lib/obstack.h

   1 /* obstack.h - 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 /* Summary:
  20
  21    All the apparent functions defined here are macros. The idea
  22    is that you would use these pre-tested macros to solve a
  23    very specific set of problems, and they would run fast.
  24    Caution: no side-effects in arguments please!! They may be
  25    evaluated MANY times!!
  26
  27    These macros operate a stack of objects.  Each object starts life
  28    small, and may grow to maturity.  (Consider building a word syllable
  29    by syllable.)  An object can move while it is growing.  Once it has
  30    been "finished" it never changes address again.  So the "top of the
  31    stack" is typically an immature growing object, while the rest of the
  32    stack is of mature, fixed size and fixed address objects.
  33
  34    These routines grab large chunks of memory, using a function you
  35    supply, called 'obstack_chunk_alloc'.  On occasion, they free chunks,
  36    by calling 'obstack_chunk_free'.  You must define them and declare
  37    them before using any obstack macros.
  38
  39    Each independent stack is represented by a 'struct obstack'.
  40    Each of the obstack macros expects a pointer to such a structure
  41    as the first argument.
  42
  43    One motivation for this package is the problem of growing char strings
  44    in symbol tables.  Unless you are "fascist pig with a read-only mind"
  45    --Gosper's immortal quote from HAKMEM item 154, out of context--you
  46    would not like to put any arbitrary upper limit on the length of your
  47    symbols.
  48
  49    In practice this often means you will build many short symbols and a
  50    few long symbols.  At the time you are reading a symbol you don't know
  51    how long it is.  One traditional method is to read a symbol into a
  52    buffer, realloc()ating the buffer every time you try to read a symbol
  53    that is longer than the buffer.  This is beaut, but you still will
  54    want to copy the symbol from the buffer to a more permanent
  55    symbol-table entry say about half the time.
  56
  57    With obstacks, you can work differently.  Use one obstack for all symbol
  58    names.  As you read a symbol, grow the name in the obstack gradually.
  59    When the name is complete, finalize it.  Then, if the symbol exists already,
  60    free the newly read name.
  61
  62    The way we do this is to take a large chunk, allocating memory from
  63    low addresses.  When you want to build a symbol in the chunk you just
  64    add chars above the current "high water mark" in the chunk.  When you
  65    have finished adding chars, because you got to the end of the symbol,
  66    you know how long the chars are, and you can create a new object.
  67    Mostly the chars will not burst over the highest address of the chunk,
  68    because you would typically expect a chunk to be (say) 100 times as
  69    long as an average object.
  70
  71    In case that isn't clear, when we have enough chars to make up
  72    the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
  73    so we just point to it where it lies.  No moving of chars is
  74    needed and this is the second win: potentially long strings need
  75    never be explicitly shuffled. Once an object is formed, it does not
  76    change its address during its lifetime.
  77
  78    When the chars burst over a chunk boundary, we allocate a larger
  79    chunk, and then copy the partly formed object from the end of the old
  80    chunk to the beginning of the new larger chunk.  We then carry on
  81    accreting characters to the end of the object as we normally would.
  82
  83    A special macro is provided to add a single char at a time to a
  84    growing object.  This allows the use of register variables, which
  85    break the ordinary 'growth' macro.
  86
  87    Summary:
  88         We allocate large chunks.
  89         We carve out one object at a time from the current chunk.
  90         Once carved, an object never moves.
  91         We are free to append data of any size to the currently
  92           growing object.
  93         Exactly one object is growing in an obstack at any one time.
  94         You can run one obstack per control block.
  95         You may have as many control blocks as you dare.
  96         Because of the way we do it, you can "unwind" an obstack
  97           back to a previous state. (You may remove objects much
  98           as you would with a stack.)
  99  */
 100
 101
 102 /* Don't do the contents of this file more than once.  */
 103
 104 #ifndef _OBSTACK_H
 105 #define _OBSTACK_H 1
 106
 107 #ifndef _OBSTACK_INTERFACE_VERSION
 108 # define _OBSTACK_INTERFACE_VERSION 2
 109 #endif
 110
 111 #include <stddef.h>             /* For size_t and ptrdiff_t.  */
 112 #include <string.h>             /* For __GNU_LIBRARY__, and memcpy.  */
 113
 114 #if __STDC_VERSION__ < 199901L
 115 # define __FLEXIBLE_ARRAY_MEMBER 1
 116 #else
 117 # define __FLEXIBLE_ARRAY_MEMBER
 118 #endif
 119
 120 #if _OBSTACK_INTERFACE_VERSION == 1
 121 /* For binary compatibility with obstack version 1, which used "int"
 122    and "long" for these two types.  */
 123 # define _OBSTACK_SIZE_T unsigned int
 124 # define _CHUNK_SIZE_T unsigned long
 125 # define _OBSTACK_CAST(type, expr) ((type) (expr))
 126 #else
 127 /* Version 2 with sane types, especially for 64-bit hosts.  */
 128 # define _OBSTACK_SIZE_T size_t
 129 # define _CHUNK_SIZE_T size_t
 130 # define _OBSTACK_CAST(type, expr) (expr)
 131 #endif
 132
 133 /* If B is the base of an object addressed by P, return the result of
 134    aligning P to the next multiple of A + 1.  B and P must be of type
 135    char *.  A + 1 must be a power of 2.  */
 136
 137 #define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A)))
 138
 139 /* Similar to __BPTR_ALIGN (B, P, A), except optimize the common case
 140    where pointers can be converted to integers, aligned as integers,
 141    and converted back again.  If ptrdiff_t is narrower than a
 142    pointer (e.g., the AS/400), play it safe and compute the alignment
 143    relative to B.  Otherwise, use the faster strategy of computing the
 144    alignment relative to 0.  */
 145
 146 #define __PTR_ALIGN(B, P, A)                                                  \
 147   __BPTR_ALIGN (sizeof (ptrdiff_t) < sizeof (void *) ? (B) : (char *) 0,      \
 148                 P, A)
 149
 150 #ifndef __attribute_pure__
 151 # define __attribute_pure__ _GL_ATTRIBUTE_PURE
 152 #endif
 153
 154 /* Not the same as _Noreturn, since it also works with function pointers.  */
 155 #ifndef __attribute_noreturn__
 156 # if 2 < __GNUC__ + (8 <= __GNUC_MINOR__) || 0x5110 <= __SUNPRO_C
 157 #  define __attribute_noreturn__ __attribute__ ((__noreturn__))
 158 # else
 159 #  define __attribute_noreturn__
 160 # endif
 161 #endif
 162
 163 #ifdef __cplusplus
 164 extern "C" {
 165 #endif
 166
 167 struct _obstack_chunk           /* Lives at front of each chunk. */
 168 {
 169   char *limit;                  /* 1 past end of this chunk */
 170   struct _obstack_chunk *prev;  /* address of prior chunk or NULL */
 171   char contents[__FLEXIBLE_ARRAY_MEMBER]; /* objects begin here */
 172 };
 173
 174 struct obstack          /* control current object in current chunk */
 175 {
 176   _CHUNK_SIZE_T chunk_size;     /* preferred size to allocate chunks in */
 177   struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
 178   char *object_base;            /* address of object we are building */
 179   char *next_free;              /* where to add next char to current object */
 180   char *chunk_limit;            /* address of char after current chunk */
 181   union
 182   {
 183     _OBSTACK_SIZE_T i;
 184     void *p;
 185   } temp;                       /* Temporary for some macros.  */
 186   _OBSTACK_SIZE_T alignment_mask;  /* Mask of alignment for each object. */
 187
 188   /* These prototypes vary based on 'use_extra_arg'.  */
 189   union
 190   {
 191     void *(*plain) (size_t);
 192     void *(*extra) (void *, size_t);
 193   } chunkfun;
 194   union
 195   {
 196     void (*plain) (void *);
 197     void (*extra) (void *, void *);
 198   } freefun;
 199
 200   void *extra_arg;              /* first arg for chunk alloc/dealloc funcs */
 201   unsigned use_extra_arg : 1;     /* chunk alloc/dealloc funcs take extra arg */
 202   unsigned maybe_empty_object : 1; /* There is a possibility that the current
 203                                       chunk contains a zero-length object.  This
 204                                       prevents freeing the chunk if we allocate
 205                                       a bigger chunk to replace it. */
 206   unsigned alloc_failed : 1;      /* No longer used, as we now call the failed
 207                                      handler on error, but retained for binary
 208                                      compatibility.  */
 209 };
 210
 211 /* Declare the external functions we use; they are in obstack.c.  */
 212
 213 extern void _obstack_newchunk (struct obstack *, _OBSTACK_SIZE_T);
 214 extern void _obstack_free (struct obstack *, void *);
 215 extern int _obstack_begin (struct obstack *,
 216                            _OBSTACK_SIZE_T, _OBSTACK_SIZE_T,
 217                            void *(*) (size_t), void (*) (void *));
 218 extern int _obstack_begin_1 (struct obstack *,
 219                              _OBSTACK_SIZE_T, _OBSTACK_SIZE_T,
 220                              void *(*) (void *, size_t),
 221                              void (*) (void *, void *), void *);
 222 extern _OBSTACK_SIZE_T _obstack_memory_used (struct obstack *)
 223   __attribute_pure__;
 224
 225
 226 /* Error handler called when 'obstack_chunk_alloc' failed to allocate
 227    more memory.  This can be set to a user defined function which
 228    should either abort gracefully or use longjump - but shouldn't
 229    return.  The default action is to print a message and abort.  */
 230 extern __attribute_noreturn__ void (*obstack_alloc_failed_handler) (void);
 231
 232 /* Exit value used when 'print_and_abort' is used.  */
 233 extern int obstack_exit_failure;
 234
 235 /* Pointer to beginning of object being allocated or to be allocated next.
 236    Note that this might not be the final address of the object
 237    because a new chunk might be needed to hold the final size.  */
 238
 239 #define obstack_base(h) ((void *) (h)->object_base)
 240
 241 /* Size for allocating ordinary chunks.  */
 242
 243 #define obstack_chunk_size(h) ((h)->chunk_size)
 244
 245 /* Pointer to next byte not yet allocated in current chunk.  */
 246
 247 #define obstack_next_free(h) ((void *) (h)->next_free)
 248
 249 /* Mask specifying low bits that should be clear in address of an object.  */
 250
 251 #define obstack_alignment_mask(h) ((h)->alignment_mask)
 252
 253 /* To prevent prototype warnings provide complete argument list.  */
 254 #define obstack_init(h)                                                       \
 255   _obstack_begin ((h), 0, 0,                                                  \
 256                   _OBSTACK_CAST (void *(*) (size_t), obstack_chunk_alloc),    \
 257                   _OBSTACK_CAST (void (*) (void *), obstack_chunk_free))
 258
 259 #define obstack_begin(h, size)                                                \
 260   _obstack_begin ((h), (size), 0,                                             \
 261                   _OBSTACK_CAST (void *(*) (size_t), obstack_chunk_alloc), \
 262                   _OBSTACK_CAST (void (*) (void *), obstack_chunk_free))
 263
 264 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun)     \
 265   _obstack_begin ((h), (size), (alignment),                                   \
 266                   _OBSTACK_CAST (void *(*) (size_t), chunkfun),               \
 267                   _OBSTACK_CAST (void (*) (void *), freefun))
 268
 269 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
 270   _obstack_begin_1 ((h), (size), (alignment),                                 \
 271                     _OBSTACK_CAST (void *(*) (void *, size_t), chunkfun),     \
 272                     _OBSTACK_CAST (void (*) (void *, void *), freefun), arg)
 273
 274 #define obstack_chunkfun(h, newchunkfun)                                      \
 275   ((void) ((h)->chunkfun.extra = (void *(*) (void *, size_t)) (newchunkfun)))
 276
 277 #define obstack_freefun(h, newfreefun)                                        \
 278   ((void) ((h)->freefun.extra = (void *(*) (void *, void *)) (newfreefun)))
 279
 280 #define obstack_1grow_fast(h, achar) ((void) (*((h)->next_free)++ = (achar)))
 281
 282 #define obstack_blank_fast(h, n) ((void) ((h)->next_free += (n)))
 283
 284 #define obstack_memory_used(h) _obstack_memory_used (h)
 285
 286 #if defined __GNUC__
 287 # if !defined __GNUC_MINOR__ || __GNUC__ * 1000 + __GNUC_MINOR__ < 2008
 288 #  define __extension__
 289 # endif
 290
 291 /* For GNU C, if not -traditional,
 292    we can define these macros to compute all args only once
 293    without using a global variable.
 294    Also, we can avoid using the 'temp' slot, to make faster code.  */
 295
 296 # define obstack_object_size(OBSTACK)                                         \
 297   __extension__                                                               \
 298     ({ struct obstack const *__o = (OBSTACK);                                 \
 299        (_OBSTACK_SIZE_T) (__o->next_free - __o->object_base); })
 300
 301 /* The local variable is named __o1 to avoid a shadowed variable
 302    warning when invoked from other obstack macros.  */
 303 # define obstack_room(OBSTACK)                                                \
 304   __extension__                                                               \
 305     ({ struct obstack const *__o1 = (OBSTACK);                                \
 306        (_OBSTACK_SIZE_T) (__o1->chunk_limit - __o1->next_free); })
 307
 308 # define obstack_make_room(OBSTACK, length)                                   \
 309   __extension__                                                               \
 310     ({ struct obstack *__o = (OBSTACK);                                       \
 311        _OBSTACK_SIZE_T __len = (length);                                      \
 312        if (obstack_room (__o) < __len)                                        \
 313          _obstack_newchunk (__o, __len);                                      \
 314        (void) 0; })
 315
 316 # define obstack_empty_p(OBSTACK)                                             \
 317   __extension__                                                               \
 318     ({ struct obstack const *__o = (OBSTACK);                                 \
 319        (__o->chunk->prev == 0                                                 \
 320         && __o->next_free == __PTR_ALIGN ((char *) __o->chunk,                \
 321                                           __o->chunk->contents,               \
 322                                           __o->alignment_mask)); })
 323
 324 # define obstack_grow(OBSTACK, where, length)                                 \
 325   __extension__                                                               \
 326     ({ struct obstack *__o = (OBSTACK);                                       \
 327        _OBSTACK_SIZE_T __len = (length);                                      \
 328        if (obstack_room (__o) < __len)                                        \
 329          _obstack_newchunk (__o, __len);                                      \
 330        memcpy (__o->next_free, where, __len);                                 \
 331        __o->next_free += __len;                                               \
 332        (void) 0; })
 333
 334 # define obstack_grow0(OBSTACK, where, length)                                \
 335   __extension__                                                               \
 336     ({ struct obstack *__o = (OBSTACK);                                       \
 337        _OBSTACK_SIZE_T __len = (length);                                      \
 338        if (obstack_room (__o) < __len + 1)                                    \
 339          _obstack_newchunk (__o, __len + 1);                                  \
 340        memcpy (__o->next_free, where, __len);                                 \
 341        __o->next_free += __len;                                               \
 342        *(__o->next_free)++ = 0;                                               \
 343        (void) 0; })
 344
 345 # define obstack_1grow(OBSTACK, datum)                                        \
 346   __extension__                                                               \
 347     ({ struct obstack *__o = (OBSTACK);                                       \
 348        if (obstack_room (__o) < 1)                                            \
 349          _obstack_newchunk (__o, 1);                                          \
 350        obstack_1grow_fast (__o, datum); })
 351
 352 /* These assume that the obstack alignment is good enough for pointers
 353    or ints, and that the data added so far to the current object
 354    shares that much alignment.  */
 355
 356 # define obstack_ptr_grow(OBSTACK, datum)                                     \
 357   __extension__                                                               \
 358     ({ struct obstack *__o = (OBSTACK);                                       \
 359        if (obstack_room (__o) < sizeof (void *))                              \
 360          _obstack_newchunk (__o, sizeof (void *));                            \
 361        obstack_ptr_grow_fast (__o, datum); })
 362
 363 # define obstack_int_grow(OBSTACK, datum)                                     \
 364   __extension__                                                               \
 365     ({ struct obstack *__o = (OBSTACK);                                       \
 366        if (obstack_room (__o) < sizeof (int))                                 \
 367          _obstack_newchunk (__o, sizeof (int));                               \
 368        obstack_int_grow_fast (__o, datum); })
 369
 370 # define obstack_ptr_grow_fast(OBSTACK, aptr)                                 \
 371   __extension__                                                               \
 372     ({ struct obstack *__o1 = (OBSTACK);                                      \
 373        void *__p1 = __o1->next_free;                                          \
 374        *(const void **) __p1 = (aptr);                                        \
 375        __o1->next_free += sizeof (const void *);                              \
 376        (void) 0; })
 377
 378 # define obstack_int_grow_fast(OBSTACK, aint)                                 \
 379   __extension__                                                               \
 380     ({ struct obstack *__o1 = (OBSTACK);                                      \
 381        void *__p1 = __o1->next_free;                                          \
 382        *(int *) __p1 = (aint);                                                \
 383        __o1->next_free += sizeof (int);                                       \
 384        (void) 0; })
 385
 386 # define obstack_blank(OBSTACK, length)                                       \
 387   __extension__                                                               \
 388     ({ struct obstack *__o = (OBSTACK);                                       \
 389        _OBSTACK_SIZE_T __len = (length);                                      \
 390        if (obstack_room (__o) < __len)                                        \
 391          _obstack_newchunk (__o, __len);                                      \
 392        obstack_blank_fast (__o, __len); })
 393
 394 # define obstack_alloc(OBSTACK, length)                                       \
 395   __extension__                                                               \
 396     ({ struct obstack *__h = (OBSTACK);                                       \
 397        obstack_blank (__h, (length));                                         \
 398        obstack_finish (__h); })
 399
 400 # define obstack_copy(OBSTACK, where, length)                                 \
 401   __extension__                                                               \
 402     ({ struct obstack *__h = (OBSTACK);                                       \
 403        obstack_grow (__h, (where), (length));                                 \
 404        obstack_finish (__h); })
 405
 406 # define obstack_copy0(OBSTACK, where, length)                                \
 407   __extension__                                                               \
 408     ({ struct obstack *__h = (OBSTACK);                                       \
 409        obstack_grow0 (__h, (where), (length));                                \
 410        obstack_finish (__h); })
 411
 412 /* The local variable is named __o1 to avoid a shadowed variable
 413    warning when invoked from other obstack macros, typically obstack_free.  */
 414 # define obstack_finish(OBSTACK)                                              \
 415   __extension__                                                               \
 416     ({ struct obstack *__o1 = (OBSTACK);                                      \
 417        void *__value = (void *) __o1->object_base;                            \
 418        if (__o1->next_free == __value)                                        \
 419          __o1->maybe_empty_object = 1;                                        \
 420        __o1->next_free                                                        \
 421          = __PTR_ALIGN (__o1->object_base, __o1->next_free,                   \
 422                         __o1->alignment_mask);                                \
 423        if ((size_t) (__o1->next_free - (char *) __o1->chunk)                  \
 424            > (size_t) (__o1->chunk_limit - (char *) __o1->chunk))             \
 425          __o1->next_free = __o1->chunk_limit;                                 \
 426        __o1->object_base = __o1->next_free;                                   \
 427        __value; })
 428
 429 # define obstack_free(OBSTACK, OBJ)                                           \
 430   __extension__                                                               \
 431     ({ struct obstack *__o = (OBSTACK);                                       \
 432        void *__obj = (void *) (OBJ);                                          \
 433        if (__obj > (void *) __o->chunk && __obj < (void *) __o->chunk_limit)  \
 434          __o->next_free = __o->object_base = (char *) __obj;                  \
 435        else                                                                   \
 436          _obstack_free (__o, __obj); })
 437
 438 #else /* not __GNUC__ */
 439
 440 # define obstack_object_size(h)                                               \
 441   ((_OBSTACK_SIZE_T) ((h)->next_free - (h)->object_base))
 442
 443 # define obstack_room(h)                                                      \
 444   ((_OBSTACK_SIZE_T) ((h)->chunk_limit - (h)->next_free))
 445
 446 # define obstack_empty_p(h)                                                   \
 447   ((h)->chunk->prev == 0                                                      \
 448    && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk,                     \
 449                                      (h)->chunk->contents,                    \
 450                                      (h)->alignment_mask))
 451
 452 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
 453    so that we can avoid having void expressions
 454    in the arms of the conditional expression.
 455    Casting the third operand to void was tried before,
 456    but some compilers won't accept it.  */
 457
 458 # define obstack_make_room(h, length)                                         \
 459   ((h)->temp.i = (length),                                                    \
 460    ((obstack_room (h) < (h)->temp.i)                                          \
 461     ? (_obstack_newchunk (h, (h)->temp.i), 0) : 0),                           \
 462    (void) 0)
 463
 464 # define obstack_grow(h, where, length)                                       \
 465   ((h)->temp.i = (length),                                                    \
 466    ((obstack_room (h) < (h)->temp.i)                                          \
 467    ? (_obstack_newchunk ((h), (h)->temp.i), 0) : 0),                          \
 468    memcpy ((h)->next_free, where, (h)->temp.i),                               \
 469    (h)->next_free += (h)->temp.i,                                             \
 470    (void) 0)
 471
 472 # define obstack_grow0(h, where, length)                                      \
 473   ((h)->temp.i = (length),                                                    \
 474    ((obstack_room (h) < (h)->temp.i + 1)                                      \
 475    ? (_obstack_newchunk ((h), (h)->temp.i + 1), 0) : 0),                      \
 476    memcpy ((h)->next_free, where, (h)->temp.i),                               \
 477    (h)->next_free += (h)->temp.i,                                             \
 478    *((h)->next_free)++ = 0,                                                   \
 479    (void) 0)
 480
 481 # define obstack_1grow(h, datum)                                              \
 482   (((obstack_room (h) < 1)                                                    \
 483     ? (_obstack_newchunk ((h), 1), 0) : 0),                                   \
 484    obstack_1grow_fast (h, datum))
 485
 486 # define obstack_ptr_grow(h, datum)                                           \
 487   (((obstack_room (h) < sizeof (char *))                                      \
 488     ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0),                     \
 489    obstack_ptr_grow_fast (h, datum))
 490
 491 # define obstack_int_grow(h, datum)                                           \
 492   (((obstack_room (h) < sizeof (int))                                         \
 493     ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0),                        \
 494    obstack_int_grow_fast (h, datum))
 495
 496 # define obstack_ptr_grow_fast(h, aptr)                                       \
 497   (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr),        \
 498    (void) 0)
 499
 500 # define obstack_int_grow_fast(h, aint)                                       \
 501   (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint),                   \
 502    (void) 0)
 503
 504 # define obstack_blank(h, length)                                             \
 505   ((h)->temp.i = (length),                                                    \
 506    ((obstack_room (h) < (h)->temp.i)                                          \
 507    ? (_obstack_newchunk ((h), (h)->temp.i), 0) : 0),                          \
 508    obstack_blank_fast (h, (h)->temp.i))
 509
 510 # define obstack_alloc(h, length)                                             \
 511   (obstack_blank ((h), (length)), obstack_finish ((h)))
 512
 513 # define obstack_copy(h, where, length)                                       \
 514   (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
 515
 516 # define obstack_copy0(h, where, length)                                      \
 517   (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
 518
 519 # define obstack_finish(h)                                                    \
 520   (((h)->next_free == (h)->object_base                                        \
 521     ? (((h)->maybe_empty_object = 1), 0)                                      \
 522     : 0),                                                                     \
 523    (h)->temp.p = (h)->object_base,                                            \
 524    (h)->next_free                                                             \
 525      = __PTR_ALIGN ((h)->object_base, (h)->next_free,                         \
 526                     (h)->alignment_mask),                                     \
 527    (((size_t) ((h)->next_free - (char *) (h)->chunk)                          \
 528      > (size_t) ((h)->chunk_limit - (char *) (h)->chunk))                     \
 529    ? ((h)->next_free = (h)->chunk_limit) : 0),                                \
 530    (h)->object_base = (h)->next_free,                                         \
 531    (h)->temp.p)
 532
 533 # define obstack_free(h, obj)                                                 \
 534   ((h)->temp.p = (void *) (obj),                                              \
 535    (((h)->temp.p > (void *) (h)->chunk                                        \
 536      && (h)->temp.p < (void *) (h)->chunk_limit)                              \
 537     ? (void) ((h)->next_free = (h)->object_base = (char *) (h)->temp.p)       \
 538     : _obstack_free ((h), (h)->temp.p)))
 539
 540 #endif /* not __GNUC__ */
 541
 542 #ifdef __cplusplus
 543 }       /* C++ */
 544 #endif
 545
 546 #endif /* _OBSTACK_H */