1 /*

     2  * copyright (c) 2001 Fabrice Bellard

     3  *

     4  * This file is part of Libav.

     5  *

     6  * Libav 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  * Libav 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 Libav; 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 #define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */

    39 

    40 /**

    41  * Callback for checking whether to abort blocking functions.

    42  * AVERROR_EXIT is returned in this case by the interrupted

    43  * function. During blocking operations, callback is called with

    44  * opaque as parameter. If the callback returns 1, the

    45  * blocking operation will be aborted.

    46  *

    47  * No members can be added to this struct without a major bump, if

    48  * new elements have been added after this struct in AVFormatContext

    49  * or AVIOContext.

    50  */

    51 typedef struct AVIOInterruptCB {

    52     int (*callback)(void*);

    53     void *opaque;

    54 } AVIOInterruptCB;

    55 

    56 /**

    57  * Bytestream IO Context.

    58  * New fields can be added to the end with minor version bumps.

    59  * Removal, reordering and changes to existing fields require a major

    60  * version bump.

    61  * sizeof(AVIOContext) must not be used outside libav*.

    62  *

    63  * @note None of the function pointers in AVIOContext should be called

    64  *       directly, they should only be set by the client application

    65  *       when implementing custom I/O. Normally these are set to the

    66  *       function pointers specified in avio_alloc_context()

    67  */

    68 typedef struct AVIOContext {

    69     /**

    70      * A class for private options.

    71      *

    72      * If this AVIOContext is created by avio_open2(), av_class is set and

    73      * passes the options down to protocols.

    74      *

    75      * If this AVIOContext is manually allocated, then av_class may be set by

    76      * the caller.

    77      *

    78      * warning -- this field can be NULL, be sure to not pass this AVIOContext

    79      * to any av_opt_* functions in that case.

    80      */

    81     const AVClass *av_class;

    82     unsigned char *buffer;  /**< Start of the buffer. */

    83     int buffer_size;        /**< Maximum buffer size */

    84     unsigned char *buf_ptr; /**< Current position in the buffer */

    85     unsigned char *buf_end; /**< End of the data, may be less than

    86                                  buffer+buffer_size if the read function returned

    87                                  less data than requested, e.g. for streams where

    88                                  no more data has been received yet. */

    89     void *opaque;           /**< A private pointer, passed to the read/write/seek/...

    90                                  functions. */

    91     int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);

    92     int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);

    93     int64_t (*seek)(void *opaque, int64_t offset, int whence);

    94     int64_t pos;            /**< position in the file of the current buffer */

    95     int must_flush;         /**< true if the next seek should flush */

    96     int eof_reached;        /**< true if eof reached */

    97     int write_flag;         /**< true if open for writing */

    98     int max_packet_size;

    99     unsigned long checksum;

   100     unsigned char *checksum_ptr;

   101     unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);

   102     int error;              /**< contains the error code or 0 if no error happened */

   103     /**

   104      * Pause or resume playback for network streaming protocols - e.g. MMS.

   105      */

   106     int (*read_pause)(void *opaque, int pause);

   107     /**

   108      * Seek to a given timestamp in stream with the specified stream_index.

   109      * Needed for some network streaming protocols which don't support seeking

   110      * to byte position.

   111      */

   112     int64_t (*read_seek)(void *opaque, int stream_index,

   113                          int64_t timestamp, int flags);

   114     /**

   115      * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.

   116      */

   117     int seekable;

   118 } AVIOContext;

   119 

   120 /* unbuffered I/O */

   121 

   122 /**

   123  * Return AVIO_FLAG_* access flags corresponding to the access permissions

   124  * of the resource in url, or a negative value corresponding to an

   125  * AVERROR code in case of failure. The returned access flags are

   126  * masked by the value in flags.

   127  *

   128  * @note This function is intrinsically unsafe, in the sense that the

   129  * checked resource may change its existence or permission status from

   130  * one call to another. Thus you should not trust the returned value,

   131  * unless you are sure that no other processes are accessing the

   132  * checked resource.

   133  */

   134 int avio_check(const char *url, int flags);

   135 

   136 /**

   137  * Allocate and initialize an AVIOContext for buffered I/O. It must be later

   138  * freed with av_free().

   139  *

   140  * @param buffer Memory block for input/output operations via AVIOContext.

   141  *        The buffer must be allocated with av_malloc() and friends.

   142  * @param buffer_size The buffer size is very important for performance.

   143  *        For protocols with fixed blocksize it should be set to this blocksize.

   144  *        For others a typical size is a cache page, e.g. 4kb.

   145  * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.

   146  * @param opaque An opaque pointer to user-specific data.

   147  * @param read_packet  A function for refilling the buffer, may be NULL.

   148  * @param write_packet A function for writing the buffer contents, may be NULL.

   149  * @param seek A function for seeking to specified byte position, may be NULL.

   150  *

   151  * @return Allocated AVIOContext or NULL on failure.

   152  */

   153 AVIOContext *avio_alloc_context(

   154                   unsigned char *buffer,

   155                   int buffer_size,

   156                   int write_flag,

   157                   void *opaque,

   158                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),

   159                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),

   160                   int64_t (*seek)(void *opaque, int64_t offset, int whence));

   161 

   162 void avio_w8(AVIOContext *s, int b);

   163 void avio_write(AVIOContext *s, const unsigned char *buf, int size);

   164 void avio_wl64(AVIOContext *s, uint64_t val);

   165 void avio_wb64(AVIOContext *s, uint64_t val);

   166 void avio_wl32(AVIOContext *s, unsigned int val);

   167 void avio_wb32(AVIOContext *s, unsigned int val);

   168 void avio_wl24(AVIOContext *s, unsigned int val);

   169 void avio_wb24(AVIOContext *s, unsigned int val);

   170 void avio_wl16(AVIOContext *s, unsigned int val);

   171 void avio_wb16(AVIOContext *s, unsigned int val);

   172 

   173 /**

   174  * Write a NULL-terminated string.

   175  * @return number of bytes written.

   176  */

   177 int avio_put_str(AVIOContext *s, const char *str);

   178 

   179 /**

   180  * Convert an UTF-8 string to UTF-16LE and write it.

   181  * @return number of bytes written.

   182  */

   183 int avio_put_str16le(AVIOContext *s, const char *str);

   184 

   185 /**

   186  * Passing this as the "whence" parameter to a seek function causes it to

   187  * return the filesize without seeking anywhere. Supporting this is optional.

   188  * If it is not supported then the seek function will return <0.

   189  */

   190 #define AVSEEK_SIZE 0x10000

   191 

   192 /**

   193  * Oring this flag as into the "whence" parameter to a seek function causes it to

   194  * seek by any means (like reopening and linear reading) or other normally unreasonble

   195  * means that can be extreemly slow.

   196  * This may be ignored by the seek code.

   197  */

   198 #define AVSEEK_FORCE 0x20000

   199 

   200 /**

   201  * fseek() equivalent for AVIOContext.

   202  * @return new position or AVERROR.

   203  */

   204 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);

   205 

   206 /**

   207  * Skip given number of bytes forward

   208  * @return new position or AVERROR.

   209  */

   210 static av_always_inline int64_t avio_skip(AVIOContext *s, int64_t offset)

   211 {

   212     return avio_seek(s, offset, SEEK_CUR);

   213 }

   214 

   215 /**

   216  * ftell() equivalent for AVIOContext.

   217  * @return position or AVERROR.

   218  */

   219 static av_always_inline int64_t avio_tell(AVIOContext *s)

   220 {

   221     return avio_seek(s, 0, SEEK_CUR);

   222 }

   223 

   224 /**

   225  * Get the filesize.

   226  * @return filesize or AVERROR

   227  */

   228 int64_t avio_size(AVIOContext *s);

   229 

   230 /** @warning currently size is limited */

   231 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);

   232 

   233 void avio_flush(AVIOContext *s);

   234 

   235 

   236 /**

   237  * Read size bytes from AVIOContext into buf.

   238  * @return number of bytes read or AVERROR

   239  */

   240 int avio_read(AVIOContext *s, unsigned char *buf, int size);

   241 

   242 /**

   243  * @name Functions for reading from AVIOContext

   244  * @{

   245  *

   246  * @note return 0 if EOF, so you cannot use it if EOF handling is

   247  *       necessary

   248  */

   249 int          avio_r8  (AVIOContext *s);

   250 unsigned int avio_rl16(AVIOContext *s);

   251 unsigned int avio_rl24(AVIOContext *s);

   252 unsigned int avio_rl32(AVIOContext *s);

   253 uint64_t     avio_rl64(AVIOContext *s);

   254 unsigned int avio_rb16(AVIOContext *s);

   255 unsigned int avio_rb24(AVIOContext *s);

   256 unsigned int avio_rb32(AVIOContext *s);

   257 uint64_t     avio_rb64(AVIOContext *s);

   258 /**

   259  * @}

   260  */

   261 

   262 /**

   263  * Read a string from pb into buf. The reading will terminate when either

   264  * a NULL character was encountered, maxlen bytes have been read, or nothing

   265  * more can be read from pb. The result is guaranteed to be NULL-terminated, it

   266  * will be truncated if buf is too small.

   267  * Note that the string is not interpreted or validated in any way, it

   268  * might get truncated in the middle of a sequence for multi-byte encodings.

   269  *

   270  * @return number of bytes read (is always <= maxlen).

   271  * If reading ends on EOF or error, the return value will be one more than

   272  * bytes actually read.

   273  */

   274 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);

   275 

   276 /**

   277  * Read a UTF-16 string from pb and convert it to UTF-8.

   278  * The reading will terminate when either a null or invalid character was

   279  * encountered or maxlen bytes have been read.

   280  * @return number of bytes read (is always <= maxlen)

   281  */

   282 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);

   283 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);

   284 

   285 

   286 /**

   287  * @name URL open modes

   288  * The flags argument to avio_open must be one of the following

   289  * constants, optionally ORed with other flags.

   290  * @{

   291  */

   292 #define AVIO_FLAG_READ  1                                      /**< read-only */

   293 #define AVIO_FLAG_WRITE 2                                      /**< write-only */

   294 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE)  /**< read-write pseudo flag */

   295 /**

   296  * @}

   297  */

   298 

   299 /**

   300  * Use non-blocking mode.

   301  * If this flag is set, operations on the context will return

   302  * AVERROR(EAGAIN) if they can not be performed immediately.

   303  * If this flag is not set, operations on the context will never return

   304  * AVERROR(EAGAIN).

   305  * Note that this flag does not affect the opening/connecting of the

   306  * context. Connecting a protocol will always block if necessary (e.g. on

   307  * network protocols) but never hang (e.g. on busy devices).

   308  * Warning: non-blocking protocols is work-in-progress; this flag may be

   309  * silently ignored.

   310  */

   311 #define AVIO_FLAG_NONBLOCK 8

   312 

   313 /**

   314  * Create and initialize a AVIOContext for accessing the

   315  * resource indicated by url.

   316  * @note When the resource indicated by url has been opened in

   317  * read+write mode, the AVIOContext can be used only for writing.

   318  *

   319  * @param s Used to return the pointer to the created AVIOContext.

   320  * In case of failure the pointed to value is set to NULL.

   321  * @param flags flags which control how the resource indicated by url

   322  * is to be opened

   323  * @return 0 in case of success, a negative value corresponding to an

   324  * AVERROR code in case of failure

   325  */

   326 int avio_open(AVIOContext **s, const char *url, int flags);

   327 

   328 /**

   329  * Create and initialize a AVIOContext for accessing the

   330  * resource indicated by url.

   331  * @note When the resource indicated by url has been opened in

   332  * read+write mode, the AVIOContext can be used only for writing.

   333  *

   334  * @param s Used to return the pointer to the created AVIOContext.

   335  * In case of failure the pointed to value is set to NULL.

   336  * @param flags flags which control how the resource indicated by url

   337  * is to be opened

   338  * @param int_cb an interrupt callback to be used at the protocols level

   339  * @param options  A dictionary filled with protocol-private options. On return

   340  * this parameter will be destroyed and replaced with a dict containing options

   341  * that were not found. May be NULL.

   342  * @return 0 in case of success, a negative value corresponding to an

   343  * AVERROR code in case of failure

   344  */

   345 int avio_open2(AVIOContext **s, const char *url, int flags,

   346                const AVIOInterruptCB *int_cb, AVDictionary **options);

   347 

   348 /**

   349  * Close the resource accessed by the AVIOContext s and free it.

   350  * This function can only be used if s was opened by avio_open().

   351  *

   352  * The internal buffer is automatically flushed before closing the

   353  * resource.

   354  *

   355  * @return 0 on success, an AVERROR < 0 on error.

   356  * @see avio_closep

   357  */

   358 int avio_close(AVIOContext *s);

   359 

   360 /**

   361  * Close the resource accessed by the AVIOContext *s, free it

   362  * and set the pointer pointing to it to NULL.

   363  * This function can only be used if s was opened by avio_open().

   364  *

   365  * The internal buffer is automatically flushed before closing the

   366  * resource.

   367  *

   368  * @return 0 on success, an AVERROR < 0 on error.

   369  * @see avio_close

   370  */

   371 int avio_closep(AVIOContext **s);

   372 

   373 

   374 /**

   375  * Open a write only memory stream.

   376  *

   377  * @param s new IO context

   378  * @return zero if no error.

   379  */

   380 int avio_open_dyn_buf(AVIOContext **s);

   381 

   382 /**

   383  * Return the written size and a pointer to the buffer. The buffer

   384  * must be freed with av_free().

   385  * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.

   386  *

   387  * @param s IO context

   388  * @param pbuffer pointer to a byte buffer

   389  * @return the length of the byte buffer

   390  */

   391 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);

   392 

   393 /**

   394  * Iterate through names of available protocols.

   395  *

   396  * @param opaque A private pointer representing current protocol.

   397  *        It must be a pointer to NULL on first iteration and will

   398  *        be updated by successive calls to avio_enum_protocols.

   399  * @param output If set to 1, iterate over output protocols,

   400  *               otherwise over input protocols.

   401  *

   402  * @return A static string containing the name of current protocol or NULL

   403  */

   404 const char *avio_enum_protocols(void **opaque, int output);

   405 

   406 /**

   407  * Pause and resume playing - only meaningful if using a network streaming

   408  * protocol (e.g. MMS).

   409  * @param pause 1 for pause, 0 for resume

   410  */

   411 int     avio_pause(AVIOContext *h, int pause);

   412 

   413 /**

   414  * Seek to a given timestamp relative to some component stream.

   415  * Only meaningful if using a network streaming protocol (e.g. MMS.).

   416  * @param stream_index The stream index that the timestamp is relative to.

   417  *        If stream_index is (-1) the timestamp should be in AV_TIME_BASE

   418  *        units from the beginning of the presentation.

   419  *        If a stream_index >= 0 is used and the protocol does not support

   420  *        seeking based on component streams, the call will fail with ENOTSUP.

   421  * @param timestamp timestamp in AVStream.time_base units

   422  *        or if there is no stream specified then in AV_TIME_BASE units.

   423  * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE

   424  *        and AVSEEK_FLAG_ANY. The protocol may silently ignore

   425  *        AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will

   426  *        fail with ENOTSUP if used and not supported.

   427  * @return >= 0 on success

   428  * @see AVInputFormat::read_seek

   429  */

   430 int64_t avio_seek_time(AVIOContext *h, int stream_index,

   431                        int64_t timestamp, int flags);

   432 

   433 #endif /* AVFORMAT_AVIO_H */