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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

/**
* @file
* @ingroup lavf_io
* Buffered I/O operations
*/

#include <stdint.h>

#include "libavutil/common.h"
#include "libavutil/dict.h"
#include "libavutil/log.h"

#include "libavformat/version.h"


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

/**
* Callback for checking whether to abort blocking functions.
* AVERROR_EXIT is returned in this case by the interrupted
* function. During blocking operations, callback is called with
* opaque as parameter. If the callback returns 1, the
* blocking operation will be aborted.
*
* No members can be added to this struct without a major bump, if
* new elements have been added after this struct in AVFormatContext
* or AVIOContext.
*/
typedef struct AVIOInterruptCB {
    int (*callback)(void*);
    void *opaque;
} AVIOInterruptCB;

/**
* Bytestream IO Context.
* New fields can be added to the end with minor version bumps.
* Removal, reordering and changes to existing fields require a major
* version bump.
* sizeof(AVIOContext) must not be used outside libav*.
*
* @note None of the function pointers in AVIOContext should be called
* directly, they should only be set by the client application
* when implementing custom I/O. Normally these are set to the
* function pointers specified in avio_alloc_context()
*/
typedef struct AVIOContext {
    /**
* A class for private options.
*
* If this AVIOContext is created by avio_open2(), av_class is set and
* passes the options down to protocols.
*
* If this AVIOContext is manually allocated, then av_class may be set by
* the caller.
*
* warning -- this field can be NULL, be sure to not pass this AVIOContext
* to any av_opt_* functions in that case.
*/
    const AVClass *av_class;
    unsigned char *buffer; /**< Start of the buffer. */
    int buffer_size; /**< Maximum buffer size */
    unsigned char *buf_ptr; /**< Current position in the buffer */
    unsigned char *buf_end; /**< End of the data, may be less than
buffer+buffer_size if the read function returned
less data than requested, e.g. for streams where
no more data has been received yet. */
    void *opaque; /**< A private pointer, passed to the read/write/seek/...
functions. */
    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 */
    int max_packet_size;
    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 */
    /**
* Pause or resume playback for network streaming protocols - e.g. MMS.
*/
    int (*read_pause)(void *opaque, int pause);
    /**
* Seek to a given timestamp in stream with the specified stream_index.
* Needed for some network streaming protocols which don't support seeking
* to byte position.
*/
    int64_t (*read_seek)(void *opaque, int stream_index,
                         int64_t timestamp, int flags);
    /**
* A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
*/
    int seekable;

    /**
* max filesize, used to limit allocations
* This field is internal to libavformat and access from outside is not allowed.
*/
    int64_t maxsize;

    /**
* avio_read and avio_write should if possible be satisfied directly
* instead of going through a buffer, and avio_seek will always
* call the underlying seek function directly.
*/
    int direct;

    /**
* Bytes read statistic
* This field is internal to libavformat and access from outside is not allowed.
*/
    int64_t bytes_read;

    /**
* seek statistic
* This field is internal to libavformat and access from outside is not allowed.
*/
    int seek_count;

    /**
* writeout statistic
* This field is internal to libavformat and access from outside is not allowed.
*/
    int writeout_count;

    /**
* Original buffer size
* used internally after probing and ensure seekback to reset the buffer size
* This field is internal to libavformat and access from outside is not allowed.
*/
    int orig_buffer_size;
} AVIOContext;

/* unbuffered I/O */

/**
* Return the name of the protocol that will handle the passed URL.
*
* NULL is returned if no protocol could be found for the given URL.
*
* @return Name of the protocol or NULL.
*/
const char *avio_find_protocol_name(const char *url);

/**
* Return AVIO_FLAG_* access flags corresponding to the access permissions
* of the resource in url, or a negative value corresponding to an
* AVERROR code in case of failure. The returned access flags are
* masked by the value in flags.
*
* @note This function is intrinsically unsafe, in the sense that the
* checked resource may change its existence or permission status from
* one call to another. Thus you should not trust the returned value,
* unless you are sure that no other processes are accessing the
* checked resource.
*/
int avio_check(const char *url, int flags);

/**
* Allocate and initialize an AVIOContext for buffered I/O. It must be later
* freed with av_free().
*
* @param buffer Memory block for input/output operations via AVIOContext.
* The buffer must be allocated with av_malloc() and friends.
* @param buffer_size The buffer size is very important for performance.
* For protocols with fixed blocksize it should be set to this blocksize.
* For others a typical size is a cache page, e.g. 4kb.
* @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
* @param opaque An opaque pointer to user-specific data.
* @param read_packet A function for refilling the buffer, may be NULL.
* @param write_packet A function for writing the buffer contents, may be NULL.
* The function may not change the input buffers content.
* @param seek A function for seeking to specified byte position, may be NULL.
*
* @return Allocated AVIOContext or NULL on failure.
*/
AVIOContext *avio_alloc_context(
                  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));

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);

/**
* 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);

/**
* 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

/**
* 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 unreasonable
* means that can be extremely slow.
* This may be ignored by the seek code.
*/
#define AVSEEK_FORCE 0x20000

/**
* fseek() equivalent for AVIOContext.
* @return new position or AVERROR.
*/
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);

/**
* Skip given number of bytes forward
* @return new position or AVERROR.
*/
int64_t avio_skip(AVIOContext *s, int64_t offset);

/**
* ftell() equivalent for AVIOContext.
* @return position or AVERROR.
*/
static av_always_inline int64_t avio_tell(AVIOContext *s)
{
    return avio_seek(s, 0, SEEK_CUR);
}

/**
* Get the filesize.
* @return filesize or AVERROR
*/
int64_t avio_size(AVIOContext *s);

/**
* feof() equivalent for AVIOContext.
* @return non zero if and only if end of file
*/
int url_feof(AVIOContext *s);

/** @warning currently size is limited */
int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);

/**
* Force flushing of buffered data to the output s.
*
* Force the buffered data to be immediately written to the output,
* without to wait to fill the internal buffer.
*/
void avio_flush(AVIOContext *s);

/**
* Read size bytes from AVIOContext into buf.
* @return number of bytes read or AVERROR
*/
int avio_read(AVIOContext *s, unsigned char *buf, int size);

/**
* @name Functions for reading from AVIOContext
* @{
*
* @note return 0 if EOF, so you cannot use it if EOF handling is
* 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);
unsigned int avio_rb16(AVIOContext *s);
unsigned int avio_rb24(AVIOContext *s);
unsigned int avio_rb32(AVIOContext *s);
uint64_t avio_rb64(AVIOContext *s);
/**
* @}
*/

/**
* 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);


/**
* @name URL open modes
* The flags argument to avio_open must be one of the following
* constants, optionally ORed with other flags.
* @{
*/
#define AVIO_FLAG_READ 1 /**< read-only */
#define AVIO_FLAG_WRITE 2 /**< write-only */
#define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
/**
* @}
*/

/**
* 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 AVIO_FLAG_NONBLOCK 8

/**
* Use direct mode.
* avio_read and avio_write should if possible be satisfied directly
* instead of going through a buffer, and avio_seek will always
* call the underlying seek function directly.
*/
#define AVIO_FLAG_DIRECT 0x8000

/**
* Create and initialize a AVIOContext for accessing the
* 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.
* In case of failure the pointed to value is set to NULL.
* @param url resource to access
* @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);

/**
* Create and initialize a AVIOContext for accessing the
* 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.
* In case of failure the pointed to value is set to NULL.
* @param url resource to access
* @param flags flags which control how the resource indicated by url
* is to be opened
* @param int_cb an interrupt callback to be used at the protocols level
* @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.
* @return >= 0 in case of success, a negative value corresponding to an
* AVERROR code in case of failure
*/
int avio_open2(AVIOContext **s, const char *url, int flags,
               const AVIOInterruptCB *int_cb, AVDictionary **options);

/**
* Close the resource accessed by the AVIOContext s and free it.
* This function can only be used if s was opened by avio_open().
*
* The internal buffer is automatically flushed before closing the
* resource.
*
* @return 0 on success, an AVERROR < 0 on error.
* @see avio_closep
*/
int avio_close(AVIOContext *s);

/**
* Close the resource accessed by the AVIOContext *s, free it
* and set the pointer pointing to it to NULL.
* This function can only be used if s was opened by avio_open().
*
* The internal buffer is automatically flushed before closing the
* resource.
*
* @return 0 on success, an AVERROR < 0 on error.
* @see avio_close
*/
int avio_closep(AVIOContext **s);


/**
* Open a write only memory stream.
*
* @param s new IO context
* @return zero if no error.
*/
int avio_open_dyn_buf(AVIOContext **s);

/**
* Return the written size and a pointer to the buffer. The buffer
* must be freed with av_free().
* Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
*
* @param s IO context
* @param pbuffer pointer to a byte buffer
* @return the length of the byte buffer
*/
int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);

/**
* Iterate through names of available protocols.
*
* @param opaque A private pointer representing current protocol.
* It must be a pointer to NULL on first iteration and will
* be updated by successive calls to avio_enum_protocols.
* @param output If set to 1, iterate over output protocols,
* otherwise over input protocols.
*
* @return A static string containing the name of current protocol or NULL
*/
const char *avio_enum_protocols(void **opaque, int output);

/**
* Pause and resume playing - only meaningful if using a network streaming
* protocol (e.g. MMS).
*
* @param h IO context from which to call the read_pause function pointer
* @param pause 1 for pause, 0 for resume
*/
int avio_pause(AVIOContext *h, int pause);

/**
* Seek to a given timestamp relative to some component stream.
* Only meaningful if using a network streaming protocol (e.g. MMS.).
*
* @param h IO context from which to call the seek function pointers
* @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.
* @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 if used and not supported.
* @return >= 0 on success
* @see AVInputFormat::read_seek
*/
int64_t avio_seek_time(AVIOContext *h, int stream_index,
                       int64_t timestamp, int flags);

#endif /* AVFORMAT_AVIO_H */
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