hb-blob.cc revision d4141a44b97377a65e6d2a3e03b3709307af38c1 
1/*
2 * Copyright © 2009  Red Hat, Inc.
3 *
4 *  This is part of HarfBuzz, a text shaping library.
5 *
6 * Permission is hereby granted, without written agreement and without
7 * license or royalty fees, to use, copy, modify, and distribute this
8 * software and its documentation for any purpose, provided that the
9 * above copyright notice and the following two paragraphs appear in
10 * all copies of this software.
11 *
12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
16 * DAMAGE.
17 *
18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
23 *
24 * Red Hat Author(s): Behdad Esfahbod
25 */
26
27#include "hb-private.hh"
28
29#include "hb-blob-private.hh"
30
31#ifdef HAVE_SYS_MMAN_H
32#ifdef HAVE_UNISTD_H
33#include <unistd.h>
34#endif /* HAVE_UNISTD_H */
35#include <sys/mman.h>
36#endif /* HAVE_SYS_MMAN_H */
37
38#include <stdio.h>
39#include <errno.h>
40
41HB_BEGIN_DECLS
42
43
44#ifndef HB_DEBUG_BLOB
45#define HB_DEBUG_BLOB (HB_DEBUG+0)
46#endif
47
48hb_blob_t _hb_blob_nil = {
49  HB_OBJECT_HEADER_STATIC,
50
51  0, /* length */
52
53  HB_MUTEX_INIT, /* lock */
54
55  0, /* lock_count */
56  HB_MEMORY_MODE_READONLY, /* mode */
57
58  NULL, /* data */
59
60  NULL, /* user_data */
61  NULL  /* destroy */
62};
63
64static void
65_hb_blob_destroy_user_data (hb_blob_t *blob)
66{
67  if (blob->destroy) {
68    blob->destroy (blob->user_data);
69    blob->user_data = NULL;
70    blob->destroy = NULL;
71  }
72}
73
74static void
75_hb_blob_unlock_and_destroy (hb_blob_t *blob)
76{
77  hb_blob_unlock (blob);
78  hb_blob_destroy (blob);
79}
80
81hb_blob_t *
82hb_blob_create (const char        *data,
83		unsigned int       length,
84		hb_memory_mode_t   mode,
85		void              *user_data,
86		hb_destroy_func_t  destroy)
87{
88  hb_blob_t *blob;
89
90  if (!length || !(blob = hb_object_create<hb_blob_t> ())) {
91    if (destroy)
92      destroy (user_data);
93    return &_hb_blob_nil;
94  }
95
96  hb_mutex_init (blob->lock);
97  blob->lock_count = 0;
98
99  blob->data = data;
100  blob->length = length;
101  blob->mode = mode;
102
103  blob->user_data = user_data;
104  blob->destroy = destroy;
105
106  if (blob->mode == HB_MEMORY_MODE_DUPLICATE) {
107    blob->mode = HB_MEMORY_MODE_READONLY;
108    if (!hb_blob_try_writable (blob)) {
109      hb_blob_destroy (blob);
110      return &_hb_blob_nil;
111    }
112  }
113
114  return blob;
115}
116
117hb_blob_t *
118hb_blob_create_sub_blob (hb_blob_t    *parent,
119			 unsigned int  offset,
120			 unsigned int  length)
121{
122  hb_blob_t *blob;
123  const char *pdata;
124
125  if (!length || offset >= parent->length || !(blob = hb_object_create<hb_blob_t> ()))
126    return &_hb_blob_nil;
127
128  pdata = hb_blob_lock (parent);
129
130  hb_mutex_lock (parent->lock);
131  blob = hb_blob_create (pdata + offset,
132			 MIN (length, parent->length - offset),
133			 parent->mode,
134			 hb_blob_reference (parent),
135			 (hb_destroy_func_t) _hb_blob_unlock_and_destroy);
136  hb_mutex_unlock (parent->lock);
137
138  return blob;
139}
140
141hb_blob_t *
142hb_blob_get_empty (void)
143{
144  return &_hb_blob_nil;
145}
146
147hb_blob_t *
148hb_blob_reference (hb_blob_t *blob)
149{
150  return hb_object_reference (blob);
151}
152
153void
154hb_blob_destroy (hb_blob_t *blob)
155{
156  if (!hb_object_destroy (blob)) return;
157
158  _hb_blob_destroy_user_data (blob);
159  hb_mutex_free (blob->lock);
160
161  free (blob);
162}
163
164hb_bool_t
165hb_blob_set_user_data (hb_blob_t          *blob,
166		       hb_user_data_key_t *key,
167		       void *              data,
168		       hb_destroy_func_t   destroy)
169{
170  return hb_object_set_user_data (blob, key, data, destroy);
171}
172
173void *
174hb_blob_get_user_data (hb_blob_t          *blob,
175		       hb_user_data_key_t *key)
176{
177  return hb_object_get_user_data (blob, key);
178}
179
180
181unsigned int
182hb_blob_get_length (hb_blob_t *blob)
183{
184  return blob->length;
185}
186
187const char *
188hb_blob_lock (hb_blob_t *blob)
189{
190  if (hb_object_is_inert (blob))
191    return NULL;
192
193  hb_mutex_lock (blob->lock);
194
195  (void) (HB_DEBUG_BLOB &&
196    fprintf (stderr, "%p %s (%d) -> %p\n", blob, HB_FUNC,
197	     blob->lock_count, blob->data));
198
199  blob->lock_count++;
200
201  hb_mutex_unlock (blob->lock);
202
203  return blob->data;
204}
205
206void
207hb_blob_unlock (hb_blob_t *blob)
208{
209  if (hb_object_is_inert (blob))
210    return;
211
212  hb_mutex_lock (blob->lock);
213
214  (void) (HB_DEBUG_BLOB &&
215    fprintf (stderr, "%p %s (%d) -> %p\n", blob, HB_FUNC,
216	     blob->lock_count, blob->data));
217
218  assert (blob->lock_count > 0);
219  blob->lock_count--;
220
221  hb_mutex_unlock (blob->lock);
222}
223
224hb_bool_t
225hb_blob_is_writable (hb_blob_t *blob)
226{
227  hb_memory_mode_t mode;
228
229  if (hb_object_is_inert (blob))
230    return FALSE;
231
232  hb_mutex_lock (blob->lock);
233
234  mode = blob->mode;
235
236  hb_mutex_unlock (blob->lock);
237
238  return mode == HB_MEMORY_MODE_WRITABLE;
239}
240
241
242static hb_bool_t
243_try_make_writable_inplace_unix_locked (hb_blob_t *blob)
244{
245#if defined(HAVE_SYS_MMAN_H) && defined(HAVE_MPROTECT)
246  uintptr_t pagesize = -1, mask, length;
247  const char *addr;
248
249#if defined(HAVE_SYSCONF) && defined(_SC_PAGE_SIZE)
250  pagesize = (uintptr_t) sysconf (_SC_PAGE_SIZE);
251#elif defined(HAVE_SYSCONF) && defined(_SC_PAGESIZE)
252  pagesize = (uintptr_t) sysconf (_SC_PAGESIZE);
253#elif defined(HAVE_GETPAGESIZE)
254  pagesize = (uintptr_t) getpagesize ();
255#endif
256
257  if ((uintptr_t) -1L == pagesize) {
258    (void) (HB_DEBUG_BLOB &&
259      fprintf (stderr, "%p %s: failed to get pagesize: %s\n", blob, HB_FUNC, strerror (errno)));
260    return FALSE;
261  }
262  (void) (HB_DEBUG_BLOB &&
263    fprintf (stderr, "%p %s: pagesize is %lu\n", blob, HB_FUNC, (unsigned long) pagesize));
264
265  mask = ~(pagesize-1);
266  addr = (const char *) (((uintptr_t) blob->data) & mask);
267  length = (const char *) (((uintptr_t) blob->data + blob->length + pagesize-1) & mask)  - addr;
268  (void) (HB_DEBUG_BLOB &&
269    fprintf (stderr, "%p %s: calling mprotect on [%p..%p] (%lu bytes)\n",
270	     blob, HB_FUNC,
271	     addr, addr+length, (unsigned long) length));
272  if (-1 == mprotect ((void *) addr, length, PROT_READ | PROT_WRITE)) {
273    (void) (HB_DEBUG_BLOB &&
274      fprintf (stderr, "%p %s: %s\n", blob, HB_FUNC, strerror (errno)));
275    return FALSE;
276  }
277
278  (void) (HB_DEBUG_BLOB &&
279    fprintf (stderr, "%p %s: successfully made [%p..%p] (%lu bytes) writable\n",
280	     blob, HB_FUNC,
281	     addr, addr+length, (unsigned long) length));
282  return TRUE;
283#else
284  return FALSE;
285#endif
286}
287
288static void
289try_writable_inplace_locked (hb_blob_t *blob)
290{
291  (void) (HB_DEBUG_BLOB &&
292    fprintf (stderr, "%p %s: making writable\n", blob, HB_FUNC));
293
294  if (_try_make_writable_inplace_unix_locked (blob)) {
295    (void) (HB_DEBUG_BLOB &&
296      fprintf (stderr, "%p %s: making writable -> succeeded\n", blob, HB_FUNC));
297    blob->mode = HB_MEMORY_MODE_WRITABLE;
298  } else {
299    (void) (HB_DEBUG_BLOB &&
300      fprintf (stderr, "%p %s: making writable -> FAILED\n", blob, HB_FUNC));
301    /* Failed to make writable inplace, mark that */
302    blob->mode = HB_MEMORY_MODE_READONLY;
303  }
304}
305
306hb_bool_t
307hb_blob_try_writable_inplace (hb_blob_t *blob)
308{
309  hb_memory_mode_t mode;
310
311  if (hb_object_is_inert (blob))
312    return FALSE;
313
314  hb_mutex_lock (blob->lock);
315
316  if (blob->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE)
317    try_writable_inplace_locked (blob);
318
319  mode = blob->mode;
320
321  hb_mutex_unlock (blob->lock);
322
323  return mode == HB_MEMORY_MODE_WRITABLE;
324}
325
326hb_bool_t
327hb_blob_try_writable (hb_blob_t *blob)
328{
329  hb_memory_mode_t mode;
330
331  if (hb_object_is_inert (blob))
332    return FALSE;
333
334  hb_mutex_lock (blob->lock);
335
336  if (blob->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE)
337    try_writable_inplace_locked (blob);
338
339  if (blob->mode == HB_MEMORY_MODE_READONLY)
340  {
341    char *new_data;
342
343    (void) (HB_DEBUG_BLOB &&
344      fprintf (stderr, "%p %s (%d) -> %p\n", blob, HB_FUNC,
345	       blob->lock_count, blob->data));
346
347    if (blob->lock_count)
348      goto done;
349
350    new_data = (char *) malloc (blob->length);
351    if (new_data) {
352      (void) (HB_DEBUG_BLOB &&
353	fprintf (stderr, "%p %s: dupped successfully -> %p\n", blob, HB_FUNC, blob->data));
354      memcpy (new_data, blob->data, blob->length);
355      _hb_blob_destroy_user_data (blob);
356      blob->mode = HB_MEMORY_MODE_WRITABLE;
357      blob->data = new_data;
358      blob->user_data = new_data;
359      blob->destroy = free;
360    }
361  }
362
363done:
364  mode = blob->mode;
365
366  hb_mutex_unlock (blob->lock);
367
368  return mode == HB_MEMORY_MODE_WRITABLE;
369}
370
371
372HB_END_DECLS
373