libiberty/obstack.c

   1 /* obstack.c - subroutines used implicitly by object stack macros
   2    Copyright (C) 1988-2015 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 = h->chunk = call_chunkfun (h, h->chunk_size);
 142   if (!chunk)
 143     (*obstack_alloc_failed_handler) ();
 144   h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
 145                                                alignment - 1);
 146   h->chunk_limit = chunk->limit = (char *) chunk + h->chunk_size;
 147   chunk->prev = 0;
 148   /* The initial chunk now contains no empty object.  */
 149   h->maybe_empty_object = 0;
 150   h->alloc_failed = 0;
 151   return 1;
 152 }
 153
 154 int
 155 _obstack_begin (struct obstack *h,
 156                 _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment,
 157                 void *(*chunkfun) (size_t),
 158                 void (*freefun) (void *))
 159 {
 160   h->chunkfun.plain = chunkfun;
 161   h->freefun.plain = freefun;
 162   h->use_extra_arg = 0;
 163   return _obstack_begin_worker (h, size, alignment);
 164 }
 165
 166 int
 167 _obstack_begin_1 (struct obstack *h,
 168                   _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment,
 169                   void *(*chunkfun) (void *, size_t),
 170                   void (*freefun) (void *, void *),
 171                   void *arg)
 172 {
 173   h->chunkfun.extra = chunkfun;
 174   h->freefun.extra = freefun;
 175   h->extra_arg = arg;
 176   h->use_extra_arg = 1;
 177   return _obstack_begin_worker (h, size, alignment);
 178 }
 179
 180 /* Allocate a new current chunk for the obstack *H
 181    on the assumption that LENGTH bytes need to be added
 182    to the current object, or a new object of length LENGTH allocated.
 183    Copies any partial object from the end of the old chunk
 184    to the beginning of the new one.  */
 185
 186 void
 187 _obstack_newchunk (struct obstack *h, _OBSTACK_SIZE_T length)
 188 {
 189   struct _obstack_chunk *old_chunk = h->chunk;
 190   struct _obstack_chunk *new_chunk = 0;
 191   size_t obj_size = h->next_free - h->object_base;
 192   char *object_base;
 193
 194   /* Compute size for new chunk.  */
 195   size_t sum1 = obj_size + length;
 196   size_t sum2 = sum1 + h->alignment_mask;
 197   size_t new_size = sum2 + (obj_size >> 3) + 100;
 198   if (new_size < sum2)
 199     new_size = sum2;
 200   if (new_size < h->chunk_size)
 201     new_size = h->chunk_size;
 202
 203   /* Allocate and initialize the new chunk.  */
 204   if (obj_size <= sum1 && sum1 <= sum2)
 205     new_chunk = call_chunkfun (h, new_size);
 206   if (!new_chunk)
 207     (*obstack_alloc_failed_handler)();
 208   h->chunk = new_chunk;
 209   new_chunk->prev = old_chunk;
 210   new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
 211
 212   /* Compute an aligned object_base in the new chunk */
 213   object_base =
 214     __PTR_ALIGN ((char *) new_chunk, new_chunk->contents, h->alignment_mask);
 215
 216   /* Move the existing object to the new chunk.  */
 217   memcpy (object_base, h->object_base, obj_size);
 218
 219   /* If the object just copied was the only data in OLD_CHUNK,
 220      free that chunk and remove it from the chain.
 221      But not if that chunk might contain an empty object.  */
 222   if (!h->maybe_empty_object
 223       && (h->object_base
 224           == __PTR_ALIGN ((char *) old_chunk, old_chunk->contents,
 225                           h->alignment_mask)))
 226     {
 227       new_chunk->prev = old_chunk->prev;
 228       call_freefun (h, old_chunk);
 229     }
 230
 231   h->object_base = object_base;
 232   h->next_free = h->object_base + obj_size;
 233   /* The new chunk certainly contains no empty object yet.  */
 234   h->maybe_empty_object = 0;
 235 }
 236
 237 /* Return nonzero if object OBJ has been allocated from obstack H.
 238    This is here for debugging.
 239    If you use it in a program, you are probably losing.  */
 240
 241 /* Suppress -Wmissing-prototypes warning.  We don't want to declare this in
 242    obstack.h because it is just for debugging.  */
 243 int _obstack_allocated_p (struct obstack *h, void *obj) __attribute_pure__;
 244
 245 int
 246 _obstack_allocated_p (struct obstack *h, void *obj)
 247 {
 248   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
 249   struct _obstack_chunk *plp;   /* point to previous chunk if any */
 250
 251   lp = (h)->chunk;
 252   /* We use >= rather than > since the object cannot be exactly at
 253      the beginning of the chunk but might be an empty object exactly
 254      at the end of an adjacent chunk.  */
 255   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 256     {
 257       plp = lp->prev;
 258       lp = plp;
 259     }
 260   return lp != 0;
 261 }
 262
 263 /* Free objects in obstack H, including OBJ and everything allocate
 264    more recently than OBJ.  If OBJ is zero, free everything in H.  */
 265
 266 void
 267 _obstack_free (struct obstack *h, void *obj)
 268 {
 269   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
 270   struct _obstack_chunk *plp;   /* point to previous chunk if any */
 271
 272   lp = h->chunk;
 273   /* We use >= because there cannot be an object at the beginning of a chunk.
 274      But there can be an empty object at that address
 275      at the end of another chunk.  */
 276   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 277     {
 278       plp = lp->prev;
 279       call_freefun (h, lp);
 280       lp = plp;
 281       /* If we switch chunks, we can't tell whether the new current
 282          chunk contains an empty object, so assume that it may.  */
 283       h->maybe_empty_object = 1;
 284     }
 285   if (lp)
 286     {
 287       h->object_base = h->next_free = (char *) (obj);
 288       h->chunk_limit = lp->limit;
 289       h->chunk = lp;
 290     }
 291   else if (obj != 0)
 292     /* obj is not in any of the chunks! */
 293     abort ();
 294 }
 295
 296 _OBSTACK_SIZE_T
 297 _obstack_memory_used (struct obstack *h)
 298 {
 299   struct _obstack_chunk *lp;
 300   _OBSTACK_SIZE_T nbytes = 0;
 301
 302   for (lp = h->chunk; lp != 0; lp = lp->prev)
 303     {
 304       nbytes += lp->limit - (char *) lp;
 305     }
 306   return nbytes;
 307 }
 308
 309 # ifndef _OBSTACK_NO_ERROR_HANDLER
 310 /* Define the error handler.  */
 311 #  include <stdio.h>
 312
 313 /* Exit value used when 'print_and_abort' is used.  */
 314 #  ifdef _LIBC
 315 int obstack_exit_failure = EXIT_FAILURE;
 316 #  else
 317 #   ifndef EXIT_FAILURE
 318 #    define EXIT_FAILURE 1
 319 #   endif
 320 #   define obstack_exit_failure EXIT_FAILURE
 321 #  endif
 322
 323 #  if defined _LIBC || (HAVE_LIBINTL_H && ENABLE_NLS)
 324 #   include <libintl.h>
 325 #   ifndef _
 326 #    define _(msgid) gettext (msgid)
 327 #   endif
 328 #  else
 329 #   ifndef _
 330 #    define _(msgid) (msgid)
 331 #   endif
 332 #  endif
 333
 334 #  if !(defined _Noreturn                                                     \
 335         || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112))
 336 #   if ((defined __GNUC__                                                     \
 337          && (__GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8)))        \
 338         || (defined __SUNPRO_C && __SUNPRO_C >= 0x5110))
 339 #    define _Noreturn __attribute__ ((__noreturn__))
 340 #   elif defined _MSC_VER && _MSC_VER >= 1200
 341 #    define _Noreturn __declspec (noreturn)
 342 #   else
 343 #    define _Noreturn
 344 #   endif
 345 #  endif
 346
 347 #  ifdef _LIBC
 348 #   include <libio/iolibio.h>
 349 #  endif
 350
 351 static _Noreturn void
 352 print_and_abort (void)
 353 {
 354   /* Don't change any of these strings.  Yes, it would be possible to add
 355      the newline to the string and use fputs or so.  But this must not
 356      happen because the "memory exhausted" message appears in other places
 357      like this and the translation should be reused instead of creating
 358      a very similar string which requires a separate translation.  */
 359 #  ifdef _LIBC
 360   (void) __fxprintf (NULL, "%s\n", _("memory exhausted"));
 361 #  else
 362   fprintf (stderr, "%s\n", _("memory exhausted"));
 363 #  endif
 364   exit (obstack_exit_failure);
 365 }
 366
 367 /* The functions allocating more room by calling 'obstack_chunk_alloc'
 368    jump to the handler pointed to by 'obstack_alloc_failed_handler'.
 369    This can be set to a user defined function which should either
 370    abort gracefully or use longjump - but shouldn't return.  This
 371    variable by default points to the internal function
 372    'print_and_abort'.  */
 373 void (*obstack_alloc_failed_handler) (void) = print_and_abort;
 374 # endif /* !_OBSTACK_NO_ERROR_HANDLER */
 375 #endif /* !_OBSTACK_ELIDE_CODE */