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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 
53 struct 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 
68 static bool _try_writable (hb_blob_t *blob);
69 
70 static void
_hb_blob_destroy_user_data(hb_blob_t * blob)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  **/
96 hb_blob_t *
hb_blob_create(const char * data,unsigned int length,hb_memory_mode_t mode,void * user_data,hb_destroy_func_t destroy)97 hb_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  **/
151 hb_blob_t *
hb_blob_create_sub_blob(hb_blob_t * parent,unsigned int offset,unsigned int length)152 hb_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  **/
183 hb_blob_t *
hb_blob_get_empty(void)184 hb_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  **/
214 hb_blob_t *
hb_blob_reference(hb_blob_t * blob)215 hb_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  **/
232 void
hb_blob_destroy(hb_blob_t * blob)233 hb_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  **/
254 hb_bool_t
hb_blob_set_user_data(hb_blob_t * blob,hb_user_data_key_t * key,void * data,hb_destroy_func_t destroy,hb_bool_t replace)255 hb_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  **/
275 void *
hb_blob_get_user_data(hb_blob_t * blob,hb_user_data_key_t * key)276 hb_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  **/
291 void
hb_blob_make_immutable(hb_blob_t * blob)292 hb_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  **/
310 hb_bool_t
hb_blob_is_immutable(hb_blob_t * blob)311 hb_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  **/
327 unsigned int
hb_blob_get_length(hb_blob_t * blob)328 hb_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  **/
344 const char *
hb_blob_get_data(hb_blob_t * blob,unsigned int * length)345 hb_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  **/
369 char *
hb_blob_get_data_writable(hb_blob_t * blob,unsigned int * length)370 hb_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 
386 static hb_bool_t
_try_make_writable_inplace_unix(hb_blob_t * blob)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 
429 static bool
_try_writable_inplace(hb_blob_t * blob)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 
444 static bool
_try_writable(hb_blob_t * blob)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