LCOV - code coverage report
Current view: top level - libavformat - avio.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 2 2 100.0 %
Date: 2017-12-11 04:34:20 Functions: 1 1 100.0 %

          Line data    Source code
       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             :  */
      58             : typedef struct AVIOInterruptCB {
      59             :     int (*callback)(void*);
      60             :     void *opaque;
      61             : } AVIOInterruptCB;
      62             : 
      63             : /**
      64             :  * Directory entry types.
      65             :  */
      66             : enum 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             :  */
      86             : typedef 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             : 
     103             : typedef 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             :  */
     111             : enum 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             :  */
     161             : typedef 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             :  */
     361             : const 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             :  */
     375             : int 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             :  */
     386             : int 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             :  */
     394             : int 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             :  */
     406             : int 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             :  */
     419             : int 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             :  */
     430             : int avio_close_dir(AVIODirContext **s);
     431             : 
     432             : /**
     433             :  * Free entry allocated by avio_read_dir().
     434             :  *
     435             :  * @param entry entry to be freed.
     436             :  */
     437             : void 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             :  */
     462             : AVIOContext *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             :  */
     477             : void avio_context_free(AVIOContext **s);
     478             : 
     479             : void avio_w8(AVIOContext *s, int b);
     480             : void avio_write(AVIOContext *s, const unsigned char *buf, int size);
     481             : void avio_wl64(AVIOContext *s, uint64_t val);
     482             : void avio_wb64(AVIOContext *s, uint64_t val);
     483             : void avio_wl32(AVIOContext *s, unsigned int val);
     484             : void avio_wb32(AVIOContext *s, unsigned int val);
     485             : void avio_wl24(AVIOContext *s, unsigned int val);
     486             : void avio_wb24(AVIOContext *s, unsigned int val);
     487             : void avio_wl16(AVIOContext *s, unsigned int val);
     488             : void avio_wb16(AVIOContext *s, unsigned int val);
     489             : 
     490             : /**
     491             :  * Write a NULL-terminated string.
     492             :  * @return number of bytes written.
     493             :  */
     494             : int 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             :  */
     503             : int 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             :  */
     512             : int 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             :  */
     524             : void 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             :  */
     545             : int64_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             :  */
     551             : int64_t avio_skip(AVIOContext *s, int64_t offset);
     552             : 
     553             : /**
     554             :  * ftell() equivalent for AVIOContext.
     555             :  * @return position or AVERROR.
     556             :  */
     557     4482963 : static av_always_inline int64_t avio_tell(AVIOContext *s)
     558             : {
     559     4482963 :     return avio_seek(s, 0, SEEK_CUR);
     560             : }
     561             : 
     562             : /**
     563             :  * Get the filesize.
     564             :  * @return filesize or AVERROR
     565             :  */
     566             : int64_t avio_size(AVIOContext *s);
     567             : 
     568             : /**
     569             :  * feof() equivalent for AVIOContext.
     570             :  * @return non zero if and only if end of file
     571             :  */
     572             : int avio_feof(AVIOContext *s);
     573             : 
     574             : /** @warning Writes up to 4 KiB per call */
     575             : int 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             :  */
     587             : void avio_flush(AVIOContext *s);
     588             : 
     589             : /**
     590             :  * Read size bytes from AVIOContext into buf.
     591             :  * @return number of bytes read or AVERROR
     592             :  */
     593             : int 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             :  */
     602             : int 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             :  */
     611             : int          avio_r8  (AVIOContext *s);
     612             : unsigned int avio_rl16(AVIOContext *s);
     613             : unsigned int avio_rl24(AVIOContext *s);
     614             : unsigned int avio_rl32(AVIOContext *s);
     615             : uint64_t     avio_rl64(AVIOContext *s);
     616             : unsigned int avio_rb16(AVIOContext *s);
     617             : unsigned int avio_rb24(AVIOContext *s);
     618             : unsigned int avio_rb32(AVIOContext *s);
     619             : uint64_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             :  */
     636             : int 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             :  */
     644             : int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
     645             : int 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             :  */
     697             : int 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             :  */
     717             : int 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             :  */
     730             : int 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             :  */
     743             : int 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             :  */
     752             : int 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             :  */
     764             : int 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             :  */
     775             : int 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             :  */
     788             : const 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             :  */
     797             : int     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             :  */
     818             : int64_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++. */
     822             : struct 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             :  */
     830             : int 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             :  */
     839             : int 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             :  */
     860             : int avio_handshake(AVIOContext *c);
     861             : #endif /* AVFORMAT_AVIO_H */

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