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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, returning a pointer.
42  * Note that the data pointed at by the returned pointer is only
43  * valid until the next call that references the same IO context.
44  * @param s IO context
45  * @param buf pointer to buffer into which to assemble the requested
46  * data if it is not available in contiguous addresses in the
47  * underlying buffer
48  * @param size number of bytes requested
49  * @param data address at which to store pointer: this will be a
50  * a direct pointer into the underlying buffer if the requested
51  * number of bytes are available at contiguous addresses, otherwise
52  * will be a copy of buf
53  * @return number of bytes read or AVERROR
54  */
55 int ffio_read_indirect(AVIOContext *s, unsigned char *buf, int size, const unsigned char **data);
56 
57 /**
58  * Read size bytes from AVIOContext into buf.
59  * This reads at most 1 packet. If that is not enough fewer bytes will be
60  * returned.
61  * @return number of bytes read or AVERROR
62  */
63 int ffio_read_partial(AVIOContext *s, unsigned char *buf, int size);
64 
65 void ffio_fill(AVIOContext *s, int b, int count);
66 
68 {
69  avio_wl32(pb, MKTAG(s[0], s[1], s[2], s[3]));
70 }
71 
72 /**
73  * Rewind the AVIOContext using the specified buffer containing the first buf_size bytes of the file.
74  * Used after probing to avoid seeking.
75  * Joins buf and s->buffer, taking any overlap into consideration.
76  * @note s->buffer must overlap with buf or they can't be joined and the function fails
77  *
78  * @param s The read-only AVIOContext to rewind
79  * @param buf The probe buffer containing the first buf_size bytes of the file
80  * @param buf_size The size of buf
81  * @return >= 0 in case of success, a negative value corresponding to an
82  * AVERROR code in case of failure
83  */
84 int ffio_rewind_with_probe_data(AVIOContext *s, unsigned char **buf, int buf_size);
85 
86 uint64_t ffio_read_varlen(AVIOContext *bc);
87 
88 /** @warning must be called before any I/O */
89 int ffio_set_buf_size(AVIOContext *s, int buf_size);
90 
91 /**
92  * Ensures that the requested seekback buffer size will be available
93  *
94  * Will ensure that when reading sequentially up to buf_size, seeking
95  * within the current pos and pos+buf_size is possible.
96  * Once the stream position moves outside this window this guarantee is lost.
97  */
98 int ffio_ensure_seekback(AVIOContext *s, int buf_size);
99 
100 int ffio_limit(AVIOContext *s, int size);
101 
103  unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
104  unsigned long checksum);
105 unsigned long ffio_get_checksum(AVIOContext *s);
106 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
107  unsigned int len);
108 unsigned long ff_crcA001_update(unsigned long checksum, const uint8_t *buf,
109  unsigned int len);
110 
111 /**
112  * Open a write only packetized memory stream with a maximum packet
113  * size of 'max_packet_size'. The stream is stored in a memory buffer
114  * with a big-endian 4 byte header giving the packet size in bytes.
115  *
116  * @param s new IO context
117  * @param max_packet_size maximum packet size (must be > 0)
118  * @return zero if no error.
119  */
120 int ffio_open_dyn_packet_buf(AVIOContext **s, int max_packet_size);
121 
122 /**
123  * Create and initialize a AVIOContext for accessing the
124  * resource referenced by the URLContext h.
125  * @note When the URLContext h has been opened in read+write mode, the
126  * AVIOContext can be used only for writing.
127  *
128  * @param s Used to return the pointer to the created AVIOContext.
129  * In case of failure the pointed to value is set to NULL.
130  * @return >= 0 in case of success, a negative value corresponding to an
131  * AVERROR code in case of failure
132  */
133 int ffio_fdopen(AVIOContext **s, URLContext *h);
134 
135 /**
136  * Open a write-only fake memory stream. The written data is not stored
137  * anywhere - this is only used for measuring the amount of data
138  * written.
139  *
140  * @param s new IO context
141  * @return zero if no error.
142  */
144 
145 /**
146  * Close a null buffer.
147  *
148  * @param s an IO context opened by ffio_open_null_buf
149  * @return the number of bytes written to the null buffer
150  */
152 
153 #endif /* AVFORMAT_AVIO_INTERNAL_H */