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FFmpeg/libavformat/avio_internal.h
Michael Niedermayer d5ec8ba7f2 Do not leave positive values undefined when negative are defined as error
Define positive return values as non errors and leave further meaning undefined
This allows future extensions to use these values

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
2013-10-19 16:42:57 +02:00

152 lines
5.4 KiB
C

/*
*
* 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_INTERNAL_H
#define AVFORMAT_AVIO_INTERNAL_H
#include "avio.h"
#include "url.h"
#include "libavutil/log.h"
extern const AVClass ffio_url_class;
int ffio_init_context(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));
/**
* Read size bytes from AVIOContext, returning a pointer.
* Note that the data pointed at by the returned pointer is only
* valid until the next call that references the same IO context.
* @param s IO context
* @param buf pointer to buffer into which to assemble the requested
* data if it is not available in contiguous addresses in the
* underlying buffer
* @param size number of bytes requested
* @param data address at which to store pointer: this will be a
* a direct pointer into the underlying buffer if the requested
* number of bytes are available at contiguous addresses, otherwise
* will be a copy of buf
* @return number of bytes read or AVERROR
*/
int ffio_read_indirect(AVIOContext *s, unsigned char *buf, int size, const unsigned char **data);
/**
* Read size bytes from AVIOContext into buf.
* This reads at most 1 packet. If that is not enough fewer bytes will be
* returned.
* @return number of bytes read or AVERROR
*/
int ffio_read_partial(AVIOContext *s, unsigned char *buf, int size);
void ffio_fill(AVIOContext *s, int b, int count);
static av_always_inline void ffio_wfourcc(AVIOContext *pb, const uint8_t *s)
{
avio_wl32(pb, MKTAG(s[0], s[1], s[2], s[3]));
}
/**
* 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
*
* @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 ffio_rewind_with_probe_data(AVIOContext *s, unsigned char **buf, int buf_size);
uint64_t ffio_read_varlen(AVIOContext *bc);
/** @warning must be called before any I/O */
int ffio_set_buf_size(AVIOContext *s, int buf_size);
/**
* Ensures that the requested seekback buffer size will be available
*
* Will ensure that when reading sequentially up to buf_size, seeking
* within the current pos and pos+buf_size is possible.
* Once the stream position moves outside this window this gurantee is lost.
*/
int ffio_ensure_seekback(AVIOContext *s, int buf_size);
int ffio_limit(AVIOContext *s, int size);
void ffio_init_checksum(AVIOContext *s,
unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
unsigned long checksum);
unsigned long ffio_get_checksum(AVIOContext *s);
unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
unsigned int len);
/**
* 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 ffio_open_dyn_packet_buf(AVIOContext **s, int max_packet_size);
/**
* Create and initialize a AVIOContext for accessing the
* 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.
* 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 ffio_fdopen(AVIOContext **s, URLContext *h);
/**
* Open a write-only fake memory stream. The written data is not stored
* anywhere - this is only used for measuring the amount of data
* written.
*
* @param s new IO context
* @return zero if no error.
*/
int ffio_open_null_buf(AVIOContext **s);
/**
* Close a null buffer.
*
* @param s an IO context opened by ffio_open_null_buf
* @return the number of bytes written to the null buffer
*/
int ffio_close_null_buf(AVIOContext *s);
#endif /* AVFORMAT_AVIO_INTERNAL_H */