers. --------------------------------*/

Void_t*
public_mALLOc(size_t bytes)
{
  mstate ar_ptr;
  Void_t *victim;

  __malloc_ptr_t (*hook) (size_t, __const __malloc_ptr_t) = __malloc_hook;
  if (hook != NULL)
    return (*hook)(bytes, RETURN_ADDRESS (0));

  arena_get(ar_ptr, bytes);
  if(!ar_ptr)
    return 0;
  victim = _int_malloc(ar_ptr, bytes);
  if(!victim) {
    /* Maybe the failure is due to running out of mmapped areas. */
    if(ar_ptr != &main_arena) {
      (void)mutex_unlock(&ar_ptr->mutex);
      (void)mutex_lock(&main_arena.mutex);
      victim = _int_malloc(&main_arena, bytes);
      (void)mutex_unlock(&main_arena.mutex);
    } else {
#if USE_ARENAS
      /* ... or sbrk() has failed and there is still a chance to mmap() */
      ar_ptr = arena_get2(ar_ptr->next ? ar_ptr : 0, bytes);
      (void)mutex_unlock(&main_arena.mutex);
      if(ar_ptr) {
        victim = _int_malloc(ar_ptr, bytes);
        (void)mutex_unlock(&ar_ptr->mutex);
      }
#endif
    }
  } else
    (void)mutex_unlock(&ar_ptr->mutex);
  assert(!victim || chunk_is_mmapped(mem2chunk(victim)) ||
         ar_ptr == arena_for_chunk(mem2chunk(victim)));
  return victim;
}
#ifdef libc_hidden_def
libc_hidden_def(public_mALLOc)
#endif

void
public_fREe(Void_t* mem)
{
  mstate ar_ptr;
  mchunkptr p;                          /* chunk corresponding to mem */

  void (*hook) (__malloc_ptr_t, __const __malloc_ptr_t) = __free_hook;
  if (hook != NULL) {
    (*hook)(mem, RETURN_ADDRESS (0));
    return;
  }

  if (mem == 0)                              /* free(0) has no effect */
    return;

  p = mem2chunk(mem);

#if HAVE_MMAP
  if (chunk_is_mmapped(p))                       /* release mmapped memory. */
  {
    /* see if the dynamic brk/mmap threshold needs adjusting */
    if (!mp_.no_dyn_threshold
        && p->size > mp_.mmap_threshold
        && p->size <= DEFAULT_MMAP_THRESHOLD_MAX)
      {
        mp_.mmap_threshold = chunksize (p);
        mp_.trim_threshold = 2 * mp_.mmap_threshold;
      }
    munmap_chunk(p);
    return;
  }
#endif

  ar_ptr = arena_for_chunk(p);
#if THREAD_STATS
  if(!mutex_trylock(&ar_ptr->mutex))
    ++(ar_ptr->stat_lock_direct);
  else {
    (void)mutex_lock(&ar_ptr->mutex);
    ++(ar_ptr->stat_lock_wait);
  }
#else
  (void)mutex_lock(&ar_ptr->mutex);
#endif
  _int_free(ar_ptr, mem);
  (void)mutex_unlock(&ar_ptr->mutex);
}
#ifdef libc_hidden_def
libc_hidden_def (public_fREe)
#endif

Void_t*
public_rEALLOc(Void_t* oldmem, size_t bytes)
{
  mstate ar_ptr;
  INTERNAL_SIZE_T    nb;      /* padded request size */

  mchunkptr oldp;             /* chunk corresponding to oldmem */
  INTERNAL_SIZE_T    oldsize; /* its size */

  Void_t* newp;             /* chunk to return */

  __malloc_ptr_t (*hook) (__malloc_ptr_t, size_t, __const __malloc_ptr_t) =
    __realloc_hook;
  if (hook != NULL)
    return (*hook)(oldmem, bytes, RETURN_ADDRESS (0));

#if REALLOC_ZERO_BYTES_FREES
  if (bytes == 0 && oldmem != NULL) { public_fREe(oldmem); return 0; }
#endif

  /* realloc of null is supposed to be same as malloc */
  if (oldmem == 0) return public_mALLOc(bytes);

  oldp    = mem2chunk(oldmem);
  oldsize = chunksize(oldp);

  /* Little security check which won't hurt performance: the
     allocator never wrapps around at the end of the address space.
     Therefore we can exclude some size values which might appear
     here by accident or by "design" from some intruder.  */
  if (__builtin_expect ((uintptr_t) oldp > (uintptr_t) -oldsize, 0)
      || __builtin_expect (misaligned_chunk (oldp), 0))
    {
      malloc_printerr (check_action, "realloc(): invalid pointer", oldmem);
      return NULL;
    }

  checked_request2size(bytes, nb);

#if HAVE_MMAP
  if (chunk_is_mmapped(oldp))
  {
    Void_t* newmem;

#if HAVE_MREMAP
    newp = mremap_chunk(oldp, nb);
    if(newp) return chunk2mem(newp);
#endif
    /* Note the extra SIZE_SZ overhead. */
    if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */
    /* Must alloc, copy, free. */
    newmem = public_mALLOc(bytes);
    if (newmem == 0) return 0; /* propagate failure */
    MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
    munmap_chunk(oldp);
    return newmem;
  }
#endif

  ar_ptr = arena_for_chunk(oldp);
#if THREAD_STATS
  if(!mutex_trylock(&ar_ptr->mutex))
    ++(ar_ptr->stat_lock_direct);
  else {
    (void)mutex_lock(&ar_ptr->mutex);
    ++(ar_ptr->stat_lock_wait);
  }
#else
  (void)mutex_lock(&ar_ptr->mutex);
#endif

#ifndef NO_THREADS
  /* As in malloc(), remember this arena for the next allocation. */
  tsd_setspecific(arena_key, (Void_t *)ar_ptr);
#endif

  newp = _int_realloc(ar_ptr, oldmem, bytes);

  (void)mutex_unlock(&ar_ptr->mutex);
  assert(!newp || chunk_is_mmapped(mem2chunk(newp)) ||
         ar_ptr == arena_for_chunk(mem2chunk(newp)));

  if (newp == NULL)
    {
      /* Try harder to allocate memory in other arenas.  */
      newp = public_mALLOc(bytes);
      if (newp != NULL)
        {
          MALLOC_COPY (newp, oldmem, oldsize - 2 * SIZE_SZ);
#if THREAD_STATS
          if(!mutex_trylock(&ar_ptr->mutex))
            ++(ar_ptr->stat_lock_direct);
          else {
            (void)mutex_lock(&ar_ptr->mutex);
            ++(ar_ptr->stat_lock_wait);
          }
#else
          (void)mutex_lock(&ar_ptr->mutex);
#endif
          _int_free(ar_ptr, oldmem);
          (void)mutex_unlock(&ar_ptr->mutex);
        }
    }

  return newp;
}
#ifdef libc_hidden_def
libc_hidden_def (public_rEALLOc)
#endif

Void_t*
public_mEMALIGn(size_t alignment, size_t bytes)
{
  mstate ar_ptr;
  Void_t *p;

  __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
                                        __const __malloc_ptr_t)) =
    __memalign_hook;
  if (hook != NULL)
    return (*hook)(alignment, bytes, RETURN_ADDRESS (0));

  /* If need less alignment than we give anyway, just relay to malloc */
  if (alignment <= MALLOC_ALIGNMENT) return public_mALLOc(bytes);

  /* Otherwise, ensure that it is at least a minimum chunk size */
  if (alignment <  MINSIZE) alignment = MINSIZE;

  arena_get(ar_ptr, bytes + alignment + MINSIZE);
  if(!ar_ptr)
    return 0;
  p = _int_memalign(ar_ptr, alignment, bytes);
  (void)mutex_unlock(&ar_ptr->mutex);
  if(!p) {
    /* Maybe the failure is due to running out of mmapped areas. */
    if(ar_ptr != &main_arena) {
      (void)mutex_lock(&main_arena.mutex);
      p = _int_memalign(&main_arena, alignment, bytes);
      (void)mutex_unlock(&main_arena.mutex);
    } else {
#if USE_ARENAS
      /* ... or sbrk() has failed and there is still a chance to mmap() */
      ar_ptr = arena_get2(ar_ptr->next ? ar_ptr : 0, bytes);
      if(ar_ptr) {
        p = _int_memalign(ar_ptr, alignment, bytes);
        (void)mutex_unlock(&ar_ptr->mutex);
      }
#endif
    }
  }
  assert(!p || chunk_is_mmapped(mem2chunk(p)) ||
         ar_ptr == arena_for_chunk(mem2chunk(p)));
  return p;
}
#ifdef libc_hidden_def
libc_hidden_def (public_mEMALIGn)
#endif

Void_t*
public_vALLOc(size_t bytes)
{
  mstate ar_ptr;
  Void_t *p;

  if(__malloc_initialized < 0)
    ptmalloc_init ();

  __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
                                        __const __malloc_ptr_t)) =
    __memalign_hook;
  if (hook != NULL)
    return (*hook)(mp_.pagesize, bytes, RETURN_ADDRESS (0));

  arena_get(ar_ptr, bytes + mp_.pagesize + MINSIZE);
  if(!ar_ptr)
    return 0;
  p = _int_valloc(ar_ptr, bytes);
  (void)mutex_unlock(&ar_ptr->mutex);
  return p;
}

Void_t*
public_pVALLOc(size_t bytes)
{
  mstate ar_ptr;
  Void_t *p;

  if(__malloc_initialized < 0)
    ptmalloc_init ();

  __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
                                        __const __malloc_ptr_t)) =
    __memalign_hook;
  if (hook != NULL)
    return (*hook)(mp_.pagesize,
                   (bytes + mp_.pagesize - 1) & ~(mp_.pagesize - 1),
                   RETURN_ADDRESS (0));

  arena_get(ar_ptr, bytes + 2*mp_.pagesize + MINSIZE);
  p = _int_pvalloc(ar_ptr, bytes);
  (void)mutex_unlock(&ar_ptr->mutex);
  return p;
}

Void_t*
public_cALLOc(size_t n, size_t elem_size)
{
  mstate av;
  mchunkptr oldtop, p;
  INTERNAL_SIZE_T bytes, sz, csz, oldtopsize;
  Void_t* mem;
  unsigned long clearsize;
  unsigned long nclears;
  INTERNAL_SIZE_T* d;
  __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, __const __malloc_ptr_t)) =
    __malloc_hook;

  /* size_t is unsigned so the behavior on overflow is defined.  */
  bytes = n * elem_size;
#define HALF_INTERNAL_SIZE_T \
  (((INTERNAL_SIZE_T) 1) << (8 * sizeof (INTERNAL_SIZE_T) / 2))
  if (__builtin_expect ((n | elem_size) >= HALF_INTERNAL_SIZE_T, 0)) {
    if (elem_size != 0 && bytes / elem_size != n) {
      MALLOC_FAILURE_ACTION;
      return 0;
    }
  }

  if (hook != NULL) {
    sz = bytes;
    mem = (*hook)(sz, RETURN_ADDRESS (0));
    if(mem == 0)
      return 0;
#ifdef HAVE_MEMCPY
    return memset(mem, 0, sz);
#else
    while(sz > 0) ((char*)mem)[--sz] = 0; /* rather inefficient */
    return mem;
#endif
  }

  sz = bytes;

  arena_get(av, sz);
  if(!av)
    return 0;

  /* Check if we hand out the top chunk, in which case there may be no
     need to clear. */
#if MORECORE_CLEARS
  oldtop = top(av);
  oldtopsize = chunksize(top(av));
#if MORECORE_CLEARS < 2
  /* Only newly allocated memory is guaranteed to be cleared.  */
  if (av == &main_arena &&
      oldtopsize < mp_.sbrk_base + av->max_system_mem - (char *)oldtop)
    oldtopsize = (mp_.sbrk_base + av->max_system_mem - (char *)oldtop);
#endif
#endif
  mem = _int_malloc(av, sz);

  /* Only clearing follows, so we can unlock early. */
  (void)mutex_unlock(&av->mutex);

  assert(!mem || chunk_is_mmapped(mem2chunk(mem)) ||
         av == arena_for_chunk(mem2chunk(mem)));

  if (mem == 0) {
    /* Maybe the failure is due to running out of mmapped areas. */
    if(av != &main_arena) {
      (void)mutex_lock(&main_arena.mutex);
      mem = _int_malloc(&main_arena, sz);
      (void)mutex_unlock(&main_arena.mutex);
    } else {
#if USE_ARENAS
      /* ... or sbrk() has failed and there is still a chance to mmap() */
      (void)mutex_lock(&main_arena.mutex);
      av = arena_get2(av->next ? av : 0, sz);
      (void)mutex_unlock(&main_arena.mutex);
      if(av) {
        mem = _int_malloc(av, sz);
        (void)mutex_unlock(&av->mutex);
      }
#endif
    }
    if (mem == 0) return 0;
  }
  p = mem2chunk(mem);

  /* Two optional cases in which clearing not necessary */
#if HAVE_MMAP
  if (chunk_is_mmapped (p))
    {
      if (__builtin_expect (perturb_byte, 0))
        MALLOC_ZERO (mem, sz);
      return mem;
    }
#endif

  csz = chunksize(p);

#if MORECORE_CLEARS
  if (perturb_byte == 0 && (p == oldtop && csz > oldtopsize)) {
    /* clear only the bytes from non-freshly-sbrked memory */
    csz = oldtopsize;
  }
#endif

  /* Unroll clear of <= 36 bytes (72 if 8byte sizes).  We know that
     contents have an odd number of INTERNAL_SIZE_T-sized words;
     minimally 3.  */
  d = (INTERNAL_SIZE_T*)mem;
  clearsize = csz - SIZE_SZ;
  nclears = clearsize / sizeof(INTERNAL_SIZE_T);
  assert(nclears >= 3);

  if (nclears > 9)
    MALLOC_ZERO(d, clearsize);

  else {
    *(d+0) = 0;
    *(d+1) = 0;
    *(d+2) = 0;
    if (nclears > 4) {
      *(d+3) = 0;
      *(d+4) = 0;
      if (nclears > 6) {
        *(d+5) = 0;
        *(d+6) = 0;
        if (nclears > 8) {
          *(d+7) = 0;
          *(d+8) = 0;
        }
      }
    }
  }

  return mem;
}

#ifndef _LIBC

Void_t**
public_iCALLOc(size_t n, size_t elem_size, Void_t** chunks)
{
  mstate ar_ptr;
  Void_t** m;

  arena_get(ar_ptr, n*elem_size);
  if(!ar_ptr)
    return 0;

  m = _int_icalloc(ar_ptr, n, elem_size, chunks);
  (void)mutex_unlock(&ar_ptr->mutex);
  return m;
}

Void_t**
public_iCOMALLOc(size_t n, size_t sizes[], Void_t** chunks)
{
  mstate ar_ptr;
  Void_t** m;

  arena_get(ar_ptr, 0);
  if(!ar_ptr)
    return 0;

  m = _int_icomalloc(ar_ptr, n, sizes, chunks);
  (void)mutex_unlock(&ar_ptr->mutex);
  return m;
}

void
public_cFREe(Void_t* m)
{
  public_fREe(m);
}

#endif /* _LIBC */

int
public_mTRIm(size_t s)
{
  int result;

  if(__malloc_initialized < 0)
    ptmalloc_init ();
  (void)mutex_lock(&main_arena.mutex);
  result = mTRIm(s);
  (void)mutex_unlock(&main_arena.mutex);
  return result;
}

size_t
public_mUSABLe(Void_t* m)
{
  size_t result;

  result = mUSABLe(m);
  return result;
}

void
public_mSTATs()
{
  mSTATs();
}

struct mallinfo public_mALLINFo()
{
  struct mallinfo m;

  if(__malloc_initialized < 0)
    ptmalloc_init ();
  (void)mutex_lock(&main_arena.mutex);
  m = mALLINFo(&main_arena);
  (void)mutex_unlock(&main_arena.mutex);
  return m;
}

int
public_mALLOPt(int p, int v)
{
  int result;
  result = mALLOPt(p, v);
  return result;
}

/*
  ------------------------------ malloc ------------------------------
*/

Void_t*
_int_malloc(mstate av, size_t bytes)
{
  INTERNAL_SIZE_T nb;               /* normalized request size */
  unsigned int    idx;              /* associated bin index */
  mbinptr         bin;              /* associated bin */
  mfastbinptr*    fb;               /* associated fastbin */

  mchunkptr       victim;           /* inspected/selected chunk */
  INTERNAL_SIZE_T size;             /* its size */
  int             victim_index;     /* its bin index */

  mchunkptr       remainder;        /* remainder from a split */
  unsigned long   remainder_size;   /* its size */

  unsigned int    block;            /* bit map traverser */
  unsigned int    bit;              /* bit map traverser */
  unsigned int    map;              /* current word of binmap */

  mchunkptr       fwd;              /* misc temp for linking */
  mchunkptr       bck;              /* misc temp for linking */

  /*
    Convert request size to internal form by adding SIZE_SZ bytes
    overhead plus possibly more to obtain necessary alignment and/or
    to obtain a size of at least MINSIZE, the smallest allocatable
    size. Also, checked_request2size traps (returning 0) request sizes
    that are so large that they wrap around zero when padded and
    aligned.
  */

  checked_request2size(bytes, nb);

  /*
    If the size qualifies as a fastbin, first check corresponding bin.
    This code is safe to execute even if av is not yet initialized, so we
    can try it without checking, which saves some time on this fast path.
  */

  if ((unsigned long)(nb) <= (unsigned long)(get_max_fast ())) {
    long int idx = fastbin_index(nb);
    fb = &(av->fastbins[idx]);
    if ( (victim = *fb) != 0) {
      if (__builtin_expect (fastbin_index (chunksize (victim)) != idx, 0))
        malloc_printerr (check_action, "malloc(): memory corruption (fast)",
                         chunk2mem (victim));
      *fb = victim->fd;
      check_remalloced_chunk(av, victim, nb);
      void *p = chunk2mem(victim);
      if (__builtin_expect (perturb_byte, 0))
        alloc_perturb (p, bytes);
      return p;
    }
  }

  /*
    If a small request, check regular bin.  Since these "smallbins"
    hold one size each, no searching within bins is necessary.
    (For a large request, we need to wait until unsorted chunks are
    processed to find best fit. But for small ones, fits are exact
    anyway, so we can check now, which is faster.)
  */

  if (in_smallbin_range(nb)) {
    idx = smallbin_index(nb);
    bin = bin_at(av,idx);

    if ( (victim = last(bin)) != bin) {
      if (victim == 0) /* initialization check */
        malloc_consolidate(av);
      else {
        bck = victim->bk;
        set_inuse_bit_at_offset(victim, nb);
        bin->bk = bck;
        bck->fd = bin;

        if (av != &main_arena)
          victim->size |= NON_MAIN_ARENA;
        check_malloced_chunk(av, victim, nb);
        void *p = chunk2mem(victim);
        if (__builtin_expect (perturb_byte, 0))
          alloc_perturb (p, bytes);
        return p;
      }
    }
  }

  /*
     If this is a large request, consolidate fastbins before continuing.
     While it might look excessive to kill all fastbins before
     even seeing if there is space available, this avoids
     fragmentation problems normally associated with fastbins.
     Also, in practice, programs tend to have runs of either small or
     large requests, but less often mixtures, so consolidation is not
     invoked all that often in most programs. And the programs that
     it is called frequently in otherwise tend to fragment.
  */

  else {
    idx = largebin_index(nb);
    if (have_fastchunks(av))
      malloc_consolidate(av);
  }

  /*
    Process recently freed or remaindered chunks, taking one only if
    it is exact fit, or, if this a small request, the chunk is remainder from
    the most recent non-exact fit.  Place other traversed chunks in
    bins.  Note that this step is the only place in any routine where
    chunks are placed in bins.

    The outer loop here is needed because we might not realize until
    near the end of malloc that we should have consolidated, so must
    do so and retry. This happens at most once, and only when we would
    otherwise need to expand memory to service a "small" request.
  */

  for(;;) {

    int iters = 0;
    while ( (victim = unsorted_chunks(av)->bk) != unsorted_chunks(av)) {
      bck = victim->bk;
      if (__builtin_expect (victim->size <= 2 * SIZE_SZ, 0)
          || __builtin_expect (victim->size > av->system_mem, 0))
        malloc_printerr (check_action, "malloc(): memory corruption",
                         chunk2mem (victim));
      size = chunksize(victim);

      /*
         If a small request, try to use last remainder if it is the
         only chunk in unsorted bin.  This helps promote locality for
         runs of consecutive small requests. This is the only
         exception to best-fit, and applies only when there is
         no exact fit for a small chunk.
      */

      if (in_smallbin_range(nb) &&
          bck == unsorted_chunks(av) &&
          victim == av->last_remainder &&
          (unsigned long)(size) > (unsigned long)(nb + MINSIZE)) {

        /* split and reattach remainder */
        remainder_size = size - nb;
        remainder = chunk_at_offset(victim, nb);
        unsorted_chunks(av)->bk = unsorted_chunks(av)->fd = remainder;
        av->last_remainder = remainder;
        remainder->bk = remainder->fd = unsorted_chunks(av);
        if (!in_smallbin_range(remainder_size))
          {
            remainder->fd_nextsize = NULL;
            remainder->bk_nextsize = NULL;
          }

        set_head(victim, nb | PREV_INUSE |
                 (av != &main_arena ? NON_MAIN_ARENA : 0));
        set_head(remainder, remainder_size | PREV_INUSE);
        set_foot(remainder, remainder_size);

        check_malloced_chunk(av, victim, nb);
        void *p = chunk2mem(victim);
        if (__builtin_expect (perturb_byte, 0))
          alloc_perturb (p, bytes);
        return p;
      }

      /* remove from unsorted list */
      unsorted_chunks(av)->bk = bck;
      bck->fd = unsorted_chunks(av);

      /* Take now instead of binning if exact fit */

      if (size == nb) {
        set_inuse_bit_at_offset(victim, size);
        if (av != &main_arena)
          victim->size |= NON_MAIN_ARENA;
        check_malloced_chunk(av, victim, nb);
        void *p = chunk2mem(victim);
        if (__builtin_expect (perturb_byte, 0))
          alloc_perturb (p, bytes);
        return p;
      }

      /* place chunk in bin */

      if (in_smallbin_range(size)) {
        victim_index = smallbin_index(size);
        bck = bin_at(av, victim_index);
        fwd = bck->fd;
      }
      else {
        victim_index = largebin_index(size);
        bck = bin_at(av, victim_index);
        fwd = bck->fd;

        /* maintain large bins in sorted order */
        if (fwd != bck) {
          /* Or with inuse bit to speed comparisons */
          size |= PREV_INUSE;
          /* if smaller than smallest, bypass loop below */
          assert((bck->bk->size & NON_MAIN_ARENA) == 0);
          if ((unsigned long)(size) < (unsigned long)(bck->bk->size)) {
            fwd = bck;
            bck = bck->bk;

            victim->fd_nextsize = fwd->fd;
            victim->bk_nextsize = fwd->fd->bk_nextsize;
            fwd->fd->bk_nextsize = victim->bk_nextsize->fd_nextsize = victim;
          }
          else {
            assert((fwd->size & NON_MAIN_ARENA) == 0);
            while ((unsigned long) size < fwd->size)
              {
                fwd = fwd->fd_nextsize;
                assert((fwd->size & NON_MAIN_ARENA) == 0);
              }

            if ((unsigned long) size == (unsigned long) fwd->size)
              /* Always insert in the second position.  */
              fwd = fwd->fd;
            else
              {
                victim->fd_nextsize = fwd;
                victim->bk_nextsize = fwd->bk_nextsize;
                fwd->bk_nextsize = victim;
                victim->bk_nextsize->fd_nextsize = victim;
              }
            bck = fwd->bk;
          }
        } else
          victim->fd_nextsize = victim->bk_nextsize = victim;
      }

      mark_bin(av, victim_index);
      victim->bk = bck;
      victim->fd = fwd;
      fwd->bk = victim;
      bck->fd = victim;

#define MAX_ITERS       10000
      if (++iters >= MAX_ITERS)
        break;
    }

    /*
      If a large request, scan through the chunks of current bin in
      sorted order to find smallest that fits.  Use the skip list for this.
    */

    if (!in_smallbin_range(nb)) {
      bin = bin_at(av, idx);

      /* skip scan if empty or largest chunk is too small */
      if ((victim = first(bin)) != bin &&
          (unsigned long)(victim->size) >= (unsigned long)(nb)) {

        victim = victim->bk_nextsize;
        while (((unsigned long)(size = chunksize(victim)) <
                (unsigned long)(nb)))
          victim = victim->bk_nextsize;

        /* Avoid removing the first entry for a size so that the skip
           list does not have to be rerouted.  */
        if (victim != last(bin) && victim->size == victim->fd->size)
          victim = victim->fd;

        remainder_size = size - nb;
        unlink(victim, bck, fwd);

        /* Exhaust */
        if (remainder_size < MINSIZE)  {
          set_inuse_bit_at_offset(victim, size);
          if (av != &main_arena)
            victim->size |= NON_MAIN_ARENA;
        }
        /* Split */
        else {
          remainder = chunk_at_offset(victim, nb);
          /* We cannot assume the unsorted list is empty and therefore
             have to perform a complete insert here.  */
          bck = unsorted_chunks(av);
          fwd = bck->fd;
          remainder->bk = bck;
          remainder->fd = fwd;
          bck->fd = remainder;
          fwd->bk = remainder;
          if (!in_smallbin_range(remainder_size))
            {
              remainder->fd_nextsize = NULL;
              remainder->bk_nextsize = NULL;
            }
          set_head(victim, nb | PREV_INUSE |
                   (av != &main_arena ? NON_MAIN_ARENA : 0));
          set_head(remainder, remainder_size | PREV_INUSE);
          set_foot(remainder, remainder_size);
        }
        check_malloced_chunk(av, victim, nb);
        void *p = chunk2mem(victim);
        if (__builtin_expect (perturb_byte, 0))
          alloc_perturb (p, bytes);
        return p;
      }
    }

    /*
      Search for a chunk by scanning bins, starting with next largest
      bin. This search is strictly by best-fit; i.e., the smallest
      (with ties going to approximately the least recently used) chunk
      that fits is selected.

      The bitmap avoids needing to check that most blocks are nonempty.
      The particular case of skipping all bins during warm-up phases
      when no chunks have been returned yet is faster than it might look.
    */

    ++idx;
    bin = bin_at(av,idx);
    block = idx2block(idx);
    map = av->binmap[block];
    bit = idx2bit(idx);

    for (;;) {

      /* Skip rest of block if there are no more set bits in this block.  */
      if (bit > map || bit == 0) {
        do {
          if (++block >= BINMAPSIZE)  /* out of bins */
            goto use_top;
        } while ( (map = av->binmap[block]) == 0);

        bin = bin_at(av, (block << BINMAPSHIFT));
        bit = 1;
      }

      /* Advance to bin with set bit. There must be one. */
      while ((bit & map) == 0) {
        bin = next_bin(bin);
        bit <<= 1;
        assert(bit != 0);
      }

      /* Inspect the bin. It is likely to be non-empty */
      victim = last(bin);

      /*  If a false alarm (empty bin), clear the bit. */
      if (victim == bin) {
        av->binmap[block] = map &= ~bit; /* Write through */
        bin = next_bin(bin);
        bit <<= 1;
      }

      else {
        size = chunksize(victim);

        /*  We know the first chunk in this bin is big enough to use. */
        assert((unsigned long)(size) >= (unsigned long)(nb));

        remainder_size = size - nb;

        /* unlink */
        unlink(victim, bck, fwd);

        /* Exhaust */
        if (remainder_size < MINSIZE) {
          set_inuse_bit_at_offset(victim, size);
          if (av != &main_arena)
            victim->size |= NON_MAIN_ARENA;
        }

        /* Split */
        else {
          remainder = chunk_at_offset(victim, nb);

          /* We cannot assume the unsorted list is empty and therefore
             have to perform a complete insert here.  */
          bck = unsorted_chunks(av);
          fwd = bck->fd;
          remainder->bk = bck;
          remainder->fd = fwd;
          bck->fd = remainder;
          fwd->bk = remainder;

          /* advertise as last remainder */
          if (in_smallbin_range(nb))
            av->last_remainder = remainder;
          if (!in_smallbin_range(remainder_size))
            {
              remainder->fd_nextsize = NULL;
              remainder->bk_nextsize = NULL;
            }
          set_head(victim, nb | PREV_INUSE |
                   (av != &main_arena ? NON_MAIN_ARENA : 0));
          set_head(remainder, remainder_size | PREV_INUSE);
          set_foot(remainder, remainder_size);
        }
        check_malloced_chunk(av, victim, nb);
        void *p = chunk2mem(victim);
        if (__builtin_expect (perturb_byte, 0))
          alloc_perturb (p, bytes);
        return p;
      }
    }

  use_top:
    /*
      If large enough, split off the chunk bordering the end of memory
      (held in av->top). Note that this is in accord with the best-fit
      search rule.  In effect, av->top is treated as larger (and thus
      less well fitting) than any other available chunk since it can
      be extended to be as large as necessary (up to system
      limitations).

      We require that av->top always exists (i.e., has size >=
      MINSIZE) after initialization, so if it would otherwise be
      exhuasted by current request, it is replenished. (The main
      reason for ensuring it exists is that we may need MINSIZE space
      to put in fenceposts in sysmalloc.)
    */

    victim = av->top;
    size = chunksize(victim);

    if ((unsigned long)(size) >= (unsigned long)(nb + MINSIZE)) {
      remainder_size = size - nb;
      remainder = chunk_at_offset(victim, nb);
      av->top = remainder;
      set_head(victim, nb | PREV_INUSE |
               (av != &main_arena ? NON_MAIN_ARENA : 0));
      set_head(remainder, remainder_size | PREV_INUSE);

      check_malloced_chunk(av, victim, nb);
      void *p = chunk2mem(victim);
      if (__builtin_expect (perturb_byte, 0))
        alloc_perturb (p, bytes);
      return p;
    }

    /*
      If there is space available in fastbins, consolidate and retry,
      to possibly avoid expanding memory. This can occur only if nb is
      in smallbin range so we didn't consolidate upon entry.
    */

    else if (have_fastchunks(av)) {
      assert(in_smallbin_range(nb));
      malloc_consolidate(av);
      idx = smallbin_index(nb); /* restore original bin index */
    }

    /*
       Otherwise, relay to handle system-dependent cases
    */
    else {
      void *p = sYSMALLOc(nb, av);
      if (__builtin_expect (perturb_byte, 0))
        alloc_perturb (p, bytes);
      return p;
    }
  }
}

/*
  ------------------------------ free ------------------------------
*/

void
_int_free(mstate av, Void_t* mem)
{
  mchunkptr       p;           /* chunk corresponding to mem */
  INTERNAL_SIZE_T size;        /* its size */
  mfastbinptr*    fb;          /* associated fastbin */
  mchunkptr       nextchunk;   /* next contiguous chunk */
  INTERNAL_SIZE_T nextsize;    /* its size */
  int             nextinuse;   /* true if nextchunk is used */
  INTERNAL_SIZE_T prevsize;    /* size of previous contiguous chunk */
  mchunkptr       bck;         /* misc temp for linking */
  mchunkptr       fwd;         /* misc temp for linking */

  const char *errstr = NULL;

  p = mem2chunk(mem);
  size = chunksize(p);

  /* Little security check which won't hurt performance: the
     allocator never wrapps around at the end of the address space.
     Therefore we can exclude some size values which might appear
     here by accident or by "design" from some intruder.  */
  if (__builtin_expect ((uintptr_t) p > (uintptr_t) -size, 0)
      || __builtin_expect (misaligned_chunk (p), 0))
    {
      errstr = "free(): invalid pointer";
    errout:
      malloc_printerr (check_action, errstr, mem);
      return;
    }
  /* We know that each chunk is at least MINSIZE bytes in size.  */
  if (__builtin_expect (size < MINSIZE, 0))
    {
      errstr = "free(): invalid size";
      goto errout;
    }

  check_inuse_chunk(av, p);

  /*
    If eligible, place chunk on a fastbin so it can be found
    and used quickly in malloc.
  */

  if ((unsigned long)(size) <= (unsigned long)(get_max_fast ())

#if TRIM_FASTBINS
      /*
        If TRIM_FASTBINS set, don't place chunks
        bordering top into fastbins
      */
      && (chunk_at_offset(p, size) != av->top)
#endif
      ) {

    if (__builtin_expect (chunk_at_offset (p, size)->size <= 2 * SIZE_SZ, 0)
        || __builtin_expect (chunksize (chunk_at_offset (p, size))
                             >= av->system_mem, 0))
      {
        errstr = "free(): invalid next size (fast)";
        goto errout;
      }

    set_fastchunks(av);
    fb = &(av->fastbins[fastbin_index(size)]);
    /* Another simple check: make sure the top of the bin is not the
       record we are going to add (i.e., double free).  */
    if (__builtin_expect (*fb == p, 0))
      {
        errstr = "double free or corruption (fasttop)";
        goto errout;
      }

    if (__builtin_expect (perturb_byte, 0))
      free_perturb (mem, size - SIZE_SZ);

    p->fd = *fb;
    *fb = p;
  }

  /*
    Consolidate other non-mmapped chunks as they arrive.
  */

  else if (!chunk_is_mmapped(p)) {
    nextchunk = chunk_at_offset(p, size);

    /* Lightweight tests: check whether the block is already the
       top block.  */
    if (__builtin_expect (p == av->top, 0))
      {
        errstr = "double free or corruption (top)";
        goto errout;
      }
    /* Or whether the next chunk is beyond the boundaries of the arena.  */
    if (__builtin_expect (contiguous (av)
                          && (char *) nextchunk
                          >= ((char *) av->top + chunksize(av->top)), 0))
      {
        errstr = "double free or corruption (out)";
        goto errout;
      }
    /* Or whether the block is actually not marked used.  */
    if (__builtin_expect (!prev_inuse(nextchunk), 0))
      {
        errstr = "double free or corruption (!prev)";
        goto errout;
      }

    nextsize = chunksize(nextchunk);
    if (__builtin_expect (nextchunk->size <= 2 * SIZE_SZ, 0)
        || __builtin_expect (nextsize >= av->system_mem, 0))
      {
        errstr = "free(): invalid next size (normal)";
        goto errout;
      }

    if (__builtin_expect (perturb_byte, 0))
      free_perturb (mem, size - SIZE_SZ);

    /* consolidate backward */
    if (!prev_inuse(p)) {
      prevsize = p->prev_size;
      size += prevsize;
      p = chunk_at_offset(p, -((long) prevsize));
      unlink(p, bck, fwd);
    }

    if (nextchunk != av->top) {
      /* get and clear inuse bit */
      nextinuse = inuse_bit_at_offset(nextchunk, nextsize);

      /* consolidate forward */
      if (!nextinuse) {
        unlink(nextchunk, bck, fwd);
        size += nextsize;
      } else
        clear_inuse_bit_at_offset(nextchunk, 0);

      /*
        Place the chunk in unsorted chunk list. Chunks are
        not placed into regular bins until after they have
        been given one chance to be used in malloc.
      */

      bck = unsorted_chunks(av);
      fwd = bck->fd;
      p->fd = fwd;
      p->bk = bck;
      if (!in_smallbin_range(size))
        {
          p->fd_nextsize = NULL;
          p->bk_nextsize = NULL;
        }
      bck->fd = p;
      fwd->bk = p;

      set_head(p, size | PREV_INUSE);
      set_foot(p, size);

      check_free_chunk(av, p);
    }

    /*
      If the chunk borders the current high end of memory,
      consolidate into top
    */

    else {
      size += nextsize;
      set_head(p, size | PREV_INUSE);
      av->top = p;
      check_chunk(av, p);
    }

    /*
      If freeing a large space, consolidate possibly-surrounding
      chunks. Then, if the total unused topmost memory exceeds trim
      threshold, ask malloc_trim to reduce top.

      Unless max_fast is 0, we don't know if there are fastbins
      bordering top, so we cannot tell for sure whether threshold
      has been reached unless fastbins are consolidated.  But we
      don't want to consolidate on each free.  As a compromise,
      consolidation is performed if FASTBIN_CONSOLIDATION_THRESHOLD
      is reached.
    */

    if ((unsigned long)(size) >= FASTBIN_CONSOLIDATION_THRESHOLD) {
      if (have_fastchunks(av))
        malloc_consolidate(av);

      if (av == &main_arena) {
#ifndef MORECORE_CANNOT_TRIM
        if ((unsigned long)(chunksize(av->top)) >=
            (unsigned long)(mp_.trim_threshold))
          sYSTRIm(mp_.top_pad, av);
#endif
      } else {
        /* Always try heap_trim(), even if the top chunk is not
           large, because the corresponding heap might go away.  */
        heap_info *heap = heap_for_ptr(top(av));

        assert(heap->ar_ptr == av);
        heap_trim(heap, mp_.top_pad);
      }
    }

  }
  /*
    If the chunk was allocated via mmap, release via munmap(). Note
    that if HAVE_MMAP is false but chunk_is_mmapped is true, then
    user must have overwritten memory. There's nothing we can do to
    catch this error unless MALLOC_DEBUG is set, in which case
    check_inuse_chunk (above) will have triggered error.
  */

  else {
#if HAVE_MMAP
    munmap_chunk (p);
#endif
  }
}

/*
  ------------------------- malloc_consolidate -------------------------

  malloc_consolidate is a specialized version of free() that tears
  down chunks held in fastbins.  Free itself cannot be used for this
  purpose since, among other things, it might place chunks back onto
  fastbins.  So, instead, we need to use a minor variant of the same
  code.

  Also, because this routine needs to be called the first time through
  malloc anyway, it turns out to be the perfect place to trigger
  initialization code.
*/

#if __STD_C
static void malloc_consolidate(mstate av)
#else
static void malloc_consolidate(av) mstate av;
#endif
{
  mfastbinptr*    fb;                 /* current fastbin being consolidated */
  mfastbinptr*    maxfb;              /* last fastbin (for loop control) */
  mchunkptr       p;                  /* current chunk being consolidated */
  mchunkptr       nextp;              /* next chunk to consolidate */
  mchunkptr       unsorted_bin;       /* bin header */
  mchunkptr       first_unsorted;     /* chunk to link to */

  /* These have same use as in free() */
  mchunkptr       nextchunk;
  INTERNAL_SIZE_T size;
  INTERNAL_SIZE_T nextsize;
  INTERNAL_SIZE_T prevsize;
  int             nextinuse;
  mchunkptr       bck;
  mchunkptr       fwd;

  /*
    If max_fast is 0, we know that av hasn't
    yet been initialized, in which case do so below
  */

  if (get_max_fast () != 0) {
    clear_fastchunks(av);

    unsorted_bin = unsorted_chunks(av);

    /*
      Remove each chunk from fast bin and consolidate it, placing it
      then in unsorted bin. Among other reasons for doing this,
      placing in unsorted bin avoids needing to calculate actual bins
      until malloc is sure that chunks aren't immediately going to be
      reused anyway.
    */

#if 0
    /* It is wrong to limit the fast bins to search using get_max_fast
       because, except for the main arena, all the others might have
       blocks in the high fast bins.  It's not worth it anyway, just
       search all bins all the time.  */
    maxfb = &(av->fastbins[fastbin_index(get_max_fast ())]);
#else
    maxfb = &(av->fastbins[NFASTBINS - 1]);
#endif
    fb = &(av->fastbins[0]);
    do {
      if ( (p = *fb) != 0) {
        *fb = 0;

        do {
          check_inuse_chunk(av, p);
          nextp = p->fd;

          /* Slightly streamlined version of consolidation code in free() */
          size = p->size & ~(PREV_INUSE|NON_MAIN_ARENA);
          nextchunk = chunk_at_offset(p, size);
          nextsize = chunksize(nextchunk);

          if (!prev_inuse(p)) {
            prevsize = p->prev_size;
            size += prevsize;
            p = chunk_at_offset(p, -((long) prevsize));
            unlink(p, bck, fwd);
          }

          if (nextchunk != av->top) {
            nextinuse = inuse_bit_at_offset(nextchunk, nextsize);

            if (!nextinuse) {
              size += nextsize;
              unlink(nextchunk, bck, fwd);
            } else
              clear_inuse_bit_at_offset(nextchunk, 0);

            first_unsorted = unsorted_bin->fd;
            unsorted_bin->fd = p;
            first_unsorted->bk = p;

            if (!in_smallbin_range (size)) {
              p->fd_nextsize = NULL;
              p->bk_nextsize = NULL;
            }

            set_head(p, size | PREV_INUSE);
            p->bk = unsorted_bin;
            p->fd = first_unsorted;
            set_foot(p, size);
          }

          else {
            size += nextsize;
            set_head(p, size | PREV_INUSE);
            av->top = p;
          }

        } while ( (p = nextp) != 0);

      }
    } while (fb++ != maxfb);
  }
  else {
    malloc_init_state(av);
    check_malloc_state(av);
  }
}

/*
  ------------------------------ realloc ------------------------------
*/

Void_t*
_int_realloc(mstate av, Void_t* oldmem, size_t bytes)
{
  INTERNAL_SIZE_T  nb;              /* padded request size */

  mchunkptr        oldp;            /* chunk corresponding to oldmem */
  INTERNAL_SIZE_T  oldsize;         /* its size */

  mchunkptr        newp;            /* chunk to return */
  INTERNAL_SIZE_T  newsize;         /* its size */
  Void_t*          newmem;          /* corresponding user mem */

  mchunkptr        next;            /* next contiguous chunk after oldp */

  mchunkptr        remainder;       /* extra space at end of newp */
  unsigned long    remainder_size;  /* its size */

  mchunkptr        bck;             /* misc temp for linking */
  mchunkptr        fwd;             /* misc temp for linking */

  unsigned long    copysize;        /* bytes to copy */
  unsigned int     ncopies;         /* INTERNAL_SIZE_T words to copy */
  INTERNAL_SIZE_T* s;               /* copy source */
  INTERNAL_SIZE_T* d;               /* copy destination */

  const char *errstr = NULL;


  checked_request2size(bytes, nb);

  oldp    = mem2chunk(oldmem);
  oldsize = chunksize(oldp);

  /* Simple tests for old block integrity.  */
  if (__builtin_expect (misaligned_chunk (oldp), 0))
    {
      errstr = "realloc(): invalid pointer";
    errout:
      malloc_printerr (check_action, errstr, oldmem);
      return NULL;
    }
  if (__builtin_expect (oldp->size <= 2 * SIZE_SZ, 0)
      || __builtin_expect (oldsize >= av->system_mem, 0))
    {
      errstr = "realloc(): invalid old size";
      goto errout;
    }

  check_inuse_chunk(av, oldp);

  if (!chunk_is_mmapped(oldp)) {

    next = chunk_at_offset(oldp, oldsize);
    INTERNAL_SIZE_T nextsize = chunksize(next);
    if (__builtin_expect (next->size <= 2 * SIZE_SZ, 0)
        || __builtin_expect (nextsize >= av->system_mem, 0))
      {
        errstr = "realloc(): invalid next size";
        goto errout;
      }

    if ((unsigned long)(oldsize) >= (unsigned long)(nb)) {
      /* already big enough; split below */
      newp = oldp;
      newsize = oldsize;
    }

    else {
      /* Try to expand forward into top */
      if (next == av->top &&
          (unsigned long)(newsize = oldsize + nextsize) >=
          (unsigned long)(nb + MINSIZE)) {
        set_head_size(oldp, nb | (av != &main_arena ? NON_MAIN_ARENA : 0));
        av->top = chunk_at_offset(oldp, nb);
        set_head(av->top, (newsize - nb) | PREV_INUSE);
        check_inuse_chunk(av, oldp);
        return chunk2mem(oldp);
      }

      /* Try to expand forward into next chunk;  split off remainder below */
      else if (next != av->top &&
               !inuse(next) &&
               (unsigned long)(newsize = oldsize + nextsize) >=
               (unsigned long)(nb)) {
        newp = oldp;
        unlink(next, bck, fwd);
      }

      /* allocate, copy, free */
      else {
        newmem = _int_malloc(av, nb - MALLOC_ALIGN_MASK);
        if (newmem == 0)
          return 0; /* propagate failure */

        newp = mem2chunk(newmem);
        newsize = chunksize(newp);

        /*
          Avoid copy if newp is next chunk after oldp.
        */
        if (newp == next) {
          newsize += oldsize;
          newp = oldp;
        }
        else {
          /*
            Unroll copy of <= 36 bytes (72 if 8byte sizes)
            We know that contents have an odd number of
            INTERNAL_SIZE_T-sized words; minimally 3.
          */

          copysize = oldsize - SIZE_SZ;
          s = (INTERNAL_SIZE_T*)(oldmem);
          d = (INTERNAL_SIZE_T*)(newmem);
          ncopies = copysize / sizeof(INTERNAL_SIZE_T);
          assert(ncopies >= 3);

          if (ncopies > 9)
            MALLOC_COPY(d, s, copysize);

          else {
            *(d+0) = *(s+0);
            *(d+1) = *(s+1);
            *(d+2) = *(s+2);
            if (ncopies > 4) {
              *(d+3) = *(s+3);
              *(d+4) = *(s+4);
              if (ncopies > 6) {
                *(d+5) = *(s+5);
                *(d+6) = *(s+6);
                if (ncopies > 8) {
                  *(d+7) = *(s+7);
                  *(d+8) = *(s+8);
                }
              }
            }
          }

          _int_free(av, oldmem);
          check_inuse_chunk(av, newp);
          return chunk2mem(newp);
        }
      }
    }

    /* If possible, free extra space in old or extended chunk */

    assert((unsigned long)(newsize) >= (unsigned long)(nb));

    remainder_size = newsize - nb;

    if (remainder_size < MINSIZE) { /* not enough extra to split off */
      set_head_size(newp, newsize | (av != &main_arena ? NON_MAIN_ARENA : 0));
      set_inuse_bit_at_offset(newp, newsize);
    }
    else { /* split remainder */
      remainder = chunk_at_offset(newp, nb);
      set_head_size(newp, nb | (av != &main_arena ? NON_MAIN_ARENA : 0));
      set_head(remainder, remainder_size | PREV_INUSE |
               (av != &main_arena ? NON_MAIN_ARENA : 0));
      /* Mark remainder as inuse so free() won't complain */
      set_inuse_bit_at_offset(remainder, remainder_size);
      _int_free(av, chunk2mem(remainder));
    }

    check_inuse_chunk(av, newp);
    return chunk2mem(newp);
  }

  /*
    Handle mmap cases
  */

  else {
#if HAVE_MMAP

#if HAVE_MREMAP
    INTERNAL_SIZE_T offset = oldp->prev_size;
    size_t pagemask = mp_.pagesize - 1;
    char *cp;
    unsigned long sum;

    /* Note the extra SIZE_SZ overhead */
    newsize = (nb + offset + SIZE_SZ + pagemask) & ~pagemask;

    /* don't need to remap if still within same page */
    if (oldsize == newsize - offset)
      return oldmem;

    cp = (char*)mremap((char*)oldp - offset, oldsize + offset, newsize, 1);

    if (cp != MAP_FAILED) {

      newp = (mchunkptr)(cp + offset);
      set_head(newp, (newsize - offset)|IS_MMAPPED);

      assert(aligned_OK(chunk2mem(newp)));
      assert((newp->prev_size == offset));

      /* update statistics */
      sum = mp_.mmapped_mem += newsize - oldsize;
      if (sum > (unsigned long)(mp_.max_mmapped_mem))
        mp_.max_mmapped_mem = sum;
#ifdef NO_THREADS
      sum += main_arena.system_mem;
      if (sum > (unsigned long)(mp_.max_total_mem))
        mp_.max_total_mem = sum;
#endif

      return chunk2mem(newp);
    }
#endif

    /* Note the extra SIZE_SZ overhead. */
    if ((unsigned long)(oldsize) >= (unsigned long)(nb + SIZE_SZ))
      newmem = oldmem; /* do nothing */
    else {
      /* Must alloc, copy, free. */
      newmem = _int_malloc(av, nb - MALLOC_ALIGN_MASK);
      if (newmem != 0) {
        MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
        _int_free(av, oldmem);
      }
    }
    return newmem;

#else
    /* If !HAVE_MMAP, but chunk_is_mmapped, user must have overwritten mem */
    check_malloc_state(av);
    MALLOC_FAILURE_ACTION;
    return 0;
#endif
  }
}

/*
  ------------------------------ memalign ------------------------------
*/

Void_t*
_int_memalign(mstate av, size_t alignment, size_t bytes)
{
  INTERNAL_SIZE_T nb;             /* padded  request size */
  char*           m;              /* memory returned by malloc call */
  mchunkptr       p;              /* corresponding chunk */
  char*           brk;            /* alignment point within p */
  mchunkptr       newp;           /* chunk to return */
  INTERNAL_SIZE_T newsize;        /* its size */
  INTERNAL_SIZE_T leadsize;       /* leading space before alignment point */
  mchunkptr       remainder;      /* spare room at end to split off */
  unsigned long   remainder_size; /* its size */
  INTERNAL_SIZE_T size;

  /* If need less alignment than we give anyway, just relay to malloc */

  if (alignment <= MALLOC_ALIGNMENT) return _int_malloc(av, bytes);

  /* Otherwise, ensure that it is at least a minimum chunk size */

  if (alignment <  MINSIZE) alignment = MINSIZE;

  /* Make sure alignment is power of 2 (in case MINSIZE is not).  */
  if ((alignment & (alignment - 1)) != 0) {
    size_t a = MALLOC_ALIGNMENT * 2;
    while ((unsigned long)a < (unsigned long)alignment) a <<= 1;
    alignment = a;
  }

  checked_request2size(bytes, nb);

  /*
    Strategy: find a spot within that chunk that meets the alignment
    request, and then possibly free the leading and trailing space.
  */


  /* Call malloc with worst case padding to hit alignment. */

  m  = (char*)(_int_malloc(av, nb + alignment + MINSIZE));

  if (m == 0) return 0; /* propagate failure */

  p = mem2chunk(m);

  if ((((unsigned long)(m)) % alignment) != 0) { /* misaligned */

    /*
      Find an aligned spot inside chunk.  Since we need to give back
      leading space in a chunk of at least MINSIZE, if the first
      calculation places us at a spot with less than MINSIZE leader,
      we can move to the next aligned spot -- we've allocated enough
      total room so that this is always possible.
    */

    brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) &
                           -((signed long) alignment));
    if ((unsigned long)(brk - (char*)(p)) < MINSIZE)
      brk += alignment;

    newp = (mchunkptr)brk;
    leadsize = brk - (char*)(p);
    newsize = chunksize(p) - leadsize;

    /* For mmapped chunks, just adjust offset */
    if (chunk_is_mmapped(p)) {
      newp->prev_size = p->prev_size + leadsize;
      set_head(newp, newsize|IS_MMAPPED);
      return chunk2mem(newp);
    }

    /* Otherwise, give back leader, use the rest */
    set_head(newp, newsize | PREV_INUSE |
             (av != &main_arena ? NON_MAIN_ARENA : 0));
    set_inuse_bit_at_offset(newp, newsize);
    set_head_size(p, leadsize | (av != &main_arena ? NON_MAIN_ARENA : 0));
    _int_free(av, chunk2mem(p));
    p = newp;

    assert (newsize >= nb &&
            (((unsigned long)(chunk2mem(p))) % alignment) == 0);
  }

  /* Also give back spare room at the end */
  if (!chunk_is_mmapped(p)) {
    size = chunksize(p);
    if ((unsigned long)(size) > (unsigned long)(nb + MINSIZE)) {
      remainder_size = size - nb;
      remainder = chunk_at_offset(p, nb);
      set_head(remainder, remainder_size | PREV_INUSE |
               (av != &main_arena ? NON_MAIN_ARENA : 0));
      set_head_size(p, nb);
      _int_free(av, chunk2mem(remainder));
    }
  }

  check_inuse_chunk(av, p);
  return chunk2mem(p);
}

#if 0
/*
  ------------------------------ calloc ------------------------------
*/

#if __STD_C
Void_t* cALLOc(size_t n_elements, size_t elem_size)
#else
Void_t* cALLOc(n_elements, elem_size) size_t n_elements; size_t elem_size;
#endif
{
  mchunkptr p;
  unsigned long clearsize;
  unsigned long nclears;
  INTERNAL_SIZE_T* d;

  Void_t* mem = mALLOc(n_elements * elem_size);

  if (mem != 0) {
    p = mem2chunk(mem);

#if MMAP_CLEARS
    if (!chunk_is_mmapped(p)) /* don't need to clear mmapped space */
#endif
    {
      /*
        Unroll clear of <= 36 bytes (72 if 8byte sizes)
        We know that contents have an odd number of
        INTERNAL_SIZE_T-sized words; minimally 3.
      */

      d = (INTERNAL_SIZE_T*)mem;
      clearsize = chunksize(p) - SIZE_SZ;
      nclears = clearsize / sizeof(INTERNAL_SIZE_T);
      assert(nclears >= 3);

      if (nclears > 9)
        MALLOC_ZERO(d, clearsize);

      else {
        *(d+0) = 0;
        *(d+1) = 0;
        *(d+2) = 0;
        if (nclears > 4) {
          *(d+3) = 0;
          *(d+4) = 0;
          if (nclears > 6) {
            *(d+5) = 0;
            *(d+6) = 0;
            if (nclears > 8) {
              *(d+7) = 0;
              *(d+8) = 0;
            }
          }
        }
      }
    }
  }
  return mem;
}
#endif /* 0 */

#ifndef _LIBC
/*
  ------------------------- independent_calloc -------------------------
*/

Void_t**
#if __STD_C
_int_icalloc(mstate av, size_t n_elements, size_t elem_size, Void_t* chunks[])
#else
_int_icalloc(av, n_elements, elem_size, chunks)
mstate av; size_t n_elements; size_t elem_size; Void_t* chunks[];
#endif
{
  size_t sz = elem_size; /* serves as 1-element array */
  /* opts arg of 3 means all elements are same size, and should be cleared */
  return iALLOc(av, n_elements, &sz, 3, chunks);
}

/*
  ------------------------- independent_comalloc -------------------------
*/

Void_t**
#if __STD_C
_int_icomalloc(mstate av, size_t n_elements, size_t sizes[], Void_t* chunks[])
#else
_int_icomalloc(av, n_elements, sizes, chunks)
mstate av; size_t n_elements; size_t sizes[]; Void_t* chunks[];
#endif
{
  return iALLOc(av, n_elements, sizes, 0, chunks);
}


/*
  ------------------------------ ialloc ------------------------------
  ialloc provides common support for independent_X routines, handling all of
  the combinations that can result.

  The opts arg has:
    bit 0 set if all elements are same size (using sizes[0])
    bit 1 set if elements should be zeroed
*/


static Void_t**
#if __STD_C
iALLOc(mstate av, size_t n_elements, size_t* sizes, int opts, Void_t* chunks[])
#else
iALLOc(av, n_elements, sizes, opts, chunks)
mstate av; size_t n_elements; size_t* sizes; int opts; Void_t* chunks[];
#endif
{
  INTERNAL_SIZE_T element_size;   /* chunksize of each element, if all same */
  INTERNAL_SIZE_T contents_size;  /* total size of elements */
  INTERNAL_SIZE_T array_size;     /* request size of pointer array */
  Void_t*         mem;            /* malloced aggregate space */
  mchunkptr       p;              /* corresponding chunk */
  INTERNAL_SIZE_T remainder_size; /* remaining bytes while splitting */
  Void_t**        marray;         /* either "chunks" or malloced ptr array */
  mchunkptr       array_chunk;    /* chunk for malloced ptr array */
  int             mmx;            /* to disable mmap */
  INTERNAL_SIZE_T size;
  INTERNAL_SIZE_T size_flags;
  size_t          i;

  /* Ensure initialization/consolidation */
  if (have_fastchunks(av)) malloc_consolidate(av);

  /* compute array length, if needed */
  if (chunks != 0) {
    if (n_elements == 0)
      return chunks; /* nothing to do */
    marray = chunks;
    array_size = 0;
  }
  else {
    /* if empty req, must still return chunk representing empty array */
    if (n_elements == 0)
      return (Void_t**) _int_malloc(av, 0);
    marray = 0;
    array_size = request2size(n_elements * (sizeof(Void_t*)));
  }

  /* compute total element size */
  if (opts & 0x1) { /* all-same-size */
    element_size = request2size(*sizes);
    contents_size = n_elements * element_size;
  }
  else { /* add up all the sizes */
    element_size = 0;
    contents_size = 0;
    for (i = 0; i != n_elements; ++i)
      contents_size += request2size(sizes[i]);
  }

  /* subtract out alignment bytes from total to minimize overallocation */
  size = contents_size + array_size - MALLOC_ALIGN_MASK;

  /*
     Allocate the aggregate chunk.
     But first disable mmap so malloc won't use it, since
     we would not be able to later free/realloc space internal
     to a segregated mmap region.
  */
  mmx = mp_.n_mmaps_max;   /* disable mmap */
  mp_.n_mmaps_max = 0;
  mem = _int_malloc(av, size);
  mp_.n_mmaps_max = mmx;   /* reset mmap */
  if (mem == 0)
    return 0;

  p = mem2chunk(mem);
  assert(!chunk_is_mmapped(p));
  remainder_size = chunksize(p);

  if (opts & 0x2) {       /* optionally clear the elements */
    MALLOC_ZERO(mem, remainder_size - SIZE_SZ - array_size);
  }

  size_flags = PREV_INUSE | (av != &main_arena ? NON_MAIN_ARENA : 0);

  /* If not provided, allocate the pointer array as final part of chunk */
  if (marray == 0) {
    array_chunk = chunk_at_offset(p, contents_size);
    marray = (Void_t**) (chunk2mem(array_chunk));
    set_head(array_chunk, (remainder_size - contents_size) | size_flags);
    remainder_size = contents_size;
  }

  /* split out elements */
  for (i = 0; ; ++i) {
    marray[i] = chunk2mem(p);
    if (i != n_elements-1) {
      if (element_size != 0)
        size = element_size;
      else
        size = request2size(sizes[i]);
      remainder_size -= size;
      set_head(p, size | size_flags);
      p = chunk_at_offset(p, size);
    }
    else { /* the final element absorbs any overallocation slop */
      set_head(p, remainder_size | size_flags);
      break;
    }
  }

#if MALLOC_DEBUG
  if (marray != chunks) {
    /* final element must have exactly exhausted chunk */
    if (element_size != 0)
      assert(remainder_size == element_size);
    else
      assert(remainder_size == request2size(sizes[i]));
    check_inuse_chunk(av, mem2chunk(marray));
  }

  for (i = 0; i != n_elements; ++i)
    check_inuse_chunk(av, mem2chunk(marray[i]));
#endif

  return marray;
}
#endif /* _LIBC */


/*
  ------------------------------ valloc ------------------------------
*/

Void_t*
#if __STD_C
_int_valloc(mstate av, size_t bytes)
#else
_int_valloc(av, bytes) mstate av; size_t bytes;
#endif
{
  /* Ensure initialization/consolidation */
  if (have_fastchunks(av)) malloc_consolidate(av);
  return _int_memalign(av, mp_.pagesize, bytes);
}

/*
  ------------------------------ pvalloc ------------------------------
*/


Void_t*
#if __STD_C
_int_pvalloc(mstate av, size_t bytes)
#else
_int_pvalloc(av, bytes) mstate av, size_t bytes;
#endif
{
  size_t pagesz;

  /* Ensure initialization/consolidation */
  if (have_fastchunks(av)) malloc_consolidate(av);
  pagesz = mp_.pagesize;
  return _int_memalign(av, pagesz, (bytes + pagesz - 1) & ~(pagesz - 1));
}


/*
  ------------------------------ malloc_trim ------------------------------
*/

#if __STD_C
int mTRIm(size_t pad)
#else
int mTRIm(pad) size_t pad;
#endif
{
  mstate av = &main_arena; /* already locked */

  /* Ensure initialization/consolidation */
  malloc_consolidate(av);

#ifndef MORECORE_CANNOT_TRIM
  return sYSTRIm(pad, av);
#else
  return 0;
#endif
}


/*
  ------------------------- malloc_usable_size -------------------------
*/

#if __STD_C
size_t mUSABLe(Void_t* mem)
#else
size_t mUSABLe(mem) Void_t* mem;
#endif
{
  mchunkptr p;
  if (mem != 0) {
    p = mem2chunk(mem);
    if (chunk_is_mmapped(p))
      return chunksize(p) - 2*SIZE_SZ;
    else if (inuse(p))
      return chunksize(p) - SIZE_SZ;
  }
  return 0;
}

/*
  ------------------------------ mallinfo ------------------------------
*/

struct mallinfo mALLINFo(mstate av)
{
  struct mallinfo mi;
  size_t i;
  mbinptr b;
  mchunkptr p;
  INTERNAL_SIZE_T avail;
  INTERNAL_SIZE_T fastavail;
  int nblocks;
  int nfastblocks;

  /* Ensure initialization */
  if (av->top == 0)  malloc_consolidate(av);

  check_malloc_state(av);

  /* Account for top */
  avail = chunksize(av->top);
  nblocks = 1;  /* top always exists */

  /* traverse fastbins */
  nfastblocks = 0;
  fastavail = 0;

  for (i = 0; i < NFASTBINS; ++i) {
    for (p = av->fastbins[i]; p != 0; p = p->fd) {
      ++nfastblocks;
      fastavail += chunksize(p);
    }
  }

  avail += fastavail;

  /* traverse regular bins */
  for (i = 1; i < NBINS; ++i) {
    b = bin_at(av, i);
    for (p = last(b); p != b; p = p->bk) {
      ++nblocks;
      avail += chunksize(p);
    }
  }

  mi.smblks = nfastblocks;
  mi.ordblks = nblocks;
  mi.fordblks = avail;
  mi.uordblks = av->system_mem - avail;
  mi.arena = av->system_mem;
  mi.hblks = mp_.n_mmaps;
  mi.hblkhd = mp_.mmapped_mem;
  mi.fsmblks = fastavail;
  mi.keepcost = chunksize(av->top);
  mi.usmblks = mp_.max_total_mem;
  return mi;
}

/*
  ------------------------------ malloc_stats ------------------------------
*/

void mSTATs()
{
  int i;
  mstate ar_ptr;
  struct mallinfo mi;
  unsigned int in_use_b = mp_.mmapped_mem, system_b = in_use_b;
#if THREAD_STATS
  long stat_lock_direct = 0, stat_lock_loop = 0, stat_lock_wait = 0;
#endif

  if(__malloc_initialized < 0)
    ptmalloc_init ();
#ifdef _LIBC
  _IO_flockfile (stderr);
  int old_flags2 = ((_IO_FILE *) stderr)->_flags2;
  ((_IO_FILE *) stderr)->_flags2 |= _IO_FLAGS2_NOTCANCEL;
#endif
  for (i=0, ar_ptr = &main_arena;; i++) {
    (void)mutex_lock(&ar_ptr->mutex);
    mi = mALLINFo(ar_ptr);
    fprintf(stderr, "Arena %d:\n", i);
    fprintf(stderr, "system bytes     = %10u\n", (unsigned int)mi.arena);
    fprintf(stderr, "in use bytes     = %10u\n", (unsigned int)mi.uordblks);
#if MALLOC_DEBUG > 1
    if (i > 0)
      dump_heap(heap_for_ptr(top(ar_ptr)));
#endif
    system_b += mi.arena;
    in_use_b += mi.uordblks;
#if THREAD_STATS
    stat_lock_direct += ar_ptr->stat_lock_direct;
    stat_lock_loop += ar_ptr->stat_lock_loop;
    stat_lock_wait += ar_ptr->stat_lock_wait;
#endif
    (void)mutex_unlock(&ar_ptr->mutex);
    ar_ptr = ar_ptr->next;
    if(ar_ptr == &main_arena) break;
  }
#if HAVE_MMAP
  fprintf(stderr, "Total (incl. mmap):\n");
#else
  fprintf(stderr, "Total:\n");
#endif
  fprintf(stderr, "system bytes     = %10u\n", system_b);
  fprintf(stderr, "in use bytes     = %10u\n", in_use_b);
#ifdef NO_THREADS
  fprintf(stderr, "max system bytes = %10u\n", (unsigned int)mp_.max_total_mem);
#endif
#if HAVE_MMAP
  fprintf(stderr, "max mmap regions = %10u\n", (unsigned int)mp_.max_n_mmaps);
  fprintf(stderr, "max mmap bytes   = %10lu\n",
          (unsigned long)mp_.max_mmapped_mem);
#endif
#if THREAD_STATS
  fprintf(stderr, "heaps created    = %10d\n",  stat_n_heaps);
  fprintf(stderr, "locked directly  = %10ld\n", stat_lock_direct);
  fprintf(stderr, "locked in loop   = %10ld\n", stat_lock_loop);
  fprintf(stderr, "locked waiting   = %10ld\n", stat_lock_wait);
  fprintf(stderr, "locked total     = %10ld\n",
          stat_lock_direct + stat_lock_loop + stat_lock_wait);
#endif
#ifdef _LIBC
  ((_IO_FILE *) stderr)->_flags2 |= old_flags2;
  _IO_funlockfile (stderr);
#endif
}


/*
  ------------------------------ mallopt ------------------------------
*/

#if __STD_C
int mALLOPt(int param_number, int value)
#else
int mALLOPt(param_number, value) int param_number; int value;
#endif
{
  mstate av = &main_arena;
  int res = 1;

  if(__malloc_initialized < 0)
    ptmalloc_init ();
  (void)mutex_lock(&av->mutex);
  /* Ensure initialization/consolidation */
  malloc_consolidate(av);

  switch(param_number) {
  case M_MXFAST:
    if (value >= 0 && value <= MAX_FAST_SIZE) {
      set_max_fast(value);
    }
    else
      res = 0;
    break;

  case M_TRIM_THRESHOLD:
    mp_.trim_threshold = value;
    mp_.no_dyn_threshold = 1;
    break;

  case M_TOP_PAD:
    mp_.top_pad = value;
    mp_.no_dyn_threshold = 1;
    break;

  case M_MMAP_THRESHOLD:
#if USE_ARENAS
    /* Forbid setting the threshold too high. */
    if((unsigned long)value > HEAP_MAX_SIZE/2)
      res = 0;
    else
#endif
      mp_.mmap_threshold = value;
      mp_.no_dyn_threshold = 1;
    break;

  case M_MMAP_MAX:
#if !HAVE_MMAP
    if (value != 0)
      res = 0;
    else
#endif
      mp_.n_mmaps_max = value;
      mp_.no_dyn_threshold = 1;
    break;

  case M_CHECK_ACTION:
    check_action = value;
    break;

  case M_PERTURB:
    perturb_byte = value;
    break;
  }
  (void)mutex_unlock(&av->mutex);
  return res;
}


/*
  -------------------- Alternative MORECORE functions --------------------
*/


/*
  General Requirements for MORECORE.

  The MORECORE function must have the following properties:

  If MORECORE_CONTIGUOUS is false:

    * MORECORE must allocate in multiples of pagesize. It will
      only be called with arguments that are multiples of pagesize.

    * MORECORE(0) must return an address that is at least
      MALLOC_ALIGNMENT aligned. (Page-aligning always suffices.)

  else (i.e. If MORECORE_CONTIGUOUS is true):

    * Consecutive calls to MORECORE with positive arguments
      return increasing addresses, indicating that space has been
      contiguously extended.

    * MORECORE need not allocate in multiples of pagesize.
      Calls to MORECORE need not have args of multiples of pagesize.

    * MORECORE need not page-align.

  In either case:

    * MORECORE may allocate more memory than requested. (Or even less,
      but this will generally result in a malloc failure.)

    * MORECORE must not allocate memory when given argument zero, but
      instead return one past the end address of memory from previous
      nonzero call. This malloc does NOT call MORECORE(0)
      until at least one call with positive arguments is made, so
      the initial value returned is not important.

    * Even though consecutive calls to MORECORE need not return contiguous
      addresses, it must be OK for malloc'ed chunks to span multiple
      regions in those cases where they do happen to be contiguous.

    * MORECORE need not handle negative arguments -- it may instead
      just return MORECORE_FAILURE when given negative arguments.
      Negative arguments are always multiples of pagesize. MORECORE
      must not misinterpret negative args as large positive unsigned
      args. You can suppress all such calls from even occurring by defining
      MORECORE_CANNOT_TRIM,

  There is some variation across systems about the type of the
  argument to sbrk/MORECORE. If size_t is unsigned, then it cannot
  actually be size_t, because sbrk supports negative args, so it is
  normally the signed type of the same width as size_t (sometimes
  declared as "intptr_t", and sometimes "ptrdiff_t").  It doesn't much
  matter though. Internally, we use "long" as arguments, which should
  work across all reasonable possibilities.

  Additionally, if MORECORE ever returns failure for a positive
  request, and HAVE_MMAP is true, then mmap is used as a noncontiguous
  system allocator. This is a useful backup strategy for systems with
  holes in address spaces -- in this case sbrk cannot contiguously
  expand the heap, but mmap may be able to map noncontiguous space.

  If you'd like mmap to ALWAYS be used, you can define MORECORE to be
  a function that always returns MORECORE_FAILURE.

  If you are using this malloc with something other than sbrk (or its
  emulation) to supply memory regions, you probably want to set
  MORECORE_CONTIGUOUS as false.  As an example, here is a custom
  allocator kindly contributed for pre-OSX macOS.  It uses virtually
  but not necessarily physically contiguous non-paged memory (locked
  in, present and won't get swapped out).  You can use it by
  uncommenting this section, adding some #includes, and setting up the
  appropriate defines above:

      #define MORECORE osMoreCore
      #define MORECORE_CONTIGUOUS 0

  There is also a shutdown routine that should somehow be called for
  cleanup upon program exit.

  #define MAX_POOL_ENTRIES 100
  #define MINIMUM_MORECORE_SIZE  (64 * 1024)
  static int next_os_pool;
  void *our_os_pools[MAX_POOL_ENTRIES];

  void *osMoreCore(int size)
  {
    void *ptr = 0;
    static void *sbrk_top = 0;

    if (size > 0)
    {
      if (size < MINIMUM_MORECORE_SIZE)
         size = MINIMUM_MORECORE_SIZE;
      if (CurrentExecutionLevel() == kTaskLevel)
         ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
      if (ptr == 0)
      {
        return (void *) MORECORE_FAILURE;
      }
      // save ptrs so they can be freed during cleanup
      our_os_pools[next_os_pool] = ptr;
      next_os_pool++;
      ptr = (void *) ((((unsigned long) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);
      sbrk_top = (char *) ptr + size;
      return ptr;
    }
    else if (size < 0)
    {
      // we don't currently support shrink behavior
      return (void *) MORECORE_FAILURE;
    }
    else
    {
      return sbrk_top;
    }
  }

  // cleanup any allocated memory pools
  // called as last thing before shutting down driver

  void osCleanupMem(void)
  {
    void **ptr;

    for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
      if (*ptr)
      {
         PoolDeallocate(*ptr);
         *ptr = 0;
      }
  }

*/


/* Helper code.  */

extern char **__libc_argv attribute_hidden;

static void
malloc_printerr(int action, const char *str, void *ptr)
{
  if ((action & 5) == 5)
    __libc_message (action & 2, "%s\n", str);
  else if (action & 1)
    {
      char buf[2 * sizeof (uintptr_t) + 1];

      buf[sizeof (buf) - 1] = '\0';
      char *cp = _itoa_word ((uintptr_t) ptr, &buf[sizeof (buf) - 1], 16, 0);
      while (cp > buf)
        *--cp = '0';

      __libc_message (action & 2,
                      "*** glibc detected *** %s: %s: 0x%s ***\n",
                      __libc_argv[0] ?: "<unknown>", str, cp);
    }
  else if (action & 2)
    abort ();
}

#ifdef _LIBC
# include <sys/param.h>

/* We need a wrapper function for one of the additions of POSIX.  */
int
__posix_memalign (void **memptr, size_t alignment, size_t size)
{
  void *mem;
  __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
                                        __const __malloc_ptr_t)) =
    __memalign_hook;

  /* Test whether the SIZE argument is valid.  It must be a power of
     two multiple of sizeof (void *).  */
  if (alignment % sizeof (void *) != 0
      || !powerof2 (alignment / sizeof (void *)) != 0
      || alignment == 0)
    return EINVAL;

  /* Call the hook here, so that caller is posix_memalign's caller
     and not posix_memalign itself.  */
  if (hook != NULL)
    mem = (*hook)(alignment, size, RETURN_ADDRESS (0));
  else
    mem = public_mEMALIGn (alignment, size);

  if (mem != NULL) {
    *memptr = mem;
    return 0;
  }

  return ENOMEM;
}
weak_alias (__posix_memalign, posix_memalign)

strong_alias (__libc_calloc, __calloc) weak_alias (__libc_calloc, calloc)
strong_alias (__libc_free, __cfree) weak_alias (__libc_free, cfree)
strong_alias (__libc_free, __free) strong_alias (__libc_free, free)
strong_alias (__libc_malloc, __malloc) strong_alias (__libc_malloc, malloc)
strong_alias (__libc_memalign, __memalign)
weak_alias (__libc_memalign, memalign)
strong_alias (__libc_realloc, __realloc) strong_alias (__libc_realloc, realloc)
strong_alias (__libc_valloc, __valloc) weak_alias (__libc_valloc, valloc)
strong_alias (__libc_pvalloc, __pvalloc) weak_alias (__libc_pvalloc, pvalloc)
strong_alias (__libc_mallinfo, __mallinfo)
weak_alias (__libc_mallinfo, mallinfo)
strong_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)

weak_alias (__malloc_stats, malloc_stats)
weak_alias (__malloc_usable_size, malloc_usable_size)
weak_alias (__malloc_trim, malloc_trim)
weak_alias (__malloc_get_state, malloc_get_state)
weak_alias (__malloc_set_state, malloc_set_state)

#endif /* _LIBC */

/* ------------------------------------------------------------
History:

[see ftp://g.oswego.edu/pub/misc/malloc.c for the history of dlmalloc]

*/
/*
 * Local variables:
 * c-basic-offset: 2
 * End:
 */