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 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 */
377