lib/obstack.c

   1 /* obstack.c - subroutines used implicitly by object stack macros
   2    Copyright (C) 1988-2018 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    <https://www.gnu.org/licenses/>.  */
  18
  19
  20 #ifdef _LIBC
  21 # include <obstack.h>
  22 #else
  23 # include <config.h>
  24 # include "obstack.h"
  25 #endif
  26
  27 /* NOTE BEFORE MODIFYING THIS FILE: _OBSTACK_INTERFACE_VERSION in
  28    obstack.h must be incremented whenever callers compiled using an old
  29    obstack.h can no longer properly call the functions in this file.  */
  30
  31 /* Comment out all this code if we are using the GNU C Library, and are not
  32    actually compiling the library itself, and the installed library
  33    supports the same library interface we do.  This code is part of the GNU
  34    C Library, but also included in many other GNU distributions.  Compiling
  35    and linking in this code is a waste when using the GNU C library
  36    (especially if it is a shared library).  Rather than having every GNU
  37    program understand 'configure --with-gnu-libc' and omit the object
  38    files, it is simpler to just do this in the source for each such file.  */
  39 #if !defined _LIBC && defined __GNU_LIBRARY__ && __GNU_LIBRARY__ > 1
  40 # include <gnu-versions.h>
  41 # if (_GNU_OBSTACK_INTERFACE_VERSION == _OBSTACK_INTERFACE_VERSION            \
  42       || (_GNU_OBSTACK_INTERFACE_VERSION == 1                                 \
  43           && _OBSTACK_INTERFACE_VERSION == 2                                  \
  44           && defined SIZEOF_INT && defined SIZEOF_SIZE_T                      \
  45           && SIZEOF_INT == SIZEOF_SIZE_T))
  46 #  define _OBSTACK_ELIDE_CODE
  47 # endif
  48 #endif
  49
  50 #ifndef _OBSTACK_ELIDE_CODE
  51 /* If GCC, or if an oddball (testing?) host that #defines __alignof__,
  52    use the already-supplied __alignof__.  Otherwise, this must be Gnulib
  53    (as glibc assumes GCC); defer to Gnulib's alignof_type.  */
  54 # if !defined __GNUC__ && !defined __alignof__
  55 #  include <alignof.h>
  56 #  define __alignof__(type) alignof_type (type)
  57 # endif
  58 # include <stdlib.h>
  59 # include <stdint.h>
  60
  61 # ifndef MAX
  62 #  define MAX(a,b) ((a) > (b) ? (a) : (b))
  63 # endif
  64
  65 /* Determine default alignment.  */
  66
  67 /* If malloc were really smart, it would round addresses to DEFAULT_ALIGNMENT.
  68    But in fact it might be less smart and round addresses to as much as
  69    DEFAULT_ROUNDING.  So we prepare for it to do that.
  70
  71    DEFAULT_ALIGNMENT cannot be an enum constant; see gnulib's alignof.h.  */
  72 #define DEFAULT_ALIGNMENT MAX (__alignof__ (long double),                     \
  73                                MAX (__alignof__ (uintmax_t),                  \
  74                                     __alignof__ (void *)))
  75 #define DEFAULT_ROUNDING MAX (sizeof (long double),                           \
  76                                MAX (sizeof (uintmax_t),                       \
  77                                     sizeof (void *)))
  78
  79 /* Call functions with either the traditional malloc/free calling
  80    interface, or the mmalloc/mfree interface (that adds an extra first
  81    argument), based on the value of use_extra_arg.  */
  82
  83 static void *
  84 call_chunkfun (struct obstack *h, size_t size)
  85 {
  86   if (h->use_extra_arg)
  87     return h->chunkfun.extra (h->extra_arg, size);
  88   else
  89     return h->chunkfun.plain (size);
  90 }
  91
  92 static void
  93 call_freefun (struct obstack *h, void *old_chunk)
  94 {
  95   if (h->use_extra_arg)
  96     h->freefun.extra (h->extra_arg, old_chunk);
  97   else
  98     h->freefun.plain (old_chunk);
  99 }
 100
 101
 102 /* Initialize an obstack H for use.  Specify chunk size SIZE (0 means default).
 103    Objects start on multiples of ALIGNMENT (0 means use default).
 104
 105    Return nonzero if successful, calls obstack_alloc_failed_handler if
 106    allocation fails.  */
 107
 108 static int
 109 _obstack_begin_worker (struct obstack *h,
 110                        _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment)
 111 {
 112   struct _obstack_chunk *chunk; /* points to new chunk */
 113
 114   if (alignment == 0)
 115     alignment = DEFAULT_ALIGNMENT;
 116   if (size == 0)
 117     /* Default size is what GNU malloc can fit in a 4096-byte block.  */
 118     {
 119       /* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
 120          Use the values for range checking, because if range checking is off,
 121          the extra bytes won't be missed terribly, but if range checking is on
 122          and we used a larger request, a whole extra 4096 bytes would be
 123          allocated.
 124
 125          These number are irrelevant to the new GNU malloc.  I suspect it is
 126          less sensitive to the size of the request.  */
 127       int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
 128                     + 4 + DEFAULT_ROUNDING - 1)
 129                    & ~(DEFAULT_ROUNDING - 1));
 130       size = 4096 - extra;
 131     }
 132
 133   h->chunk_size = size;
 134   h->alignment_mask = alignment - 1;
 135
 136   chunk = h->chunk = call_chunkfun (h, h->chunk_size);
 137   if (!chunk)
 138     (*obstack_alloc_failed_handler) ();
 139   h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
 140                                                alignment - 1);
 141   h->chunk_limit = chunk->limit = (char *) chunk + h->chunk_size;
 142   chunk->prev = 0;
 143   /* The initial chunk now contains no empty object.  */
 144   h->maybe_empty_object = 0;
 145   h->alloc_failed = 0;
 146   return 1;
 147 }
 148
 149 int
 150 _obstack_begin (struct obstack *h,
 151                 _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment,
 152                 void *(*chunkfun) (size_t),
 153                 void (*freefun) (void *))
 154 {
 155   h->chunkfun.plain = chunkfun;
 156   h->freefun.plain = freefun;
 157   h->use_extra_arg = 0;
 158   return _obstack_begin_worker (h, size, alignment);
 159 }
 160
 161 int
 162 _obstack_begin_1 (struct obstack *h,
 163                   _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment,
 164                   void *(*chunkfun) (void *, size_t),
 165                   void (*freefun) (void *, void *),
 166                   void *arg)
 167 {
 168   h->chunkfun.extra = chunkfun;
 169   h->freefun.extra = freefun;
 170   h->extra_arg = arg;
 171   h->use_extra_arg = 1;
 172   return _obstack_begin_worker (h, size, alignment);
 173 }
 174
 175 /* Allocate a new current chunk for the obstack *H
 176    on the assumption that LENGTH bytes need to be added
 177    to the current object, or a new object of length LENGTH allocated.
 178    Copies any partial object from the end of the old chunk
 179    to the beginning of the new one.  */
 180
 181 void
 182 _obstack_newchunk (struct obstack *h, _OBSTACK_SIZE_T length)
 183 {
 184   struct _obstack_chunk *old_chunk = h->chunk;
 185   struct _obstack_chunk *new_chunk = 0;
 186   size_t obj_size = h->next_free - h->object_base;
 187   char *object_base;
 188
 189   /* Compute size for new chunk.  */
 190   size_t sum1 = obj_size + length;
 191   size_t sum2 = sum1 + h->alignment_mask;
 192   size_t new_size = sum2 + (obj_size >> 3) + 100;
 193   if (new_size < sum2)
 194     new_size = sum2;
 195   if (new_size < h->chunk_size)
 196     new_size = h->chunk_size;
 197
 198   /* Allocate and initialize the new chunk.  */
 199   if (obj_size <= sum1 && sum1 <= sum2)
 200     new_chunk = call_chunkfun (h, new_size);
 201   if (!new_chunk)
 202     (*obstack_alloc_failed_handler)();
 203   h->chunk = new_chunk;
 204   new_chunk->prev = old_chunk;
 205   new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
 206
 207   /* Compute an aligned object_base in the new chunk */
 208   object_base =
 209     __PTR_ALIGN ((char *) new_chunk, new_chunk->contents, h->alignment_mask);
 210
 211   /* Move the existing object to the new chunk.  */
 212   memcpy (object_base, h->object_base, obj_size);
 213
 214   /* If the object just copied was the only data in OLD_CHUNK,
 215      free that chunk and remove it from the chain.
 216      But not if that chunk might contain an empty object.  */
 217   if (!h->maybe_empty_object
 218       && (h->object_base
 219           == __PTR_ALIGN ((char *) old_chunk, old_chunk->contents,
 220                           h->alignment_mask)))
 221     {
 222       new_chunk->prev = old_chunk->prev;
 223       call_freefun (h, old_chunk);
 224     }
 225
 226   h->object_base = object_base;
 227   h->next_free = h->object_base + obj_size;
 228   /* The new chunk certainly contains no empty object yet.  */
 229   h->maybe_empty_object = 0;
 230 }
 231
 232 /* Return nonzero if object OBJ has been allocated from obstack H.
 233    This is here for debugging.
 234    If you use it in a program, you are probably losing.  */
 235
 236 /* Suppress -Wmissing-prototypes warning.  We don't want to declare this in
 237    obstack.h because it is just for debugging.  */
 238 int _obstack_allocated_p (struct obstack *h, void *obj) __attribute_pure__;
 239
 240 int
 241 _obstack_allocated_p (struct obstack *h, void *obj)
 242 {
 243   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
 244   struct _obstack_chunk *plp;   /* point to previous chunk if any */
 245
 246   lp = (h)->chunk;
 247   /* We use >= rather than > since the object cannot be exactly at
 248      the beginning of the chunk but might be an empty object exactly
 249      at the end of an adjacent chunk.  */
 250   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 251     {
 252       plp = lp->prev;
 253       lp = plp;
 254     }
 255   return lp != 0;
 256 }
 257
 258 /* Free objects in obstack H, including OBJ and everything allocate
 259    more recently than OBJ.  If OBJ is zero, free everything in H.  */
 260
 261 void
 262 _obstack_free (struct obstack *h, void *obj)
 263 {
 264   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
 265   struct _obstack_chunk *plp;   /* point to previous chunk if any */
 266
 267   lp = h->chunk;
 268   /* We use >= because there cannot be an object at the beginning of a chunk.
 269      But there can be an empty object at that address
 270      at the end of another chunk.  */
 271   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 272     {
 273       plp = lp->prev;
 274       call_freefun (h, lp);
 275       lp = plp;
 276       /* If we switch chunks, we can't tell whether the new current
 277          chunk contains an empty object, so assume that it may.  */
 278       h->maybe_empty_object = 1;
 279     }
 280   if (lp)
 281     {
 282       h->object_base = h->next_free = (char *) (obj);
 283       h->chunk_limit = lp->limit;
 284       h->chunk = lp;
 285     }
 286   else if (obj != 0)
 287     /* obj is not in any of the chunks! */
 288     abort ();
 289 }
 290
 291 _OBSTACK_SIZE_T
 292 _obstack_memory_used (struct obstack *h)
 293 {
 294   struct _obstack_chunk *lp;
 295   _OBSTACK_SIZE_T nbytes = 0;
 296
 297   for (lp = h->chunk; lp != 0; lp = lp->prev)
 298     {
 299       nbytes += lp->limit - (char *) lp;
 300     }
 301   return nbytes;
 302 }
 303
 304 # ifndef _OBSTACK_NO_ERROR_HANDLER
 305 /* Define the error handler.  */
 306 #  include <stdio.h>
 307
 308 /* Exit value used when 'print_and_abort' is used.  */
 309 #  ifdef _LIBC
 310 int obstack_exit_failure = EXIT_FAILURE;
 311 #  else
 312 #   include "exitfail.h"
 313 #   define obstack_exit_failure exit_failure
 314 #  endif
 315
 316 #  ifdef _LIBC
 317 #   include <libintl.h>
 318 #  else
 319 #   include "gettext.h"
 320 #  endif
 321 #  ifndef _
 322 #   define _(msgid) gettext (msgid)
 323 #  endif
 324
 325 #  ifdef _LIBC
 326 #   include <libio/iolibio.h>
 327 #  endif
 328
 329 static _Noreturn void
 330 print_and_abort (void)
 331 {
 332   /* Don't change any of these strings.  Yes, it would be possible to add
 333      the newline to the string and use fputs or so.  But this must not
 334      happen because the "memory exhausted" message appears in other places
 335      like this and the translation should be reused instead of creating
 336      a very similar string which requires a separate translation.  */
 337 #  ifdef _LIBC
 338   (void) __fxprintf (NULL, "%s\n", _("memory exhausted"));
 339 #  else
 340   fprintf (stderr, "%s\n", _("memory exhausted"));
 341 #  endif
 342   exit (obstack_exit_failure);
 343 }
 344
 345 /* The functions allocating more room by calling 'obstack_chunk_alloc'
 346    jump to the handler pointed to by 'obstack_alloc_failed_handler'.
 347    This can be set to a user defined function which should either
 348    abort gracefully or use longjump - but shouldn't return.  This
 349    variable by default points to the internal function
 350    'print_and_abort'.  */
 351 __attribute_noreturn__ void (*obstack_alloc_failed_handler) (void)
 352   = print_and_abort;
 353 # endif /* !_OBSTACK_NO_ERROR_HANDLER */
 354 #endif /* !_OBSTACK_ELIDE_CODE */