lib/eealloc.h

   1 /* Memory allocation with expensive empty allocations.
   2    Copyright (C) 2003, 2008, 2010-2024 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2003,
   4    based on prior work by Jim Meyering.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation, either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _EEALLOC_H
  20 #define _EEALLOC_H
  21
  22 /* malloc() and realloc() are allowed to return NULL when asked to allocate
  23    a memory block of 0 bytes; this is not an out-of-memory condition.
  24    (See ISO C 99 section 7.20.3.)  In some places, this is not welcome,
  25    because it requires extra checking (so as not to confuse a zero-sized
  26    allocation with an out-of-memory condition).  This file provides
  27    malloc()/realloc() workalikes which return non-NULL pointers for
  28    succeeding zero-sized allocations.  GNU libc already defines malloc()
  29    and realloc() this way; on such platforms the workalikes are aliased
  30    to the original malloc()/realloc() functions.  */
  31
  32 /* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE, _GL_ATTRIBUTE_ALLOC_SIZE,
  33    _GL_ATTRIBUTE_MALLOC.  */
  34 #if !_GL_CONFIG_H_INCLUDED
  35  #error "Please include config.h first."
  36 #endif
  37
  38 #include <stdlib.h>
  39 #if defined __CHERI_PURE_CAPABILITY__
  40 # include <cheri.h>
  41 #endif
  42
  43 _GL_INLINE_HEADER_BEGIN
  44 #ifndef EEALLOC_INLINE
  45 # define EEALLOC_INLINE _GL_INLINE
  46 #endif
  47
  48 #if MALLOC_0_IS_NONNULL
  49 # define eemalloc malloc
  50 #else
  51 EEALLOC_INLINE void *eemalloc (size_t n)
  52      _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((1))
  53      _GL_ATTRIBUTE_DEALLOC_FREE;
  54 EEALLOC_INLINE void *
  55 eemalloc (size_t n)
  56 {
  57   /* If n is zero, allocate a 1-byte block.  */
  58   size_t nx = n;
  59   if (n == 0)
  60     nx = 1;
  61   void *ptr = malloc (nx);
  62 # if defined __CHERI_PURE_CAPABILITY__
  63   if (ptr != NULL)
  64     ptr = cheri_bounds_set (ptr, n);
  65 # endif
  66   return ptr;
  67 }
  68 #endif
  69
  70 #if REALLOC_0_IS_NONNULL
  71 # define eerealloc realloc
  72 #else
  73 EEALLOC_INLINE void *eerealloc (void *p, size_t n)
  74      _GL_ATTRIBUTE_ALLOC_SIZE ((2));
  75 EEALLOC_INLINE void *
  76 eerealloc (void *p, size_t n)
  77 {
  78   /* If n is zero, allocate or keep a 1-byte block.  */
  79   size_t nx = n;
  80   if (n == 0)
  81     nx = 1;
  82   void *ptr = realloc (p, nx);
  83 # if defined __CHERI_PURE_CAPABILITY__
  84   if (ptr != NULL)
  85     ptr = cheri_bounds_set (ptr, n);
  86 # endif
  87   return ptr;
  88 }
  89 #endif
  90
  91 /* Maybe we should also define variants
  92     eenmalloc (size_t n, size_t s) - behaves like eemalloc (n * s)
  93     eezalloc (size_t n) - like eemalloc followed by memset 0
  94     eecalloc (size_t n, size_t s) - like eemalloc (n * s) followed by memset 0
  95     eenrealloc (void *p, size_t n, size_t s) - like eerealloc (p, n * s)
  96    If this would be useful in your application. please speak up.  */
  97
  98 _GL_INLINE_HEADER_END
  99
 100 #endif /* _EEALLOC_H */