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: (Xconstructor)
82 * @data: (array length=length) (closure user_data) (destroy destroy) (scope notified) (transfer none): 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: 1.0
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 || !(blob = hb_object_create<hb_blob_t> ())) {
106    if (destroy)
107      destroy (user_data);
108    return hb_blob_get_empty ();
109  }
110
111  blob->data = data;
112  blob->length = length;
113  blob->mode = mode;
114
115  blob->user_data = user_data;
116  blob->destroy = destroy;
117
118  if (blob->mode == HB_MEMORY_MODE_DUPLICATE) {
119    blob->mode = HB_MEMORY_MODE_READONLY;
120    if (!_try_writable (blob)) {
121      hb_blob_destroy (blob);
122      return hb_blob_get_empty ();
123    }
124  }
125
126  return blob;
127}
128
129/**
130 * hb_blob_create_sub_blob:
131 * @parent: Parent blob.
132 * @offset: Start offset of sub-blob within @parent, in bytes.
133 * @length: Length of sub-blob.
134 *
135 * Returns a blob that represents a range of bytes in @parent.  The new
136 * blob is always created with %HB_MEMORY_MODE_READONLY, meaning that it
137 * will never modify data in the parent blob.  The parent data is not
138 * expected to be modified, and will result in undefined behavior if it
139 * is.
140 *
141 * Makes @parent immutable.
142 *
143 * Return value: New blob, or the empty blob if something failed or if
144 * @length is zero or @offset is beyond the end of @parent's data.  Destroy
145 * with hb_blob_destroy().
146 *
147 * Since: 1.0
148 **/
149hb_blob_t *
150hb_blob_create_sub_blob (hb_blob_t    *parent,
151			 unsigned int  offset,
152			 unsigned int  length)
153{
154  hb_blob_t *blob;
155
156  if (!length || offset >= parent->length)
157    return hb_blob_get_empty ();
158
159  hb_blob_make_immutable (parent);
160
161  blob = hb_blob_create (parent->data + offset,
162			 MIN (length, parent->length - offset),
163			 HB_MEMORY_MODE_READONLY,
164			 hb_blob_reference (parent),
165			 (hb_destroy_func_t) hb_blob_destroy);
166
167  return blob;
168}
169
170/**
171 * hb_blob_get_empty:
172 *
173 * Returns the singleton empty blob.
174 *
175 * See TODO:link object types for more information.
176 *
177 * Return value: (transfer full): the empty blob.
178 *
179 * Since: 1.0
180 **/
181hb_blob_t *
182hb_blob_get_empty (void)
183{
184  static const hb_blob_t _hb_blob_nil = {
185    HB_OBJECT_HEADER_STATIC,
186
187    true, /* immutable */
188
189    NULL, /* data */
190    0, /* length */
191    HB_MEMORY_MODE_READONLY, /* mode */
192
193    NULL, /* user_data */
194    NULL  /* destroy */
195  };
196
197  return const_cast<hb_blob_t *> (&_hb_blob_nil);
198}
199
200/**
201 * hb_blob_reference: (skip)
202 * @blob: a blob.
203 *
204 * Increases the reference count on @blob.
205 *
206 * See TODO:link object types for more information.
207 *
208 * Return value: @blob.
209 *
210 * Since: 1.0
211 **/
212hb_blob_t *
213hb_blob_reference (hb_blob_t *blob)
214{
215  return hb_object_reference (blob);
216}
217
218/**
219 * hb_blob_destroy: (skip)
220 * @blob: a blob.
221 *
222 * Descreases the reference count on @blob, and if it reaches zero, destroys
223 * @blob, freeing all memory, possibly calling the destroy-callback the blob
224 * was created for if it has not been called already.
225 *
226 * See TODO:link object types for more information.
227 *
228 * Since: 1.0
229 **/
230void
231hb_blob_destroy (hb_blob_t *blob)
232{
233  if (!hb_object_destroy (blob)) return;
234
235  _hb_blob_destroy_user_data (blob);
236
237  free (blob);
238}
239
240/**
241 * hb_blob_set_user_data: (skip)
242 * @blob: a blob.
243 * @key: key for data to set.
244 * @data: data to set.
245 * @destroy: callback to call when @data is not needed anymore.
246 * @replace: whether to replace an existing data with the same key.
247 *
248 * Return value:
249 *
250 * Since: 1.0
251 **/
252hb_bool_t
253hb_blob_set_user_data (hb_blob_t          *blob,
254		       hb_user_data_key_t *key,
255		       void *              data,
256		       hb_destroy_func_t   destroy,
257		       hb_bool_t           replace)
258{
259  return hb_object_set_user_data (blob, key, data, destroy, replace);
260}
261
262/**
263 * hb_blob_get_user_data: (skip)
264 * @blob: a blob.
265 * @key: key for data to get.
266 *
267 *
268 *
269 * Return value: (transfer none):
270 *
271 * Since: 1.0
272 **/
273void *
274hb_blob_get_user_data (hb_blob_t          *blob,
275		       hb_user_data_key_t *key)
276{
277  return hb_object_get_user_data (blob, key);
278}
279
280
281/**
282 * hb_blob_make_immutable:
283 * @blob: a blob.
284 *
285 *
286 *
287 * Since: 1.0
288 **/
289void
290hb_blob_make_immutable (hb_blob_t *blob)
291{
292  if (hb_object_is_inert (blob))
293    return;
294
295  blob->immutable = true;
296}
297
298/**
299 * hb_blob_is_immutable:
300 * @blob: a blob.
301 *
302 *
303 *
304 * Return value: TODO
305 *
306 * Since: 1.0
307 **/
308hb_bool_t
309hb_blob_is_immutable (hb_blob_t *blob)
310{
311  return blob->immutable;
312}
313
314
315/**
316 * hb_blob_get_length:
317 * @blob: a blob.
318 *
319 *
320 *
321 * Return value: the length of blob data in bytes.
322 *
323 * Since: 1.0
324 **/
325unsigned int
326hb_blob_get_length (hb_blob_t *blob)
327{
328  return blob->length;
329}
330
331/**
332 * hb_blob_get_data:
333 * @blob: a blob.
334 * @length: (out):
335 *
336 *
337 *
338 * Returns: (transfer none) (array length=length):
339 *
340 * Since: 1.0
341 **/
342const char *
343hb_blob_get_data (hb_blob_t *blob, unsigned int *length)
344{
345  if (length)
346    *length = blob->length;
347
348  return blob->data;
349}
350
351/**
352 * hb_blob_get_data_writable:
353 * @blob: a blob.
354 * @length: (out): output length of the writable data.
355 *
356 * Tries to make blob data writable (possibly copying it) and
357 * return pointer to data.
358 *
359 * Fails if blob has been made immutable, or if memory allocation
360 * fails.
361 *
362 * Returns: (transfer none) (array length=length): Writable blob data,
363 * or %NULL if failed.
364 *
365 * Since: 1.0
366 **/
367char *
368hb_blob_get_data_writable (hb_blob_t *blob, unsigned int *length)
369{
370  if (!_try_writable (blob)) {
371    if (length)
372      *length = 0;
373
374    return NULL;
375  }
376
377  if (length)
378    *length = blob->length;
379
380  return const_cast<char *> (blob->data);
381}
382
383
384static hb_bool_t
385_try_make_writable_inplace_unix (hb_blob_t *blob)
386{
387#if defined(HAVE_SYS_MMAN_H) && defined(HAVE_MPROTECT)
388  uintptr_t pagesize = -1, mask, length;
389  const char *addr;
390
391#if defined(HAVE_SYSCONF) && defined(_SC_PAGE_SIZE)
392  pagesize = (uintptr_t) sysconf (_SC_PAGE_SIZE);
393#elif defined(HAVE_SYSCONF) && defined(_SC_PAGESIZE)
394  pagesize = (uintptr_t) sysconf (_SC_PAGESIZE);
395#elif defined(HAVE_GETPAGESIZE)
396  pagesize = (uintptr_t) getpagesize ();
397#endif
398
399  if ((uintptr_t) -1L == pagesize) {
400    DEBUG_MSG_FUNC (BLOB, blob, "failed to get pagesize: %s", strerror (errno));
401    return false;
402  }
403  DEBUG_MSG_FUNC (BLOB, blob, "pagesize is %lu", (unsigned long) pagesize);
404
405  mask = ~(pagesize-1);
406  addr = (const char *) (((uintptr_t) blob->data) & mask);
407  length = (const char *) (((uintptr_t) blob->data + blob->length + pagesize-1) & mask)  - addr;
408  DEBUG_MSG_FUNC (BLOB, blob,
409		  "calling mprotect on [%p..%p] (%lu bytes)",
410		  addr, addr+length, (unsigned long) length);
411  if (-1 == mprotect ((void *) addr, length, PROT_READ | PROT_WRITE)) {
412    DEBUG_MSG_FUNC (BLOB, blob, "mprotect failed: %s", strerror (errno));
413    return false;
414  }
415
416  blob->mode = HB_MEMORY_MODE_WRITABLE;
417
418  DEBUG_MSG_FUNC (BLOB, blob,
419		  "successfully made [%p..%p] (%lu bytes) writable\n",
420		  addr, addr+length, (unsigned long) length);
421  return true;
422#else
423  return false;
424#endif
425}
426
427static bool
428_try_writable_inplace (hb_blob_t *blob)
429{
430  DEBUG_MSG_FUNC (BLOB, blob, "making writable inplace\n");
431
432  if (_try_make_writable_inplace_unix (blob))
433    return true;
434
435  DEBUG_MSG_FUNC (BLOB, blob, "making writable -> FAILED\n");
436
437  /* Failed to make writable inplace, mark that */
438  blob->mode = HB_MEMORY_MODE_READONLY;
439  return false;
440}
441
442static bool
443_try_writable (hb_blob_t *blob)
444{
445  if (blob->immutable)
446    return false;
447
448  if (blob->mode == HB_MEMORY_MODE_WRITABLE)
449    return true;
450
451  if (blob->mode == HB_MEMORY_MODE_READONLY_MAY_MAKE_WRITABLE && _try_writable_inplace (blob))
452    return true;
453
454  if (blob->mode == HB_MEMORY_MODE_WRITABLE)
455    return true;
456
457
458  DEBUG_MSG_FUNC (BLOB, blob, "current data is -> %p\n", blob->data);
459
460  char *new_data;
461
462  new_data = (char *) malloc (blob->length);
463  if (unlikely (!new_data))
464    return false;
465
466  DEBUG_MSG_FUNC (BLOB, blob, "dupped successfully -> %p\n", blob->data);
467
468  memcpy (new_data, blob->data, blob->length);
469  _hb_blob_destroy_user_data (blob);
470  blob->mode = HB_MEMORY_MODE_WRITABLE;
471  blob->data = new_data;
472  blob->user_data = new_data;
473  blob->destroy = free;
474
475  return true;
476}
477