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/* http://www.oracle.com/technetwork/articles/servers-storage-dev/standardheaderfiles-453865.html */
28#ifndef _POSIX_C_SOURCE
29#define _POSIX_C_SOURCE 199309L
30#endif
31
32#include "hb-private.hh"
33
34#include "hb-object-private.hh"
35
36#ifdef HAVE_SYS_MMAN_H
37#ifdef HAVE_UNISTD_H
38#include <unistd.h>
39#endif /* HAVE_UNISTD_H */
40#include <sys/mman.h>
41#endif /* HAVE_SYS_MMAN_H */
42
43#include <stdio.h>
44#include <errno.h>
45
46
47
48#ifndef HB_DEBUG_BLOB
49#define HB_DEBUG_BLOB (HB_DEBUG+0)
50#endif
51
52
53struct hb_blob_t {
54  hb_object_header_t header;
55  ASSERT_POD ();
56
57  bool immutable;
58
59  const char *data;
60  unsigned int length;
61  hb_memory_mode_t mode;
62
63  void *user_data;
64  hb_destroy_func_t destroy;
65};
66
67
68static bool _try_writable (hb_blob_t *blob);
69
70static void
71_hb_blob_destroy_user_data (hb_blob_t *blob)
72{
73  if (blob->destroy) {
74    blob->destroy (blob->user_data);
75    blob->user_data = NULL;
76    blob->destroy = NULL;
77  }
78}
79
80/**
81 * hb_blob_create: (skip)
82 * @data: Pointer to blob data.
83 * @length: Length of @data in bytes.
84 * @mode: Memory mode for @data.
85 * @user_data: Data parameter to pass to @destroy.
86 * @destroy: Callback to call when @data is not needed anymore.
87 *
88 * Creates a new "blob" object wrapping @data.  The @mode parameter is used
89 * to negotiate ownership and lifecycle of @data.
90 *
91 * Return value: New blob, or the empty blob if something failed or if @length is
92 * zero.  Destroy with hb_blob_destroy().
93 *
94 * Since: 0.9.2
95 **/
96hb_blob_t *
97hb_blob_create (const char        *data,
98                unsigned int       length,
99                hb_memory_mode_t   mode,
100                void              *user_data,
101                hb_destroy_func_t  destroy)
102{
103  hb_blob_t *blob;
104
105  if (!length ||
106      length >= 1u << 31 ||
107      !(blob = hb_object_create<hb_blob_t> ())) {
108    if (destroy)
109      destroy (user_data);
110    return hb_blob_get_empty ();
111  }
112
113  blob->data = data;
114  blob->length = length;
115  blob->mode = mode;
116
117  blob->user_data = user_data;
118  blob->destroy = destroy;
119
120  if (blob->mode == HB_MEMORY_MODE_DUPLICATE) {
121    blob->mode = HB_MEMORY_MODE_READONLY;
122    if (!_try_writable (blob)) {
123      hb_blob_destroy (blob);
124      return hb_blob_get_empty ();
125    }
126  }
127
128  return blob;
129}
130
131/**
132 * hb_blob_create_sub_blob:
133 * @parent: Parent blob.
134 * @offset: Start offset of sub-blob within @parent, in bytes.
135 * @length: Length of sub-blob.
136 *
137 * Returns a blob that represents a range of bytes in @parent.  The new
138 * blob is always created with %HB_MEMORY_MODE_READONLY, meaning that it
139 * will never modify data in the parent blob.  The parent data is not
140 * expected to be modified, and will result in undefined behavior if it
141 * is.
142 *
143 * Makes @parent immutable.
144 *
145 * Return value: New blob, or the empty blob if something failed or if
146 * @length is zero or @offset is beyond the end of @parent's data.  Destroy
147 * with hb_blob_destroy().
148 *
149 * Since: 0.9.2
150 **/
151hb_blob_t *
152hb_blob_create_sub_blob (hb_blob_t    *parent,
153                         unsigned int  offset,
154                         unsigned int  length)
155{
156  hb_blob_t *blob;
157
158  if (!length || offset >= parent->length)
159    return hb_blob_get_empty ();
160
161  hb_blob_make_immutable (parent);
162
163  blob = hb_blob_create (parent->data + offset,
164                         MIN (length, parent->length - offset),
165                         HB_MEMORY_MODE_READONLY,
166                         hb_blob_reference (parent),
167                         (hb_destroy_func_t) hb_blob_destroy);
168
169  return blob;
170}
171
172/**
173 * hb_blob_get_empty:
174 *
175 * Returns the singleton empty blob.
176 *
177 * See TODO:link object types for more information.
178 *
179 * Return value: (transfer full): the empty blob.
180 *
181 * Since: 0.9.2
182 **/
183hb_blob_t *
184hb_blob_get_empty (void)
185{
186  static const hb_blob_t _hb_blob_nil = {
187    HB_OBJECT_HEADER_STATIC,
188
189    true, /* immutable */
190
191    NULL, /* data */
192    0, /* length */
193    HB_MEMORY_MODE_READONLY, /* mode */
194
195    NULL, /* user_data */
196    NULL  /* destroy */
197  };
198
199  return const_cast<hb_blob_t *> (&_hb_blob_nil);
200}
201
202/**
203 * hb_blob_reference: (skip)
204 * @blob: a blob.
205 *
206 * Increases the reference count on @blob.
207 *
208 * See TODO:link object types for more information.
209 *
210 * Return value: @blob.
211 *
212 * Since: 0.9.2
213 **/
214hb_blob_t *
215hb_blob_reference (hb_blob_t *blob)
216{
217  return hb_object_reference (blob);
218}
219
220/**
221 * hb_blob_destroy: (skip)
222 * @blob: a blob.
223 *
224 * Descreases the reference count on @blob, and if it reaches zero, destroys
225 * @blob, freeing all memory, possibly calling the destroy-callback the blob
226 * was created for if it has not been called already.
227 *
228 * See TODO:link object types for more information.
229 *
230 * Since: 0.9.2
231 **/
232void
233hb_blob_destroy (hb_blob_t *blob)
234{
235  if (!hb_object_destroy (blob)) return;
236
237  _hb_blob_destroy_user_data (blob);
238
239  free (blob);
240}
241
242/**
243 * hb_blob_set_user_data: (skip)
244 * @blob: a blob.
245 * @key: key for data to set.
246 * @data: data to set.
247 * @destroy: callback to call when @data is not needed anymore.
248 * @replace: whether to replace an existing data with the same key.
249 *
250 * Return value:
251 *
252 * Since: 0.9.2
253 **/
254hb_bool_t
255hb_blob_set_user_data (hb_blob_t          *blob,
256                       hb_user_data_key_t *key,
257                       void *              data,
258                       hb_destroy_func_t   destroy,
259                       hb_bool_t           replace)
260{
261  return hb_object_set_user_data (blob, key, data, destroy, replace);
262}
263
264/**
265 * hb_blob_get_user_data: (skip)
266 * @blob: a blob.
267 * @key: key for data to get.
268 *
269 *
270 *
271 * Return value: (transfer none):
272 *
273 * Since: 0.9.2
274 **/
275void *
276hb_blob_get_user_data (hb_blob_t          *blob,
277                       hb_user_data_key_t *key)
278{
279  return hb_object_get_user_data (blob, key);
280}
281
282
283/**
284 * hb_blob_make_immutable:
285 * @blob: a blob.
286 *
287 *
288 *
289 * Since: 0.9.2
290 **/
291void
292hb_blob_make_immutable (hb_blob_t *blob)
293{
294  if (hb_object_is_inert (blob))
295    return;
296
297  blob->immutable = true;
298}
299
300/**
301 * hb_blob_is_immutable:
302 * @blob: a blob.
303 *
304 *
305 *
306 * Return value: TODO
307 *
308 * Since: 0.9.2
309 **/
310hb_bool_t
311hb_blob_is_immutable (hb_blob_t *blob)
312{
313  return blob->immutable;
314}
315
316
317/**
318 * hb_blob_get_length:
319 * @blob: a blob.
320 *
321 *
322 *
323 * Return value: the length of blob data in bytes.
324 *
325 * Since: 0.9.2
326 **/
327unsigned int
328hb_blob_get_length (hb_blob_t *blob)
329{
330  return blob->length;
331}
332
333/**
334 * hb_blob_get_data:
335 * @blob: a blob.
336 * @length: (out):
337 *
338 *
339 *
340 * Returns: (transfer none) (array length=length):
341 *
342 * Since: 0.9.2
343 **/
344const char *
345hb_blob_get_data (hb_blob_t *blob, unsigned int *length)
346{
347  if (length)
348    *length = blob->length;
349
350  return blob->data;
351}
352
353/**
354 * hb_blob_get_data_writable:
355 * @blob: a blob.
356 * @length: (out): output length of the writable data.
357 *
358 * Tries to make blob data writable (possibly copying it) and
359 * return pointer to data.
360 *
361 * Fails if blob has been made immutable, or if memory allocation
362 * fails.
363 *
364 * Returns: (transfer none) (array length=length): Writable blob data,
365 * or %NULL if failed.
366 *
367 * Since: 0.9.2
368 **/
369char *
370hb_blob_get_data_writable (hb_blob_t *blob, unsigned int *length)
371{
372  if (!_try_writable (blob)) {
373    if (length)
374      *length = 0;
375
376    return NULL;
377  }
378
379  if (length)
380    *length = blob->length;
381
382  return const_cast<char *> (blob->data);
383}
384
385
386static hb_bool_t
387_try_make_writable_inplace_unix (hb_blob_t *blob)
388{
389#if defined(HAVE_SYS_MMAN_H) && defined(HAVE_MPROTECT)
390  uintptr_t pagesize = -1, mask, length;
391  const char *addr;
392
393#if defined(HAVE_SYSCONF) && defined(_SC_PAGE_SIZE)
394  pagesize = (uintptr_t) sysconf (_SC_PAGE_SIZE);
395#elif defined(HAVE_SYSCONF) && defined(_SC_PAGESIZE)
396  pagesize = (uintptr_t) sysconf (_SC_PAGESIZE);
397#elif defined(HAVE_GETPAGESIZE)
398  pagesize = (uintptr_t) getpagesize ();
399#endif
400
401  if ((uintptr_t) -1L == pagesize) {
402    DEBUG_MSG_FUNC (BLOB, blob, "failed to get pagesize: %s", strerror (errno));
403    return false;
404  }
405  DEBUG_MSG_FUNC (BLOB, blob, "pagesize is %lu", (unsigned long) pagesize);
406
407  mask = ~(pagesize-1);
408  addr = (const char *) (((uintptr_t) blob->data) & mask);
409  length = (const char *) (((uintptr_t) blob->data + blob->length + pagesize-1) & mask)  - addr;
410  DEBUG_MSG_FUNC (BLOB, blob,
411                  "calling mprotect on [%p..%p] (%lu bytes)",
412                  addr, addr+length, (unsigned long) length);
413  if (-1 == mprotect ((void *) addr, length, PROT_READ | PROT_WRITE)) {
414    DEBUG_MSG_FUNC (BLOB, blob, "mprotect failed: %s", strerror (errno));
415    return false;
416  }
417
418  blob->mode = HB_MEMORY_MODE_WRITABLE;
419
420  DEBUG_MSG_FUNC (BLOB, blob,
421                  "successfully made [%p..%p] (%lu bytes) writable\n",
422                  addr, addr+length, (unsigned long) length);
423  return true;
424#else
425  return false;
426#endif
427}
428
429static bool
430_try_writable_inplace (hb_blob_t *blob)
431{
432  DEBUG_MSG_FUNC (BLOB, blob, "making writable inplace\n");
433
434  if (_try_make_writable_inplace_unix (blob))
435    return true;
436
437  DEBUG_MSG_FUNC (BLOB, blob, "making writable -> FAILED\n");
438
439  /* Failed to make writable inplace, mark that */
440  blob->mode = HB_MEMORY_MODE_READONLY;
441  return false;
442}
443
444static bool
445_try_writable (hb_blob_t *blob)
446{
447  if (blob->immutable)
448    return false;
449
450  if (blob->mode == HB_MEMORY_MODE_WRITABLE)
451    return true;
452
453  if (blob->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE && _try_writable_inplace (blob))
454    return true;
455
456  if (blob->mode == HB_MEMORY_MODE_WRITABLE)
457    return true;
458
459
460  DEBUG_MSG_FUNC (BLOB, blob, "current data is -> %p\n", blob->data);
461
462  char *new_data;
463
464  new_data = (char *) malloc (blob->length);
465  if (unlikely (!new_data))
466    return false;
467
468  DEBUG_MSG_FUNC (BLOB, blob, "dupped successfully -> %p\n", blob->data);
469
470  memcpy (new_data, blob->data, blob->length);
471  _hb_blob_destroy_user_data (blob);
472  blob->mode = HB_MEMORY_MODE_WRITABLE;
473  blob->data = new_data;
474  blob->user_data = new_data;
475  blob->destroy = free;
476
477  return true;
478}
479