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1/*
2 * copyright (c) 2001 Fabrice Bellard
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20#ifndef AVFORMAT_AVIO_H
21#define AVFORMAT_AVIO_H
22
23/**
24 * @file
25 * @ingroup lavf_io
26 * Buffered I/O operations
27 */
28
29#include <stdint.h>
30
31#include "libavutil/common.h"
32#include "libavutil/dict.h"
33#include "libavutil/log.h"
34
35#include "libavformat/version.h"
36
37
38#define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */
39
40/**
41 * Callback for checking whether to abort blocking functions.
42 * AVERROR_EXIT is returned in this case by the interrupted
43 * function. During blocking operations, callback is called with
44 * opaque as parameter. If the callback returns 1, the
45 * blocking operation will be aborted.
46 *
47 * No members can be added to this struct without a major bump, if
48 * new elements have been added after this struct in AVFormatContext
49 * or AVIOContext.
50 */
51typedef struct AVIOInterruptCB {
52 int (*callback)(void*);
53 void *opaque;
54} AVIOInterruptCB;
55
56/**
57 * Bytestream IO Context.
58 * New fields can be added to the end with minor version bumps.
59 * Removal, reordering and changes to existing fields require a major
60 * version bump.
61 * sizeof(AVIOContext) must not be used outside libav*.
62 *
63 * @note None of the function pointers in AVIOContext should be called
64 * directly, they should only be set by the client application
65 * when implementing custom I/O. Normally these are set to the
66 * function pointers specified in avio_alloc_context()
67 */
68typedef struct AVIOContext {
69 /**
70 * A class for private options.
71 *
72 * If this AVIOContext is created by avio_open2(), av_class is set and
73 * passes the options down to protocols.
74 *
75 * If this AVIOContext is manually allocated, then av_class may be set by
76 * the caller.
77 *
78 * warning -- this field can be NULL, be sure to not pass this AVIOContext
79 * to any av_opt_* functions in that case.
80 */
81 const AVClass *av_class;
82 unsigned char *buffer; /**< Start of the buffer. */
83 int buffer_size; /**< Maximum buffer size */
84 unsigned char *buf_ptr; /**< Current position in the buffer */
85 unsigned char *buf_end; /**< End of the data, may be less than
86 buffer+buffer_size if the read function returned
87 less data than requested, e.g. for streams where
88 no more data has been received yet. */
89 void *opaque; /**< A private pointer, passed to the read/write/seek/...
90 functions. */
91 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
92 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
93 int64_t (*seek)(void *opaque, int64_t offset, int whence);
94 int64_t pos; /**< position in the file of the current buffer */
95 int must_flush; /**< true if the next seek should flush */
96 int eof_reached; /**< true if eof reached */
97 int write_flag; /**< true if open for writing */
98 int max_packet_size;
99 unsigned long checksum;
100 unsigned char *checksum_ptr;
101 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
102 int error; /**< contains the error code or 0 if no error happened */
103 /**
104 * Pause or resume playback for network streaming protocols - e.g. MMS.
105 */
106 int (*read_pause)(void *opaque, int pause);
107 /**
108 * Seek to a given timestamp in stream with the specified stream_index.
109 * Needed for some network streaming protocols which don't support seeking
110 * to byte position.
111 */
112 int64_t (*read_seek)(void *opaque, int stream_index,
113 int64_t timestamp, int flags);
114 /**
115 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
116 */
117 int seekable;
118
119 /**
120 * max filesize, used to limit allocations
121 * This field is internal to libavformat and access from outside is not allowed.
122 */
123 int64_t maxsize;
124
125 /**
126 * avio_read and avio_write should if possible be satisfied directly
127 * instead of going through a buffer, and avio_seek will always
128 * call the underlying seek function directly.
129 */
130 int direct;
131
132 /**
133 * Bytes read statistic
134 * This field is internal to libavformat and access from outside is not allowed.
135 */
136 int64_t bytes_read;
137
138 /**
139 * seek statistic
140 * This field is internal to libavformat and access from outside is not allowed.
141 */
142 int seek_count;
143
144 /**
145 * writeout statistic
146 * This field is internal to libavformat and access from outside is not allowed.
147 */
148 int writeout_count;
149} AVIOContext;
150
151/* unbuffered I/O */
152
153/**
154 * Return AVIO_FLAG_* access flags corresponding to the access permissions
155 * of the resource in url, or a negative value corresponding to an
156 * AVERROR code in case of failure. The returned access flags are
157 * masked by the value in flags.
158 *
159 * @note This function is intrinsically unsafe, in the sense that the
160 * checked resource may change its existence or permission status from
161 * one call to another. Thus you should not trust the returned value,
162 * unless you are sure that no other processes are accessing the
163 * checked resource.
164 */
165int avio_check(const char *url, int flags);
166
167/**
168 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
169 * freed with av_free().
170 *
171 * @param buffer Memory block for input/output operations via AVIOContext.
172 * The buffer must be allocated with av_malloc() and friends.
173 * @param buffer_size The buffer size is very important for performance.
174 * For protocols with fixed blocksize it should be set to this blocksize.
175 * For others a typical size is a cache page, e.g. 4kb.
176 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
177 * @param opaque An opaque pointer to user-specific data.
178 * @param read_packet A function for refilling the buffer, may be NULL.
179 * @param write_packet A function for writing the buffer contents, may be NULL.
180 * The function may not change the input buffers content.
181 * @param seek A function for seeking to specified byte position, may be NULL.
182 *
183 * @return Allocated AVIOContext or NULL on failure.
184 */
185AVIOContext *avio_alloc_context(
186 unsigned char *buffer,
187 int buffer_size,
188 int write_flag,
189 void *opaque,
190 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
191 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
192 int64_t (*seek)(void *opaque, int64_t offset, int whence));
193
194void avio_w8(AVIOContext *s, int b);
195void avio_write(AVIOContext *s, const unsigned char *buf, int size);
196void avio_wl64(AVIOContext *s, uint64_t val);
197void avio_wb64(AVIOContext *s, uint64_t val);
198void avio_wl32(AVIOContext *s, unsigned int val);
199void avio_wb32(AVIOContext *s, unsigned int val);
200void avio_wl24(AVIOContext *s, unsigned int val);
201void avio_wb24(AVIOContext *s, unsigned int val);
202void avio_wl16(AVIOContext *s, unsigned int val);
203void avio_wb16(AVIOContext *s, unsigned int val);
204
205/**
206 * Write a NULL-terminated string.
207 * @return number of bytes written.
208 */
209int avio_put_str(AVIOContext *s, const char *str);
210
211/**
212 * Convert an UTF-8 string to UTF-16LE and write it.
213 * @return number of bytes written.
214 */
215int avio_put_str16le(AVIOContext *s, const char *str);
216
217/**
218 * Passing this as the "whence" parameter to a seek function causes it to
219 * return the filesize without seeking anywhere. Supporting this is optional.
220 * If it is not supported then the seek function will return <0.
221 */
222#define AVSEEK_SIZE 0x10000
223
224/**
225 * Oring this flag as into the "whence" parameter to a seek function causes it to
226 * seek by any means (like reopening and linear reading) or other normally unreasonable
227 * means that can be extremely slow.
228 * This may be ignored by the seek code.
229 */
230#define AVSEEK_FORCE 0x20000
231
232/**
233 * fseek() equivalent for AVIOContext.
234 * @return new position or AVERROR.
235 */
236int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
237
238/**
239 * Skip given number of bytes forward
240 * @return new position or AVERROR.
241 */
242int64_t avio_skip(AVIOContext *s, int64_t offset);
243
244/**
245 * ftell() equivalent for AVIOContext.
246 * @return position or AVERROR.
247 */
248static av_always_inline int64_t avio_tell(AVIOContext *s)
249{
250 return avio_seek(s, 0, SEEK_CUR);
251}
252
253/**
254 * Get the filesize.
255 * @return filesize or AVERROR
256 */
257int64_t avio_size(AVIOContext *s);
258
259/**
260 * feof() equivalent for AVIOContext.
261 * @return non zero if and only if end of file
262 */
263int url_feof(AVIOContext *s);
264
265/** @warning currently size is limited */
266int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
267
268/**
269 * Force flushing of buffered data to the output s.
270 *
271 * Force the buffered data to be immediately written to the output,
272 * without to wait to fill the internal buffer.
273 */
274void avio_flush(AVIOContext *s);
275
276/**
277 * Read size bytes from AVIOContext into buf.
278 * @return number of bytes read or AVERROR
279 */
280int avio_read(AVIOContext *s, unsigned char *buf, int size);
281
282/**
283 * @name Functions for reading from AVIOContext
284 * @{
285 *
286 * @note return 0 if EOF, so you cannot use it if EOF handling is
287 * necessary
288 */
289int avio_r8 (AVIOContext *s);
290unsigned int avio_rl16(AVIOContext *s);
291unsigned int avio_rl24(AVIOContext *s);
292unsigned int avio_rl32(AVIOContext *s);
293uint64_t avio_rl64(AVIOContext *s);
294unsigned int avio_rb16(AVIOContext *s);
295unsigned int avio_rb24(AVIOContext *s);
296unsigned int avio_rb32(AVIOContext *s);
297uint64_t avio_rb64(AVIOContext *s);
298/**
299 * @}
300 */
301
302/**
303 * Read a string from pb into buf. The reading will terminate when either
304 * a NULL character was encountered, maxlen bytes have been read, or nothing
305 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
306 * will be truncated if buf is too small.
307 * Note that the string is not interpreted or validated in any way, it
308 * might get truncated in the middle of a sequence for multi-byte encodings.
309 *
310 * @return number of bytes read (is always <= maxlen).
311 * If reading ends on EOF or error, the return value will be one more than
312 * bytes actually read.
313 */
314int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
315
316/**
317 * Read a UTF-16 string from pb and convert it to UTF-8.
318 * The reading will terminate when either a null or invalid character was
319 * encountered or maxlen bytes have been read.
320 * @return number of bytes read (is always <= maxlen)
321 */
322int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
323int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
324
325
326/**
327 * @name URL open modes
328 * The flags argument to avio_open must be one of the following
329 * constants, optionally ORed with other flags.
330 * @{
331 */
332#define AVIO_FLAG_READ 1 /**< read-only */
333#define AVIO_FLAG_WRITE 2 /**< write-only */
334#define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
335/**
336 * @}
337 */
338
339/**
340 * Use non-blocking mode.
341 * If this flag is set, operations on the context will return
342 * AVERROR(EAGAIN) if they can not be performed immediately.
343 * If this flag is not set, operations on the context will never return
344 * AVERROR(EAGAIN).
345 * Note that this flag does not affect the opening/connecting of the
346 * context. Connecting a protocol will always block if necessary (e.g. on
347 * network protocols) but never hang (e.g. on busy devices).
348 * Warning: non-blocking protocols is work-in-progress; this flag may be
349 * silently ignored.
350 */
351#define AVIO_FLAG_NONBLOCK 8
352
353/**
354 * Use direct mode.
355 * avio_read and avio_write should if possible be satisfied directly
356 * instead of going through a buffer, and avio_seek will always
357 * call the underlying seek function directly.
358 */
359#define AVIO_FLAG_DIRECT 0x8000
360
361/**
362 * Create and initialize a AVIOContext for accessing the
363 * resource indicated by url.
364 * @note When the resource indicated by url has been opened in
365 * read+write mode, the AVIOContext can be used only for writing.
366 *
367 * @param s Used to return the pointer to the created AVIOContext.
368 * In case of failure the pointed to value is set to NULL.
369 * @param flags flags which control how the resource indicated by url
370 * is to be opened
371 * @return >= 0 in case of success, a negative value corresponding to an
372 * AVERROR code in case of failure
373 */
374int avio_open(AVIOContext **s, const char *url, int flags);
375
376/**
377 * Create and initialize a AVIOContext for accessing the
378 * resource indicated by url.
379 * @note When the resource indicated by url has been opened in
380 * read+write mode, the AVIOContext can be used only for writing.
381 *
382 * @param s Used to return the pointer to the created AVIOContext.
383 * In case of failure the pointed to value is set to NULL.
384 * @param flags flags which control how the resource indicated by url
385 * is to be opened
386 * @param int_cb an interrupt callback to be used at the protocols level
387 * @param options A dictionary filled with protocol-private options. On return
388 * this parameter will be destroyed and replaced with a dict containing options
389 * that were not found. May be NULL.
390 * @return >= 0 in case of success, a negative value corresponding to an
391 * AVERROR code in case of failure
392 */
393int avio_open2(AVIOContext **s, const char *url, int flags,
394 const AVIOInterruptCB *int_cb, AVDictionary **options);
395
396/**
397 * Close the resource accessed by the AVIOContext s and free it.
398 * This function can only be used if s was opened by avio_open().
399 *
400 * The internal buffer is automatically flushed before closing the
401 * resource.
402 *
403 * @return 0 on success, an AVERROR < 0 on error.
404 * @see avio_closep
405 */
406int avio_close(AVIOContext *s);
407
408/**
409 * Close the resource accessed by the AVIOContext *s, free it
410 * and set the pointer pointing to it to NULL.
411 * This function can only be used if s was opened by avio_open().
412 *
413 * The internal buffer is automatically flushed before closing the
414 * resource.
415 *
416 * @return 0 on success, an AVERROR < 0 on error.
417 * @see avio_close
418 */
419int avio_closep(AVIOContext **s);
420
421
422/**
423 * Open a write only memory stream.
424 *
425 * @param s new IO context
426 * @return zero if no error.
427 */
428int avio_open_dyn_buf(AVIOContext **s);
429
430/**
431 * Return the written size and a pointer to the buffer. The buffer
432 * must be freed with av_free().
433 * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
434 *
435 * @param s IO context
436 * @param pbuffer pointer to a byte buffer
437 * @return the length of the byte buffer
438 */
439int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
440
441/**
442 * Iterate through names of available protocols.
443 *
444 * @param opaque A private pointer representing current protocol.
445 * It must be a pointer to NULL on first iteration and will
446 * be updated by successive calls to avio_enum_protocols.
447 * @param output If set to 1, iterate over output protocols,
448 * otherwise over input protocols.
449 *
450 * @return A static string containing the name of current protocol or NULL
451 */
452const char *avio_enum_protocols(void **opaque, int output);
453
454/**
455 * Pause and resume playing - only meaningful if using a network streaming
456 * protocol (e.g. MMS).
457 * @param pause 1 for pause, 0 for resume
458 */
459int avio_pause(AVIOContext *h, int pause);
460
461/**
462 * Seek to a given timestamp relative to some component stream.
463 * Only meaningful if using a network streaming protocol (e.g. MMS.).
464 * @param stream_index The stream index that the timestamp is relative to.
465 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
466 * units from the beginning of the presentation.
467 * If a stream_index >= 0 is used and the protocol does not support
468 * seeking based on component streams, the call will fail.
469 * @param timestamp timestamp in AVStream.time_base units
470 * or if there is no stream specified then in AV_TIME_BASE units.
471 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
472 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
473 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
474 * fail if used and not supported.
475 * @return >= 0 on success
476 * @see AVInputFormat::read_seek
477 */
478int64_t avio_seek_time(AVIOContext *h, int stream_index,
479 int64_t timestamp, int flags);
480
481#endif /* AVFORMAT_AVIO_H */
482
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