malloc/obstack.c

   1 /* obstack.c - subroutines used implicitly by object stack macros
   2    Copyright (C) 1988-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #ifdef _LIBC
  25 # include <obstack.h>
  26 # include <shlib-compat.h>
  27 #else
  28 # include "obstack.h"
  29 #endif
  30
  31 /* NOTE BEFORE MODIFYING THIS FILE: This version number must be
  32    incremented whenever callers compiled using an old obstack.h can no
  33    longer properly call the functions in this obstack.c.  */
  34 #define OBSTACK_INTERFACE_VERSION 1
  35
  36 /* Comment out all this code if we are using the GNU C Library, and are not
  37    actually compiling the library itself, and the installed library
  38    supports the same library interface we do.  This code is part of the GNU
  39    C Library, but also included in many other GNU distributions.  Compiling
  40    and linking in this code is a waste when using the GNU C library
  41    (especially if it is a shared library).  Rather than having every GNU
  42    program understand `configure --with-gnu-libc' and omit the object
  43    files, it is simpler to just do this in the source for each such file.  */
  44
  45 #include <stdio.h>              /* Random thing to get __GNU_LIBRARY__.  */
  46 #if !defined _LIBC && defined __GNU_LIBRARY__ && __GNU_LIBRARY__ > 1
  47 # include <gnu-versions.h>
  48 # if _GNU_OBSTACK_INTERFACE_VERSION == OBSTACK_INTERFACE_VERSION
  49 #  define ELIDE_CODE
  50 # endif
  51 #endif
  52
  53 #include <stddef.h>
  54
  55 #ifndef ELIDE_CODE
  56
  57
  58 # if HAVE_INTTYPES_H
  59 #  include <inttypes.h>
  60 # endif
  61 # if HAVE_STDINT_H || defined _LIBC
  62 #  include <stdint.h>
  63 # endif
  64
  65 /* Determine default alignment.  */
  66 union fooround
  67 {
  68   uintmax_t i;
  69   long double d;
  70   void *p;
  71 };
  72 struct fooalign
  73 {
  74   char c;
  75   union fooround u;
  76 };
  77 /* If malloc were really smart, it would round addresses to DEFAULT_ALIGNMENT.
  78    But in fact it might be less smart and round addresses to as much as
  79    DEFAULT_ROUNDING.  So we prepare for it to do that.  */
  80 enum
  81 {
  82   DEFAULT_ALIGNMENT = offsetof (struct fooalign, u),
  83   DEFAULT_ROUNDING = sizeof (union fooround)
  84 };
  85
  86 /* When we copy a long block of data, this is the unit to do it with.
  87    On some machines, copying successive ints does not work;
  88    in such a case, redefine COPYING_UNIT to `long' (if that works)
  89    or `char' as a last resort.  */
  90 # ifndef COPYING_UNIT
  91 #  define COPYING_UNIT int
  92 # endif
  93
  94
  95 /* The functions allocating more room by calling `obstack_chunk_alloc'
  96    jump to the handler pointed to by `obstack_alloc_failed_handler'.
  97    This can be set to a user defined function which should either
  98    abort gracefully or use longjump - but shouldn't return.  This
  99    variable by default points to the internal function
 100    `print_and_abort'.  */
 101 static void print_and_abort (void);
 102 void (*obstack_alloc_failed_handler) (void) = print_and_abort;
 103
 104 /* Exit value used when `print_and_abort' is used.  */
 105 # include <stdlib.h>
 106 # ifdef _LIBC
 107 int obstack_exit_failure = EXIT_FAILURE;
 108 # else
 109 #  include "exitfail.h"
 110 #  define obstack_exit_failure exit_failure
 111 # endif
 112
 113 # ifdef _LIBC
 114 #  if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_3_4)
 115 /* A looong time ago (before 1994, anyway; we're not sure) this global variable
 116    was used by non-GNU-C macros to avoid multiple evaluation.  The GNU C
 117    library still exports it because somebody might use it.  */
 118 struct obstack *_obstack_compat = 0;
 119 compat_symbol (libc, _obstack_compat, _obstack, GLIBC_2_0);
 120 #  endif
 121 # endif
 122
 123 /* Define a macro that either calls functions with the traditional malloc/free
 124    calling interface, or calls functions with the mmalloc/mfree interface
 125    (that adds an extra first argument), based on the state of use_extra_arg.
 126    For free, do not use ?:, since some compilers, like the MIPS compilers,
 127    do not allow (expr) ? void : void.  */
 128
 129 # define CALL_CHUNKFUN(h, size) \
 130   (((h)->use_extra_arg)                                                       \
 131    ? (*(h)->chunkfun)((h)->extra_arg, (size))                                 \
 132    : (*(struct _obstack_chunk *(*)(long))(h)->chunkfun)((size)))
 133
 134 # define CALL_FREEFUN(h, old_chunk) \
 135   do { \
 136       if ((h)->use_extra_arg)                                                 \
 137         (*(h)->freefun)((h)->extra_arg, (old_chunk));                         \
 138       else                                                                    \
 139         (*(void (*)(void *))(h)->freefun)((old_chunk));                       \
 140     } while (0)
 141
 142
 143 /* Initialize an obstack H for use.  Specify chunk size SIZE (0 means default).
 144    Objects start on multiples of ALIGNMENT (0 means use default).
 145    CHUNKFUN is the function to use to allocate chunks,
 146    and FREEFUN the function to free them.
 147
 148    Return nonzero if successful, calls obstack_alloc_failed_handler if
 149    allocation fails.  */
 150
 151 int
 152 _obstack_begin (struct obstack *h,
 153                 int size, int alignment,
 154                 void *(*chunkfun)(long),
 155                 void (*freefun)(void *))
 156 {
 157   struct _obstack_chunk *chunk; /* points to new chunk */
 158
 159   if (alignment == 0)
 160     alignment = DEFAULT_ALIGNMENT;
 161   if (size == 0)
 162   /* Default size is what GNU malloc can fit in a 4096-byte block.  */
 163     {
 164       /* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
 165          Use the values for range checking, because if range checking is off,
 166          the extra bytes won't be missed terribly, but if range checking is on
 167          and we used a larger request, a whole extra 4096 bytes would be
 168          allocated.
 169
 170          These number are irrelevant to the new GNU malloc.  I suspect it is
 171          less sensitive to the size of the request.  */
 172       int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
 173                     + 4 + DEFAULT_ROUNDING - 1)
 174                    & ~(DEFAULT_ROUNDING - 1));
 175       size = 4096 - extra;
 176     }
 177
 178   h->chunkfun = (struct _obstack_chunk * (*)(void *, long))chunkfun;
 179   h->freefun = (void (*)(void *, struct _obstack_chunk *))freefun;
 180   h->chunk_size = size;
 181   h->alignment_mask = alignment - 1;
 182   h->use_extra_arg = 0;
 183
 184   chunk = h->chunk = CALL_CHUNKFUN (h, h->chunk_size);
 185   if (!chunk)
 186     (*obstack_alloc_failed_handler)();
 187   h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
 188                                                alignment - 1);
 189   h->chunk_limit = chunk->limit
 190                      = (char *) chunk + h->chunk_size;
 191   chunk->prev = 0;
 192   /* The initial chunk now contains no empty object.  */
 193   h->maybe_empty_object = 0;
 194   h->alloc_failed = 0;
 195   return 1;
 196 }
 197
 198 int
 199 _obstack_begin_1 (struct obstack *h, int size, int alignment,
 200                   void *(*chunkfun)(void *, long),
 201                   void (*freefun)(void *, void *),
 202                   void *arg)
 203 {
 204   struct _obstack_chunk *chunk; /* points to new chunk */
 205
 206   if (alignment == 0)
 207     alignment = DEFAULT_ALIGNMENT;
 208   if (size == 0)
 209   /* Default size is what GNU malloc can fit in a 4096-byte block.  */
 210     {
 211       /* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
 212          Use the values for range checking, because if range checking is off,
 213          the extra bytes won't be missed terribly, but if range checking is on
 214          and we used a larger request, a whole extra 4096 bytes would be
 215          allocated.
 216
 217          These number are irrelevant to the new GNU malloc.  I suspect it is
 218          less sensitive to the size of the request.  */
 219       int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
 220                     + 4 + DEFAULT_ROUNDING - 1)
 221                    & ~(DEFAULT_ROUNDING - 1));
 222       size = 4096 - extra;
 223     }
 224
 225   h->chunkfun = (struct _obstack_chunk * (*)(void *, long))chunkfun;
 226   h->freefun = (void (*)(void *, struct _obstack_chunk *))freefun;
 227   h->chunk_size = size;
 228   h->alignment_mask = alignment - 1;
 229   h->extra_arg = arg;
 230   h->use_extra_arg = 1;
 231
 232   chunk = h->chunk = CALL_CHUNKFUN (h, h->chunk_size);
 233   if (!chunk)
 234     (*obstack_alloc_failed_handler)();
 235   h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
 236                                                alignment - 1);
 237   h->chunk_limit = chunk->limit
 238                      = (char *) chunk + h->chunk_size;
 239   chunk->prev = 0;
 240   /* The initial chunk now contains no empty object.  */
 241   h->maybe_empty_object = 0;
 242   h->alloc_failed = 0;
 243   return 1;
 244 }
 245
 246 /* Allocate a new current chunk for the obstack *H
 247    on the assumption that LENGTH bytes need to be added
 248    to the current object, or a new object of length LENGTH allocated.
 249    Copies any partial object from the end of the old chunk
 250    to the beginning of the new one.  */
 251
 252 void
 253 _obstack_newchunk (struct obstack *h, int length)
 254 {
 255   struct _obstack_chunk *old_chunk = h->chunk;
 256   struct _obstack_chunk *new_chunk;
 257   long new_size;
 258   long obj_size = h->next_free - h->object_base;
 259   long i;
 260   long already;
 261   char *object_base;
 262
 263   /* Compute size for new chunk.  */
 264   new_size = (obj_size + length) + (obj_size >> 3) + h->alignment_mask + 100;
 265   if (new_size < h->chunk_size)
 266     new_size = h->chunk_size;
 267
 268   /* Allocate and initialize the new chunk.  */
 269   new_chunk = CALL_CHUNKFUN (h, new_size);
 270   if (!new_chunk)
 271     (*obstack_alloc_failed_handler)();
 272   h->chunk = new_chunk;
 273   new_chunk->prev = old_chunk;
 274   new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
 275
 276   /* Compute an aligned object_base in the new chunk */
 277   object_base =
 278     __PTR_ALIGN ((char *) new_chunk, new_chunk->contents, h->alignment_mask);
 279
 280   /* Move the existing object to the new chunk.
 281      Word at a time is fast and is safe if the object
 282      is sufficiently aligned.  */
 283   if (h->alignment_mask + 1 >= DEFAULT_ALIGNMENT)
 284     {
 285       for (i = obj_size / sizeof (COPYING_UNIT) - 1;
 286            i >= 0; i--)
 287         ((COPYING_UNIT *) object_base)[i]
 288           = ((COPYING_UNIT *) h->object_base)[i];
 289       /* We used to copy the odd few remaining bytes as one extra COPYING_UNIT,
 290          but that can cross a page boundary on a machine
 291          which does not do strict alignment for COPYING_UNITS.  */
 292       already = obj_size / sizeof (COPYING_UNIT) * sizeof (COPYING_UNIT);
 293     }
 294   else
 295     already = 0;
 296   /* Copy remaining bytes one by one.  */
 297   for (i = already; i < obj_size; i++)
 298     object_base[i] = h->object_base[i];
 299
 300   /* If the object just copied was the only data in OLD_CHUNK,
 301      free that chunk and remove it from the chain.
 302      But not if that chunk might contain an empty object.  */
 303   if (!h->maybe_empty_object
 304       && (h->object_base
 305           == __PTR_ALIGN ((char *) old_chunk, old_chunk->contents,
 306                           h->alignment_mask)))
 307     {
 308       new_chunk->prev = old_chunk->prev;
 309       CALL_FREEFUN (h, old_chunk);
 310     }
 311
 312   h->object_base = object_base;
 313   h->next_free = h->object_base + obj_size;
 314   /* The new chunk certainly contains no empty object yet.  */
 315   h->maybe_empty_object = 0;
 316 }
 317 # ifdef _LIBC
 318 libc_hidden_def (_obstack_newchunk)
 319 # endif
 320
 321 /* Return nonzero if object OBJ has been allocated from obstack H.
 322    This is here for debugging.
 323    If you use it in a program, you are probably losing.  */
 324
 325 /* Suppress -Wmissing-prototypes warning.  We don't want to declare this in
 326    obstack.h because it is just for debugging.  */
 327 int _obstack_allocated_p (struct obstack *h, void *obj);
 328
 329 int
 330 _obstack_allocated_p (struct obstack *h, void *obj)
 331 {
 332   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
 333   struct _obstack_chunk *plp;   /* point to previous chunk if any */
 334
 335   lp = (h)->chunk;
 336   /* We use >= rather than > since the object cannot be exactly at
 337      the beginning of the chunk but might be an empty object exactly
 338      at the end of an adjacent chunk.  */
 339   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 340     {
 341       plp = lp->prev;
 342       lp = plp;
 343     }
 344   return lp != 0;
 345 }
 346
 347 /* Free objects in obstack H, including OBJ and everything allocate
 348    more recently than OBJ.  If OBJ is zero, free everything in H.  */
 349
 350 # undef obstack_free
 351
 352 void
 353 obstack_free (struct obstack *h, void *obj)
 354 {
 355   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
 356   struct _obstack_chunk *plp;   /* point to previous chunk if any */
 357
 358   lp = h->chunk;
 359   /* We use >= because there cannot be an object at the beginning of a chunk.
 360      But there can be an empty object at that address
 361      at the end of another chunk.  */
 362   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 363     {
 364       plp = lp->prev;
 365       CALL_FREEFUN (h, lp);
 366       lp = plp;
 367       /* If we switch chunks, we can't tell whether the new current
 368          chunk contains an empty object, so assume that it may.  */
 369       h->maybe_empty_object = 1;
 370     }
 371   if (lp)
 372     {
 373       h->object_base = h->next_free = (char *) (obj);
 374       h->chunk_limit = lp->limit;
 375       h->chunk = lp;
 376     }
 377   else if (obj != 0)
 378     /* obj is not in any of the chunks! */
 379     abort ();
 380 }
 381
 382 # ifdef _LIBC
 383 /* Older versions of libc used a function _obstack_free intended to be
 384    called by non-GCC compilers.  */
 385 strong_alias (obstack_free, _obstack_free)
 386 # endif
 387
 388 int
 389 _obstack_memory_used (struct obstack *h)
 390 {
 391   struct _obstack_chunk *lp;
 392   int nbytes = 0;
 393
 394   for (lp = h->chunk; lp != 0; lp = lp->prev)
 395     {
 396       nbytes += lp->limit - (char *) lp;
 397     }
 398   return nbytes;
 399 }
 400
 401 /* Define the error handler.  */
 402 # ifdef _LIBC
 403 #  include <libintl.h>
 404 # else
 405 #  include "gettext.h"
 406 # endif
 407 # ifndef _
 408 #  define _(msgid) gettext (msgid)
 409 # endif
 410
 411 # ifdef _LIBC
 412 #  include <libio/iolibio.h>
 413 # endif
 414
 415 # ifndef __attribute__
 416 /* This feature is available in gcc versions 2.5 and later.  */
 417 #  if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5)
 418 #   define __attribute__(Spec) /* empty */
 419 #  endif
 420 # endif
 421
 422 static void
 423 __attribute__ ((noreturn))
 424 print_and_abort (void)
 425 {
 426   /* Don't change any of these strings.  Yes, it would be possible to add
 427      the newline to the string and use fputs or so.  But this must not
 428      happen because the "memory exhausted" message appears in other places
 429      like this and the translation should be reused instead of creating
 430      a very similar string which requires a separate translation.  */
 431 # ifdef _LIBC
 432   (void) __fxprintf (NULL, "%s\n", _ ("memory exhausted"));
 433 # else
 434   fprintf (stderr, "%s\n", _ ("memory exhausted"));
 435 # endif
 436   exit (obstack_exit_failure);
 437 }
 438 #endif  /* !ELIDE_CODE */