1 /*****************************************************************************
2 * block.c: Data blocks management functions
3 *****************************************************************************
4 * Copyright (C) 2003-2004 VLC authors and VideoLAN
5 * Copyright (C) 2007-2009 RĂ©mi Denis-Courmont
7 * Authors: Laurent Aimar <fenrir@videolan.org>
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU Lesser General Public License as published by
11 * the Free Software Foundation; either version 2.1 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU Lesser General Public License for more details.
19 * You should have received a copy of the GNU Lesser General Public License
20 * along with this program; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
22 *****************************************************************************/
24 /*****************************************************************************
26 *****************************************************************************/
37 #include <vlc_common.h>
38 #include <vlc_block.h>
42 * @section Block handling functions.
46 static void BlockNoRelease( block_t
*b
)
48 fprintf( stderr
, "block %p has no release callback! This is a bug!\n", b
);
52 static void block_Check (block_t
*block
)
56 unsigned char *start
= block
->p_start
;
57 unsigned char *end
= block
->p_start
+ block
->i_size
;
58 unsigned char *bufstart
= block
->p_buffer
;
59 unsigned char *bufend
= block
->p_buffer
+ block
->i_buffer
;
61 assert (block
->pf_release
!= BlockNoRelease
);
62 assert (start
<= end
);
63 assert (bufstart
<= bufend
);
64 assert (bufstart
>= start
);
65 assert (bufend
<= end
);
67 block
= block
->p_next
;
71 static void block_Invalidate (block_t
*block
)
75 block
->pf_release
= BlockNoRelease
;
78 # define block_Check(b) ((void)(b))
79 # define block_Invalidate(b) ((void)(b))
82 void block_Init( block_t
*restrict b
, void *buf
, size_t size
)
84 /* Fill all fields to their default */
93 b
->i_dts
= VLC_TS_INVALID
;
96 b
->pf_release
= BlockNoRelease
;
100 static void block_generic_Release (block_t
*block
)
102 /* That is always true for blocks allocated with block_Alloc(). */
103 assert (block
->p_start
== (unsigned char *)(block
+ 1));
104 block_Invalidate (block
);
108 static void BlockMetaCopy( block_t
*restrict out
, const block_t
*in
)
110 out
->p_next
= in
->p_next
;
111 out
->i_nb_samples
= in
->i_nb_samples
;
112 out
->i_dts
= in
->i_dts
;
113 out
->i_pts
= in
->i_pts
;
114 out
->i_flags
= in
->i_flags
;
115 out
->i_length
= in
->i_length
;
118 /** Initial memory alignment of data block.
119 * @note This must be a multiple of sizeof(void*) and a power of two.
120 * libavcodec AVX optimizations require at least 32-bytes. */
121 #define BLOCK_ALIGN 32
123 /** Initial reserved header and footer size. */
124 #define BLOCK_PADDING 32
126 /* Maximum size of reserved footer before shrinking with realloc(). */
127 #define BLOCK_WASTE_SIZE 2048
129 block_t
*block_Alloc (size_t size
)
131 /* 2 * BLOCK_PADDING: pre + post padding */
132 const size_t alloc
= sizeof (block_t
) + BLOCK_ALIGN
+ (2 * BLOCK_PADDING
)
134 if (unlikely(alloc
<= size
))
137 block_t
*b
= malloc (alloc
);
138 if (unlikely(b
== NULL
))
141 block_Init (b
, b
+ 1, alloc
- sizeof (*b
));
142 static_assert ((BLOCK_PADDING
% BLOCK_ALIGN
) == 0,
143 "BLOCK_PADDING must be a multiple of BLOCK_ALIGN");
144 b
->p_buffer
+= BLOCK_PADDING
+ BLOCK_ALIGN
- 1;
145 b
->p_buffer
= (void *)(((uintptr_t)b
->p_buffer
) & ~(BLOCK_ALIGN
- 1));
147 b
->pf_release
= block_generic_Release
;
151 block_t
*block_Realloc( block_t
*p_block
, ssize_t i_prebody
, size_t i_body
)
153 size_t requested
= i_prebody
+ i_body
;
155 block_Check( p_block
);
157 /* Corner case: empty block requested */
158 if( i_prebody
<= 0 && i_body
<= (size_t)(-i_prebody
) )
160 block_Release( p_block
);
164 assert( p_block
->p_start
<= p_block
->p_buffer
);
165 assert( p_block
->p_start
+ p_block
->i_size
166 >= p_block
->p_buffer
+ p_block
->i_buffer
);
168 /* Corner case: the current payload is discarded completely */
169 if( i_prebody
<= 0 && p_block
->i_buffer
<= (size_t)-i_prebody
)
170 p_block
->i_buffer
= 0; /* discard current payload */
171 if( p_block
->i_buffer
== 0 )
173 if( requested
<= p_block
->i_size
)
174 { /* Enough room: recycle buffer */
175 size_t extra
= p_block
->i_size
- requested
;
177 p_block
->p_buffer
= p_block
->p_start
+ (extra
/ 2);
178 p_block
->i_buffer
= requested
;
181 /* Not enough room: allocate a new buffer */
182 block_t
*p_rea
= block_Alloc( requested
);
184 BlockMetaCopy( p_rea
, p_block
);
185 block_Release( p_block
);
189 /* First, shrink payload */
191 /* Pull payload start */
194 assert( p_block
->i_buffer
>= (size_t)-i_prebody
);
195 p_block
->p_buffer
-= i_prebody
;
196 p_block
->i_buffer
+= i_prebody
;
201 /* Trim payload end */
202 if( p_block
->i_buffer
> i_body
)
203 p_block
->i_buffer
= i_body
;
205 uint8_t *p_start
= p_block
->p_start
;
206 uint8_t *p_end
= p_start
+ p_block
->i_size
;
208 /* Second, reallocate the buffer if we lack space. This is done now to
209 * minimize the payload size for memory copy. */
210 assert( i_prebody
>= 0 );
211 if( (size_t)(p_block
->p_buffer
- p_start
) < (size_t)i_prebody
212 || (size_t)(p_end
- p_block
->p_buffer
) < i_body
)
214 block_t
*p_rea
= block_Alloc( requested
);
217 BlockMetaCopy( p_rea
, p_block
);
218 p_rea
->p_buffer
+= i_prebody
;
219 p_rea
->i_buffer
-= i_prebody
;
220 memcpy( p_rea
->p_buffer
, p_block
->p_buffer
, p_block
->i_buffer
);
222 block_Release( p_block
);
228 /* We have a very large reserved footer now? Release some of it.
229 * XXX it might not preserve the alignment of p_buffer */
230 if( p_end
- (p_block
->p_buffer
+ i_body
) > BLOCK_WASTE_SIZE
)
232 block_t
*p_rea
= block_Alloc( requested
);
235 BlockMetaCopy( p_rea
, p_block
);
236 p_rea
->p_buffer
+= i_prebody
;
237 p_rea
->i_buffer
-= i_prebody
;
238 memcpy( p_rea
->p_buffer
, p_block
->p_buffer
, p_block
->i_buffer
);
239 block_Release( p_block
);
244 /* NOTE: p_start and p_end are corrupted from this point */
246 /* Third, expand payload */
248 /* Push payload start */
251 p_block
->p_buffer
-= i_prebody
;
252 p_block
->i_buffer
+= i_prebody
;
257 /* Expand payload to requested size */
258 p_block
->i_buffer
= i_body
;
264 static void block_heap_Release (block_t
*block
)
266 block_Invalidate (block
);
267 free (block
->p_start
);
272 * Creates a block from a heap allocation.
273 * This is provided by LibVLC so that manually heap-allocated blocks can safely
274 * be deallocated even after the origin plugin has been unloaded from memory.
276 * When block_Release() is called, VLC will free() the specified pointer.
278 * @param addr base address of the heap allocation (will be free()'d)
279 * @param length bytes length of the heap allocation
280 * @return NULL in case of error (ptr free()'d in that case), or a valid
283 block_t
*block_heap_Alloc (void *addr
, size_t length
)
285 block_t
*block
= malloc (sizeof (*block
));
292 block_Init (block
, addr
, length
);
293 block
->pf_release
= block_heap_Release
;
298 # include <sys/mman.h>
300 static void block_mmap_Release (block_t
*block
)
302 block_Invalidate (block
);
303 munmap (block
->p_start
, block
->i_size
);
308 * Creates a block from a virtual address memory mapping (mmap).
309 * This is provided by LibVLC so that mmap blocks can safely be deallocated
310 * even after the allocating plugin has been unloaded from memory.
312 * @param addr base address of the mapping (as returned by mmap)
313 * @param length length (bytes) of the mapping (as passed to mmap)
314 * @return NULL if addr is MAP_FAILED, or an error occurred (in the later
315 * case, munmap(addr, length) is invoked before returning).
317 block_t
*block_mmap_Alloc (void *addr
, size_t length
)
319 if (addr
== MAP_FAILED
)
322 long page_mask
= sysconf(_SC_PAGESIZE
) - 1;
323 size_t left
= ((uintptr_t)addr
) & page_mask
;
324 size_t right
= (-length
) & page_mask
;
326 block_t
*block
= malloc (sizeof (*block
));
329 munmap (addr
, length
);
333 block_Init (block
, ((char *)addr
) - left
, left
+ length
+ right
);
334 block
->p_buffer
= addr
;
335 block
->i_buffer
= length
;
336 block
->pf_release
= block_mmap_Release
;
340 block_t
*block_mmap_Alloc (void *addr
, size_t length
)
342 (void)addr
; (void)length
; return NULL
;
346 #ifdef HAVE_SYS_SHM_H
347 # include <sys/shm.h>
349 typedef struct block_shm_t
355 static void block_shm_Release (block_t
*block
)
357 block_shm_t
*p_sys
= (block_shm_t
*)block
;
359 shmdt (p_sys
->base_addr
);
364 * Creates a block from a System V shared memory segment (shmget()).
365 * This is provided by LibVLC so that segments can safely be deallocated
366 * even after the allocating plugin has been unloaded from memory.
368 * @param addr base address of the segment (as returned by shmat())
369 * @param length length (bytes) of the segment (as passed to shmget())
370 * @return NULL if an error occurred (in that case, shmdt(addr) is invoked
371 * before returning NULL).
373 block_t
*block_shm_Alloc (void *addr
, size_t length
)
375 block_shm_t
*block
= malloc (sizeof (*block
));
376 if (unlikely(block
== NULL
))
382 block_Init (&block
->self
, (uint8_t *)addr
, length
);
383 block
->self
.pf_release
= block_shm_Release
;
384 block
->base_addr
= addr
;
388 block_t
*block_shm_Alloc (void *addr
, size_t length
)
390 (void) addr
; (void) length
;
400 ssize_t
pread (int fd
, void *buf
, size_t count
, off_t offset
)
402 HANDLE handle
= (HANDLE
)(intptr_t)_get_osfhandle (fd
);
403 if (handle
== INVALID_HANDLE_VALUE
)
406 OVERLAPPED olap
; olap
.Offset
= offset
; olap
.OffsetHigh
= (offset
>> 32);
408 /* This braindead API will override the file pointer even if we specify
409 * an explicit read offset... So do not expect this to mix well with
410 * regular read() calls. */
411 if (ReadFile (handle
, buf
, count
, &written
, &olap
))
418 * Loads a file into a block of memory through a file descriptor.
419 * If possible a private file mapping is created. Otherwise, the file is read
420 * normally. This function is a cancellation point.
422 * @note On 32-bits platforms,
423 * this function will not work for very large files,
424 * due to memory space constraints.
426 * @param fd file descriptor to load from
427 * @return a new block with the file content at p_buffer, and file length at
428 * i_buffer (release it with block_Release()), or NULL upon error (see errno).
430 block_t
*block_File (int fd
)
435 /* First, get the file size */
439 /* st_size is meaningful for regular files, shared memory and typed memory.
440 * It's also meaning for symlinks, but that's not possible with fstat().
441 * In other cases, it's undefined, and we should really not go further. */
443 # define S_TYPEISSHM( buf ) (0)
445 if (S_ISDIR (st
.st_mode
))
450 if (!S_ISREG (st
.st_mode
) && !S_TYPEISSHM (&st
))
456 /* Prevent an integer overflow in mmap() and malloc() */
457 if ((uintmax_t)st
.st_size
>= SIZE_MAX
)
462 length
= (size_t)st
.st_size
;
469 addr
= mmap (NULL
, length
, PROT_READ
|PROT_WRITE
, MAP_PRIVATE
, fd
, 0);
470 if (addr
!= MAP_FAILED
)
471 return block_mmap_Alloc (addr
, length
);
475 /* If mmap() is not implemented by the OS _or_ the filesystem... */
476 block_t
*block
= block_Alloc (length
);
479 block_cleanup_push (block
);
481 for (size_t i
= 0; i
< length
;)
483 ssize_t len
= pread (fd
, block
->p_buffer
+ i
, length
- i
, i
);
486 block_Release (block
);
497 * Loads a file into a block of memory from the file path.
498 * See also block_File().
500 block_t
*block_FilePath (const char *path
)
502 int fd
= vlc_open (path
, O_RDONLY
);
506 block_t
*block
= block_File (fd
);