1 /* obstack.c - subroutines used implicitly by object stack macros
2 Copyright (C) 1988-2023 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 */