libiberty/obstack.c

   1 /* obstack.c - subroutines used implicitly by object stack macros
   2    Copyright (C) 1988-2024 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 _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 __IBM__ALIGNOF__ && !defined __alignof__
  55 #  if defined __cplusplus
  56 template <class type> struct alignof_helper { char __slot1; type __slot2; };
  57 #   define __alignof__(type) offsetof (alignof_helper<type>, __slot2)
  58 #  else
  59 #   define __alignof__(type)                                                  \
  60   offsetof (struct { char __slot1; type __slot2; }, __slot2)
  61 #  endif
  62 # endif
  63 # include <stdlib.h>
  64 # include <stdint.h>
  65
  66 # ifndef MAX
  67 #  define MAX(a,b) ((a) > (b) ? (a) : (b))
  68 # endif
  69
  70 /* Determine default alignment.  */
  71
  72 /* If malloc were really smart, it would round addresses to DEFAULT_ALIGNMENT.
  73    But in fact it might be less smart and round addresses to as much as
  74    DEFAULT_ROUNDING.  So we prepare for it to do that.
  75
  76    DEFAULT_ALIGNMENT cannot be an enum constant; see gnulib's alignof.h.  */
  77 #define DEFAULT_ALIGNMENT MAX (__alignof__ (long double),                     \
  78                                MAX (__alignof__ (uintmax_t),                  \
  79                                     __alignof__ (void *)))
  80 #define DEFAULT_ROUNDING MAX (sizeof (long double),                           \
  81                                MAX (sizeof (uintmax_t),                       \
  82                                     sizeof (void *)))
  83
  84 /* Call functions with either the traditional malloc/free calling
  85    interface, or the mmalloc/mfree interface (that adds an extra first
  86    argument), based on the value of use_extra_arg.  */
  87
  88 static void *
  89 call_chunkfun (struct obstack *h, size_t size)
  90 {
  91   if (h->use_extra_arg)
  92     return h->chunkfun.extra (h->extra_arg, size);
  93   else
  94     return h->chunkfun.plain (size);
  95 }
  96
  97 static void
  98 call_freefun (struct obstack *h, void *old_chunk)
  99 {
 100   if (h->use_extra_arg)
 101     h->freefun.extra (h->extra_arg, old_chunk);
 102   else
 103     h->freefun.plain (old_chunk);
 104 }
 105
 106
 107 /* Initialize an obstack H for use.  Specify chunk size SIZE (0 means default).
 108    Objects start on multiples of ALIGNMENT (0 means use default).
 109
 110    Return nonzero if successful, calls obstack_alloc_failed_handler if
 111    allocation fails.  */
 112
 113 static int
 114 _obstack_begin_worker (struct obstack *h,
 115                        _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment)
 116 {
 117   struct _obstack_chunk *chunk; /* points to new chunk */
 118
 119   if (alignment == 0)
 120     alignment = DEFAULT_ALIGNMENT;
 121   if (size == 0)
 122     /* Default size is what GNU malloc can fit in a 4096-byte block.  */
 123     {
 124       /* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
 125          Use the values for range checking, because if range checking is off,
 126          the extra bytes won't be missed terribly, but if range checking is on
 127          and we used a larger request, a whole extra 4096 bytes would be
 128          allocated.
 129
 130          These number are irrelevant to the new GNU malloc.  I suspect it is
 131          less sensitive to the size of the request.  */
 132       int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
 133                     + 4 + DEFAULT_ROUNDING - 1)
 134                    & ~(DEFAULT_ROUNDING - 1));
 135       size = 4096 - extra;
 136     }
 137
 138   h->chunk_size = size;
 139   h->alignment_mask = alignment - 1;
 140
 141   chunk = (struct _obstack_chunk *) call_chunkfun (h, h->chunk_size);
 142   if (!chunk)
 143     (*obstack_alloc_failed_handler) ();
 144   h->chunk = chunk;
 145   h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
 146                                                alignment - 1);
 147   h->chunk_limit = chunk->limit = (char *) chunk + h->chunk_size;
 148   chunk->prev = 0;
 149   /* The initial chunk now contains no empty object.  */
 150   h->maybe_empty_object = 0;
 151   h->alloc_failed = 0;
 152   return 1;
 153 }
 154
 155 int
 156 _obstack_begin (struct obstack *h,
 157                 _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment,
 158                 void *(*chunkfun) (size_t),
 159                 void (*freefun) (void *))
 160 {
 161   h->chunkfun.plain = chunkfun;
 162   h->freefun.plain = freefun;
 163   h->use_extra_arg = 0;
 164   return _obstack_begin_worker (h, size, alignment);
 165 }
 166
 167 int
 168 _obstack_begin_1 (struct obstack *h,
 169                   _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment,
 170                   void *(*chunkfun) (void *, size_t),
 171                   void (*freefun) (void *, void *),
 172                   void *arg)
 173 {
 174   h->chunkfun.extra = chunkfun;
 175   h->freefun.extra = freefun;
 176   h->extra_arg = arg;
 177   h->use_extra_arg = 1;
 178   return _obstack_begin_worker (h, size, alignment);
 179 }
 180
 181 /* Allocate a new current chunk for the obstack *H
 182    on the assumption that LENGTH bytes need to be added
 183    to the current object, or a new object of length LENGTH allocated.
 184    Copies any partial object from the end of the old chunk
 185    to the beginning of the new one.  */
 186
 187 void
 188 _obstack_newchunk (struct obstack *h, _OBSTACK_SIZE_T length)
 189 {
 190   struct _obstack_chunk *old_chunk = h->chunk;
 191   struct _obstack_chunk *new_chunk = 0;
 192   size_t obj_size = h->next_free - h->object_base;
 193   char *object_base;
 194
 195   /* Compute size for new chunk.  */
 196   size_t sum1 = obj_size + length;
 197   size_t sum2 = sum1 + h->alignment_mask;
 198   size_t new_size = sum2 + (obj_size >> 3) + 100;
 199   if (new_size < sum2)
 200     new_size = sum2;
 201   if (new_size < h->chunk_size)
 202     new_size = h->chunk_size;
 203
 204   /* Allocate and initialize the new chunk.  */
 205   if (obj_size <= sum1 && sum1 <= sum2)
 206     new_chunk = (struct _obstack_chunk *) call_chunkfun (h, new_size);
 207   if (!new_chunk)
 208     (*obstack_alloc_failed_handler)();
 209   h->chunk = new_chunk;
 210   new_chunk->prev = old_chunk;
 211   new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
 212
 213   /* Compute an aligned object_base in the new chunk */
 214   object_base =
 215     __PTR_ALIGN ((char *) new_chunk, new_chunk->contents, h->alignment_mask);
 216
 217   /* Move the existing object to the new chunk.  */
 218   memcpy (object_base, h->object_base, obj_size);
 219
 220   /* If the object just copied was the only data in OLD_CHUNK,
 221      free that chunk and remove it from the chain.
 222      But not if that chunk might contain an empty object.  */
 223   if (!h->maybe_empty_object
 224       && (h->object_base
 225           == __PTR_ALIGN ((char *) old_chunk, old_chunk->contents,
 226                           h->alignment_mask)))
 227     {
 228       new_chunk->prev = old_chunk->prev;
 229       call_freefun (h, old_chunk);
 230     }
 231
 232   h->object_base = object_base;
 233   h->next_free = h->object_base + obj_size;
 234   /* The new chunk certainly contains no empty object yet.  */
 235   h->maybe_empty_object = 0;
 236 }
 237
 238 /* Return nonzero if object OBJ has been allocated from obstack H.
 239    This is here for debugging.
 240    If you use it in a program, you are probably losing.  */
 241
 242 /* Suppress -Wmissing-prototypes warning.  We don't want to declare this in
 243    obstack.h because it is just for debugging.  */
 244 int _obstack_allocated_p (struct obstack *h, void *obj) __attribute_pure__;
 245
 246 int
 247 _obstack_allocated_p (struct obstack *h, void *obj)
 248 {
 249   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
 250   struct _obstack_chunk *plp;   /* point to previous chunk if any */
 251
 252   lp = (h)->chunk;
 253   /* We use >= rather than > since the object cannot be exactly at
 254      the beginning of the chunk but might be an empty object exactly
 255      at the end of an adjacent chunk.  */
 256   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 257     {
 258       plp = lp->prev;
 259       lp = plp;
 260     }
 261   return lp != 0;
 262 }
 263
 264 /* Free objects in obstack H, including OBJ and everything allocate
 265    more recently than OBJ.  If OBJ is zero, free everything in H.  */
 266
 267 void
 268 _obstack_free (struct obstack *h, void *obj)
 269 {
 270   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
 271   struct _obstack_chunk *plp;   /* point to previous chunk if any */
 272
 273   lp = h->chunk;
 274   /* We use >= because there cannot be an object at the beginning of a chunk.
 275      But there can be an empty object at that address
 276      at the end of another chunk.  */
 277   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 278     {
 279       plp = lp->prev;
 280       call_freefun (h, lp);
 281       lp = plp;
 282       /* If we switch chunks, we can't tell whether the new current
 283          chunk contains an empty object, so assume that it may.  */
 284       h->maybe_empty_object = 1;
 285     }
 286   if (lp)
 287     {
 288       h->object_base = h->next_free = (char *) (obj);
 289       h->chunk_limit = lp->limit;
 290       h->chunk = lp;
 291     }
 292   else if (obj != 0)
 293     /* obj is not in any of the chunks! */
 294     abort ();
 295 }
 296
 297 _OBSTACK_SIZE_T
 298 _obstack_memory_used (struct obstack *h)
 299 {
 300   struct _obstack_chunk *lp;
 301   _OBSTACK_SIZE_T nbytes = 0;
 302
 303   for (lp = h->chunk; lp != 0; lp = lp->prev)
 304     {
 305       nbytes += lp->limit - (char *) lp;
 306     }
 307   return nbytes;
 308 }
 309
 310 # ifndef _OBSTACK_NO_ERROR_HANDLER
 311 /* Define the error handler.  */
 312 #  include <stdio.h>
 313
 314 /* Exit value used when 'print_and_abort' is used.  */
 315 #  ifdef _LIBC
 316 int obstack_exit_failure = EXIT_FAILURE;
 317 #  else
 318 #   ifndef EXIT_FAILURE
 319 #    define EXIT_FAILURE 1
 320 #   endif
 321 #   define obstack_exit_failure EXIT_FAILURE
 322 #  endif
 323
 324 #  if defined _LIBC || (HAVE_LIBINTL_H && ENABLE_NLS)
 325 #   include <libintl.h>
 326 #   ifndef _
 327 #    define _(msgid) gettext (msgid)
 328 #   endif
 329 #  else
 330 #   ifndef _
 331 #    define _(msgid) (msgid)
 332 #   endif
 333 #  endif
 334
 335 #  if !(defined _Noreturn                                                     \
 336         || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112))
 337 #   if ((defined __GNUC__                                                     \
 338          && (__GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8)))        \
 339         || (defined __SUNPRO_C && __SUNPRO_C >= 0x5110))
 340 #    define _Noreturn __attribute__ ((__noreturn__))
 341 #   elif defined _MSC_VER && _MSC_VER >= 1200
 342 #    define _Noreturn __declspec (noreturn)
 343 #   else
 344 #    define _Noreturn
 345 #   endif
 346 #  endif
 347
 348 #  ifdef _LIBC
 349 #   include <libio/iolibio.h>
 350 #  endif
 351
 352 static _Noreturn void
 353 print_and_abort (void)
 354 {
 355   /* Don't change any of these strings.  Yes, it would be possible to add
 356      the newline to the string and use fputs or so.  But this must not
 357      happen because the "memory exhausted" message appears in other places
 358      like this and the translation should be reused instead of creating
 359      a very similar string which requires a separate translation.  */
 360 #  ifdef _LIBC
 361   (void) __fxprintf (NULL, "%s\n", _("memory exhausted"));
 362 #  else
 363   fprintf (stderr, "%s\n", _("memory exhausted"));
 364 #  endif
 365   exit (obstack_exit_failure);
 366 }
 367
 368 /* The functions allocating more room by calling 'obstack_chunk_alloc'
 369    jump to the handler pointed to by 'obstack_alloc_failed_handler'.
 370    This can be set to a user defined function which should either
 371    abort gracefully or use longjump - but shouldn't return.  This
 372    variable by default points to the internal function
 373    'print_and_abort'.  */
 374 void (*obstack_alloc_failed_handler) (void) = print_and_abort;
 375 # endif /* !_OBSTACK_NO_ERROR_HANDLER */
 376 #endif /* !_OBSTACK_ELIDE_CODE */