aviobuf.c
Go to the documentation of this file.
1 /*
2  * buffered I/O
3  * Copyright (c) 2000,2001 Fabrice Bellard
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * Libav is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/crc.h"
23 #include "libavutil/dict.h"
24 #include "libavutil/intreadwrite.h"
25 #include "libavutil/log.h"
26 #include "libavutil/opt.h"
27 #include "avformat.h"
28 #include "avio.h"
29 #include "avio_internal.h"
30 #include "internal.h"
31 #include "url.h"
32 #include <stdarg.h>
33 
34 #define IO_BUFFER_SIZE 32768
35 
41 #define SHORT_SEEK_THRESHOLD 4096
42 
43 static void *ffio_url_child_next(void *obj, void *prev)
44 {
45  AVIOContext *s = obj;
46  return prev ? NULL : s->opaque;
47 }
48 
49 static const AVClass *ffio_url_child_class_next(const AVClass *prev)
50 {
51  return prev ? NULL : &ffurl_context_class;
52 }
53 
54 static const AVOption ffio_url_options[] = {
55  { NULL },
56 };
57 
59  .class_name = "AVIOContext",
60  .item_name = av_default_item_name,
61  .version = LIBAVUTIL_VERSION_INT,
62  .option = ffio_url_options,
63  .child_next = ffio_url_child_next,
64  .child_class_next = ffio_url_child_class_next,
65 };
66 
67 static void fill_buffer(AVIOContext *s);
68 static int url_resetbuf(AVIOContext *s, int flags);
69 
71  unsigned char *buffer,
72  int buffer_size,
73  int write_flag,
74  void *opaque,
75  int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
76  int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
77  int64_t (*seek)(void *opaque, int64_t offset, int whence))
78 {
79  s->buffer = buffer;
80  s->buffer_size = buffer_size;
81  s->buf_ptr = buffer;
82  s->opaque = opaque;
83 
84  url_resetbuf(s, write_flag ? AVIO_FLAG_WRITE : AVIO_FLAG_READ);
85 
88  s->seek = seek;
89  s->pos = 0;
90  s->must_flush = 0;
91  s->eof_reached = 0;
92  s->error = 0;
94  s->max_packet_size = 0;
95  s->update_checksum = NULL;
96 
97  if (!read_packet && !write_flag) {
98  s->pos = buffer_size;
99  s->buf_end = s->buffer + buffer_size;
100  }
101  s->read_pause = NULL;
102  s->read_seek = NULL;
103 
104  return 0;
105 }
106 
108  unsigned char *buffer,
109  int buffer_size,
110  int write_flag,
111  void *opaque,
112  int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
113  int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
114  int64_t (*seek)(void *opaque, int64_t offset, int whence))
115 {
116  AVIOContext *s = av_mallocz(sizeof(AVIOContext));
117  if (!s)
118  return NULL;
119  ffio_init_context(s, buffer, buffer_size, write_flag, opaque,
120  read_packet, write_packet, seek);
121  return s;
122 }
123 
124 static void flush_buffer(AVIOContext *s)
125 {
126  if (s->buf_ptr > s->buffer) {
127  if (s->write_packet && !s->error) {
128  int ret = s->write_packet(s->opaque, s->buffer,
129  s->buf_ptr - s->buffer);
130  if (ret < 0) {
131  s->error = ret;
132  }
133  }
134  if (s->update_checksum) {
136  s->buf_ptr - s->checksum_ptr);
137  s->checksum_ptr = s->buffer;
138  }
139  s->pos += s->buf_ptr - s->buffer;
140  }
141  s->buf_ptr = s->buffer;
142 }
143 
144 void avio_w8(AVIOContext *s, int b)
145 {
146  *s->buf_ptr++ = b;
147  if (s->buf_ptr >= s->buf_end)
148  flush_buffer(s);
149 }
150 
151 void ffio_fill(AVIOContext *s, int b, int count)
152 {
153  while (count > 0) {
154  int len = FFMIN(s->buf_end - s->buf_ptr, count);
155  memset(s->buf_ptr, b, len);
156  s->buf_ptr += len;
157 
158  if (s->buf_ptr >= s->buf_end)
159  flush_buffer(s);
160 
161  count -= len;
162  }
163 }
164 
165 void avio_write(AVIOContext *s, const unsigned char *buf, int size)
166 {
167  while (size > 0) {
168  int len = FFMIN(s->buf_end - s->buf_ptr, size);
169  memcpy(s->buf_ptr, buf, len);
170  s->buf_ptr += len;
171 
172  if (s->buf_ptr >= s->buf_end)
173  flush_buffer(s);
174 
175  buf += len;
176  size -= len;
177  }
178 }
179 
181 {
182  flush_buffer(s);
183  s->must_flush = 0;
184 }
185 
186 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
187 {
188  int64_t offset1;
189  int64_t pos;
190  int force = whence & AVSEEK_FORCE;
191  whence &= ~AVSEEK_FORCE;
192 
193  if(!s)
194  return AVERROR(EINVAL);
195 
196  pos = s->pos - (s->write_flag ? 0 : (s->buf_end - s->buffer));
197 
198  if (whence != SEEK_CUR && whence != SEEK_SET)
199  return AVERROR(EINVAL);
200 
201  if (whence == SEEK_CUR) {
202  offset1 = pos + (s->buf_ptr - s->buffer);
203  if (offset == 0)
204  return offset1;
205  offset += offset1;
206  }
207  offset1 = offset - pos;
208  if (!s->must_flush &&
209  offset1 >= 0 && offset1 <= (s->buf_end - s->buffer)) {
210  /* can do the seek inside the buffer */
211  s->buf_ptr = s->buffer + offset1;
212  } else if ((!s->seekable ||
213  offset1 <= s->buf_end + SHORT_SEEK_THRESHOLD - s->buffer) &&
214  !s->write_flag && offset1 >= 0 &&
215  (whence != SEEK_END || force)) {
216  while(s->pos < offset && !s->eof_reached)
217  fill_buffer(s);
218  if (s->eof_reached)
219  return AVERROR_EOF;
220  s->buf_ptr = s->buf_end + offset - s->pos;
221  } else {
222  int64_t res;
223 
224  if (s->write_flag) {
225  flush_buffer(s);
226  s->must_flush = 1;
227  }
228  if (!s->seek)
229  return AVERROR(EPIPE);
230  if ((res = s->seek(s->opaque, offset, SEEK_SET)) < 0)
231  return res;
232  if (!s->write_flag)
233  s->buf_end = s->buffer;
234  s->buf_ptr = s->buffer;
235  s->pos = offset;
236  }
237  s->eof_reached = 0;
238  return offset;
239 }
240 
242 {
243  int64_t size;
244 
245  if (!s)
246  return AVERROR(EINVAL);
247 
248  if (!s->seek)
249  return AVERROR(ENOSYS);
250  size = s->seek(s->opaque, 0, AVSEEK_SIZE);
251  if (size < 0) {
252  if ((size = s->seek(s->opaque, -1, SEEK_END)) < 0)
253  return size;
254  size++;
255  s->seek(s->opaque, s->pos, SEEK_SET);
256  }
257  return size;
258 }
259 
260 void avio_wl32(AVIOContext *s, unsigned int val)
261 {
262  avio_w8(s, val);
263  avio_w8(s, val >> 8);
264  avio_w8(s, val >> 16);
265  avio_w8(s, val >> 24);
266 }
267 
268 void avio_wb32(AVIOContext *s, unsigned int val)
269 {
270  avio_w8(s, val >> 24);
271  avio_w8(s, val >> 16);
272  avio_w8(s, val >> 8);
273  avio_w8(s, val);
274 }
275 
276 int avio_put_str(AVIOContext *s, const char *str)
277 {
278  int len = 1;
279  if (str) {
280  len += strlen(str);
281  avio_write(s, (const unsigned char *) str, len);
282  } else
283  avio_w8(s, 0);
284  return len;
285 }
286 
287 int avio_put_str16le(AVIOContext *s, const char *str)
288 {
289  const uint8_t *q = str;
290  int ret = 0;
291 
292  while (*q) {
293  uint32_t ch;
294  uint16_t tmp;
295 
296  GET_UTF8(ch, *q++, break;)
297  PUT_UTF16(ch, tmp, avio_wl16(s, tmp); ret += 2;)
298  }
299  avio_wl16(s, 0);
300  ret += 2;
301  return ret;
302 }
303 
304 int ff_get_v_length(uint64_t val)
305 {
306  int i = 1;
307 
308  while (val >>= 7)
309  i++;
310 
311  return i;
312 }
313 
314 void ff_put_v(AVIOContext *bc, uint64_t val)
315 {
316  int i = ff_get_v_length(val);
317 
318  while (--i > 0)
319  avio_w8(bc, 128 | (val >> (7 * i)));
320 
321  avio_w8(bc, val & 127);
322 }
323 
324 void avio_wl64(AVIOContext *s, uint64_t val)
325 {
326  avio_wl32(s, (uint32_t)(val & 0xffffffff));
327  avio_wl32(s, (uint32_t)(val >> 32));
328 }
329 
330 void avio_wb64(AVIOContext *s, uint64_t val)
331 {
332  avio_wb32(s, (uint32_t)(val >> 32));
333  avio_wb32(s, (uint32_t)(val & 0xffffffff));
334 }
335 
336 void avio_wl16(AVIOContext *s, unsigned int val)
337 {
338  avio_w8(s, val);
339  avio_w8(s, val >> 8);
340 }
341 
342 void avio_wb16(AVIOContext *s, unsigned int val)
343 {
344  avio_w8(s, val >> 8);
345  avio_w8(s, val);
346 }
347 
348 void avio_wl24(AVIOContext *s, unsigned int val)
349 {
350  avio_wl16(s, val & 0xffff);
351  avio_w8(s, val >> 16);
352 }
353 
354 void avio_wb24(AVIOContext *s, unsigned int val)
355 {
356  avio_wb16(s, val >> 8);
357  avio_w8(s, val);
358 }
359 
360 /* Input stream */
361 
362 static void fill_buffer(AVIOContext *s)
363 {
364  uint8_t *dst = !s->max_packet_size &&
365  s->buf_end - s->buffer < s->buffer_size ?
366  s->buf_end : s->buffer;
367  int len = s->buffer_size - (dst - s->buffer);
368  int max_buffer_size = s->max_packet_size ?
370 
371  /* can't fill the buffer without read_packet, just set EOF if appropriate */
372  if (!s->read_packet && s->buf_ptr >= s->buf_end)
373  s->eof_reached = 1;
374 
375  /* no need to do anything if EOF already reached */
376  if (s->eof_reached)
377  return;
378 
379  if (s->update_checksum && dst == s->buffer) {
380  if (s->buf_end > s->checksum_ptr)
382  s->buf_end - s->checksum_ptr);
383  s->checksum_ptr = s->buffer;
384  }
385 
386  /* make buffer smaller in case it ended up large after probing */
387  if (s->buffer_size > max_buffer_size) {
388  ffio_set_buf_size(s, max_buffer_size);
389 
390  s->checksum_ptr = dst = s->buffer;
391  len = s->buffer_size;
392  }
393 
394  if (s->read_packet)
395  len = s->read_packet(s->opaque, dst, len);
396  else
397  len = 0;
398  if (len <= 0) {
399  /* do not modify buffer if EOF reached so that a seek back can
400  be done without rereading data */
401  s->eof_reached = 1;
402  if (len < 0)
403  s->error = len;
404  } else {
405  s->pos += len;
406  s->buf_ptr = dst;
407  s->buf_end = dst + len;
408  }
409 }
410 
411 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
412  unsigned int len)
413 {
414  return av_crc(av_crc_get_table(AV_CRC_32_IEEE), checksum, buf, len);
415 }
416 
418 {
420  s->buf_ptr - s->checksum_ptr);
421  s->update_checksum = NULL;
422  return s->checksum;
423 }
424 
426  unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
427  unsigned long checksum)
428 {
429  s->update_checksum = update_checksum;
430  if (s->update_checksum) {
431  s->checksum = checksum;
432  s->checksum_ptr = s->buf_ptr;
433  }
434 }
435 
436 /* XXX: put an inline version */
438 {
439  if (s->buf_ptr >= s->buf_end)
440  fill_buffer(s);
441  if (s->buf_ptr < s->buf_end)
442  return *s->buf_ptr++;
443  return 0;
444 }
445 
446 int avio_read(AVIOContext *s, unsigned char *buf, int size)
447 {
448  int len, size1;
449 
450  size1 = size;
451  while (size > 0) {
452  len = s->buf_end - s->buf_ptr;
453  if (len > size)
454  len = size;
455  if (len == 0 || s->write_flag) {
456  if(size > s->buffer_size && !s->update_checksum){
457  if(s->read_packet)
458  len = s->read_packet(s->opaque, buf, size);
459  if (len <= 0) {
460  /* do not modify buffer if EOF reached so that a seek back can
461  be done without rereading data */
462  s->eof_reached = 1;
463  if(len<0)
464  s->error= len;
465  break;
466  } else {
467  s->pos += len;
468  size -= len;
469  buf += len;
470  s->buf_ptr = s->buffer;
471  s->buf_end = s->buffer/* + len*/;
472  }
473  } else {
474  fill_buffer(s);
475  len = s->buf_end - s->buf_ptr;
476  if (len == 0)
477  break;
478  }
479  } else {
480  memcpy(buf, s->buf_ptr, len);
481  buf += len;
482  s->buf_ptr += len;
483  size -= len;
484  }
485  }
486  if (size1 == size) {
487  if (s->error) return s->error;
488  if (s->eof_reached) return AVERROR_EOF;
489  }
490  return size1 - size;
491 }
492 
493 int ffio_read_indirect(AVIOContext *s, unsigned char *buf, int size, const unsigned char **data)
494 {
495  if (s->buf_end - s->buf_ptr >= size && !s->write_flag) {
496  *data = s->buf_ptr;
497  s->buf_ptr += size;
498  return size;
499  } else {
500  *data = buf;
501  return avio_read(s, buf, size);
502  }
503 }
504 
505 int ffio_read_partial(AVIOContext *s, unsigned char *buf, int size)
506 {
507  int len;
508 
509  if (size < 0)
510  return -1;
511 
512  if (s->read_packet && s->write_flag) {
513  len = s->read_packet(s->opaque, buf, size);
514  if (len > 0)
515  s->pos += len;
516  return len;
517  }
518 
519  len = s->buf_end - s->buf_ptr;
520  if (len == 0) {
521  /* Reset the buf_end pointer to the start of the buffer, to make sure
522  * the fill_buffer call tries to read as much data as fits into the
523  * full buffer, instead of just what space is left after buf_end.
524  * This avoids returning partial packets at the end of the buffer,
525  * for packet based inputs.
526  */
527  s->buf_end = s->buf_ptr = s->buffer;
528  fill_buffer(s);
529  len = s->buf_end - s->buf_ptr;
530  }
531  if (len > size)
532  len = size;
533  memcpy(buf, s->buf_ptr, len);
534  s->buf_ptr += len;
535  if (!len) {
536  if (s->error) return s->error;
537  if (s->eof_reached) return AVERROR_EOF;
538  }
539  return len;
540 }
541 
542 unsigned int avio_rl16(AVIOContext *s)
543 {
544  unsigned int val;
545  val = avio_r8(s);
546  val |= avio_r8(s) << 8;
547  return val;
548 }
549 
550 unsigned int avio_rl24(AVIOContext *s)
551 {
552  unsigned int val;
553  val = avio_rl16(s);
554  val |= avio_r8(s) << 16;
555  return val;
556 }
557 
558 unsigned int avio_rl32(AVIOContext *s)
559 {
560  unsigned int val;
561  val = avio_rl16(s);
562  val |= avio_rl16(s) << 16;
563  return val;
564 }
565 
566 uint64_t avio_rl64(AVIOContext *s)
567 {
568  uint64_t val;
569  val = (uint64_t)avio_rl32(s);
570  val |= (uint64_t)avio_rl32(s) << 32;
571  return val;
572 }
573 
574 unsigned int avio_rb16(AVIOContext *s)
575 {
576  unsigned int val;
577  val = avio_r8(s) << 8;
578  val |= avio_r8(s);
579  return val;
580 }
581 
582 unsigned int avio_rb24(AVIOContext *s)
583 {
584  unsigned int val;
585  val = avio_rb16(s) << 8;
586  val |= avio_r8(s);
587  return val;
588 }
589 unsigned int avio_rb32(AVIOContext *s)
590 {
591  unsigned int val;
592  val = avio_rb16(s) << 16;
593  val |= avio_rb16(s);
594  return val;
595 }
596 
597 int ff_get_line(AVIOContext *s, char *buf, int maxlen)
598 {
599  int i = 0;
600  char c;
601 
602  do {
603  c = avio_r8(s);
604  if (c && i < maxlen-1)
605  buf[i++] = c;
606  } while (c != '\n' && c);
607 
608  buf[i] = 0;
609  return i;
610 }
611 
612 int avio_get_str(AVIOContext *s, int maxlen, char *buf, int buflen)
613 {
614  int i;
615 
616  if (buflen <= 0)
617  return AVERROR(EINVAL);
618  // reserve 1 byte for terminating 0
619  buflen = FFMIN(buflen - 1, maxlen);
620  for (i = 0; i < buflen; i++)
621  if (!(buf[i] = avio_r8(s)))
622  return i + 1;
623  buf[i] = 0;
624  for (; i < maxlen; i++)
625  if (!avio_r8(s))
626  return i + 1;
627  return maxlen;
628 }
629 
630 #define GET_STR16(type, read) \
631  int avio_get_str16 ##type(AVIOContext *pb, int maxlen, char *buf, int buflen)\
632 {\
633  char* q = buf;\
634  int ret = 0;\
635  if (buflen <= 0) \
636  return AVERROR(EINVAL); \
637  while (ret + 1 < maxlen) {\
638  uint8_t tmp;\
639  uint32_t ch;\
640  GET_UTF16(ch, (ret += 2) <= maxlen ? read(pb) : 0, break;)\
641  if (!ch)\
642  break;\
643  PUT_UTF8(ch, tmp, if (q - buf < buflen - 1) *q++ = tmp;)\
644  }\
645  *q = 0;\
646  return ret;\
647 }\
648 
650 GET_STR16(be, avio_rb16)
651 
652 #undef GET_STR16
653 
654 uint64_t avio_rb64(AVIOContext *s)
655 {
656  uint64_t val;
657  val = (uint64_t)avio_rb32(s) << 32;
658  val |= (uint64_t)avio_rb32(s);
659  return val;
660 }
661 
663  uint64_t val = 0;
664  int tmp;
665 
666  do{
667  tmp = avio_r8(bc);
668  val= (val<<7) + (tmp&127);
669  }while(tmp&128);
670  return val;
671 }
672 
674 {
675  uint8_t *buffer;
676  int buffer_size, max_packet_size;
677 
678  max_packet_size = h->max_packet_size;
679  if (max_packet_size) {
680  buffer_size = max_packet_size; /* no need to bufferize more than one packet */
681  } else {
682  buffer_size = IO_BUFFER_SIZE;
683  }
684  buffer = av_malloc(buffer_size);
685  if (!buffer)
686  return AVERROR(ENOMEM);
687 
688  *s = avio_alloc_context(buffer, buffer_size, h->flags & AVIO_FLAG_WRITE, h,
690  if (!*s) {
691  av_free(buffer);
692  return AVERROR(ENOMEM);
693  }
694  (*s)->seekable = h->is_streamed ? 0 : AVIO_SEEKABLE_NORMAL;
695  (*s)->max_packet_size = max_packet_size;
696  if(h->prot) {
697  (*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
698  (*s)->read_seek = (int64_t (*)(void *, int, int64_t, int))h->prot->url_read_seek;
699  }
700  (*s)->av_class = &ffio_url_class;
701  return 0;
702 }
703 
704 int ffio_set_buf_size(AVIOContext *s, int buf_size)
705 {
706  uint8_t *buffer;
707  buffer = av_malloc(buf_size);
708  if (!buffer)
709  return AVERROR(ENOMEM);
710 
711  av_free(s->buffer);
712  s->buffer = buffer;
713  s->buffer_size = buf_size;
714  s->buf_ptr = buffer;
716  return 0;
717 }
718 
719 static int url_resetbuf(AVIOContext *s, int flags)
720 {
721  assert(flags == AVIO_FLAG_WRITE || flags == AVIO_FLAG_READ);
722 
723  if (flags & AVIO_FLAG_WRITE) {
724  s->buf_end = s->buffer + s->buffer_size;
725  s->write_flag = 1;
726  } else {
727  s->buf_end = s->buffer;
728  s->write_flag = 0;
729  }
730  return 0;
731 }
732 
733 int ffio_rewind_with_probe_data(AVIOContext *s, unsigned char *buf, int buf_size)
734 {
735  int64_t buffer_start;
736  int buffer_size;
737  int overlap, new_size, alloc_size;
738 
739  if (s->write_flag)
740  return AVERROR(EINVAL);
741 
742  buffer_size = s->buf_end - s->buffer;
743 
744  /* the buffers must touch or overlap */
745  if ((buffer_start = s->pos - buffer_size) > buf_size)
746  return AVERROR(EINVAL);
747 
748  overlap = buf_size - buffer_start;
749  new_size = buf_size + buffer_size - overlap;
750 
751  alloc_size = FFMAX(s->buffer_size, new_size);
752  if (alloc_size > buf_size)
753  if (!(buf = av_realloc(buf, alloc_size)))
754  return AVERROR(ENOMEM);
755 
756  if (new_size > buf_size) {
757  memcpy(buf + buf_size, s->buffer + overlap, buffer_size - overlap);
758  buf_size = new_size;
759  }
760 
761  av_free(s->buffer);
762  s->buf_ptr = s->buffer = buf;
763  s->buffer_size = alloc_size;
764  s->pos = buf_size;
765  s->buf_end = s->buf_ptr + buf_size;
766  s->eof_reached = 0;
767  s->must_flush = 0;
768 
769  return 0;
770 }
771 
772 int avio_open(AVIOContext **s, const char *filename, int flags)
773 {
774  return avio_open2(s, filename, flags, NULL, NULL);
775 }
776 
777 int avio_open2(AVIOContext **s, const char *filename, int flags,
779 {
780  URLContext *h;
781  int err;
782 
783  err = ffurl_open(&h, filename, flags, int_cb, options);
784  if (err < 0)
785  return err;
786  err = ffio_fdopen(s, h);
787  if (err < 0) {
788  ffurl_close(h);
789  return err;
790  }
791  return 0;
792 }
793 
795 {
796  URLContext *h;
797 
798  if (!s)
799  return 0;
800 
801  avio_flush(s);
802  h = s->opaque;
803  av_freep(&s->buffer);
804  av_free(s);
805  return ffurl_close(h);
806 }
807 
809 {
810  int ret = avio_close(*s);
811  *s = NULL;
812  return ret;
813 }
814 
815 int avio_printf(AVIOContext *s, const char *fmt, ...)
816 {
817  va_list ap;
818  char buf[4096];
819  int ret;
820 
821  va_start(ap, fmt);
822  ret = vsnprintf(buf, sizeof(buf), fmt, ap);
823  va_end(ap);
824  avio_write(s, buf, strlen(buf));
825  return ret;
826 }
827 
828 int avio_pause(AVIOContext *s, int pause)
829 {
830  if (!s->read_pause)
831  return AVERROR(ENOSYS);
832  return s->read_pause(s->opaque, pause);
833 }
834 
835 int64_t avio_seek_time(AVIOContext *s, int stream_index,
836  int64_t timestamp, int flags)
837 {
838  URLContext *h = s->opaque;
839  int64_t ret;
840  if (!s->read_seek)
841  return AVERROR(ENOSYS);
842  ret = s->read_seek(h, stream_index, timestamp, flags);
843  if (ret >= 0) {
844  int64_t pos;
845  s->buf_ptr = s->buf_end; // Flush buffer
846  pos = s->seek(h, 0, SEEK_CUR);
847  if (pos >= 0)
848  s->pos = pos;
849  else if (pos != AVERROR(ENOSYS))
850  ret = pos;
851  }
852  return ret;
853 }
854 
855 /* output in a dynamic buffer */
856 
857 typedef struct DynBuffer {
862 } DynBuffer;
863 
864 static int dyn_buf_write(void *opaque, uint8_t *buf, int buf_size)
865 {
866  DynBuffer *d = opaque;
867  unsigned new_size, new_allocated_size;
868 
869  /* reallocate buffer if needed */
870  new_size = d->pos + buf_size;
871  new_allocated_size = d->allocated_size;
872  if (new_size < d->pos || new_size > INT_MAX/2)
873  return -1;
874  while (new_size > new_allocated_size) {
875  if (!new_allocated_size)
876  new_allocated_size = new_size;
877  else
878  new_allocated_size += new_allocated_size / 2 + 1;
879  }
880 
881  if (new_allocated_size > d->allocated_size) {
882  d->buffer = av_realloc(d->buffer, new_allocated_size);
883  if(d->buffer == NULL)
884  return AVERROR(ENOMEM);
885  d->allocated_size = new_allocated_size;
886  }
887  memcpy(d->buffer + d->pos, buf, buf_size);
888  d->pos = new_size;
889  if (d->pos > d->size)
890  d->size = d->pos;
891  return buf_size;
892 }
893 
894 static int dyn_packet_buf_write(void *opaque, uint8_t *buf, int buf_size)
895 {
896  unsigned char buf1[4];
897  int ret;
898 
899  /* packetized write: output the header */
900  AV_WB32(buf1, buf_size);
901  ret = dyn_buf_write(opaque, buf1, 4);
902  if (ret < 0)
903  return ret;
904 
905  /* then the data */
906  return dyn_buf_write(opaque, buf, buf_size);
907 }
908 
909 static int64_t dyn_buf_seek(void *opaque, int64_t offset, int whence)
910 {
911  DynBuffer *d = opaque;
912 
913  if (whence == SEEK_CUR)
914  offset += d->pos;
915  else if (whence == SEEK_END)
916  offset += d->size;
917  if (offset < 0 || offset > 0x7fffffffLL)
918  return -1;
919  d->pos = offset;
920  return 0;
921 }
922 
923 static int url_open_dyn_buf_internal(AVIOContext **s, int max_packet_size)
924 {
925  DynBuffer *d;
926  unsigned io_buffer_size = max_packet_size ? max_packet_size : 1024;
927 
928  if (sizeof(DynBuffer) + io_buffer_size < io_buffer_size)
929  return -1;
930  d = av_mallocz(sizeof(DynBuffer) + io_buffer_size);
931  if (!d)
932  return AVERROR(ENOMEM);
933  d->io_buffer_size = io_buffer_size;
934  *s = avio_alloc_context(d->io_buffer, d->io_buffer_size, 1, d, NULL,
935  max_packet_size ? dyn_packet_buf_write : dyn_buf_write,
936  max_packet_size ? NULL : dyn_buf_seek);
937  if(!*s) {
938  av_free(d);
939  return AVERROR(ENOMEM);
940  }
941  (*s)->max_packet_size = max_packet_size;
942  return 0;
943 }
944 
946 {
947  return url_open_dyn_buf_internal(s, 0);
948 }
949 
950 int ffio_open_dyn_packet_buf(AVIOContext **s, int max_packet_size)
951 {
952  if (max_packet_size <= 0)
953  return -1;
954  return url_open_dyn_buf_internal(s, max_packet_size);
955 }
956 
958 {
959  DynBuffer *d = s->opaque;
960  int size;
961  static const char padbuf[FF_INPUT_BUFFER_PADDING_SIZE] = {0};
962  int padding = 0;
963 
964  /* don't attempt to pad fixed-size packet buffers */
965  if (!s->max_packet_size) {
966  avio_write(s, padbuf, sizeof(padbuf));
968  }
969 
970  avio_flush(s);
971 
972  *pbuffer = d->buffer;
973  size = d->size;
974  av_free(d);
975  av_free(s);
976  return size - padding;
977 }