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da74a74061
Previously ffio_ensure_seekback never flushed the buffer, so successive ffio_ensure_seekback calls were all respected. This could eventually cause unlimited memory and CPU usage if a demuxer called ffio_ensure_seekback on all it's read data. Most demuxers however only rely on being able to seek back till the position of the last ffio_ensure_seekback call, therefore we change the semantics of ffio_ensure_seekback so that a new call can invalidate seek guarantees of the old. In order to support some level of "nested" ffio_ensure_seekback calls, we document that the function only invalidates the old window (and potentially discards the already read data from the IO buffer), if the newly requested window does not fit into the old one. This way we limit the memory usage for ffio_ensure_seekback calls requesting consecutive data windows. Signed-off-by: Marton Balint <cus@passwd.hu>
191 lines
6.7 KiB
C
191 lines
6.7 KiB
C
/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVFORMAT_AVIO_INTERNAL_H
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#define AVFORMAT_AVIO_INTERNAL_H
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#include "avio.h"
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#include "url.h"
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#include "libavutil/log.h"
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extern const AVClass ff_avio_class;
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int ffio_init_context(AVIOContext *s,
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unsigned char *buffer,
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int buffer_size,
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int write_flag,
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void *opaque,
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int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
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int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
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int64_t (*seek)(void *opaque, int64_t offset, int whence));
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/**
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* Read size bytes from AVIOContext, returning a pointer.
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* Note that the data pointed at by the returned pointer is only
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* valid until the next call that references the same IO context.
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* @param s IO context
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* @param buf pointer to buffer into which to assemble the requested
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* data if it is not available in contiguous addresses in the
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* underlying buffer
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* @param size number of bytes requested
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* @param data address at which to store pointer: this will be a
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* a direct pointer into the underlying buffer if the requested
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* number of bytes are available at contiguous addresses, otherwise
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* will be a copy of buf
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* @return number of bytes read or AVERROR
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*/
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int ffio_read_indirect(AVIOContext *s, unsigned char *buf, int size, const unsigned char **data);
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void ffio_fill(AVIOContext *s, int b, int count);
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static av_always_inline void ffio_wfourcc(AVIOContext *pb, const uint8_t *s)
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{
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avio_wl32(pb, MKTAG(s[0], s[1], s[2], s[3]));
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}
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/**
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* Rewind the AVIOContext using the specified buffer containing the first buf_size bytes of the file.
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* Used after probing to avoid seeking.
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* Joins buf and s->buffer, taking any overlap into consideration.
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* @note s->buffer must overlap with buf or they can't be joined and the function fails
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*
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* @param s The read-only AVIOContext to rewind
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* @param buf The probe buffer containing the first buf_size bytes of the file
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* @param buf_size The size of buf
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* @return >= 0 in case of success, a negative value corresponding to an
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* AVERROR code in case of failure
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*/
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int ffio_rewind_with_probe_data(AVIOContext *s, unsigned char **buf, int buf_size);
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uint64_t ffio_read_varlen(AVIOContext *bc);
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/**
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* Read size bytes from AVIOContext into buf.
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* Check that exactly size bytes have been read.
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* @return number of bytes read or AVERROR
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*/
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int ffio_read_size(AVIOContext *s, unsigned char *buf, int size);
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/** @warning must be called before any I/O */
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int ffio_set_buf_size(AVIOContext *s, int buf_size);
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/**
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* Reallocate a given buffer for AVIOContext.
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*
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* @param s the AVIOContext to realloc.
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* @param buf_size required new buffer size.
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* @return 0 on success, a negative AVERROR on failure.
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*/
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int ffio_realloc_buf(AVIOContext *s, int buf_size);
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/**
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* Ensures that the requested seekback buffer size will be available
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*
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* Will ensure that when reading sequentially up to buf_size, seeking
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* within the current pos and pos+buf_size is possible.
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* Once the stream position moves outside this window or another
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* ffio_ensure_seekback call requests a buffer outside this window this
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* guarantee is lost.
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*/
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int ffio_ensure_seekback(AVIOContext *s, int64_t buf_size);
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int ffio_limit(AVIOContext *s, int size);
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void ffio_init_checksum(AVIOContext *s,
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unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
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unsigned long checksum);
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unsigned long ffio_get_checksum(AVIOContext *s);
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unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
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unsigned int len);
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unsigned long ff_crcEDB88320_update(unsigned long checksum, const uint8_t *buf,
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unsigned int len);
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unsigned long ff_crcA001_update(unsigned long checksum, const uint8_t *buf,
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unsigned int len);
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/**
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* Open a write only packetized memory stream with a maximum packet
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* size of 'max_packet_size'. The stream is stored in a memory buffer
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* with a big-endian 4 byte header giving the packet size in bytes.
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*
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* @param s new IO context
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* @param max_packet_size maximum packet size (must be > 0)
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* @return zero if no error.
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*/
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int ffio_open_dyn_packet_buf(AVIOContext **s, int max_packet_size);
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/**
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* Create and initialize a AVIOContext for accessing the
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* resource referenced by the URLContext h.
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* @note When the URLContext h has been opened in read+write mode, the
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* AVIOContext can be used only for writing.
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*
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* @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.
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* @return >= 0 in case of success, a negative value corresponding to an
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* AVERROR code in case of failure
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*/
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int ffio_fdopen(AVIOContext **s, URLContext *h);
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/**
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* Return the URLContext associated with the AVIOContext
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*
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* @param s IO context
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* @return pointer to URLContext or NULL.
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*/
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URLContext *ffio_geturlcontext(AVIOContext *s);
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/**
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* Open a write-only fake memory stream. The written data is not stored
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* anywhere - this is only used for measuring the amount of data
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* written.
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*
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* @param s new IO context
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* @return zero if no error.
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*/
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int ffio_open_null_buf(AVIOContext **s);
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int ffio_open_whitelist(AVIOContext **s, const char *url, int flags,
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const AVIOInterruptCB *int_cb, AVDictionary **options,
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const char *whitelist, const char *blacklist);
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/**
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* Close a null buffer.
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*
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* @param s an IO context opened by ffio_open_null_buf
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* @return the number of bytes written to the null buffer
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*/
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int ffio_close_null_buf(AVIOContext *s);
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/**
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* Reset a dynamic buffer.
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*
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* Resets everything, but keeps the allocated buffer for later use.
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*/
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void ffio_reset_dyn_buf(AVIOContext *s);
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/**
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* Free a dynamic buffer.
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*
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* @param s a pointer to an IO context opened by avio_open_dyn_buf()
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*/
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void ffio_free_dyn_buf(AVIOContext **s);
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#endif /* AVFORMAT_AVIO_INTERNAL_H */
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