include/vlc_stream.h

   1 /*****************************************************************************
   2  * vlc_stream.h: Stream (between access and demux) descriptor and methods
   3  *****************************************************************************
   4  * Copyright (C) 1999-2004 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 #ifndef VLC_STREAM_H
  25 #define VLC_STREAM_H 1
  26
  27 #include <vlc_block.h>
  28
  29 # ifdef __cplusplus
  30 extern "C" {
  31 # endif
  32
  33 /**
  34  * \defgroup stream Stream
  35  * \ingroup input
  36  * Buffered input byte streams
  37  * @{
  38  * \file
  39  * Byte streams and byte stream filter modules interface
  40  */
  41
  42 /**
  43  * stream_t definition
  44  */
  45
  46 struct stream_t
  47 {
  48     struct vlc_common_members obj;
  49
  50     /* Module properties for stream filter */
  51     module_t    *p_module;
  52
  53     char        *psz_name;
  54     char        *psz_url; /**< Full URL or MRL (can be NULL) */
  55     const char  *psz_location; /**< Location (URL with the scheme stripped) */
  56     char        *psz_filepath; /**< Local file path (if applicable) */
  57     bool         b_preparsing; /**< True if this access is used to preparse */
  58
  59     /* Stream source for stream filter */
  60     stream_t    *s;
  61
  62     /**
  63      * Read data.
  64      *
  65      * Callback to read data from the stream into a caller-supplied buffer.
  66      *
  67      * This may be NULL if the stream is actually a directory rather than a
  68      * byte stream, or if \ref stream_t.pf_block is non-NULL.
  69      *
  70      * \param buf buffer to read data into
  71      * \param len buffer length (in bytes)
  72      *
  73      * \retval -1 no data available yet
  74      * \retval 0 end of stream (incl. fatal error)
  75      * \retval positive number of bytes read (no more than len)
  76      */
  77     ssize_t     (*pf_read)(stream_t *, void *buf, size_t len);
  78
  79     /**
  80      * Read data block.
  81      *
  82      * Callback to read a block of data. The data is read into a block of
  83      * memory allocated by the stream. For some streams, data can be read more
  84      * efficiently in block of a certain size, and/or using a custom allocator
  85      * for buffers. In such case, this callback should be provided instead of
  86      * \ref stream_t.pf_read; otherwise, this should be NULL.
  87      *
  88      * \param eof storage space for end-of-stream flag [OUT]
  89      * (*eof is always false when invoking pf_block(); pf_block() should set
  90      *  *eof to true if it detects the end of the stream)
  91      *
  92      * \return a data block,
  93      * NULL if no data available yet, on error and at end-of-stream
  94      */
  95     block_t    *(*pf_block)(stream_t *, bool *eof);
  96
  97     /**
  98      * Read directory.
  99      *
 100      * Callback to fill an item node from a directory
 101      * (see doc/browsing.txt for details).
 102      *
 103      * NULL if the stream is not a directory.
 104      */
 105     int         (*pf_readdir)(stream_t *, input_item_node_t *);
 106
 107     /**
 108      * Seek.
 109      *
 110      * Callback to set the stream pointer (in bytes from start).
 111      *
 112      * May be NULL if seeking is not supported.
 113      */
 114     int         (*pf_seek)(stream_t *, uint64_t);
 115
 116     /**
 117      * Stream control.
 118      *
 119      * Cannot be NULL.
 120      *
 121      * \see stream_query_e
 122      */
 123     int         (*pf_control)(stream_t *, int i_query, va_list);
 124
 125     /**
 126      * Private data pointer
 127      */
 128     void *p_sys;
 129
 130     /* Weak link to parent input */
 131     input_thread_t *p_input;
 132 };
 133
 134 /**
 135  * Possible commands to send to vlc_stream_Control() and vlc_stream_vaControl()
 136  */
 137 enum stream_query_e
 138 {
 139     /* capabilities */
 140     STREAM_CAN_SEEK,            /**< arg1= bool *   res=cannot fail*/
 141     STREAM_CAN_FASTSEEK,        /**< arg1= bool *   res=cannot fail*/
 142     STREAM_CAN_PAUSE,           /**< arg1= bool *   res=cannot fail*/
 143     STREAM_CAN_CONTROL_PACE,    /**< arg1= bool *   res=cannot fail*/
 144     /* */
 145     STREAM_GET_SIZE=6,          /**< arg1= uint64_t *     res=can fail */
 146     STREAM_IS_DIRECTORY,        /**< res=can fail */
 147
 148     /* */
 149     STREAM_GET_PTS_DELAY = 0x101,/**< arg1= int64_t* res=cannot fail */
 150     STREAM_GET_TITLE_INFO, /**< arg1=input_title_t*** arg2=int* res=can fail */
 151     STREAM_GET_TITLE,       /**< arg1=unsigned * res=can fail */
 152     STREAM_GET_SEEKPOINT,   /**< arg1=unsigned * res=can fail */
 153     STREAM_GET_META,        /**< arg1= vlc_meta_t *       res=can fail */
 154     STREAM_GET_CONTENT_TYPE,    /**< arg1= char **         res=can fail */
 155     STREAM_GET_SIGNAL,      /**< arg1=double *pf_quality, arg2=double *pf_strength   res=can fail */
 156     STREAM_GET_TAGS,        /**< arg1=const block_t ** res=can fail */
 157
 158     STREAM_SET_PAUSE_STATE = 0x200, /**< arg1= bool        res=can fail */
 159     STREAM_SET_TITLE,       /**< arg1= int          res=can fail */
 160     STREAM_SET_SEEKPOINT,   /**< arg1= int          res=can fail */
 161
 162     /* XXX only data read through vlc_stream_Read/Block will be recorded */
 163     STREAM_SET_RECORD_STATE,     /**< arg1=bool, arg2=const char *psz_ext (if arg1 is true)  res=can fail */
 164
 165     STREAM_SET_PRIVATE_ID_STATE = 0x1000, /* arg1= int i_private_data, bool b_selected    res=can fail */
 166     STREAM_SET_PRIVATE_ID_CA,             /* arg1= int i_program_number, uint16_t i_vpid, uint16_t i_apid1, uint16_t i_apid2, uint16_t i_apid3, uint8_t i_length, uint8_t *p_data */
 167     STREAM_GET_PRIVATE_ID_STATE,          /* arg1=int i_private_data arg2=bool *          res=can fail */
 168 };
 169
 170 /**
 171  * Reads data from a byte stream.
 172  *
 173  * This function always waits for the requested number of bytes, unless a fatal
 174  * error is encountered or the end-of-stream is reached first.
 175  *
 176  * If the buffer is NULL, data is skipped instead of read. This is effectively
 177  * a relative forward seek, but it works even on non-seekable streams.
 178  *
 179  * \param buf start of buffer to read data into [OUT]
 180  * \param len number of bytes to read
 181  * \return the number of bytes read or a negative value on error.
 182  */
 183 VLC_API ssize_t vlc_stream_Read(stream_t *, void *buf, size_t len) VLC_USED;
 184
 185 /**
 186  * Reads partial data from a byte stream.
 187  *
 188  * This function waits until some data is available for reading from the
 189  * stream, a fatal error is encountered or the end-of-stream is reached.
 190  *
 191  * Unlike vlc_stream_Read(), this function does not wait for the full requested
 192  * bytes count. It can return a short count even before the end of the stream
 193  * and in the absence of any error.
 194  *
 195  * \param buf start of buffer to read data into [OUT]
 196  * \param len buffer size (maximum number of bytes to read)
 197  * \return the number of bytes read or a negative value on error.
 198  */
 199 VLC_API ssize_t vlc_stream_ReadPartial(stream_t *, void *buf, size_t len)
 200 VLC_USED;
 201
 202 /**
 203  * Peeks at data from a byte stream.
 204  *
 205  * This function buffers for the requested number of bytes, waiting if
 206  * necessary. Then it stores a pointer to the buffer. Unlike vlc_stream_Read()
 207  * or vlc_stream_Block(), this function does not modify the stream read offset.
 208  *
 209  * \note
 210  * The buffer remains valid until the next read/peek or seek operation on the
 211  * same stream. In case of error, the buffer address is undefined.
 212  *
 213  * \param bufp storage space for the buffer address [OUT]
 214  * \param len number of bytes to peek
 215  * \return the number of bytes actually available (shorter than requested if
 216  * the end-of-stream is reached), or a negative value on error.
 217  */
 218 VLC_API ssize_t vlc_stream_Peek(stream_t *, const uint8_t **, size_t) VLC_USED;
 219
 220 /**
 221  * Reads a data block from a byte stream.
 222  *
 223  * This function dequeues the next block of data from the byte stream. The
 224  * byte stream back-end decides on the size of the block; the caller cannot
 225  * make any assumption about it.
 226  *
 227  * The function might also return NULL spuriously - this does not necessarily
 228  * imply that the stream is ended nor that it has encountered a nonrecoverable
 229  * error.
 230  *
 231  * This function should be used instead of vlc_stream_Read() or
 232  * vlc_stream_Peek() when the caller can handle reads of any size.
 233  *
 234  * \return either a data block or NULL
 235  */
 236 VLC_API block_t *vlc_stream_ReadBlock(stream_t *) VLC_USED;
 237
 238 /**
 239  * Tells the current stream position.
 240  *
 241  * This function tells the current read offset (in bytes) from the start of
 242  * the start of the stream.
 243  * @note The read offset may be larger than the stream size, either because of
 244  * a seek past the end, or because the stream shrank asynchronously.
 245  *
 246  * @return the byte offset from the beginning of the stream (cannot fail)
 247  */
 248 VLC_API uint64_t vlc_stream_Tell(const stream_t *) VLC_USED;
 249
 250 /**
 251  * Checks for end of stream.
 252  *
 253  * Checks if the last attempt to reads data from the stream encountered the
 254  * end of stream before the attempt could be fully satisfied.
 255  * The value is initially false, and is reset to false by vlc_stream_Seek().
 256  *
 257  * \note The function can return false even though the current stream position
 258  * is equal to the stream size. It will return true after the following attempt
 259  * to read more than zero bytes.
 260  *
 261  * \note It might be possible to read after the end of the stream.
 262  * It implies the size of the stream increased asynchronously in the mean time.
 263  * Streams of most types cannot trigger such a case,
 264  * but regular local files notably can.
 265  *
 266  * \note In principles, the stream size should match the stream offset when
 267  * the end-of-stream is reached. But that rule is not enforced; it is entirely
 268  * dependent on the underlying implementation of the stream.
 269  */
 270 VLC_API bool vlc_stream_Eof(const stream_t *) VLC_USED;
 271
 272 /**
 273  * Sets the current stream position.
 274  *
 275  * This function changes the read offset within a stream, if the stream
 276  * supports seeking. In case of error, the read offset is not changed.
 277  *
 278  * @note It is possible (but not useful) to seek past the end of a stream.
 279  *
 280  * @param offset byte offset from the beginning of the stream
 281  * @return zero on success, a negative value on error
 282  */
 283 VLC_API int vlc_stream_Seek(stream_t *, uint64_t offset) VLC_USED;
 284
 285 VLC_API int vlc_stream_vaControl(stream_t *s, int query, va_list args);
 286
 287 static inline int vlc_stream_Control(stream_t *s, int query, ...)
 288 {
 289     va_list ap;
 290     int ret;
 291
 292     va_start(ap, query);
 293     ret = vlc_stream_vaControl(s, query, ap);
 294     va_end(ap);
 295     return ret;
 296 }
 297
 298 VLC_API block_t *vlc_stream_Block(stream_t *s, size_t);
 299 VLC_API char *vlc_stream_ReadLine(stream_t *);
 300 VLC_API int vlc_stream_ReadDir(stream_t *, input_item_node_t *);
 301
 302 /**
 303  * Closes a byte stream.
 304  * \param s byte stream to close
 305  */
 306 VLC_API void vlc_stream_Delete(stream_t *s);
 307
 308 VLC_API stream_t *vlc_stream_CommonNew(vlc_object_t *, void (*)(stream_t *));
 309
 310 /**
 311  * Get the size of the stream.
 312  */
 313 VLC_USED static inline int vlc_stream_GetSize( stream_t *s, uint64_t *size )
 314 {
 315     return vlc_stream_Control( s, STREAM_GET_SIZE, size );
 316 }
 317
 318 static inline int64_t stream_Size( stream_t *s )
 319 {
 320     uint64_t i_pos;
 321
 322     if( vlc_stream_GetSize( s, &i_pos ) )
 323         return 0;
 324     if( i_pos >> 62 )
 325         return (int64_t)1 << 62;
 326     return i_pos;
 327 }
 328
 329 VLC_USED
 330 static inline bool stream_HasExtension( stream_t *s, const char *extension )
 331 {
 332     const char *name = (s->psz_filepath != NULL) ? s->psz_filepath
 333                                                  : s->psz_url;
 334     const char *ext = strrchr( name, '.' );
 335     return ext != NULL && !strcasecmp( ext, extension );
 336 }
 337
 338 /**
 339  * Get the Content-Type of a stream, or NULL if unknown.
 340  * Result must be free()'d.
 341  */
 342 static inline char *stream_ContentType( stream_t *s )
 343 {
 344     char *res;
 345     if( vlc_stream_Control( s, STREAM_GET_CONTENT_TYPE, &res ) )
 346         return NULL;
 347     return res;
 348 }
 349
 350 /**
 351  * Get the mime-type of a stream
 352  *
 353  * \warning the returned resource is to be freed by the caller
 354  * \return the mime-type, or `NULL` if unknown
 355  **/
 356 VLC_USED
 357 static inline char *stream_MimeType( stream_t *s )
 358 {
 359     char* mime_type = stream_ContentType( s );
 360
 361     if( mime_type ) /* strip parameters */
 362         mime_type[strcspn( mime_type, " ;" )] = '\0';
 363
 364     return mime_type;
 365 }
 366
 367 /**
 368  * Checks for a MIME type.
 369  *
 370  * Checks if the stream has a specific MIME type.
 371  */
 372 VLC_USED
 373 static inline bool stream_IsMimeType(stream_t *s, const char *type)
 374 {
 375     char *mime = stream_MimeType(s);
 376     if (mime == NULL)
 377         return false;
 378
 379     bool ok = !strcasecmp(mime, type);
 380     free(mime);
 381     return ok;
 382 }
 383
 384 /**
 385  * Create a stream from a memory buffer.
 386  *
 387  * \param obj parent VLC object
 388  * \param base start address of the memory buffer to read from
 389  * \param size size in bytes of the memory buffer
 390  * \param preserve if false, free(base) will be called when the stream is
 391  *                 destroyed; if true, the memory buffer is preserved
 392  */
 393 VLC_API stream_t *vlc_stream_MemoryNew(vlc_object_t *obj, uint8_t *base,
 394                                        size_t size, bool preserve) VLC_USED;
 395 #define vlc_stream_MemoryNew(a, b, c, d) \
 396         vlc_stream_MemoryNew(VLC_OBJECT(a), b, c, d)
 397
 398 /**
 399  * Create a stream_t reading from a URL.
 400  * You must delete it using vlc_stream_Delete.
 401  */
 402 VLC_API stream_t * vlc_stream_NewURL(vlc_object_t *obj, const char *url)
 403 VLC_USED;
 404 #define vlc_stream_NewURL(a, b) vlc_stream_NewURL(VLC_OBJECT(a), b)
 405
 406 /**
 407  * \defgroup stream_fifo FIFO stream
 408  * In-memory anonymous pipe
 409   @{
 410  */
 411
 412 /**
 413  * Creates a FIFO stream.
 414  *
 415  * Creates a non-seekable byte stream object whose byte stream is generated
 416  * by another thread in the process. This is the LibVLC equivalent of an
 417  * anonymous pipe/FIFO.
 418  *
 419  * On the reader side, the normal stream functions are used,
 420  * e.g. vlc_stream_Read() and vlc_stream_Delete().
 421  *
 422  * The created stream object is automatically destroyed when both the reader
 423  * and the writer sides have been closed, with vlc_stream_Delete() and
 424  * vlc_stream_fifo_Close() respectively.
 425  *
 426  * \param parent parent VLC object for the stream
 427  * \return a stream object or NULL on memory error.
 428  */
 429 VLC_API stream_t *vlc_stream_fifo_New(vlc_object_t *parent);
 430
 431 /**
 432  * Writes a block to a FIFO stream.
 433  *
 434  * \param s FIFO stream created by vlc_stream_fifo_New()
 435  * \param block data block to write to the stream
 436  * \return 0 on success. -1 if the reader end has already been closed
 437  * (errno is then set to EPIPE, and the block is deleted).
 438  *
 439  * \bug No congestion control is performed. If the reader end is not keeping
 440  * up with the writer end, buffers will accumulate in memory.
 441  */
 442 VLC_API int vlc_stream_fifo_Queue(stream_t *s, block_t *block);
 443
 444 /**
 445  * Writes data to a FIFO stream.
 446  *
 447  * This is a convenience helper for vlc_stream_fifo_Queue().
 448  * \param s FIFO stream created by vlc_stream_fifo_New()
 449  * \param buf start address of data to write
 450  * \param len length of data to write in bytes
 451  * \return len on success, or -1 on error (errno is set accordingly)
 452  */
 453 VLC_API ssize_t vlc_stream_fifo_Write(stream_t *s, const void *buf,
 454                                       size_t len);
 455
 456 /**
 457  * Terminates a FIFO stream.
 458  *
 459  * Marks the end of the FIFO stream and releases any underlying resources.
 460  * \param s FIFO stream created by vlc_stream_fifo_New()
 461  */
 462 VLC_API void vlc_stream_fifo_Close(stream_t *s);
 463
 464 /**
 465  * @}
 466  */
 467
 468 /**
 469  * Try to add a stream filter to an open stream.
 470  * @return New stream to use, or NULL if the filter could not be added.
 471  **/
 472 VLC_API stream_t* vlc_stream_FilterNew( stream_t *p_source, const char *psz_stream_filter );
 473
 474 /**
 475  * Default ReadDir implementation for stream Filter. This implementation just
 476  * forward the pf_readdir call to the p_source stream.
 477  */
 478 VLC_API int vlc_stream_FilterDefaultReadDir(stream_t *s,
 479                                             input_item_node_t *p_node);
 480
 481 /**
 482  * Sets vlc_stream_FilterDefaultReadDir as the pf_readdir callback for this
 483  * stream filter.
 484  */
 485 #define stream_FilterSetDefaultReadDir(stream) \
 486 do { \
 487     (stream)->pf_readdir = vlc_stream_FilterDefaultReadDir; \
 488 } while (0)
 489
 490 /**
 491  * @}
 492  */
 493
 494 # ifdef __cplusplus
 495 }
 496 # endif
 497
 498 #endif