2 * copyright (c) 2001 Fabrice Bellard
4 * This file is part of FFmpeg.
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.
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.
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
20 #ifndef AVFORMAT_AVIO_H
21 #define AVFORMAT_AVIO_H
26 * Buffered I/O operations
31 #include "libavutil/common.h"
32 #include "libavutil/dict.h"
33 #include "libavutil/log.h"
35 #include "libavformat/version.h"
37 #define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */
40 * Callback for checking whether to abort blocking functions.
41 * AVERROR_EXIT is returned in this case by the interrupted
42 * function. During blocking operations, callback is called with
43 * opaque as parameter. If the callback returns 1, the
44 * blocking operation will be aborted.
46 * No members can be added to this struct without a major bump, if
47 * new elements have been added after this struct in AVFormatContext
50 typedef struct AVIOInterruptCB {
51 int (*callback)(void*);
56 * Directory entry types.
58 enum AVIODirEntryType {
60 AVIO_ENTRY_BLOCK_DEVICE,
61 AVIO_ENTRY_CHARACTER_DEVICE,
63 AVIO_ENTRY_NAMED_PIPE,
64 AVIO_ENTRY_SYMBOLIC_LINK,
73 * Describes single entry of the directory.
75 * Only name and type fields are guaranteed be set.
76 * Rest of fields are protocol or/and platform dependent and might be unknown.
78 typedef struct AVIODirEntry {
79 char *name; /**< Filename */
80 int type; /**< Type of the entry */
81 int utf8; /**< Set to 1 when name is encoded with UTF-8, 0 otherwise.
82 Name can be encoded with UTF-8 even though 0 is set. */
83 int64_t size; /**< File size in bytes, -1 if unknown. */
84 int64_t modification_timestamp; /**< Time of last modification in microseconds since unix
85 epoch, -1 if unknown. */
86 int64_t access_timestamp; /**< Time of last access in microseconds since unix epoch,
88 int64_t status_change_timestamp; /**< Time of last status change in microseconds since unix
89 epoch, -1 if unknown. */
90 int64_t user_id; /**< User ID of owner, -1 if unknown. */
91 int64_t group_id; /**< Group ID of owner, -1 if unknown. */
92 int64_t filemode; /**< Unix file mode, -1 if unknown. */
95 typedef struct AVIODirContext {
96 struct URLContext *url_context;
100 * Bytestream IO Context.
101 * New fields can be added to the end with minor version bumps.
102 * Removal, reordering and changes to existing fields require a major
104 * sizeof(AVIOContext) must not be used outside libav*.
106 * @note None of the function pointers in AVIOContext should be called
107 * directly, they should only be set by the client application
108 * when implementing custom I/O. Normally these are set to the
109 * function pointers specified in avio_alloc_context()
111 typedef struct AVIOContext {
113 * A class for private options.
115 * If this AVIOContext is created by avio_open2(), av_class is set and
116 * passes the options down to protocols.
118 * If this AVIOContext is manually allocated, then av_class may be set by
121 * warning -- this field can be NULL, be sure to not pass this AVIOContext
122 * to any av_opt_* functions in that case.
124 const AVClass *av_class;
127 * The following shows the relationship between buffer, buf_ptr, buf_end, buf_size,
128 * and pos, when reading and when writing (since AVIOContext is used for both):
130 **********************************************************************************
132 **********************************************************************************
135 * |---------------------------------------|
138 * buffer buf_ptr buf_end
139 * +---------------+-----------------------+
140 * |/ / / / / / / /|/ / / / / / /| |
141 * read buffer: |/ / consumed / | to be read /| |
142 * |/ / / / / / / /|/ / / / / / /| |
143 * +---------------+-----------------------+
146 * +-------------------------------------------+-----------------+
148 * +-------------------------------------------+-----------------+
151 **********************************************************************************
153 **********************************************************************************
156 * |-------------------------------|
159 * buffer buf_ptr buf_end
160 * +-------------------+-----------+
161 * |/ / / / / / / / / /| |
162 * write buffer: | / to be flushed / | |
163 * |/ / / / / / / / / /| |
164 * +-------------------+-----------+
167 * +--------------------------+-----------------------------------+
169 * +--------------------------+-----------------------------------+
172 unsigned char *buffer; /**< Start of the buffer. */
173 int buffer_size; /**< Maximum buffer size */
174 unsigned char *buf_ptr; /**< Current position in the buffer */
175 unsigned char *buf_end; /**< End of the data, may be less than
176 buffer+buffer_size if the read function returned
177 less data than requested, e.g. for streams where
178 no more data has been received yet. */
179 void *opaque; /**< A private pointer, passed to the read/write/seek/...
181 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
182 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
183 int64_t (*seek)(void *opaque, int64_t offset, int whence);
184 int64_t pos; /**< position in the file of the current buffer */
185 int must_flush; /**< true if the next seek should flush */
186 int eof_reached; /**< true if eof reached */
187 int write_flag; /**< true if open for writing */
189 unsigned long checksum;
190 unsigned char *checksum_ptr;
191 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
192 int error; /**< contains the error code or 0 if no error happened */
194 * Pause or resume playback for network streaming protocols - e.g. MMS.
196 int (*read_pause)(void *opaque, int pause);
198 * Seek to a given timestamp in stream with the specified stream_index.
199 * Needed for some network streaming protocols which don't support seeking
202 int64_t (*read_seek)(void *opaque, int stream_index,
203 int64_t timestamp, int flags);
205 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
210 * max filesize, used to limit allocations
211 * This field is internal to libavformat and access from outside is not allowed.
216 * avio_read and avio_write should if possible be satisfied directly
217 * instead of going through a buffer, and avio_seek will always
218 * call the underlying seek function directly.
223 * Bytes read statistic
224 * This field is internal to libavformat and access from outside is not allowed.
230 * This field is internal to libavformat and access from outside is not allowed.
236 * This field is internal to libavformat and access from outside is not allowed.
241 * Original buffer size
242 * used internally after probing and ensure seekback to reset the buffer size
243 * This field is internal to libavformat and access from outside is not allowed.
245 int orig_buffer_size;
248 * Threshold to favor readahead over seek.
249 * This is current internal only, do not use from outside.
251 int short_seek_threshold;
257 * Return the name of the protocol that will handle the passed URL.
259 * NULL is returned if no protocol could be found for the given URL.
261 * @return Name of the protocol or NULL.
263 const char *avio_find_protocol_name(const char *url);
266 * Return AVIO_FLAG_* access flags corresponding to the access permissions
267 * of the resource in url, or a negative value corresponding to an
268 * AVERROR code in case of failure. The returned access flags are
269 * masked by the value in flags.
271 * @note This function is intrinsically unsafe, in the sense that the
272 * checked resource may change its existence or permission status from
273 * one call to another. Thus you should not trust the returned value,
274 * unless you are sure that no other processes are accessing the
277 int avio_check(const char *url, int flags);
280 * Move or rename a resource.
282 * @note url_src and url_dst should share the same protocol and authority.
284 * @param url_src url to resource to be moved
285 * @param url_dst new url to resource if the operation succeeded
286 * @return >=0 on success or negative on error.
288 int avpriv_io_move(const char *url_src, const char *url_dst);
293 * @param url resource to be deleted.
294 * @return >=0 on success or negative on error.
296 int avpriv_io_delete(const char *url);
299 * Open directory for reading.
301 * @param s directory read context. Pointer to a NULL pointer must be passed.
302 * @param url directory to be listed.
303 * @param options A dictionary filled with protocol-private options. On return
304 * this parameter will be destroyed and replaced with a dictionary
305 * containing options that were not found. May be NULL.
306 * @return >=0 on success or negative on error.
308 int avio_open_dir(AVIODirContext **s, const char *url, AVDictionary **options);
311 * Get next directory entry.
313 * Returned entry must be freed with avio_free_directory_entry(). In particular
314 * it may outlive AVIODirContext.
316 * @param s directory read context.
317 * @param[out] next next entry or NULL when no more entries.
318 * @return >=0 on success or negative on error. End of list is not considered an
321 int avio_read_dir(AVIODirContext *s, AVIODirEntry **next);
326 * @note Entries created using avio_read_dir() are not deleted and must be
327 * freeded with avio_free_directory_entry().
329 * @param s directory read context.
330 * @return >=0 on success or negative on error.
332 int avio_close_dir(AVIODirContext **s);
335 * Free entry allocated by avio_read_dir().
337 * @param entry entry to be freed.
339 void avio_free_directory_entry(AVIODirEntry **entry);
342 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
343 * freed with av_free().
345 * @param buffer Memory block for input/output operations via AVIOContext.
346 * The buffer must be allocated with av_malloc() and friends.
347 * It may be freed and replaced with a new buffer by libavformat.
348 * AVIOContext.buffer holds the buffer currently in use,
349 * which must be later freed with av_free().
350 * @param buffer_size The buffer size is very important for performance.
351 * For protocols with fixed blocksize it should be set to this blocksize.
352 * For others a typical size is a cache page, e.g. 4kb.
353 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
354 * @param opaque An opaque pointer to user-specific data.
355 * @param read_packet A function for refilling the buffer, may be NULL.
356 * @param write_packet A function for writing the buffer contents, may be NULL.
357 * The function may not change the input buffers content.
358 * @param seek A function for seeking to specified byte position, may be NULL.
360 * @return Allocated AVIOContext or NULL on failure.
362 AVIOContext *avio_alloc_context(
363 unsigned char *buffer,
367 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
368 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
369 int64_t (*seek)(void *opaque, int64_t offset, int whence));
371 void avio_w8(AVIOContext *s, int b);
372 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
373 void avio_wl64(AVIOContext *s, uint64_t val);
374 void avio_wb64(AVIOContext *s, uint64_t val);
375 void avio_wl32(AVIOContext *s, unsigned int val);
376 void avio_wb32(AVIOContext *s, unsigned int val);
377 void avio_wl24(AVIOContext *s, unsigned int val);
378 void avio_wb24(AVIOContext *s, unsigned int val);
379 void avio_wl16(AVIOContext *s, unsigned int val);
380 void avio_wb16(AVIOContext *s, unsigned int val);
383 * Write a NULL-terminated string.
384 * @return number of bytes written.
386 int avio_put_str(AVIOContext *s, const char *str);
389 * Convert an UTF-8 string to UTF-16LE and write it.
390 * @param s the AVIOContext
391 * @param str NULL-terminated UTF-8 string
393 * @return number of bytes written.
395 int avio_put_str16le(AVIOContext *s, const char *str);
398 * Convert an UTF-8 string to UTF-16BE and write it.
399 * @param s the AVIOContext
400 * @param str NULL-terminated UTF-8 string
402 * @return number of bytes written.
404 int avio_put_str16be(AVIOContext *s, const char *str);
407 * Passing this as the "whence" parameter to a seek function causes it to
408 * return the filesize without seeking anywhere. Supporting this is optional.
409 * If it is not supported then the seek function will return <0.
411 #define AVSEEK_SIZE 0x10000
414 * Oring this flag as into the "whence" parameter to a seek function causes it to
415 * seek by any means (like reopening and linear reading) or other normally unreasonable
416 * means that can be extremely slow.
417 * This may be ignored by the seek code.
419 #define AVSEEK_FORCE 0x20000
422 * fseek() equivalent for AVIOContext.
423 * @return new position or AVERROR.
425 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
428 * Skip given number of bytes forward
429 * @return new position or AVERROR.
431 int64_t avio_skip(AVIOContext *s, int64_t offset);
434 * ftell() equivalent for AVIOContext.
435 * @return position or AVERROR.
437 static av_always_inline int64_t avio_tell(AVIOContext *s)
439 return avio_seek(s, 0, SEEK_CUR);
444 * @return filesize or AVERROR
446 int64_t avio_size(AVIOContext *s);
449 * feof() equivalent for AVIOContext.
450 * @return non zero if and only if end of file
452 int avio_feof(AVIOContext *s);
455 * @deprecated use avio_feof()
458 int url_feof(AVIOContext *s);
461 /** @warning Writes up to 4 KiB per call */
462 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
465 * Force flushing of buffered data.
467 * For write streams, force the buffered data to be immediately written to the output,
468 * without to wait to fill the internal buffer.
470 * For read streams, discard all currently buffered data, and advance the
471 * reported file position to that of the underlying stream. This does not
472 * read new data, and does not perform any seeks.
474 void avio_flush(AVIOContext *s);
477 * Read size bytes from AVIOContext into buf.
478 * @return number of bytes read or AVERROR
480 int avio_read(AVIOContext *s, unsigned char *buf, int size);
483 * @name Functions for reading from AVIOContext
486 * @note return 0 if EOF, so you cannot use it if EOF handling is
489 int avio_r8 (AVIOContext *s);
490 unsigned int avio_rl16(AVIOContext *s);
491 unsigned int avio_rl24(AVIOContext *s);
492 unsigned int avio_rl32(AVIOContext *s);
493 uint64_t avio_rl64(AVIOContext *s);
494 unsigned int avio_rb16(AVIOContext *s);
495 unsigned int avio_rb24(AVIOContext *s);
496 unsigned int avio_rb32(AVIOContext *s);
497 uint64_t avio_rb64(AVIOContext *s);
503 * Read a string from pb into buf. The reading will terminate when either
504 * a NULL character was encountered, maxlen bytes have been read, or nothing
505 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
506 * will be truncated if buf is too small.
507 * Note that the string is not interpreted or validated in any way, it
508 * might get truncated in the middle of a sequence for multi-byte encodings.
510 * @return number of bytes read (is always <= maxlen).
511 * If reading ends on EOF or error, the return value will be one more than
512 * bytes actually read.
514 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
517 * Read a UTF-16 string from pb and convert it to UTF-8.
518 * The reading will terminate when either a null or invalid character was
519 * encountered or maxlen bytes have been read.
520 * @return number of bytes read (is always <= maxlen)
522 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
523 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
527 * @name URL open modes
528 * The flags argument to avio_open must be one of the following
529 * constants, optionally ORed with other flags.
532 #define AVIO_FLAG_READ 1 /**< read-only */
533 #define AVIO_FLAG_WRITE 2 /**< write-only */
534 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
540 * Use non-blocking mode.
541 * If this flag is set, operations on the context will return
542 * AVERROR(EAGAIN) if they can not be performed immediately.
543 * If this flag is not set, operations on the context will never return
545 * Note that this flag does not affect the opening/connecting of the
546 * context. Connecting a protocol will always block if necessary (e.g. on
547 * network protocols) but never hang (e.g. on busy devices).
548 * Warning: non-blocking protocols is work-in-progress; this flag may be
551 #define AVIO_FLAG_NONBLOCK 8
555 * avio_read and avio_write should if possible be satisfied directly
556 * instead of going through a buffer, and avio_seek will always
557 * call the underlying seek function directly.
559 #define AVIO_FLAG_DIRECT 0x8000
562 * Create and initialize a AVIOContext for accessing the
563 * resource indicated by url.
564 * @note When the resource indicated by url has been opened in
565 * read+write mode, the AVIOContext can be used only for writing.
567 * @param s Used to return the pointer to the created AVIOContext.
568 * In case of failure the pointed to value is set to NULL.
569 * @param url resource to access
570 * @param flags flags which control how the resource indicated by url
572 * @return >= 0 in case of success, a negative value corresponding to an
573 * AVERROR code in case of failure
575 int avio_open(AVIOContext **s, const char *url, int flags);
578 * Create and initialize a AVIOContext for accessing the
579 * resource indicated by url.
580 * @note When the resource indicated by url has been opened in
581 * read+write mode, the AVIOContext can be used only for writing.
583 * @param s Used to return the pointer to the created AVIOContext.
584 * In case of failure the pointed to value is set to NULL.
585 * @param url resource to access
586 * @param flags flags which control how the resource indicated by url
588 * @param int_cb an interrupt callback to be used at the protocols level
589 * @param options A dictionary filled with protocol-private options. On return
590 * this parameter will be destroyed and replaced with a dict containing options
591 * that were not found. May be NULL.
592 * @return >= 0 in case of success, a negative value corresponding to an
593 * AVERROR code in case of failure
595 int avio_open2(AVIOContext **s, const char *url, int flags,
596 const AVIOInterruptCB *int_cb, AVDictionary **options);
599 * Close the resource accessed by the AVIOContext s and free it.
600 * This function can only be used if s was opened by avio_open().
602 * The internal buffer is automatically flushed before closing the
605 * @return 0 on success, an AVERROR < 0 on error.
608 int avio_close(AVIOContext *s);
611 * Close the resource accessed by the AVIOContext *s, free it
612 * and set the pointer pointing to it to NULL.
613 * This function can only be used if s was opened by avio_open().
615 * The internal buffer is automatically flushed before closing the
618 * @return 0 on success, an AVERROR < 0 on error.
621 int avio_closep(AVIOContext **s);
625 * Open a write only memory stream.
627 * @param s new IO context
628 * @return zero if no error.
630 int avio_open_dyn_buf(AVIOContext **s);
633 * Return the written size and a pointer to the buffer. The buffer
634 * must be freed with av_free().
635 * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
637 * @param s IO context
638 * @param pbuffer pointer to a byte buffer
639 * @return the length of the byte buffer
641 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
644 * Iterate through names of available protocols.
646 * @param opaque A private pointer representing current protocol.
647 * It must be a pointer to NULL on first iteration and will
648 * be updated by successive calls to avio_enum_protocols.
649 * @param output If set to 1, iterate over output protocols,
650 * otherwise over input protocols.
652 * @return A static string containing the name of current protocol or NULL
654 const char *avio_enum_protocols(void **opaque, int output);
657 * Pause and resume playing - only meaningful if using a network streaming
658 * protocol (e.g. MMS).
660 * @param h IO context from which to call the read_pause function pointer
661 * @param pause 1 for pause, 0 for resume
663 int avio_pause(AVIOContext *h, int pause);
666 * Seek to a given timestamp relative to some component stream.
667 * Only meaningful if using a network streaming protocol (e.g. MMS.).
669 * @param h IO context from which to call the seek function pointers
670 * @param stream_index The stream index that the timestamp is relative to.
671 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
672 * units from the beginning of the presentation.
673 * If a stream_index >= 0 is used and the protocol does not support
674 * seeking based on component streams, the call will fail.
675 * @param timestamp timestamp in AVStream.time_base units
676 * or if there is no stream specified then in AV_TIME_BASE units.
677 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
678 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
679 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
680 * fail if used and not supported.
681 * @return >= 0 on success
682 * @see AVInputFormat::read_seek
684 int64_t avio_seek_time(AVIOContext *h, int stream_index,
685 int64_t timestamp, int flags);
687 /* Avoid a warning. The header can not be included because it breaks c++. */
691 * Read contents of h into print buffer, up to max_size bytes, or up to EOF.
693 * @return 0 for success (max_size bytes read or EOF reached), negative error
696 int avio_read_to_bprint(AVIOContext *h, struct AVBPrint *pb, size_t max_size);
699 * Accept and allocate a client context on a server context.
700 * @param s the server context
701 * @param c the client context, must be unallocated
702 * @return >= 0 on success or a negative value corresponding
703 * to an AVERROR on failure
705 int avio_accept(AVIOContext *s, AVIOContext **c);
708 * Perform one step of the protocol handshake to accept a new client.
709 * This function must be called on a client returned by avio_accept() before
710 * using it as a read/write context.
711 * It is separate from avio_accept() because it may block.
712 * A step of the handshake is defined by places where the application may
713 * decide to change the proceedings.
714 * For example, on a protocol with a request header and a reply header, each
715 * one can constitute a step because the application may use the parameters
716 * from the request to change parameters in the reply; or each individual
717 * chunk of the request can constitute a step.
718 * If the handshake is already finished, avio_handshake() does nothing and
719 * returns 0 immediately.
721 * @param c the client context to perform the handshake on
722 * @return 0 on a complete and successful handshake
723 * > 0 if the handshake progressed, but is not complete
724 * < 0 for an AVERROR code
726 int avio_handshake(AVIOContext *c);
727 #endif /* AVFORMAT_AVIO_H */