text: /*
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  /**
   * @file
   * unbuffered private I/O API
   */
  
  #ifndef AVFORMAT_URL_H
  #define AVFORMAT_URL_H
  
  #include "avio.h"
  #include "libavformat/version.h"
  
  #include "libavutil/dict.h"
  #include "libavutil/log.h"
  
  #define URL_PROTOCOL_FLAG_NESTED_SCHEME 1 /*< The protocol name can be the first part of a nested protocol scheme */
  #define URL_PROTOCOL_FLAG_NETWORK       2 /*< The protocol uses network */
  
  extern const AVClass ffurl_context_class;
  
  typedef struct URLContext {
      const AVClass *av_class;    /**< information for av_log(). Set by url_open(). */
      const struct URLProtocol *prot;
      void *priv_data;
      char *filename;             /**< specified URL */
      int flags;
      int max_packet_size;        /**< if non zero, the stream is packetized with this max packet size */
      int is_streamed;            /**< true if streamed (no seek possible), default = false */
      int is_connected;
      AVIOInterruptCB interrupt_callback;
      int64_t rw_timeout;         /**< maximum time to wait for (network) read/write operation completion, in mcs */
      const char *protocol_whitelist;
      const char *protocol_blacklist;
  } URLContext;
  
  typedef struct URLProtocol {
      const char *name;
      int     (*url_open)( URLContext *h, const char *url, int flags);
      /**
       * This callback is to be used by protocols which open further nested
       * protocols. options are then to be passed to ffurl_open()/ffurl_connect()
       * for those nested protocols.
       */
      int     (*url_open2)(URLContext *h, const char *url, int flags, AVDictionary **options);
      int     (*url_accept)(URLContext *s, URLContext **c);
      int     (*url_handshake)(URLContext *c);
  
      /**
       * Read data from the protocol.
       * If data is immediately available (even less than size), EOF is
       * reached or an error occurs (including EINTR), return immediately.
       * Otherwise:
       * In non-blocking mode, return AVERROR(EAGAIN) immediately.
       * In blocking mode, wait for data/EOF/error with a short timeout (0.1s),
       * and return AVERROR(EAGAIN) on timeout.
       * Checking interrupt_callback, looping on EINTR and EAGAIN and until
       * enough data has been read is left to the calling function; see
       * retry_transfer_wrapper in avio.c.
       */
      int     (*url_read)( URLContext *h, unsigned char *buf, int size);
      int     (*url_write)(URLContext *h, const unsigned char *buf, int size);
      int64_t (*url_seek)( URLContext *h, int64_t pos, int whence);
      int     (*url_close)(URLContext *h);
      int (*url_read_pause)(URLContext *h, int pause);
      int64_t (*url_read_seek)(URLContext *h, int stream_index,
                               int64_t timestamp, int flags);
      int (*url_get_file_handle)(URLContext *h);
      int (*url_get_multi_file_handle)(URLContext *h, int **handles,
                                       int *numhandles);
      int (*url_get_short_seek)(URLContext *h);
      int (*url_shutdown)(URLContext *h, int flags);
      int priv_data_size;
      const AVClass *priv_data_class;
      int flags;
      int (*url_check)(URLContext *h, int mask);
      int (*url_open_dir)(URLContext *h);
      int (*url_read_dir)(URLContext *h, AVIODirEntry **next);
      int (*url_close_dir)(URLContext *h);
      int (*url_delete)(URLContext *h);
      int (*url_move)(URLContext *h_src, URLContext *h_dst);
      int (*url_read_drop_video)( URLContext *h, int flags);
      const char *default_whitelist;
  } URLProtocol;
  
  /**
   * Create a URLContext for accessing to the resource indicated by
   * url, but do not initiate the connection yet.
   *
   * @param puc pointer to the location where, in case of success, the
   * function puts the pointer to the created URLContext
   * @param flags flags which control how the resource indicated by url
   * is to be opened
   * @param int_cb interrupt callback to use for the URLContext, may be
   * NULL
   * @return >= 0 in case of success, a negative value corresponding to an
   * AVERROR code in case of failure
   */
  int ffurl_alloc(URLContext **puc, const char *filename, int flags,
                  const AVIOInterruptCB *int_cb);
  
  /**
   * Connect an URLContext that has been allocated by ffurl_alloc
   *
   * @param options  A dictionary filled with options for nested protocols,
   * i.e. it will be passed to url_open2() for protocols implementing it.
   * This parameter will be destroyed and replaced with a dict containing options
   * that were not found. May be NULL.
   */
  int ffurl_connect(URLContext *uc, AVDictionary **options);
  
  /**
   * Create an URLContext for accessing to the resource indicated by
   * url, and open it.
   *
   * @param puc pointer to the location where, in case of success, the
   * function puts the pointer to the created URLContext
   * @param flags flags which control how the resource indicated by url
   * is to be opened
   * @param int_cb interrupt callback to use for the URLContext, may be
   * NULL
   * @param options  A dictionary filled with protocol-private options. On return
   * this parameter will be destroyed and replaced with a dict containing options
   * that were not found. May be NULL.
   * @param parent An enclosing URLContext, whose generic options should
   *               be applied to this URLContext as well.
   * @return >= 0 in case of success, a negative value corresponding to an
   * AVERROR code in case of failure
   */
  int ffurl_open_whitelist(URLContext **puc, const char *filename, int flags,
                 const AVIOInterruptCB *int_cb, AVDictionary **options,
                 const char *whitelist, const char* blacklist,
                 URLContext *parent);
  
  int ffurl_open(URLContext **puc, const char *filename, int flags,
                 const AVIOInterruptCB *int_cb, AVDictionary **options);
  
  /**
   * Accept an URLContext c on an URLContext s
   *
   * @param  s server context
   * @param  c client context, must be unallocated.
   * @return >= 0 on success, ff_neterrno() on failure.
   */
  int ffurl_accept(URLContext *s, URLContext **c);
  
  /**
   * Perform one step of the protocol handshake to accept a new client.
   * See avio_handshake() for details.
   * Implementations should try to return decreasing values.
   * If the protocol uses an underlying protocol, the underlying handshake is
   * usually the first step, and the return value can be:
   * (largest value for this protocol) + (return value from other protocol)
   *
   * @param  c the client context
   * @return >= 0 on success or a negative value corresponding
   *         to an AVERROR code on failure
   */
  int ffurl_handshake(URLContext *c);
  
  /**
   * Read up to size bytes from the resource accessed by h, and store
   * the read bytes in buf.
   *
   * @return The number of bytes actually read, or a negative value
   * corresponding to an AVERROR code in case of error. A value of zero
   * indicates that it is not possible to read more from the accessed
   * resource (except if the value of the size argument is also zero).
   */
  int ffurl_read(URLContext *h, unsigned char *buf, int size);
  
  /**
   * Read as many bytes as possible (up to size), calling the
   * read function multiple times if necessary.
   * This makes special short-read handling in applications
   * unnecessary, if the return value is < size then it is
   * certain there was either an error or the end of file was reached.
   */
  int ffurl_read_complete(URLContext *h, unsigned char *buf, int size);
  
  /**
   * Write size bytes from buf to the resource accessed by h.
   *
   * @return the number of bytes actually written, or a negative value
   * corresponding to an AVERROR code in case of failure
   */
  int ffurl_write(URLContext *h, const unsigned char *buf, int size);
  
  /**
   * Change the position that will be used by the next read/write
   * operation on the resource accessed by h.
   *
   * @param pos specifies the new position to set
   * @param whence specifies how pos should be interpreted, it must be
   * one of SEEK_SET (seek from the beginning), SEEK_CUR (seek from the
   * current position), SEEK_END (seek from the end), or AVSEEK_SIZE
   * (return the filesize of the requested resource, pos is ignored).
   * @return a negative value corresponding to an AVERROR code in case
   * of failure, or the resulting file position, measured in bytes from
   * the beginning of the file. You can use this feature together with
   * SEEK_CUR to read the current file position.
   */
  int64_t ffurl_seek(URLContext *h, int64_t pos, int whence);
  
  /**
   * Close the resource accessed by the URLContext h, and free the
   * memory used by it. Also set the URLContext pointer to NULL.
   *
   * @return a negative value if an error condition occurred, 0
   * otherwise
   */
  int ffurl_closep(URLContext **h);
  int ffurl_close(URLContext *h);
  
  /**
   * Return the filesize of the resource accessed by h, AVERROR(ENOSYS)
   * if the operation is not supported by h, or another negative value
   * corresponding to an AVERROR error code in case of failure.
   */
  int64_t ffurl_size(URLContext *h);
  
  /**
   * Return the file descriptor associated with this URL. For RTP, this
   * will return only the RTP file descriptor, not the RTCP file descriptor.
   *
   * @return the file descriptor associated with this URL, or <0 on error.
   */
  int ffurl_get_file_handle(URLContext *h);
  
  /**
   * Return the file descriptors associated with this URL.
   *
   * @return 0 on success or <0 on error.
   */
  int ffurl_get_multi_file_handle(URLContext *h, int **handles, int *numhandles);
  
  /**
   * Return the current short seek threshold value for this URL.
   *
   * @return threshold (>0) on success or <=0 on error.
   */
  int ffurl_get_short_seek(URLContext *h);
  
  /**
   * Signal the URLContext that we are done reading or writing the stream.
   *
   * @param h pointer to the resource
   * @param flags flags which control how the resource indicated by url
   * is to be shutdown
   *
   * @return a negative value if an error condition occurred, 0
   * otherwise
   */
  int ffurl_shutdown(URLContext *h, int flags);
  
  /**
   * Check if the user has requested to interrupt a blocking function
   * associated with cb.
   */
  int ff_check_interrupt(AVIOInterruptCB *cb);
  
  /* udp.c */
  int ff_udp_set_remote_url(URLContext *h, const char *uri);
  int ff_udp_get_local_port(URLContext *h);
  
  /**
   * Assemble a URL string from components. This is the reverse operation
   * of av_url_split.
   *
   * Note, this requires networking to be initialized, so the caller must
   * ensure ff_network_init has been called.
   *
   * @see av_url_split
   *
   * @param str the buffer to fill with the url
   * @param size the size of the str buffer
   * @param proto the protocol identifier, if null, the separator
   *              after the identifier is left out, too
   * @param authorization an optional authorization string, may be null.
   *                      An empty string is treated the same as a null string.
   * @param hostname the host name string
   * @param port the port number, left out from the string if negative
   * @param fmt a generic format string for everything to add after the
   *            host/port, may be null
   * @return the number of characters written to the destination buffer
   */
  int ff_url_join(char *str, int size, const char *proto,
                  const char *authorization, const char *hostname,
                  int port, const char *fmt, ...) av_printf_format(7, 8);
  
  /**
   * Convert a relative url into an absolute url, given a base url.
   *
   * @param buf the buffer where output absolute url is written
   * @param size the size of buf
   * @param base the base url, may be equal to buf.
   * @param rel the new url, which is interpreted relative to base
   */
  void ff_make_absolute_url(char *buf, int size, const char *base,
                            const char *rel);
  
  /**
   * Allocate directory entry with default values.
   *
   * @return entry or NULL on error
   */
  AVIODirEntry *ff_alloc_dir_entry(void);
  
  const AVClass *ff_urlcontext_child_class_next(const AVClass *prev);
  
  /**
   * Construct a list of protocols matching a given whitelist and/or blacklist.
   *
   * @param whitelist a comma-separated list of allowed protocol names or NULL. If
   *                  this is a non-empty string, only protocols in this list will
   *                  be included.
   * @param blacklist a comma-separated list of forbidden protocol names or NULL.
   *                  If this is a non-empty string, all protocols in this list
   *                  will be excluded.
   *
   * @return a NULL-terminated array of matching protocols. The array must be
   * freed by the caller.
   */
  const URLProtocol **ffurl_get_protocols(const char *whitelist,
                                          const char *blacklist);
  
  #endif /* AVFORMAT_URL_H */
  