1/* obstack.c - subroutines used implicitly by object stack macros
2   Copyright (C) 1988-2015 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
56template <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
88static void *
89call_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
97static void
98call_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
113static 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
155int
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
167int
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
187void
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.  */
244int _obstack_allocated_p (struct obstack *h, void *obj) __attribute_pure__;
245
246int
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
267void
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
316int 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
352static _Noreturn void
353print_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'.  */
374void (*obstack_alloc_failed_handler) (void) = print_and_abort;
375# endif /* !_OBSTACK_NO_ERROR_HANDLER */
376#endif /* !_OBSTACK_ELIDE_CODE */
377