source: trunk/essentials/app-arch/cpio/lib/obstack.h

Last change on this file was 3332, checked in by bird, 18 years ago

cpio 2.7

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1/* obstack.h - object stack macros
2 Copyright (C) 1988-1994,1996-1999,2003,2004,2005
3 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
10
11 This program 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
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License along
17 with this program; if not, write to the Free Software Foundation,
18 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
19
20/* Summary:
21
22All the apparent functions defined here are macros. The idea
23is that you would use these pre-tested macros to solve a
24very specific set of problems, and they would run fast.
25Caution: no side-effects in arguments please!! They may be
26evaluated MANY times!!
27
28These macros operate a stack of objects. Each object starts life
29small, and may grow to maturity. (Consider building a word syllable
30by syllable.) An object can move while it is growing. Once it has
31been "finished" it never changes address again. So the "top of the
32stack" is typically an immature growing object, while the rest of the
33stack is of mature, fixed size and fixed address objects.
34
35These routines grab large chunks of memory, using a function you
36supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
37by calling `obstack_chunk_free'. You must define them and declare
38them before using any obstack macros.
39
40Each independent stack is represented by a `struct obstack'.
41Each of the obstack macros expects a pointer to such a structure
42as the first argument.
43
44One motivation for this package is the problem of growing char strings
45in symbol tables. Unless you are "fascist pig with a read-only mind"
46--Gosper's immortal quote from HAKMEM item 154, out of context--you
47would not like to put any arbitrary upper limit on the length of your
48symbols.
49
50In practice this often means you will build many short symbols and a
51few long symbols. At the time you are reading a symbol you don't know
52how long it is. One traditional method is to read a symbol into a
53buffer, realloc()ating the buffer every time you try to read a symbol
54that is longer than the buffer. This is beaut, but you still will
55want to copy the symbol from the buffer to a more permanent
56symbol-table entry say about half the time.
57
58With obstacks, you can work differently. Use one obstack for all symbol
59names. As you read a symbol, grow the name in the obstack gradually.
60When the name is complete, finalize it. Then, if the symbol exists already,
61free the newly read name.
62
63The way we do this is to take a large chunk, allocating memory from
64low addresses. When you want to build a symbol in the chunk you just
65add chars above the current "high water mark" in the chunk. When you
66have finished adding chars, because you got to the end of the symbol,
67you know how long the chars are, and you can create a new object.
68Mostly the chars will not burst over the highest address of the chunk,
69because you would typically expect a chunk to be (say) 100 times as
70long as an average object.
71
72In case that isn't clear, when we have enough chars to make up
73the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
74so we just point to it where it lies. No moving of chars is
75needed and this is the second win: potentially long strings need
76never be explicitly shuffled. Once an object is formed, it does not
77change its address during its lifetime.
78
79When the chars burst over a chunk boundary, we allocate a larger
80chunk, and then copy the partly formed object from the end of the old
81chunk to the beginning of the new larger chunk. We then carry on
82accreting characters to the end of the object as we normally would.
83
84A special macro is provided to add a single char at a time to a
85growing object. This allows the use of register variables, which
86break the ordinary 'growth' macro.
87
88Summary:
89 We allocate large chunks.
90 We carve out one object at a time from the current chunk.
91 Once carved, an object never moves.
92 We are free to append data of any size to the currently
93 growing object.
94 Exactly one object is growing in an obstack at any one time.
95 You can run one obstack per control block.
96 You may have as many control blocks as you dare.
97 Because of the way we do it, you can `unwind' an obstack
98 back to a previous state. (You may remove objects much
99 as you would with a stack.)
100*/
101
102
103/* Don't do the contents of this file more than once. */
104
105#ifndef _OBSTACK_H
106#define _OBSTACK_H 1
107
108#ifdef __cplusplus
109extern "C" {
110#endif
111
112
113/* We need the type of a pointer subtraction. If __PTRDIFF_TYPE__ is
114 defined, as with GNU C, use that; that way we don't pollute the
115 namespace with <stddef.h>'s symbols. Otherwise, include <stddef.h>
116 and use ptrdiff_t. */
117
118#ifdef __PTRDIFF_TYPE__
119# define PTR_INT_TYPE __PTRDIFF_TYPE__
120#else
121# include <stddef.h>
122# define PTR_INT_TYPE ptrdiff_t
123#endif
124
125/* If B is the base of an object addressed by P, return the result of
126 aligning P to the next multiple of A + 1. B and P must be of type
127 char *. A + 1 must be a power of 2. */
128
129#define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A)))
130
131/* Similiar to _BPTR_ALIGN (B, P, A), except optimize the common case
132 where pointers can be converted to integers, aligned as integers,
133 and converted back again. If PTR_INT_TYPE is narrower than a
134 pointer (e.g., the AS/400), play it safe and compute the alignment
135 relative to B. Otherwise, use the faster strategy of computing the
136 alignment relative to 0. */
137
138#define __PTR_ALIGN(B, P, A) \
139 __BPTR_ALIGN (sizeof (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \
140 P, A)
141
142#include <string.h>
143
144struct _obstack_chunk /* Lives at front of each chunk. */
145{
146 char *limit; /* 1 past end of this chunk */
147 struct _obstack_chunk *prev; /* address of prior chunk or NULL */
148 char contents[4]; /* objects begin here */
149};
150
151struct obstack /* control current object in current chunk */
152{
153 long chunk_size; /* preferred size to allocate chunks in */
154 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
155 char *object_base; /* address of object we are building */
156 char *next_free; /* where to add next char to current object */
157 char *chunk_limit; /* address of char after current chunk */
158 union
159 {
160 PTR_INT_TYPE tempint;
161 void *tempptr;
162 } temp; /* Temporary for some macros. */
163 int alignment_mask; /* Mask of alignment for each object. */
164 /* These prototypes vary based on `use_extra_arg', and we use
165 casts to the prototypeless function type in all assignments,
166 but having prototypes here quiets -Wstrict-prototypes. */
167 struct _obstack_chunk *(*chunkfun) (void *, long);
168 void (*freefun) (void *, struct _obstack_chunk *);
169 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */
170 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
171 unsigned maybe_empty_object:1;/* There is a possibility that the current
172 chunk contains a zero-length object. This
173 prevents freeing the chunk if we allocate
174 a bigger chunk to replace it. */
175 unsigned alloc_failed:1; /* No longer used, as we now call the failed
176 handler on error, but retained for binary
177 compatibility. */
178};
179
180/* Declare the external functions we use; they are in obstack.c. */
181
182extern void _obstack_newchunk (struct obstack *, int);
183extern int _obstack_begin (struct obstack *, int, int,
184 void *(*) (long), void (*) (void *));
185extern int _obstack_begin_1 (struct obstack *, int, int,
186 void *(*) (void *, long),
187 void (*) (void *, void *), void *);
188extern int _obstack_memory_used (struct obstack *);
189
190void obstack_free (struct obstack *obstack, void *block);
191
192
193
194/* Error handler called when `obstack_chunk_alloc' failed to allocate
195 more memory. This can be set to a user defined function which
196 should either abort gracefully or use longjump - but shouldn't
197 return. The default action is to print a message and abort. */
198extern void (*obstack_alloc_failed_handler) (void);
199
200/* Exit value used when `print_and_abort' is used. */
201extern int obstack_exit_failure;
202
203
204/* Pointer to beginning of object being allocated or to be allocated next.
205 Note that this might not be the final address of the object
206 because a new chunk might be needed to hold the final size. */
207
208#define obstack_base(h) ((void *) (h)->object_base)
209
210/* Size for allocating ordinary chunks. */
211
212#define obstack_chunk_size(h) ((h)->chunk_size)
213
214/* Pointer to next byte not yet allocated in current chunk. */
215
216#define obstack_next_free(h) ((h)->next_free)
217
218/* Mask specifying low bits that should be clear in address of an object. */
219
220#define obstack_alignment_mask(h) ((h)->alignment_mask)
221
222/* To prevent prototype warnings provide complete argument list. */
223#define obstack_init(h) \
224 _obstack_begin ((h), 0, 0, \
225 (void *(*) (long)) obstack_chunk_alloc, \
226 (void (*) (void *)) obstack_chunk_free)
227
228#define obstack_begin(h, size) \
229 _obstack_begin ((h), (size), 0, \
230 (void *(*) (long)) obstack_chunk_alloc, \
231 (void (*) (void *)) obstack_chunk_free)
232
233#define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
234 _obstack_begin ((h), (size), (alignment), \
235 (void *(*) (long)) (chunkfun), \
236 (void (*) (void *)) (freefun))
237
238#define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
239 _obstack_begin_1 ((h), (size), (alignment), \
240 (void *(*) (void *, long)) (chunkfun), \
241 (void (*) (void *, void *)) (freefun), (arg))
242
243#define obstack_chunkfun(h, newchunkfun) \
244 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
245
246#define obstack_freefun(h, newfreefun) \
247 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
248
249#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar))
250
251#define obstack_blank_fast(h,n) ((h)->next_free += (n))
252
253#define obstack_memory_used(h) _obstack_memory_used (h)
254
255
256#if defined __GNUC__ && defined __STDC__ && __STDC__
257/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
258 does not implement __extension__. But that compiler doesn't define
259 __GNUC_MINOR__. */
260# if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
261# define __extension__
262# endif
263
264/* For GNU C, if not -traditional,
265 we can define these macros to compute all args only once
266 without using a global variable.
267 Also, we can avoid using the `temp' slot, to make faster code. */
268
269# define obstack_object_size(OBSTACK) \
270 __extension__ \
271 ({ struct obstack const *__o = (OBSTACK); \
272 (unsigned) (__o->next_free - __o->object_base); })
273
274# define obstack_room(OBSTACK) \
275 __extension__ \
276 ({ struct obstack const *__o = (OBSTACK); \
277 (unsigned) (__o->chunk_limit - __o->next_free); })
278
279# define obstack_make_room(OBSTACK,length) \
280__extension__ \
281({ struct obstack *__o = (OBSTACK); \
282 int __len = (length); \
283 if (__o->chunk_limit - __o->next_free < __len) \
284 _obstack_newchunk (__o, __len); \
285 (void) 0; })
286
287# define obstack_empty_p(OBSTACK) \
288 __extension__ \
289 ({ struct obstack const *__o = (OBSTACK); \
290 (__o->chunk->prev == 0 \
291 && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \
292 __o->chunk->contents, \
293 __o->alignment_mask)); })
294
295# define obstack_grow(OBSTACK,where,length) \
296__extension__ \
297({ struct obstack *__o = (OBSTACK); \
298 int __len = (length); \
299 if (__o->next_free + __len > __o->chunk_limit) \
300 _obstack_newchunk (__o, __len); \
301 memcpy (__o->next_free, where, __len); \
302 __o->next_free += __len; \
303 (void) 0; })
304
305# define obstack_grow0(OBSTACK,where,length) \
306__extension__ \
307({ struct obstack *__o = (OBSTACK); \
308 int __len = (length); \
309 if (__o->next_free + __len + 1 > __o->chunk_limit) \
310 _obstack_newchunk (__o, __len + 1); \
311 memcpy (__o->next_free, where, __len); \
312 __o->next_free += __len; \
313 *(__o->next_free)++ = 0; \
314 (void) 0; })
315
316# define obstack_1grow(OBSTACK,datum) \
317__extension__ \
318({ struct obstack *__o = (OBSTACK); \
319 if (__o->next_free + 1 > __o->chunk_limit) \
320 _obstack_newchunk (__o, 1); \
321 obstack_1grow_fast (__o, datum); \
322 (void) 0; })
323
324/* These assume that the obstack alignment is good enough for pointers
325 or ints, and that the data added so far to the current object
326 shares that much alignment. */
327
328# define obstack_ptr_grow(OBSTACK,datum) \
329__extension__ \
330({ struct obstack *__o = (OBSTACK); \
331 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
332 _obstack_newchunk (__o, sizeof (void *)); \
333 obstack_ptr_grow_fast (__o, datum); }) \
334
335# define obstack_int_grow(OBSTACK,datum) \
336__extension__ \
337({ struct obstack *__o = (OBSTACK); \
338 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
339 _obstack_newchunk (__o, sizeof (int)); \
340 obstack_int_grow_fast (__o, datum); })
341
342# define obstack_ptr_grow_fast(OBSTACK,aptr) \
343__extension__ \
344({ struct obstack *__o1 = (OBSTACK); \
345 *(const void **) __o1->next_free = (aptr); \
346 __o1->next_free += sizeof (const void *); \
347 (void) 0; })
348
349# define obstack_int_grow_fast(OBSTACK,aint) \
350__extension__ \
351({ struct obstack *__o1 = (OBSTACK); \
352 *(int *) __o1->next_free = (aint); \
353 __o1->next_free += sizeof (int); \
354 (void) 0; })
355
356# define obstack_blank(OBSTACK,length) \
357__extension__ \
358({ struct obstack *__o = (OBSTACK); \
359 int __len = (length); \
360 if (__o->chunk_limit - __o->next_free < __len) \
361 _obstack_newchunk (__o, __len); \
362 obstack_blank_fast (__o, __len); \
363 (void) 0; })
364
365# define obstack_alloc(OBSTACK,length) \
366__extension__ \
367({ struct obstack *__h = (OBSTACK); \
368 obstack_blank (__h, (length)); \
369 obstack_finish (__h); })
370
371# define obstack_copy(OBSTACK,where,length) \
372__extension__ \
373({ struct obstack *__h = (OBSTACK); \
374 obstack_grow (__h, (where), (length)); \
375 obstack_finish (__h); })
376
377# define obstack_copy0(OBSTACK,where,length) \
378__extension__ \
379({ struct obstack *__h = (OBSTACK); \
380 obstack_grow0 (__h, (where), (length)); \
381 obstack_finish (__h); })
382
383/* The local variable is named __o1 to avoid a name conflict
384 when obstack_blank is called. */
385# define obstack_finish(OBSTACK) \
386__extension__ \
387({ struct obstack *__o1 = (OBSTACK); \
388 void *__value = (void *) __o1->object_base; \
389 if (__o1->next_free == __value) \
390 __o1->maybe_empty_object = 1; \
391 __o1->next_free \
392 = __PTR_ALIGN (__o1->object_base, __o1->next_free, \
393 __o1->alignment_mask); \
394 if (__o1->next_free - (char *)__o1->chunk \
395 > __o1->chunk_limit - (char *)__o1->chunk) \
396 __o1->next_free = __o1->chunk_limit; \
397 __o1->object_base = __o1->next_free; \
398 __value; })
399
400# define obstack_free(OBSTACK, OBJ) \
401__extension__ \
402({ struct obstack *__o = (OBSTACK); \
403 void *__obj = (OBJ); \
404 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
405 __o->next_free = __o->object_base = (char *)__obj; \
406 else (obstack_free) (__o, __obj); })
407
408
409#else /* not __GNUC__ or not __STDC__ */
410
411# define obstack_object_size(h) \
412 (unsigned) ((h)->next_free - (h)->object_base)
413
414# define obstack_room(h) \
415 (unsigned) ((h)->chunk_limit - (h)->next_free)
416
417# define obstack_empty_p(h) \
418 ((h)->chunk->prev == 0 \
419 && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \
420 (h)->chunk->contents, \
421 (h)->alignment_mask))
422
423/* Note that the call to _obstack_newchunk is enclosed in (..., 0)
424 so that we can avoid having void expressions
425 in the arms of the conditional expression.
426 Casting the third operand to void was tried before,
427 but some compilers won't accept it. */
428
429# define obstack_make_room(h,length) \
430( (h)->temp.tempint = (length), \
431 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
432 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0))
433
434# define obstack_grow(h,where,length) \
435( (h)->temp.tempint = (length), \
436 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \
437 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
438 memcpy ((h)->next_free, where, (h)->temp.tempint), \
439 (h)->next_free += (h)->temp.tempint)
440
441# define obstack_grow0(h,where,length) \
442( (h)->temp.tempint = (length), \
443 (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \
444 ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \
445 memcpy ((h)->next_free, where, (h)->temp.tempint), \
446 (h)->next_free += (h)->temp.tempint, \
447 *((h)->next_free)++ = 0)
448
449# define obstack_1grow(h,datum) \
450( (((h)->next_free + 1 > (h)->chunk_limit) \
451 ? (_obstack_newchunk ((h), 1), 0) : 0), \
452 obstack_1grow_fast (h, datum))
453
454# define obstack_ptr_grow(h,datum) \
455( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
456 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
457 obstack_ptr_grow_fast (h, datum))
458
459# define obstack_int_grow(h,datum) \
460( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
461 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
462 obstack_int_grow_fast (h, datum))
463
464# define obstack_ptr_grow_fast(h,aptr) \
465 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr))
466
467# define obstack_int_grow_fast(h,aint) \
468 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint))
469
470# define obstack_blank(h,length) \
471( (h)->temp.tempint = (length), \
472 (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \
473 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \
474 obstack_blank_fast (h, (h)->temp.tempint))
475
476# define obstack_alloc(h,length) \
477 (obstack_blank ((h), (length)), obstack_finish ((h)))
478
479# define obstack_copy(h,where,length) \
480 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
481
482# define obstack_copy0(h,where,length) \
483 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
484
485# define obstack_finish(h) \
486( ((h)->next_free == (h)->object_base \
487 ? (((h)->maybe_empty_object = 1), 0) \
488 : 0), \
489 (h)->temp.tempptr = (h)->object_base, \
490 (h)->next_free \
491 = __PTR_ALIGN ((h)->object_base, (h)->next_free, \
492 (h)->alignment_mask), \
493 (((h)->next_free - (char *) (h)->chunk \
494 > (h)->chunk_limit - (char *) (h)->chunk) \
495 ? ((h)->next_free = (h)->chunk_limit) : 0), \
496 (h)->object_base = (h)->next_free, \
497 (h)->temp.tempptr)
498
499# define obstack_free(h,obj) \
500( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \
501 ((((h)->temp.tempint > 0 \
502 && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \
503 ? (int) ((h)->next_free = (h)->object_base \
504 = (h)->temp.tempint + (char *) (h)->chunk) \
505 : (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0)))
506
507#endif /* not __GNUC__ or not __STDC__ */
508
509#ifdef __cplusplus
510} /* C++ */
511#endif
512
513#endif /* obstack.h */
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