1 /* obstack.c - subroutines used implicitly by object stack macros
2    Copyright (C) 1988-2020 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 General Public
7    License as published by the Free Software Foundation; either
8    version 3 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    General Public License for more details.
14 
15    You should have received a copy of the GNU General Public
16    License along with the GNU C Library; if not, see
17    <https://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 __alignof__
55 #  include <alignof.h>
56 #  define __alignof__(type) alignof_type (type)
57 # endif
58 # include <stdlib.h>
59 # include <stdint.h>
60 
61 # ifndef MAX
62 #  define MAX(a,b) ((a) > (b) ? (a) : (b))
63 # endif
64 
65 /* Determine default alignment.  */
66 
67 /* If malloc were really smart, it would round addresses to DEFAULT_ALIGNMENT.
68    But in fact it might be less smart and round addresses to as much as
69    DEFAULT_ROUNDING.  So we prepare for it to do that.
70 
71    DEFAULT_ALIGNMENT cannot be an enum constant; see gnulib's alignof.h.  */
72 #define DEFAULT_ALIGNMENT MAX (__alignof__ (long double),		      \
73                                MAX (__alignof__ (uintmax_t),		      \
74                                     __alignof__ (void *)))
75 #define DEFAULT_ROUNDING MAX (sizeof (long double),			      \
76                                MAX (sizeof (uintmax_t),			      \
77                                     sizeof (void *)))
78 
79 /* Call functions with either the traditional malloc/free calling
80    interface, or the mmalloc/mfree interface (that adds an extra first
81    argument), based on the value of use_extra_arg.  */
82 
83 static void *
call_chunkfun(struct obstack * h,size_t size)84 call_chunkfun (struct obstack *h, size_t size)
85 {
86   if (h->use_extra_arg)
87     return h->chunkfun.extra (h->extra_arg, size);
88   else
89     return h->chunkfun.plain (size);
90 }
91 
92 static void
call_freefun(struct obstack * h,void * old_chunk)93 call_freefun (struct obstack *h, void *old_chunk)
94 {
95   if (h->use_extra_arg)
96     h->freefun.extra (h->extra_arg, old_chunk);
97   else
98     h->freefun.plain (old_chunk);
99 }
100 
101 
102 /* Initialize an obstack H for use.  Specify chunk size SIZE (0 means default).
103    Objects start on multiples of ALIGNMENT (0 means use default).
104 
105    Return nonzero if successful, calls obstack_alloc_failed_handler if
106    allocation fails.  */
107 
108 static int
_obstack_begin_worker(struct obstack * h,_OBSTACK_SIZE_T size,_OBSTACK_SIZE_T alignment)109 _obstack_begin_worker (struct obstack *h,
110                        _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment)
111 {
112   struct _obstack_chunk *chunk; /* points to new chunk */
113 
114   if (alignment == 0)
115     alignment = DEFAULT_ALIGNMENT;
116   if (size == 0)
117     /* Default size is what GNU malloc can fit in a 4096-byte block.  */
118     {
119       /* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
120          Use the values for range checking, because if range checking is off,
121          the extra bytes won't be missed terribly, but if range checking is on
122          and we used a larger request, a whole extra 4096 bytes would be
123          allocated.
124 
125          These number are irrelevant to the new GNU malloc.  I suspect it is
126          less sensitive to the size of the request.  */
127       int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
128                     + 4 + DEFAULT_ROUNDING - 1)
129                    & ~(DEFAULT_ROUNDING - 1));
130       size = 4096 - extra;
131     }
132 
133   h->chunk_size = size;
134   h->alignment_mask = alignment - 1;
135 
136   chunk = h->chunk = call_chunkfun (h, h->chunk_size);
137   if (!chunk)
138     (*obstack_alloc_failed_handler) ();
139   h->next_free = h->object_base = __PTR_ALIGN ((char *) chunk, chunk->contents,
140                                                alignment - 1);
141   h->chunk_limit = chunk->limit = (char *) chunk + h->chunk_size;
142   chunk->prev = 0;
143   /* The initial chunk now contains no empty object.  */
144   h->maybe_empty_object = 0;
145   h->alloc_failed = 0;
146   return 1;
147 }
148 
149 int
_obstack_begin(struct obstack * h,_OBSTACK_SIZE_T size,_OBSTACK_SIZE_T alignment,void * (* chunkfun)(size_t),void (* freefun)(void *))150 _obstack_begin (struct obstack *h,
151                 _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment,
152                 void *(*chunkfun) (size_t),
153                 void (*freefun) (void *))
154 {
155   h->chunkfun.plain = chunkfun;
156   h->freefun.plain = freefun;
157   h->use_extra_arg = 0;
158   return _obstack_begin_worker (h, size, alignment);
159 }
160 
161 int
_obstack_begin_1(struct obstack * h,_OBSTACK_SIZE_T size,_OBSTACK_SIZE_T alignment,void * (* chunkfun)(void *,size_t),void (* freefun)(void *,void *),void * arg)162 _obstack_begin_1 (struct obstack *h,
163                   _OBSTACK_SIZE_T size, _OBSTACK_SIZE_T alignment,
164                   void *(*chunkfun) (void *, size_t),
165                   void (*freefun) (void *, void *),
166                   void *arg)
167 {
168   h->chunkfun.extra = chunkfun;
169   h->freefun.extra = freefun;
170   h->extra_arg = arg;
171   h->use_extra_arg = 1;
172   return _obstack_begin_worker (h, size, alignment);
173 }
174 
175 /* Allocate a new current chunk for the obstack *H
176    on the assumption that LENGTH bytes need to be added
177    to the current object, or a new object of length LENGTH allocated.
178    Copies any partial object from the end of the old chunk
179    to the beginning of the new one.  */
180 
181 void
_obstack_newchunk(struct obstack * h,_OBSTACK_SIZE_T length)182 _obstack_newchunk (struct obstack *h, _OBSTACK_SIZE_T length)
183 {
184   struct _obstack_chunk *old_chunk = h->chunk;
185   struct _obstack_chunk *new_chunk = 0;
186   size_t obj_size = h->next_free - h->object_base;
187   char *object_base;
188 
189   /* Compute size for new chunk.  */
190   size_t sum1 = obj_size + length;
191   size_t sum2 = sum1 + h->alignment_mask;
192   size_t new_size = sum2 + (obj_size >> 3) + 100;
193   if (new_size < sum2)
194     new_size = sum2;
195   if (new_size < h->chunk_size)
196     new_size = h->chunk_size;
197 
198   /* Allocate and initialize the new chunk.  */
199   if (obj_size <= sum1 && sum1 <= sum2)
200     new_chunk = call_chunkfun (h, new_size);
201   if (!new_chunk)
202     (*obstack_alloc_failed_handler)();
203   h->chunk = new_chunk;
204   new_chunk->prev = old_chunk;
205   new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
206 
207   /* Compute an aligned object_base in the new chunk */
208   object_base =
209     __PTR_ALIGN ((char *) new_chunk, new_chunk->contents, h->alignment_mask);
210 
211   /* Move the existing object to the new chunk.  */
212   memcpy (object_base, h->object_base, obj_size);
213 
214   /* If the object just copied was the only data in OLD_CHUNK,
215      free that chunk and remove it from the chain.
216      But not if that chunk might contain an empty object.  */
217   if (!h->maybe_empty_object
218       && (h->object_base
219           == __PTR_ALIGN ((char *) old_chunk, old_chunk->contents,
220                           h->alignment_mask)))
221     {
222       new_chunk->prev = old_chunk->prev;
223       call_freefun (h, old_chunk);
224     }
225 
226   h->object_base = object_base;
227   h->next_free = h->object_base + obj_size;
228   /* The new chunk certainly contains no empty object yet.  */
229   h->maybe_empty_object = 0;
230 }
231 
232 /* Return nonzero if object OBJ has been allocated from obstack H.
233    This is here for debugging.
234    If you use it in a program, you are probably losing.  */
235 
236 /* Suppress -Wmissing-prototypes warning.  We don't want to declare this in
237    obstack.h because it is just for debugging.  */
238 int _obstack_allocated_p (struct obstack *h, void *obj) __attribute_pure__;
239 
240 int
_obstack_allocated_p(struct obstack * h,void * obj)241 _obstack_allocated_p (struct obstack *h, void *obj)
242 {
243   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
244   struct _obstack_chunk *plp;   /* point to previous chunk if any */
245 
246   lp = (h)->chunk;
247   /* We use >= rather than > since the object cannot be exactly at
248      the beginning of the chunk but might be an empty object exactly
249      at the end of an adjacent chunk.  */
250   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
251     {
252       plp = lp->prev;
253       lp = plp;
254     }
255   return lp != 0;
256 }
257 
258 /* Free objects in obstack H, including OBJ and everything allocate
259    more recently than OBJ.  If OBJ is zero, free everything in H.  */
260 
261 void
_obstack_free(struct obstack * h,void * obj)262 _obstack_free (struct obstack *h, void *obj)
263 {
264   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
265   struct _obstack_chunk *plp;   /* point to previous chunk if any */
266 
267   lp = h->chunk;
268   /* We use >= because there cannot be an object at the beginning of a chunk.
269      But there can be an empty object at that address
270      at the end of another chunk.  */
271   while (lp != 0 && ((void *) lp >= obj || (void *) (lp)->limit < obj))
272     {
273       plp = lp->prev;
274       call_freefun (h, lp);
275       lp = plp;
276       /* If we switch chunks, we can't tell whether the new current
277          chunk contains an empty object, so assume that it may.  */
278       h->maybe_empty_object = 1;
279     }
280   if (lp)
281     {
282       h->object_base = h->next_free = (char *) (obj);
283       h->chunk_limit = lp->limit;
284       h->chunk = lp;
285     }
286   else if (obj != 0)
287     /* obj is not in any of the chunks! */
288     abort ();
289 }
290 
291 _OBSTACK_SIZE_T
_obstack_memory_used(struct obstack * h)292 _obstack_memory_used (struct obstack *h)
293 {
294   struct _obstack_chunk *lp;
295   _OBSTACK_SIZE_T nbytes = 0;
296 
297   for (lp = h->chunk; lp != 0; lp = lp->prev)
298     {
299       nbytes += lp->limit - (char *) lp;
300     }
301   return nbytes;
302 }
303 
304 # ifndef _OBSTACK_NO_ERROR_HANDLER
305 /* Define the error handler.  */
306 #  include <stdio.h>
307 
308 /* Exit value used when 'print_and_abort' is used.  */
309 #  ifdef _LIBC
310 int obstack_exit_failure = EXIT_FAILURE;
311 #  else
312 #   include "exitfail.h"
313 #   define obstack_exit_failure exit_failure
314 #  endif
315 
316 #  ifdef _LIBC
317 #   include <libintl.h>
318 #  else
319 #   include "gettext.h"
320 #  endif
321 #  ifndef _
322 #   define _(msgid) gettext (msgid)
323 #  endif
324 
325 #  ifdef _LIBC
326 #   include <libio/iolibio.h>
327 #  endif
328 
329 static _Noreturn void
print_and_abort(void)330 print_and_abort (void)
331 {
332   /* Don't change any of these strings.  Yes, it would be possible to add
333      the newline to the string and use fputs or so.  But this must not
334      happen because the "memory exhausted" message appears in other places
335      like this and the translation should be reused instead of creating
336      a very similar string which requires a separate translation.  */
337 #  ifdef _LIBC
338   (void) __fxprintf (NULL, "%s\n", _("memory exhausted"));
339 #  else
340   fprintf (stderr, "%s\n", _("memory exhausted"));
341 #  endif
342   exit (obstack_exit_failure);
343 }
344 
345 /* The functions allocating more room by calling 'obstack_chunk_alloc'
346    jump to the handler pointed to by 'obstack_alloc_failed_handler'.
347    This can be set to a user defined function which should either
348    abort gracefully or use longjump - but shouldn't return.  This
349    variable by default points to the internal function
350    'print_and_abort'.  */
351 __attribute_noreturn__ void (*obstack_alloc_failed_handler) (void)
352   = print_and_abort;
353 # endif /* !_OBSTACK_NO_ERROR_HANDLER */
354 #endif /* !_OBSTACK_ELIDE_CODE */
355