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  • /*
     * copyright (c) 2001 Fabrice Bellard
     *
    
     * 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
     */
    
    #ifndef AVFORMAT_AVIO_H
    #define AVFORMAT_AVIO_H
    
     * unbuffered I/O operations
    
     *
     * @warning This file has to be considered an internal but installed
     * header, so it should not be directly included in your projects.
    
    #include <stdint.h>
    
    
    #include "libavutil/common.h"
    
    #include "libavutil/log.h"
    
    #include "libavformat/version.h"
    
    
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    /* unbuffered I/O */
    
    
    /**
     * URL Context.
     * New fields can be added to the end with minor version bumps.
    
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     * Removal, reordering and changes to existing fields require a major
    
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     * sizeof(URLContext) must not be used outside libav*.
    
        const AVClass *av_class; ///< information for av_log(). Set by url_open().
    #endif
    
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        struct URLProtocol *prot;
    
        int is_streamed;  /**< true if streamed (no seek possible), default = false */
        int max_packet_size;  /**< if non zero, the stream is packetized with this max packet size */
    
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        void *priv_data;
    
        char *filename; /**< specified URL */
    
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    typedef struct URLPollEntry {
        URLContext *handle;
        int events;
        int revents;
    } URLPollEntry;
    
    
    /**
     * @defgroup open_modes URL open modes
     * The flags argument to url_open and cosins must be one of the following
     * constants, optionally ORed with other flags.
     * @{
     */
    #define URL_RDONLY 0  /**< read-only */
    #define URL_WRONLY 1  /**< write-only */
    #define URL_RDWR   2  /**< read-write */
    /**
     * @}
     */
    
    /**
     * Use non-blocking mode.
     * If this flag is set, operations on the context will return
     * AVERROR(EAGAIN) if they can not be performed immediately.
     * If this flag is not set, operations on the context will never return
     * AVERROR(EAGAIN).
     * Note that this flag does not affect the opening/connecting of the
     * context. Connecting a protocol will always block if necessary (e.g. on
     * network protocols) but never hang (e.g. on busy devices).
     * Warning: non-blocking protocols is work-in-progress; this flag may be
     * silently ignored.
     */
    #define URL_FLAG_NONBLOCK 4
    
    typedef int URLInterruptCB(void);
    
    
     * Create a URLContext for accessing to the resource indicated by
     * url, and open it using the URLProtocol up.
    
     *
     * @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
     * @return 0 in case of success, a negative value corresponding to an
     * AVERROR code in case of failure
     */
    
    int url_open_protocol (URLContext **puc, struct URLProtocol *up,
    
     * 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
     * @return 0 in case of success, a negative value corresponding to an
     * AVERROR code in case of failure
     */
    int url_alloc(URLContext **h, const char *url, int flags);
    
    /**
     * Connect an URLContext that has been allocated by url_alloc
     */
    int url_connect(URLContext *h);
    
    
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    /**
    
     * Create an URLContext for accessing to the resource indicated by
     * url, and open it.
    
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     *
     * @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
     * @return 0 in case of success, a negative value corresponding to an
     * AVERROR code in case of failure
     */
    
    int url_open(URLContext **h, const char *url, int flags);
    
     * Read up to size bytes from the resource accessed by h, and store
    
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     * 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).
     */
    
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    int url_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 url_read_complete(URLContext *h, unsigned char *buf, int size);
    
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    /**
     * 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 url_write(URLContext *h, const unsigned char *buf, int size);
    
    /**
     * Passing this as the "whence" parameter to a seek function causes it to
     * return the filesize without seeking anywhere. Supporting this is optional.
     * If it is not supported then the seek function will return <0.
     */
    #define AVSEEK_SIZE 0x10000
    
    
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    /**
    
     * Change the position that will be used by the next read/write
    
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     * 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 url_seek(URLContext *h, int64_t pos, int whence);
    
     * Close the resource accessed by the URLContext h, and free the
    
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     * memory used by it.
     *
     * @return a negative value if an error condition occurred, 0
     * otherwise
     */
    
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    int url_close(URLContext *h);
    
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    /**
    
     * Return a non-zero value if the resource indicated by url
    
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     * exists, 0 otherwise.
     */
    
    int url_exist(const char *url);
    
    /**
     * 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 url_filesize(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 url_get_file_handle(URLContext *h);
    
    
     * Return the maximum packet size associated to packetized file
    
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     * handle. If the file is not packetized (stream like HTTP or file on
    
     * disk), then 0 is returned.
     *
     * @param h file handle
     * @return maximum packet size in bytes
     */
    
    int url_get_max_packet_size(URLContext *h);
    
    
    /**
     * Copy the filename of the resource accessed by h to buf.
     *
     * @param buf_size size in bytes of buf
     */
    
    void url_get_filename(URLContext *h, char *buf, int buf_size);
    
    
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     * The callback is called in blocking functions to test regulary if
    
     * asynchronous interruption is needed. AVERROR(EINTR) is returned
     * in this case by the interrupted function. 'NULL' means no interrupt
    
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     * callback is given.
    
    void url_set_interrupt_cb(URLInterruptCB *interrupt_cb);
    
    
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    /* not implemented */
    int url_poll(URLPollEntry *poll_table, int n, int timeout);
    
    
    /**
     * Pause and resume playing - only meaningful if using a network streaming
     * protocol (e.g. MMS).
     * @param pause 1 for pause, 0 for resume
     */
    int av_url_read_pause(URLContext *h, int pause);
    
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    /**
     * Seek to a given timestamp relative to some component stream.
    
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     * Only meaningful if using a network streaming protocol (e.g. MMS.).
    
     * @param stream_index The stream index that the timestamp is relative to.
     *        If stream_index is (-1) the timestamp should be in AV_TIME_BASE
     *        units from the beginning of the presentation.
     *        If a stream_index >= 0 is used and the protocol does not support
     *        seeking based on component streams, the call will fail with ENOTSUP.
    
     * @param timestamp timestamp in AVStream.time_base units
    
     *        or if there is no stream specified then in AV_TIME_BASE units.
     * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
     *        and AVSEEK_FLAG_ANY. The protocol may silently ignore
     *        AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
     *        fail with ENOTSUP if used and not supported.
     * @return >= 0 on success
     * @see AVInputFormat::read_seek
     */
    
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    int64_t av_url_read_seek(URLContext *h, int stream_index,
                             int64_t timestamp, int flags);
    
    /**
     * Oring this flag as into the "whence" parameter to a seek function causes it to
     * seek by any means (like reopening and linear reading) or other normally unreasonble
     * means that can be extreemly slow.
     * This may be ignored by the seek code.
     */
    #define AVSEEK_FORCE 0x20000
    
    
    #define URL_PROTOCOL_FLAG_NESTED_SCHEME 1 /*< The protocol name can be the first part of a nested protocol scheme */
    
    
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    typedef struct URLProtocol {
        const char *name;
    
        int (*url_open)(URLContext *h, const char *url, int flags);
    
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        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);
    
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        int (*url_close)(URLContext *h);
        struct URLProtocol *next;
    
        int (*url_read_pause)(URLContext *h, int pause);
    
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        int64_t (*url_read_seek)(URLContext *h, int stream_index,
                                 int64_t timestamp, int flags);
    
        int (*url_get_file_handle)(URLContext *h);
    
        int priv_data_size;
        const AVClass *priv_data_class;
    
        int flags;
    
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    } URLProtocol;
    
    
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    extern URLProtocol *first_protocol;
    
    extern URLInterruptCB *url_interrupt_cb;
    
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    /**
     * If protocol is NULL, returns the first registered protocol,
    
     * if protocol is non-NULL, returns the next registered protocol after protocol,
    
     * or NULL if protocol is the last one.
     */
    
    URLProtocol *av_protocol_next(URLProtocol *p);
    
    
    /**
     * @deprecated Use av_register_protocol() instead.
     */
    attribute_deprecated int register_protocol(URLProtocol *protocol);
    
    
    /**
     * @deprecated Use av_register_protocol2() instead.
     */
    attribute_deprecated int av_register_protocol(URLProtocol *protocol);
    
     * Register the URLProtocol protocol.
    
     *
     * @param size the size of the URLProtocol struct referenced
    
    int av_register_protocol2(URLProtocol *protocol, int size);
    
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    /**
     * Bytestream IO Context.
     * New fields can be added to the end with minor version bumps.
    
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     * Removal, reordering and changes to existing fields require a major
    
     * sizeof(AVIOContext) must not be used outside libav*.
    
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    typedef struct {
        unsigned char *buffer;
        int buffer_size;
        unsigned char *buf_ptr, *buf_end;
        void *opaque;
    
        int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
    
        int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
    
        int64_t (*seek)(void *opaque, int64_t offset, int whence);
        int64_t pos; /**< position in the file of the current buffer */
    
        int must_flush; /**< true if the next seek should flush */
        int eof_reached; /**< true if eof reached */
        int write_flag;  /**< true if open for writing */
    
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        int is_streamed;
    
        unsigned long checksum;
        unsigned char *checksum_ptr;
        unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
    
        int error;         ///< contains the error code or 0 if no error happened
    
        int (*read_pause)(void *opaque, int pause);
    
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        int64_t (*read_seek)(void *opaque, int stream_index,
                             int64_t timestamp, int flags);
    
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    #if FF_API_OLD_AVIO
    typedef attribute_deprecated AVIOContext ByteIOContext;
    
    
    attribute_deprecated int init_put_byte(AVIOContext *s,
    
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                      unsigned char *buffer,
                      int buffer_size,
                      int write_flag,
                      void *opaque,
    
                      int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
                      int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
    
                      int64_t (*seek)(void *opaque, int64_t offset, int whence));
    
    attribute_deprecated AVIOContext *av_alloc_put_byte(
                      unsigned char *buffer,
                      int buffer_size,
                      int write_flag,
                      void *opaque,
                      int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
                      int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
                      int64_t (*seek)(void *opaque, int64_t offset, int whence));
    
    
    /**
     * @defgroup old_avio_funcs Old put_/get_*() functions
     * @deprecated use the avio_ -prefixed functions instead.
     * @{
     */
    attribute_deprecated int          get_buffer(AVIOContext *s, unsigned char *buf, int size);
    
    attribute_deprecated int          get_partial_buffer(AVIOContext *s, unsigned char *buf, int size);
    
    attribute_deprecated int          get_byte(AVIOContext *s);
    attribute_deprecated unsigned int get_le16(AVIOContext *s);
    attribute_deprecated unsigned int get_le24(AVIOContext *s);
    attribute_deprecated unsigned int get_le32(AVIOContext *s);
    attribute_deprecated uint64_t     get_le64(AVIOContext *s);
    attribute_deprecated unsigned int get_be16(AVIOContext *s);
    attribute_deprecated unsigned int get_be24(AVIOContext *s);
    attribute_deprecated unsigned int get_be32(AVIOContext *s);
    attribute_deprecated uint64_t     get_be64(AVIOContext *s);
    
    
    attribute_deprecated void         put_byte(AVIOContext *s, int b);
    
    attribute_deprecated void         put_nbyte(AVIOContext *s, int b, int count);
    
    attribute_deprecated void         put_buffer(AVIOContext *s, const unsigned char *buf, int size);
    attribute_deprecated void         put_le64(AVIOContext *s, uint64_t val);
    attribute_deprecated void         put_be64(AVIOContext *s, uint64_t val);
    attribute_deprecated void         put_le32(AVIOContext *s, unsigned int val);
    attribute_deprecated void         put_be32(AVIOContext *s, unsigned int val);
    attribute_deprecated void         put_le24(AVIOContext *s, unsigned int val);
    attribute_deprecated void         put_be24(AVIOContext *s, unsigned int val);
    attribute_deprecated void         put_le16(AVIOContext *s, unsigned int val);
    attribute_deprecated void         put_be16(AVIOContext *s, unsigned int val);
    
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    attribute_deprecated void         put_tag(AVIOContext *s, const char *tag);
    
    
    
    /**
     * @defgroup old_url_f_funcs Old url_f* functions
     * @deprecated use the avio_ -prefixed functions instead.
     * @{
     */
    attribute_deprecated int url_fopen( AVIOContext **s, const char *url, int flags);
    attribute_deprecated int url_fclose(AVIOContext *s);
    
    attribute_deprecated int64_t url_fseek(AVIOContext *s, int64_t offset, int whence);
    
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    attribute_deprecated int url_fskip(AVIOContext *s, int64_t offset);
    
    attribute_deprecated int64_t url_ftell(AVIOContext *s);
    
                      unsigned char *buffer,
                      int buffer_size,
                      int write_flag,
                      void *opaque,
    
                      int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
    
                      int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
    
                      int64_t (*seek)(void *opaque, int64_t offset, int whence));
    
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    void avio_w8(AVIOContext *s, int b);
    void avio_write(AVIOContext *s, const unsigned char *buf, int size);
    void avio_wl64(AVIOContext *s, uint64_t val);
    void avio_wb64(AVIOContext *s, uint64_t val);
    void avio_wl32(AVIOContext *s, unsigned int val);
    void avio_wb32(AVIOContext *s, unsigned int val);
    void avio_wl24(AVIOContext *s, unsigned int val);
    void avio_wb24(AVIOContext *s, unsigned int val);
    void avio_wl16(AVIOContext *s, unsigned int val);
    void avio_wb16(AVIOContext *s, unsigned int val);
    
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    attribute_deprecated void put_strz(AVIOContext *s, const char *buf);
    
    #endif
    
    /**
     * Write a NULL-terminated string.
     * @return number of bytes written.
     */
    
    int avio_put_str(AVIOContext *s, const char *str);
    
    /**
     * Convert an UTF-8 string to UTF-16LE and write it.
     * @return number of bytes written.
     */
    
    int avio_put_str16le(AVIOContext *s, const char *str);
    
     * fseek() equivalent for AVIOContext.
    
     * @return new position or AVERROR.
     */
    
    int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
    
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    /**
     * Skip given number of bytes forward
     * @return new position or AVERROR.
     */
    #define avio_skip(s, offset) avio_seek(s, offset, SEEK_CUR)
    
    
     * ftell() equivalent for AVIOContext.
    
     * @return position or AVERROR.
     */
    
    #define avio_tell(s) avio_seek((s), 0, SEEK_CUR)
    
     * Get the filesize.
    
     * @return filesize or AVERROR
     */
    
    int64_t url_fsize(AVIOContext *s);
    
     * feof() equivalent for AVIOContext.
    
     * @return non zero if and only if end of file
     */
    
    int url_feof(AVIOContext *s);
    
    int url_ferror(AVIOContext *s);
    
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    int av_url_read_fpause(AVIOContext *h, int pause);
    int64_t av_url_read_fseek(AVIOContext *h, int stream_index,
    
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                              int64_t timestamp, int flags);
    
    int url_fgetc(AVIOContext *s);
    
    /** @warning currently size is limited */
    
    int url_fprintf(AVIOContext *s, const char *fmt, ...) __attribute__ ((__format__ (__printf__, 2, 3)));
    
    int url_fprintf(AVIOContext *s, const char *fmt, ...);
    
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    #if FF_API_OLD_AVIO
    
    /** @note unlike fgets, the EOL character is not returned and a whole
    
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        line is parsed. return NULL if first char read was EOF */
    
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    attribute_deprecated char *url_fgets(AVIOContext *s, char *buf, int buf_size);
    #endif
    
    void put_flush_packet(AVIOContext *s);
    
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     * Read size bytes from AVIOContext into buf.
    
     * @return number of bytes read or AVERROR
    
    int avio_read(AVIOContext *s, unsigned char *buf, int size);
    
    /** @note return 0 if EOF, so you cannot use it if EOF handling is
    
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        necessary */
    
    int          avio_r8  (AVIOContext *s);
    unsigned int avio_rl16(AVIOContext *s);
    unsigned int avio_rl24(AVIOContext *s);
    unsigned int avio_rl32(AVIOContext *s);
    uint64_t     avio_rl64(AVIOContext *s);
    
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    /**
     * Read a string from pb into buf. The reading will terminate when either
     * a NULL character was encountered, maxlen bytes have been read, or nothing
     * more can be read from pb. The result is guaranteed to be NULL-terminated, it
     * will be truncated if buf is too small.
     * Note that the string is not interpreted or validated in any way, it
     * might get truncated in the middle of a sequence for multi-byte encodings.
     *
     * @return number of bytes read (is always <= maxlen).
     * If reading ends on EOF or error, the return value will be one more than
     * bytes actually read.
     */
    int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
    
    
    /**
     * Read a UTF-16 string from pb and convert it to UTF-8.
     * The reading will terminate when either a null or invalid character was
     * encountered or maxlen bytes have been read.
     * @return number of bytes read (is always <= maxlen)
     */
    
    int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
    int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
    
    #if FF_API_OLD_AVIO
    /**
     * @deprecated use avio_get_str instead
     */
    attribute_deprecated char *get_strz(AVIOContext *s, char *buf, int maxlen);
    #endif
    
    unsigned int avio_rb16(AVIOContext *s);
    unsigned int avio_rb24(AVIOContext *s);
    unsigned int avio_rb32(AVIOContext *s);
    uint64_t     avio_rb64(AVIOContext *s);
    
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    uint64_t ff_get_v(AVIOContext *bc);
    
    static inline int url_is_streamed(AVIOContext *s)
    
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    {
        return s->is_streamed;
    }
    
    
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    /**
    
     * Create and initialize a AVIOContext for accessing the
    
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     * resource referenced by the URLContext h.
     * @note When the URLContext h has been opened in read+write mode, the
    
     * AVIOContext can be used only for writing.
    
     * @param s Used to return the pointer to the created AVIOContext.
    
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     * In case of failure the pointed to value is set to NULL.
     * @return 0 in case of success, a negative value corresponding to an
     * AVERROR code in case of failure
     */
    
    int url_fdopen(AVIOContext **s, URLContext *h);
    
    /** @warning must be called before any I/O */
    
    int url_setbufsize(AVIOContext *s, int buf_size);
    
    /** Reset the buffer for reading or writing.
     * @note Will drop any data currently in the buffer without transmitting it.
     * @param flags URL_RDONLY to set up the buffer for reading, or URL_WRONLY
     *        to set up the buffer for writing. */
    
    int url_resetbuf(AVIOContext *s, int flags);
    
     * Rewind the AVIOContext using the specified buffer containing the first buf_size bytes of the file.
    
     * Used after probing to avoid seeking.
     * Joins buf and s->buffer, taking any overlap into consideration.
     * @note s->buffer must overlap with buf or they can't be joined and the function fails
     * @note This function is NOT part of the public API
     *
    
     * @param s The read-only AVIOContext to rewind
    
     * @param buf The probe buffer containing the first buf_size bytes of the file
     * @param buf_size The size of buf
     * @return 0 in case of success, a negative value corresponding to an
     * AVERROR code in case of failure
     */
    
    int ff_rewind_with_probe_data(AVIOContext *s, unsigned char *buf, int buf_size);
    
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    /**
    
     * Create and initialize a AVIOContext for accessing the
    
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     * resource indicated by url.
     * @note When the resource indicated by url has been opened in
    
     * read+write mode, the AVIOContext can be used only for writing.
    
     * @param s Used to return the pointer to the created AVIOContext.
    
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     * In case of failure the pointed to value is set to NULL.
     * @param flags flags which control how the resource indicated by url
     * is to be opened
     * @return 0 in case of success, a negative value corresponding to an
     * AVERROR code in case of failure
     */
    
    int avio_open(AVIOContext **s, const char *url, int flags);
    
    int avio_close(AVIOContext *s);
    
    URLContext *url_fileno(AVIOContext *s);
    
     * Return the maximum packet size associated to packetized buffered file
     * handle. If the file is not packetized (stream like http or file on
     * disk), then 0 is returned.
     *
    
     * @param s buffered file handle
    
    int url_fget_max_packet_size(AVIOContext *s);
    
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    int url_open_buf(AVIOContext **s, uint8_t *buf, int buf_size, int flags);
    
    int url_close_buf(AVIOContext *s);
    
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     * Open a write only memory stream.
     *
     * @param s new IO context
     * @return zero if no error.
     */
    
    int url_open_dyn_buf(AVIOContext **s);
    
     * Open a write only packetized memory stream with a maximum packet
     * size of 'max_packet_size'.  The stream is stored in a memory buffer
     * with a big endian 4 byte header giving the packet size in bytes.
     *
     * @param s new IO context
     * @param max_packet_size maximum packet size (must be > 0)
     * @return zero if no error.
     */
    
    int url_open_dyn_packet_buf(AVIOContext **s, int max_packet_size);
    
     * Return the written size and a pointer to the buffer. The buffer
    
     * must be freed with av_free(). If the buffer is opened with
     * url_open_dyn_buf, then padding of FF_INPUT_BUFFER_PADDING_SIZE is
     * added; if opened with url_open_dyn_packet_buf, no padding is added.
     *
    
     * @param pbuffer pointer to a byte buffer
    
    int url_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
    
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    unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
                                        unsigned int len);
    
    unsigned long get_checksum(AVIOContext *s);
    void init_checksum(AVIOContext *s,
    
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                       unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
                       unsigned long checksum);
    
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    /* udp.c */
    
    int udp_set_remote_url(URLContext *h, const char *uri);
    int udp_get_local_port(URLContext *h);
    
    int udp_get_file_handle(URLContext *h);
    
    #endif /* AVFORMAT_AVIO_H */