1/*
2 * copyright (c) 2001 Fabrice Bellard
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20#ifndef AVFORMAT_AVIO_H
21#define AVFORMAT_AVIO_H
22
23/**
24 * @file
25 * @ingroup lavf_io
26 * Buffered I/O operations
27 */
28
29#include <stdint.h>
30
31#include "libavutil/common.h"
32#include "libavutil/dict.h"
33#include "libavutil/log.h"
34
35#include "libavformat/version.h"
36
37/**
38 * Seeking works like for a local file.
39 */
40#define AVIO_SEEKABLE_NORMAL (1 << 0)
41
42/**
43 * Seeking by timestamp with avio_seek_time() is possible.
44 */
45#define AVIO_SEEKABLE_TIME (1 << 1)
46
47/**
48 * Callback for checking whether to abort blocking functions.
49 * AVERROR_EXIT is returned in this case by the interrupted
50 * function. During blocking operations, callback is called with
51 * opaque as parameter. If the callback returns 1, the
52 * blocking operation will be aborted.
53 *
54 * No members can be added to this struct without a major bump, if
55 * new elements have been added after this struct in AVFormatContext
56 * or AVIOContext.
57 */
58typedef struct AVIOInterruptCB {
59 int (*callback)(void*);
60 void *opaque;
61} AVIOInterruptCB;
62
63/**
64 * Directory entry types.
65 */
66enum AVIODirEntryType {
67 AVIO_ENTRY_UNKNOWN,
68 AVIO_ENTRY_BLOCK_DEVICE,
69 AVIO_ENTRY_CHARACTER_DEVICE,
70 AVIO_ENTRY_DIRECTORY,
71 AVIO_ENTRY_NAMED_PIPE,
72 AVIO_ENTRY_SYMBOLIC_LINK,
73 AVIO_ENTRY_SOCKET,
74 AVIO_ENTRY_FILE,
75 AVIO_ENTRY_SERVER,
76 AVIO_ENTRY_SHARE,
77 AVIO_ENTRY_WORKGROUP,
78};
79
80/**
81 * Describes single entry of the directory.
82 *
83 * Only name and type fields are guaranteed be set.
84 * Rest of fields are protocol or/and platform dependent and might be unknown.
85 */
86typedef struct AVIODirEntry {
87 char *name; /**< Filename */
88 int type; /**< Type of the entry */
89 int utf8; /**< Set to 1 when name is encoded with UTF-8, 0 otherwise.
90 Name can be encoded with UTF-8 even though 0 is set. */
91 int64_t size; /**< File size in bytes, -1 if unknown. */
92 int64_t modification_timestamp; /**< Time of last modification in microseconds since unix
93 epoch, -1 if unknown. */
94 int64_t access_timestamp; /**< Time of last access in microseconds since unix epoch,
95 -1 if unknown. */
96 int64_t status_change_timestamp; /**< Time of last status change in microseconds since unix
97 epoch, -1 if unknown. */
98 int64_t user_id; /**< User ID of owner, -1 if unknown. */
99 int64_t group_id; /**< Group ID of owner, -1 if unknown. */
100 int64_t filemode; /**< Unix file mode, -1 if unknown. */
101} AVIODirEntry;
102
103typedef struct AVIODirContext {
104 struct URLContext *url_context;
105} AVIODirContext;
106
107/**
108 * Different data types that can be returned via the AVIO
109 * write_data_type callback.
110 */
111enum AVIODataMarkerType {
112 /**
113 * Header data; this needs to be present for the stream to be decodeable.
114 */
115 AVIO_DATA_MARKER_HEADER,
116 /**
117 * A point in the output bytestream where a decoder can start decoding
118 * (i.e. a keyframe). A demuxer/decoder given the data flagged with
119 * AVIO_DATA_MARKER_HEADER, followed by any AVIO_DATA_MARKER_SYNC_POINT,
120 * should give decodeable results.
121 */
122 AVIO_DATA_MARKER_SYNC_POINT,
123 /**
124 * A point in the output bytestream where a demuxer can start parsing
125 * (for non self synchronizing bytestream formats). That is, any
126 * non-keyframe packet start point.
127 */
128 AVIO_DATA_MARKER_BOUNDARY_POINT,
129 /**
130 * This is any, unlabelled data. It can either be a muxer not marking
131 * any positions at all, it can be an actual boundary/sync point
132 * that the muxer chooses not to mark, or a later part of a packet/fragment
133 * that is cut into multiple write callbacks due to limited IO buffer size.
134 */
135 AVIO_DATA_MARKER_UNKNOWN,
136 /**
137 * Trailer data, which doesn't contain actual content, but only for
138 * finalizing the output file.
139 */
140 AVIO_DATA_MARKER_TRAILER,
141 /**
142 * A point in the output bytestream where the underlying AVIOContext might
143 * flush the buffer depending on latency or buffering requirements. Typically
144 * means the end of a packet.
145 */
146 AVIO_DATA_MARKER_FLUSH_POINT,
147};
148
149/**
150 * Bytestream IO Context.
151 * New fields can be added to the end with minor version bumps.
152 * Removal, reordering and changes to existing fields require a major
153 * version bump.
154 * sizeof(AVIOContext) must not be used outside libav*.
155 *
156 * @note None of the function pointers in AVIOContext should be called
157 * directly, they should only be set by the client application
158 * when implementing custom I/O. Normally these are set to the
159 * function pointers specified in avio_alloc_context()
160 */
161typedef struct AVIOContext {
162 /**
163 * A class for private options.
164 *
165 * If this AVIOContext is created by avio_open2(), av_class is set and
166 * passes the options down to protocols.
167 *
168 * If this AVIOContext is manually allocated, then av_class may be set by
169 * the caller.
170 *
171 * warning -- this field can be NULL, be sure to not pass this AVIOContext
172 * to any av_opt_* functions in that case.
173 */
174 const AVClass *av_class;
175
176 /*
177 * The following shows the relationship between buffer, buf_ptr,
178 * buf_ptr_max, buf_end, buf_size, and pos, when reading and when writing
179 * (since AVIOContext is used for both):
180 *
181 **********************************************************************************
182 * READING
183 **********************************************************************************
184 *
185 * | buffer_size |
186 * |---------------------------------------|
187 * | |
188 *
189 * buffer buf_ptr buf_end
190 * +---------------+-----------------------+
191 * |/ / / / / / / /|/ / / / / / /| |
192 * read buffer: |/ / consumed / | to be read /| |
193 * |/ / / / / / / /|/ / / / / / /| |
194 * +---------------+-----------------------+
195 *
196 * pos
197 * +-------------------------------------------+-----------------+
198 * input file: | | |
199 * +-------------------------------------------+-----------------+
200 *
201 *
202 **********************************************************************************
203 * WRITING
204 **********************************************************************************
205 *
206 * | buffer_size |
207 * |--------------------------------------|
208 * | |
209 *
210 * buf_ptr_max
211 * buffer (buf_ptr) buf_end
212 * +-----------------------+--------------+
213 * |/ / / / / / / / / / / /| |
214 * write buffer: | / / to be flushed / / | |
215 * |/ / / / / / / / / / / /| |
216 * +-----------------------+--------------+
217 * buf_ptr can be in this
218 * due to a backward seek
219 *
220 * pos
221 * +-------------+----------------------------------------------+
222 * output file: | | |
223 * +-------------+----------------------------------------------+
224 *
225 */
226 unsigned char *buffer; /**< Start of the buffer. */
227 int buffer_size; /**< Maximum buffer size */
228 unsigned char *buf_ptr; /**< Current position in the buffer */
229 unsigned char *buf_end; /**< End of the data, may be less than
230 buffer+buffer_size if the read function returned
231 less data than requested, e.g. for streams where
232 no more data has been received yet. */
233 void *opaque; /**< A private pointer, passed to the read/write/seek/...
234 functions. */
235 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
236 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
237 int64_t (*seek)(void *opaque, int64_t offset, int whence);
238 int64_t pos; /**< position in the file of the current buffer */
239 int eof_reached; /**< true if eof reached */
240 int write_flag; /**< true if open for writing */
241 int max_packet_size;
242 unsigned long checksum;
243 unsigned char *checksum_ptr;
244 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
245 int error; /**< contains the error code or 0 if no error happened */
246 /**
247 * Pause or resume playback for network streaming protocols - e.g. MMS.
248 */
249 int (*read_pause)(void *opaque, int pause);
250 /**
251 * Seek to a given timestamp in stream with the specified stream_index.
252 * Needed for some network streaming protocols which don't support seeking
253 * to byte position.
254 */
255 int64_t (*read_seek)(void *opaque, int stream_index,
256 int64_t timestamp, int flags);
257 /**
258 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
259 */
260 int seekable;
261
262 /**
263 * max filesize, used to limit allocations
264 * This field is internal to libavformat and access from outside is not allowed.
265 */
266 int64_t maxsize;
267
268 /**
269 * avio_read and avio_write should if possible be satisfied directly
270 * instead of going through a buffer, and avio_seek will always
271 * call the underlying seek function directly.
272 */
273 int direct;
274
275 /**
276 * Bytes read statistic
277 * This field is internal to libavformat and access from outside is not allowed.
278 */
279 int64_t bytes_read;
280
281 /**
282 * seek statistic
283 * This field is internal to libavformat and access from outside is not allowed.
284 */
285 int seek_count;
286
287 /**
288 * writeout statistic
289 * This field is internal to libavformat and access from outside is not allowed.
290 */
291 int writeout_count;
292
293 /**
294 * Original buffer size
295 * used internally after probing and ensure seekback to reset the buffer size
296 * This field is internal to libavformat and access from outside is not allowed.
297 */
298 int orig_buffer_size;
299
300 /**
301 * Threshold to favor readahead over seek.
302 * This is current internal only, do not use from outside.
303 */
304 int short_seek_threshold;
305
306 /**
307 * ',' separated list of allowed protocols.
308 */
309 const char *protocol_whitelist;
310
311 /**
312 * ',' separated list of disallowed protocols.
313 */
314 const char *protocol_blacklist;
315
316 /**
317 * A callback that is used instead of write_packet.
318 */
319 int (*write_data_type)(void *opaque, uint8_t *buf, int buf_size,
320 enum AVIODataMarkerType type, int64_t time);
321 /**
322 * If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT,
323 * but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly
324 * small chunks of data returned from the callback).
325 */
326 int ignore_boundary_point;
327
328 /**
329 * Internal, not meant to be used from outside of AVIOContext.
330 */
331 enum AVIODataMarkerType current_type;
332 int64_t last_time;
333
334 /**
335 * A callback that is used instead of short_seek_threshold.
336 * This is current internal only, do not use from outside.
337 */
338 int (*short_seek_get)(void *opaque);
339
340 int64_t written;
341
342 /**
343 * Maximum reached position before a backward seek in the write buffer,
344 * used keeping track of already written data for a later flush.
345 */
346 unsigned char *buf_ptr_max;
347
348 /**
349 * Try to buffer at least this amount of data before flushing it
350 */
351 int min_packet_size;
352} AVIOContext;
353
354/**
355 * Return the name of the protocol that will handle the passed URL.
356 *
357 * NULL is returned if no protocol could be found for the given URL.
358 *
359 * @return Name of the protocol or NULL.
360 */
361const char *avio_find_protocol_name(const char *url);
362
363/**
364 * Return AVIO_FLAG_* access flags corresponding to the access permissions
365 * of the resource in url, or a negative value corresponding to an
366 * AVERROR code in case of failure. The returned access flags are
367 * masked by the value in flags.
368 *
369 * @note This function is intrinsically unsafe, in the sense that the
370 * checked resource may change its existence or permission status from
371 * one call to another. Thus you should not trust the returned value,
372 * unless you are sure that no other processes are accessing the
373 * checked resource.
374 */
375int avio_check(const char *url, int flags);
376
377/**
378 * Move or rename a resource.
379 *
380 * @note url_src and url_dst should share the same protocol and authority.
381 *
382 * @param url_src url to resource to be moved
383 * @param url_dst new url to resource if the operation succeeded
384 * @return >=0 on success or negative on error.
385 */
386int avpriv_io_move(const char *url_src, const char *url_dst);
387
388/**
389 * Delete a resource.
390 *
391 * @param url resource to be deleted.
392 * @return >=0 on success or negative on error.
393 */
394int avpriv_io_delete(const char *url);
395
396/**
397 * Open directory for reading.
398 *
399 * @param s directory read context. Pointer to a NULL pointer must be passed.
400 * @param url directory to be listed.
401 * @param options A dictionary filled with protocol-private options. On return
402 * this parameter will be destroyed and replaced with a dictionary
403 * containing options that were not found. May be NULL.
404 * @return >=0 on success or negative on error.
405 */
406int avio_open_dir(AVIODirContext **s, const char *url, AVDictionary **options);
407
408/**
409 * Get next directory entry.
410 *
411 * Returned entry must be freed with avio_free_directory_entry(). In particular
412 * it may outlive AVIODirContext.
413 *
414 * @param s directory read context.
415 * @param[out] next next entry or NULL when no more entries.
416 * @return >=0 on success or negative on error. End of list is not considered an
417 * error.
418 */
419int avio_read_dir(AVIODirContext *s, AVIODirEntry **next);
420
421/**
422 * Close directory.
423 *
424 * @note Entries created using avio_read_dir() are not deleted and must be
425 * freeded with avio_free_directory_entry().
426 *
427 * @param s directory read context.
428 * @return >=0 on success or negative on error.
429 */
430int avio_close_dir(AVIODirContext **s);
431
432/**
433 * Free entry allocated by avio_read_dir().
434 *
435 * @param entry entry to be freed.
436 */
437void avio_free_directory_entry(AVIODirEntry **entry);
438
439/**
440 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
441 * freed with avio_context_free().
442 *
443 * @param buffer Memory block for input/output operations via AVIOContext.
444 * The buffer must be allocated with av_malloc() and friends.
445 * It may be freed and replaced with a new buffer by libavformat.
446 * AVIOContext.buffer holds the buffer currently in use,
447 * which must be later freed with av_free().
448 * @param buffer_size The buffer size is very important for performance.
449 * For protocols with fixed blocksize it should be set to this blocksize.
450 * For others a typical size is a cache page, e.g. 4kb.
451 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
452 * @param opaque An opaque pointer to user-specific data.
453 * @param read_packet A function for refilling the buffer, may be NULL.
454 * For stream protocols, must never return 0 but rather
455 * a proper AVERROR code.
456 * @param write_packet A function for writing the buffer contents, may be NULL.
457 * The function may not change the input buffers content.
458 * @param seek A function for seeking to specified byte position, may be NULL.
459 *
460 * @return Allocated AVIOContext or NULL on failure.
461 */
462AVIOContext *avio_alloc_context(
463 unsigned char *buffer,
464 int buffer_size,
465 int write_flag,
466 void *opaque,
467 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
468 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
469 int64_t (*seek)(void *opaque, int64_t offset, int whence));
470
471/**
472 * Free the supplied IO context and everything associated with it.
473 *
474 * @param s Double pointer to the IO context. This function will write NULL
475 * into s.
476 */
477void avio_context_free(AVIOContext **s);
478
479void avio_w8(AVIOContext *s, int b);
480void avio_write(AVIOContext *s, const unsigned char *buf, int size);
481void avio_wl64(AVIOContext *s, uint64_t val);
482void avio_wb64(AVIOContext *s, uint64_t val);
483void avio_wl32(AVIOContext *s, unsigned int val);
484void avio_wb32(AVIOContext *s, unsigned int val);
485void avio_wl24(AVIOContext *s, unsigned int val);
486void avio_wb24(AVIOContext *s, unsigned int val);
487void avio_wl16(AVIOContext *s, unsigned int val);
488void avio_wb16(AVIOContext *s, unsigned int val);
489
490/**
491 * Write a NULL-terminated string.
492 * @return number of bytes written.
493 */
494int avio_put_str(AVIOContext *s, const char *str);
495
496/**
497 * Convert an UTF-8 string to UTF-16LE and write it.
498 * @param s the AVIOContext
499 * @param str NULL-terminated UTF-8 string
500 *
501 * @return number of bytes written.
502 */
503int avio_put_str16le(AVIOContext *s, const char *str);
504
505/**
506 * Convert an UTF-8 string to UTF-16BE and write it.
507 * @param s the AVIOContext
508 * @param str NULL-terminated UTF-8 string
509 *
510 * @return number of bytes written.
511 */
512int avio_put_str16be(AVIOContext *s, const char *str);
513
514/**
515 * Mark the written bytestream as a specific type.
516 *
517 * Zero-length ranges are omitted from the output.
518 *
519 * @param time the stream time the current bytestream pos corresponds to
520 * (in AV_TIME_BASE units), or AV_NOPTS_VALUE if unknown or not
521 * applicable
522 * @param type the kind of data written starting at the current pos
523 */
524void avio_write_marker(AVIOContext *s, int64_t time, enum AVIODataMarkerType type);
525
526/**
527 * ORing this as the "whence" parameter to a seek function causes it to
528 * return the filesize without seeking anywhere. Supporting this is optional.
529 * If it is not supported then the seek function will return <0.
530 */
531#define AVSEEK_SIZE 0x10000
532
533/**
534 * Passing this flag as the "whence" parameter to a seek function causes it to
535 * seek by any means (like reopening and linear reading) or other normally unreasonable
536 * means that can be extremely slow.
537 * This may be ignored by the seek code.
538 */
539#define AVSEEK_FORCE 0x20000
540
541/**
542 * fseek() equivalent for AVIOContext.
543 * @return new position or AVERROR.
544 */
545int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
546
547/**
548 * Skip given number of bytes forward
549 * @return new position or AVERROR.
550 */
551int64_t avio_skip(AVIOContext *s, int64_t offset);
552
553/**
554 * ftell() equivalent for AVIOContext.
555 * @return position or AVERROR.
556 */
557static av_always_inline int64_t avio_tell(AVIOContext *s)
558{
559 return avio_seek(s, 0, SEEK_CUR);
560}
561
562/**
563 * Get the filesize.
564 * @return filesize or AVERROR
565 */
566int64_t avio_size(AVIOContext *s);
567
568/**
569 * feof() equivalent for AVIOContext.
570 * @return non zero if and only if end of file
571 */
572int avio_feof(AVIOContext *s);
573
574/** @warning Writes up to 4 KiB per call */
575int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
576
577/**
578 * Force flushing of buffered data.
579 *
580 * For write streams, force the buffered data to be immediately written to the output,
581 * without to wait to fill the internal buffer.
582 *
583 * For read streams, discard all currently buffered data, and advance the
584 * reported file position to that of the underlying stream. This does not
585 * read new data, and does not perform any seeks.
586 */
587void avio_flush(AVIOContext *s);
588
589/**
590 * Read size bytes from AVIOContext into buf.
591 * @return number of bytes read or AVERROR
592 */
593int avio_read(AVIOContext *s, unsigned char *buf, int size);
594
595/**
596 * Read size bytes from AVIOContext into buf. Unlike avio_read(), this is allowed
597 * to read fewer bytes than requested. The missing bytes can be read in the next
598 * call. This always tries to read at least 1 byte.
599 * Useful to reduce latency in certain cases.
600 * @return number of bytes read or AVERROR
601 */
602int avio_read_partial(AVIOContext *s, unsigned char *buf, int size);
603
604/**
605 * @name Functions for reading from AVIOContext
606 * @{
607 *
608 * @note return 0 if EOF, so you cannot use it if EOF handling is
609 * necessary
610 */
611int avio_r8 (AVIOContext *s);
612unsigned int avio_rl16(AVIOContext *s);
613unsigned int avio_rl24(AVIOContext *s);
614unsigned int avio_rl32(AVIOContext *s);
615uint64_t avio_rl64(AVIOContext *s);
616unsigned int avio_rb16(AVIOContext *s);
617unsigned int avio_rb24(AVIOContext *s);
618unsigned int avio_rb32(AVIOContext *s);
619uint64_t avio_rb64(AVIOContext *s);
620/**
621 * @}
622 */
623
624/**
625 * Read a string from pb into buf. The reading will terminate when either
626 * a NULL character was encountered, maxlen bytes have been read, or nothing
627 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
628 * will be truncated if buf is too small.
629 * Note that the string is not interpreted or validated in any way, it
630 * might get truncated in the middle of a sequence for multi-byte encodings.
631 *
632 * @return number of bytes read (is always <= maxlen).
633 * If reading ends on EOF or error, the return value will be one more than
634 * bytes actually read.
635 */
636int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
637
638/**
639 * Read a UTF-16 string from pb and convert it to UTF-8.
640 * The reading will terminate when either a null or invalid character was
641 * encountered or maxlen bytes have been read.
642 * @return number of bytes read (is always <= maxlen)
643 */
644int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
645int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
646
647
648/**
649 * @name URL open modes
650 * The flags argument to avio_open must be one of the following
651 * constants, optionally ORed with other flags.
652 * @{
653 */
654#define AVIO_FLAG_READ 1 /**< read-only */
655#define AVIO_FLAG_WRITE 2 /**< write-only */
656#define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
657/**
658 * @}
659 */
660
661/**
662 * Use non-blocking mode.
663 * If this flag is set, operations on the context will return
664 * AVERROR(EAGAIN) if they can not be performed immediately.
665 * If this flag is not set, operations on the context will never return
666 * AVERROR(EAGAIN).
667 * Note that this flag does not affect the opening/connecting of the
668 * context. Connecting a protocol will always block if necessary (e.g. on
669 * network protocols) but never hang (e.g. on busy devices).
670 * Warning: non-blocking protocols is work-in-progress; this flag may be
671 * silently ignored.
672 */
673#define AVIO_FLAG_NONBLOCK 8
674
675/**
676 * Use direct mode.
677 * avio_read and avio_write should if possible be satisfied directly
678 * instead of going through a buffer, and avio_seek will always
679 * call the underlying seek function directly.
680 */
681#define AVIO_FLAG_DIRECT 0x8000
682
683/**
684 * Create and initialize a AVIOContext for accessing the
685 * resource indicated by url.
686 * @note When the resource indicated by url has been opened in
687 * read+write mode, the AVIOContext can be used only for writing.
688 *
689 * @param s Used to return the pointer to the created AVIOContext.
690 * In case of failure the pointed to value is set to NULL.
691 * @param url resource to access
692 * @param flags flags which control how the resource indicated by url
693 * is to be opened
694 * @return >= 0 in case of success, a negative value corresponding to an
695 * AVERROR code in case of failure
696 */
697int avio_open(AVIOContext **s, const char *url, int flags);
698
699/**
700 * Create and initialize a AVIOContext for accessing the
701 * resource indicated by url.
702 * @note When the resource indicated by url has been opened in
703 * read+write mode, the AVIOContext can be used only for writing.
704 *
705 * @param s Used to return the pointer to the created AVIOContext.
706 * In case of failure the pointed to value is set to NULL.
707 * @param url resource to access
708 * @param flags flags which control how the resource indicated by url
709 * is to be opened
710 * @param int_cb an interrupt callback to be used at the protocols level
711 * @param options A dictionary filled with protocol-private options. On return
712 * this parameter will be destroyed and replaced with a dict containing options
713 * that were not found. May be NULL.
714 * @return >= 0 in case of success, a negative value corresponding to an
715 * AVERROR code in case of failure
716 */
717int avio_open2(AVIOContext **s, const char *url, int flags,
718 const AVIOInterruptCB *int_cb, AVDictionary **options);
719
720/**
721 * Close the resource accessed by the AVIOContext s and free it.
722 * This function can only be used if s was opened by avio_open().
723 *
724 * The internal buffer is automatically flushed before closing the
725 * resource.
726 *
727 * @return 0 on success, an AVERROR < 0 on error.
728 * @see avio_closep
729 */
730int avio_close(AVIOContext *s);
731
732/**
733 * Close the resource accessed by the AVIOContext *s, free it
734 * and set the pointer pointing to it to NULL.
735 * This function can only be used if s was opened by avio_open().
736 *
737 * The internal buffer is automatically flushed before closing the
738 * resource.
739 *
740 * @return 0 on success, an AVERROR < 0 on error.
741 * @see avio_close
742 */
743int avio_closep(AVIOContext **s);
744
745
746/**
747 * Open a write only memory stream.
748 *
749 * @param s new IO context
750 * @return zero if no error.
751 */
752int avio_open_dyn_buf(AVIOContext **s);
753
754/**
755 * Return the written size and a pointer to the buffer.
756 * The AVIOContext stream is left intact.
757 * The buffer must NOT be freed.
758 * No padding is added to the buffer.
759 *
760 * @param s IO context
761 * @param pbuffer pointer to a byte buffer
762 * @return the length of the byte buffer
763 */
764int avio_get_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
765
766/**
767 * Return the written size and a pointer to the buffer. The buffer
768 * must be freed with av_free().
769 * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
770 *
771 * @param s IO context
772 * @param pbuffer pointer to a byte buffer
773 * @return the length of the byte buffer
774 */
775int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
776
777/**
778 * Iterate through names of available protocols.
779 *
780 * @param opaque A private pointer representing current protocol.
781 * It must be a pointer to NULL on first iteration and will
782 * be updated by successive calls to avio_enum_protocols.
783 * @param output If set to 1, iterate over output protocols,
784 * otherwise over input protocols.
785 *
786 * @return A static string containing the name of current protocol or NULL
787 */
788const char *avio_enum_protocols(void **opaque, int output);
789
790/**
791 * Pause and resume playing - only meaningful if using a network streaming
792 * protocol (e.g. MMS).
793 *
794 * @param h IO context from which to call the read_pause function pointer
795 * @param pause 1 for pause, 0 for resume
796 */
797int avio_pause(AVIOContext *h, int pause);
798
799/**
800 * Seek to a given timestamp relative to some component stream.
801 * Only meaningful if using a network streaming protocol (e.g. MMS.).
802 *
803 * @param h IO context from which to call the seek function pointers
804 * @param stream_index The stream index that the timestamp is relative to.
805 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
806 * units from the beginning of the presentation.
807 * If a stream_index >= 0 is used and the protocol does not support
808 * seeking based on component streams, the call will fail.
809 * @param timestamp timestamp in AVStream.time_base units
810 * or if there is no stream specified then in AV_TIME_BASE units.
811 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
812 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
813 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
814 * fail if used and not supported.
815 * @return >= 0 on success
816 * @see AVInputFormat::read_seek
817 */
818int64_t avio_seek_time(AVIOContext *h, int stream_index,
819 int64_t timestamp, int flags);
820
821/* Avoid a warning. The header can not be included because it breaks c++. */
822struct AVBPrint;
823
824/**
825 * Read contents of h into print buffer, up to max_size bytes, or up to EOF.
826 *
827 * @return 0 for success (max_size bytes read or EOF reached), negative error
828 * code otherwise
829 */
830int avio_read_to_bprint(AVIOContext *h, struct AVBPrint *pb, size_t max_size);
831
832/**
833 * Accept and allocate a client context on a server context.
834 * @param s the server context
835 * @param c the client context, must be unallocated
836 * @return >= 0 on success or a negative value corresponding
837 * to an AVERROR on failure
838 */
839int avio_accept(AVIOContext *s, AVIOContext **c);
840
841/**
842 * Perform one step of the protocol handshake to accept a new client.
843 * This function must be called on a client returned by avio_accept() before
844 * using it as a read/write context.
845 * It is separate from avio_accept() because it may block.
846 * A step of the handshake is defined by places where the application may
847 * decide to change the proceedings.
848 * For example, on a protocol with a request header and a reply header, each
849 * one can constitute a step because the application may use the parameters
850 * from the request to change parameters in the reply; or each individual
851 * chunk of the request can constitute a step.
852 * If the handshake is already finished, avio_handshake() does nothing and
853 * returns 0 immediately.
854 *
855 * @param c the client context to perform the handshake on
856 * @return 0 on a complete and successful handshake
857 * > 0 if the handshake progressed, but is not complete
858 * < 0 for an AVERROR code
859 */
860int avio_handshake(AVIOContext *c);
861#endif /* AVFORMAT_AVIO_H */
862