compat/obstack.c

   1 /* obstack.c - subroutines used implicitly by object stack macros
   2    Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library 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 GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  19    Boston, MA 02110-1301, USA.  */
  20
  21 #include "git-compat-util.h"
  22 #include <gettext.h>
  23 #include "obstack.h"
  24
  25 /* NOTE BEFORE MODIFYING THIS FILE: This version number must be
  26    incremented whenever callers compiled using an old obstack.h can no
  27    longer properly call the functions in this obstack.c.  */
  28 #define OBSTACK_INTERFACE_VERSION 1
  29
  30 /* Comment out all this code if we are using the GNU C Library, and are not
  31    actually compiling the library itself, and the installed library
  32    supports the same library interface we do.  This code is part of the GNU
  33    C Library, but also included in many other GNU distributions.  Compiling
  34    and linking in this code is a waste when using the GNU C library
  35    (especially if it is a shared library).  Rather than having every GNU
  36    program understand `configure --with-gnu-libc' and omit the object
  37    files, it is simpler to just do this in the source for each such file.  */
  38
  39 #include <stdio.h>              /* Random thing to get __GNU_LIBRARY__.  */
  40 #if !defined _LIBC && defined __GNU_LIBRARY__ && __GNU_LIBRARY__ > 1
  41 # include <gnu-versions.h>
  42 # if _GNU_OBSTACK_INTERFACE_VERSION == OBSTACK_INTERFACE_VERSION
  43 #  define ELIDE_CODE
  44 # endif
  45 #endif
  46
  47 #include <stddef.h>
  48
  49 #ifndef ELIDE_CODE
  50
  51
  52 # if HAVE_INTTYPES_H
  53 #  include <inttypes.h>
  54 # endif
  55 # if HAVE_STDINT_H || defined _LIBC
  56 #  include <stdint.h>
  57 # endif
  58
  59 /* Determine default alignment.  */
  60 union fooround
  61 {
  62   uintmax_t i;
  63   long double d;
  64   void *p;
  65 };
  66 struct fooalign
  67 {
  68   char c;
  69   union fooround u;
  70 };
  71 /* If malloc were really smart, it would round addresses to DEFAULT_ALIGNMENT.
  72    But in fact it might be less smart and round addresses to as much as
  73    DEFAULT_ROUNDING.  So we prepare for it to do that.  */
  74 enum
  75   {
  76     DEFAULT_ALIGNMENT = offsetof (struct fooalign, u),
  77     DEFAULT_ROUNDING = sizeof (union fooround)
  78   };
  79
  80 /* When we copy a long block of data, this is the unit to do it with.
  81    On some machines, copying successive ints does not work;
  82    in such a case, redefine COPYING_UNIT to `long' (if that works)
  83    or `char' as a last resort.  */
  84 # ifndef COPYING_UNIT
  85 #  define COPYING_UNIT int
  86 # endif
  87
  88
  89 /* The functions allocating more room by calling `obstack_chunk_alloc'
  90    jump to the handler pointed to by `obstack_alloc_failed_handler'.
  91    This can be set to a user defined function which should either
  92    abort gracefully or use longjump - but shouldn't return.  This
  93    variable by default points to the internal function
  94    `print_and_abort'.  */
  95 static void print_and_abort (void);
  96 void (*obstack_alloc_failed_handler) (void) = print_and_abort;
  97
  98 # ifdef _LIBC
  99 #  if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_3_4)
 100 /* A looong time ago (before 1994, anyway; we're not sure) this global variable
 101    was used by non-GNU-C macros to avoid multiple evaluation.  The GNU C
 102    library still exports it because somebody might use it.  */
 103 struct obstack *_obstack_compat;
 104 compat_symbol (libc, _obstack_compat, _obstack, GLIBC_2_0);
 105 #  endif
 106 # endif
 107
 108 /* Define a macro that either calls functions with the traditional malloc/free
 109    calling interface, or calls functions with the mmalloc/mfree interface
 110    (that adds an extra first argument), based on the state of use_extra_arg.
 111    For free, do not use ?:, since some compilers, like the MIPS compilers,
 112    do not allow (expr) ? void : void.  */
 113
 114 # define CALL_CHUNKFUN(h, size) \
 115   (((h) -> use_extra_arg) \
 116    ? (*(h)->chunkfun) ((h)->extra_arg, (size)) \
 117    : (*(struct _obstack_chunk *(*) (long)) (h)->chunkfun) ((size)))
 118
 119 # define CALL_FREEFUN(h, old_chunk) \
 120   do { \
 121     if ((h) -> use_extra_arg) \
 122       (*(h)->freefun) ((h)->extra_arg, (old_chunk)); \
 123     else \
 124       (*(void (*) (void *)) (h)->freefun) ((old_chunk)); \
 125   } while (0)
 126
 127 \f
 128 /* Initialize an obstack H for use.  Specify chunk size SIZE (0 means default).
 129    Objects start on multiples of ALIGNMENT (0 means use default).
 130    CHUNKFUN is the function to use to allocate chunks,
 131    and FREEFUN the function to free them.
 132
 133    Return nonzero if successful, calls obstack_alloc_failed_handler if
 134    allocation fails.  */
 135
 136 int
 137 _obstack_begin (struct obstack *h,
 138                 int size, int alignment,
 139                 void *(*chunkfun) (long),
 140                 void (*freefun) (void *))
 141 {
 142   register struct _obstack_chunk *chunk; /* points to new chunk */
 143
 144   if (alignment == 0)
 145     alignment = DEFAULT_ALIGNMENT;
 146   if (size == 0)
 147     /* Default size is what GNU malloc can fit in a 4096-byte block.  */
 148     {
 149       /* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
 150          Use the values for range checking, because if range checking is off,
 151          the extra bytes won't be missed terribly, but if range checking is on
 152          and we used a larger request, a whole extra 4096 bytes would be
 153          allocated.
 154
 155          These number are irrelevant to the new GNU malloc.  I suspect it is
 156          less sensitive to the size of the request.  */
 157       int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
 158                     + 4 + DEFAULT_ROUNDING - 1)
 159                    & ~(DEFAULT_ROUNDING - 1));
 160       size = 4096 - extra;
 161     }
 162
 163   h->chunkfun = (struct _obstack_chunk * (*)(void *, long)) chunkfun;
 164   h->freefun = (void (*) (void *, struct _obstack_chunk *)) freefun;
 165   h->chunk_size = size;
 166   h->alignment_mask = alignment - 1;
 167   h->use_extra_arg = 0;
 168
 169   chunk = h->chunk = CALL_CHUNKFUN (h, h -> chunk_size);
 170   if (!chunk)
 171     (*obstack_alloc_failed_handler) ();
 172   h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
 173                                                alignment - 1);
 174   h->chunk_limit = chunk->limit
 175     = (char *) chunk + h->chunk_size;
 176   chunk->prev = NULL;
 177   /* The initial chunk now contains no empty object.  */
 178   h->maybe_empty_object = 0;
 179   h->alloc_failed = 0;
 180   return 1;
 181 }
 182
 183 int
 184 _obstack_begin_1 (struct obstack *h, int size, int alignment,
 185                   void *(*chunkfun) (void *, long),
 186                   void (*freefun) (void *, void *),
 187                   void *arg)
 188 {
 189   register struct _obstack_chunk *chunk; /* points to new chunk */
 190
 191   if (alignment == 0)
 192     alignment = DEFAULT_ALIGNMENT;
 193   if (size == 0)
 194     /* Default size is what GNU malloc can fit in a 4096-byte block.  */
 195     {
 196       /* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
 197          Use the values for range checking, because if range checking is off,
 198          the extra bytes won't be missed terribly, but if range checking is on
 199          and we used a larger request, a whole extra 4096 bytes would be
 200          allocated.
 201
 202          These number are irrelevant to the new GNU malloc.  I suspect it is
 203          less sensitive to the size of the request.  */
 204       int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
 205                     + 4 + DEFAULT_ROUNDING - 1)
 206                    & ~(DEFAULT_ROUNDING - 1));
 207       size = 4096 - extra;
 208     }
 209
 210   h->chunkfun = (struct _obstack_chunk * (*)(void *,long)) chunkfun;
 211   h->freefun = (void (*) (void *, struct _obstack_chunk *)) freefun;
 212   h->chunk_size = size;
 213   h->alignment_mask = alignment - 1;
 214   h->extra_arg = arg;
 215   h->use_extra_arg = 1;
 216
 217   chunk = h->chunk = CALL_CHUNKFUN (h, h -> chunk_size);
 218   if (!chunk)
 219     (*obstack_alloc_failed_handler) ();
 220   h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
 221                                                alignment - 1);
 222   h->chunk_limit = chunk->limit
 223     = (char *) chunk + h->chunk_size;
 224   chunk->prev = NULL;
 225   /* The initial chunk now contains no empty object.  */
 226   h->maybe_empty_object = 0;
 227   h->alloc_failed = 0;
 228   return 1;
 229 }
 230
 231 /* Allocate a new current chunk for the obstack *H
 232    on the assumption that LENGTH bytes need to be added
 233    to the current object, or a new object of length LENGTH allocated.
 234    Copies any partial object from the end of the old chunk
 235    to the beginning of the new one.  */
 236
 237 void
 238 _obstack_newchunk (struct obstack *h, int length)
 239 {
 240   register struct _obstack_chunk *old_chunk = h->chunk;
 241   register struct _obstack_chunk *new_chunk;
 242   register long new_size;
 243   register long obj_size = h->next_free - h->object_base;
 244   register long i;
 245   long already;
 246   char *object_base;
 247
 248   /* Compute size for new chunk.  */
 249   new_size = (obj_size + length) + (obj_size >> 3) + h->alignment_mask + 100;
 250   if (new_size < h->chunk_size)
 251     new_size = h->chunk_size;
 252
 253   /* Allocate and initialize the new chunk.  */
 254   new_chunk = CALL_CHUNKFUN (h, new_size);
 255   if (!new_chunk)
 256     (*obstack_alloc_failed_handler) ();
 257   h->chunk = new_chunk;
 258   new_chunk->prev = old_chunk;
 259   new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
 260
 261   /* Compute an aligned object_base in the new chunk */
 262   object_base =
 263     __PTR_ALIGN ((char *) new_chunk, new_chunk->contents, h->alignment_mask);
 264
 265   /* Move the existing object to the new chunk.
 266      Word at a time is fast and is safe if the object
 267      is sufficiently aligned.  */
 268   if (h->alignment_mask + 1 >= DEFAULT_ALIGNMENT)
 269     {
 270       for (i = obj_size / sizeof (COPYING_UNIT) - 1;
 271            i >= 0; i--)
 272         ((COPYING_UNIT *)object_base)[i]
 273           = ((COPYING_UNIT *)h->object_base)[i];
 274       /* We used to copy the odd few remaining bytes as one extra COPYING_UNIT,
 275          but that can cross a page boundary on a machine
 276          which does not do strict alignment for COPYING_UNITS.  */
 277       already = obj_size / sizeof (COPYING_UNIT) * sizeof (COPYING_UNIT);
 278     }
 279   else
 280     already = 0;
 281   /* Copy remaining bytes one by one.  */
 282   for (i = already; i < obj_size; i++)
 283     object_base[i] = h->object_base[i];
 284
 285   /* If the object just copied was the only data in OLD_CHUNK,
 286      free that chunk and remove it from the chain.
 287      But not if that chunk might contain an empty object.  */
 288   if (! h->maybe_empty_object
 289       && (h->object_base
 290           == __PTR_ALIGN ((char *) old_chunk, old_chunk->contents,
 291                           h->alignment_mask)))
 292     {
 293       new_chunk->prev = old_chunk->prev;
 294       CALL_FREEFUN (h, old_chunk);
 295     }
 296
 297   h->object_base = object_base;
 298   h->next_free = h->object_base + obj_size;
 299   /* The new chunk certainly contains no empty object yet.  */
 300   h->maybe_empty_object = 0;
 301 }
 302 # ifdef _LIBC
 303 libc_hidden_def (_obstack_newchunk)
 304 # endif
 305
 306 /* Return nonzero if object OBJ has been allocated from obstack H.
 307    This is here for debugging.
 308    If you use it in a program, you are probably losing.  */
 309
 310 /* Suppress -Wmissing-prototypes warning.  We don't want to declare this in
 311    obstack.h because it is just for debugging.  */
 312 int _obstack_allocated_p (struct obstack *h, void *obj);
 313
 314 int
 315 _obstack_allocated_p (struct obstack *h, void *obj)
 316 {
 317   register struct _obstack_chunk *lp;   /* below addr of any objects in this chunk */
 318   register struct _obstack_chunk *plp;  /* point to previous chunk if any */
 319
 320   lp = (h)->chunk;
 321   /* We use >= rather than > since the object cannot be exactly at
 322      the beginning of the chunk but might be an empty object exactly
 323      at the end of an adjacent chunk.  */
 324   while (lp != NULL && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 325     {
 326       plp = lp->prev;
 327       lp = plp;
 328     }
 329   return lp != NULL;
 330 }
 331 \f
 332 /* Free objects in obstack H, including OBJ and everything allocate
 333    more recently than OBJ.  If OBJ is zero, free everything in H.  */
 334
 335 # undef obstack_free
 336
 337 void
 338 obstack_free (struct obstack *h, void *obj)
 339 {
 340   register struct _obstack_chunk *lp;   /* below addr of any objects in this chunk */
 341   register struct _obstack_chunk *plp;  /* point to previous chunk if any */
 342
 343   lp = h->chunk;
 344   /* We use >= because there cannot be an object at the beginning of a chunk.
 345      But there can be an empty object at that address
 346      at the end of another chunk.  */
 347   while (lp != NULL && ((void *) lp >= obj || (void *) (lp)->limit < obj))
 348     {
 349       plp = lp->prev;
 350       CALL_FREEFUN (h, lp);
 351       lp = plp;
 352       /* If we switch chunks, we can't tell whether the new current
 353          chunk contains an empty object, so assume that it may.  */
 354       h->maybe_empty_object = 1;
 355     }
 356   if (lp)
 357     {
 358       h->object_base = h->next_free = (char *) (obj);
 359       h->chunk_limit = lp->limit;
 360       h->chunk = lp;
 361     }
 362   else if (obj != NULL)
 363     /* obj is not in any of the chunks! */
 364     abort ();
 365 }
 366
 367 # ifdef _LIBC
 368 /* Older versions of libc used a function _obstack_free intended to be
 369    called by non-GCC compilers.  */
 370 strong_alias (obstack_free, _obstack_free)
 371 # endif
 372 \f
 373 int
 374 _obstack_memory_used (struct obstack *h)
 375 {
 376   register struct _obstack_chunk* lp;
 377   register int nbytes = 0;
 378
 379   for (lp = h->chunk; lp != NULL; lp = lp->prev)
 380     {
 381       nbytes += lp->limit - (char *) lp;
 382     }
 383   return nbytes;
 384 }
 385 \f
 386 # ifdef _LIBC
 387 #  include <libio/iolibio.h>
 388 # endif
 389
 390 # ifndef __attribute__
 391 /* This feature is available in gcc versions 2.5 and later.  */
 392 #  if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5)
 393 #   define __attribute__(Spec) /* empty */
 394 #  endif
 395 # endif
 396
 397 static void
 398 print_and_abort (void)
 399 {
 400   /* Don't change any of these strings.  Yes, it would be possible to add
 401      the newline to the string and use fputs or so.  But this must not
 402      happen because the "memory exhausted" message appears in other places
 403      like this and the translation should be reused instead of creating
 404      a very similar string which requires a separate translation.  */
 405 # ifdef _LIBC
 406   (void) __fxprintf (NULL, "%s\n", _("memory exhausted"));
 407 # else
 408   fprintf (stderr, "%s\n", _("memory exhausted"));
 409 # endif
 410   exit (1);
 411 }
 412
 413 #endif  /* !ELIDE_CODE */