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avio_internal.h
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1 /*
2  *
3  * This file is part of FFmpeg.
4  *
5  * FFmpeg is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Lesser General Public
7  * License as published by the Free Software Foundation; either
8  * version 2.1 of the License, or (at your option) any later version.
9  *
10  * FFmpeg is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13  * Lesser General Public License for more details.
14  *
15  * You should have received a copy of the GNU Lesser General Public
16  * License along with FFmpeg; if not, write to the Free Software
17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18  */
19 
20 #ifndef AVFORMAT_AVIO_INTERNAL_H
21 #define AVFORMAT_AVIO_INTERNAL_H
22 
23 #include "avio.h"
24 #include "url.h"
25 
26 #include "libavutil/log.h"
27 
28 extern const AVClass ffio_url_class;
29 
31  unsigned char *buffer,
32  int buffer_size,
33  int write_flag,
34  void *opaque,
35  int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
36  int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
37  int64_t (*seek)(void *opaque, int64_t offset, int whence));
38 
39 
40 /**
41  * Read size bytes from AVIOContext into buf.
42  * This reads at most 1 packet. If that is not enough fewer bytes will be
43  * returned.
44  * @return number of bytes read or AVERROR
45  */
46 int ffio_read_partial(AVIOContext *s, unsigned char *buf, int size);
47 
48 void ffio_fill(AVIOContext *s, int b, int count);
49 
51 {
52  avio_wl32(pb, MKTAG(s[0], s[1], s[2], s[3]));
53 }
54 
55 /**
56  * Rewind the AVIOContext using the specified buffer containing the first buf_size bytes of the file.
57  * Used after probing to avoid seeking.
58  * Joins buf and s->buffer, taking any overlap into consideration.
59  * @note s->buffer must overlap with buf or they can't be joined and the function fails
60  *
61  * @param s The read-only AVIOContext to rewind
62  * @param buf The probe buffer containing the first buf_size bytes of the file
63  * @param buf_size The size of buf
64  * @return 0 in case of success, a negative value corresponding to an
65  * AVERROR code in case of failure
66  */
67 int ffio_rewind_with_probe_data(AVIOContext *s, unsigned char **buf, int buf_size);
68 
69 uint64_t ffio_read_varlen(AVIOContext *bc);
70 
71 /** @warning must be called before any I/O */
72 int ffio_set_buf_size(AVIOContext *s, int buf_size);
73 
74 /**
75  * Ensures that the requested seekback buffer size will be available
76  *
77  * Will ensure that when reading sequentially up to buf_size, seeking
78  * within the current pos and pos+buf_size is possible.
79  * Once the stream position moves outside this window this gurantee is lost.
80  */
81 int ffio_ensure_seekback(AVIOContext *s, int buf_size);
82 
83 int ffio_limit(AVIOContext *s, int size);
84 
86  unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
87  unsigned long checksum);
88 unsigned long ffio_get_checksum(AVIOContext *s);
89 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
90  unsigned int len);
91 
92 /**
93  * Open a write only packetized memory stream with a maximum packet
94  * size of 'max_packet_size'. The stream is stored in a memory buffer
95  * with a big-endian 4 byte header giving the packet size in bytes.
96  *
97  * @param s new IO context
98  * @param max_packet_size maximum packet size (must be > 0)
99  * @return zero if no error.
100  */
101 int ffio_open_dyn_packet_buf(AVIOContext **s, int max_packet_size);
102 
103 /**
104  * Create and initialize a AVIOContext for accessing the
105  * resource referenced by the URLContext h.
106  * @note When the URLContext h has been opened in read+write mode, the
107  * AVIOContext can be used only for writing.
108  *
109  * @param s Used to return the pointer to the created AVIOContext.
110  * In case of failure the pointed to value is set to NULL.
111  * @return 0 in case of success, a negative value corresponding to an
112  * AVERROR code in case of failure
113  */
114 int ffio_fdopen(AVIOContext **s, URLContext *h);
115 
116 #endif /* AVFORMAT_AVIO_INTERNAL_H */