libavformat/aviobuf.c

   1 /*
   2  * Buffered I/O for ffmpeg system
   3  * Copyright (c) 2000,2001 Fabrice Bellard
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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/intreadwrite.h"
  24 #include "avformat.h"
  25 #include "avio.h"
  26 #include <stdarg.h>
  27
  28 #define IO_BUFFER_SIZE 32768
  29
  30 static void fill_buffer(ByteIOContext *s);
  31
  32 int init_put_byte(ByteIOContext *s,
  33                   unsigned char *buffer,
  34                   int buffer_size,
  35                   int write_flag,
  36                   void *opaque,
  37                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
  38                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
  39                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
  40 {
  41     s->buffer = buffer;
  42     s->buffer_size = buffer_size;
  43     s->buf_ptr = buffer;
  44     s->opaque = opaque;
  45     url_resetbuf(s, write_flag ? URL_WRONLY : URL_RDONLY);
  46     s->write_packet = write_packet;
  47     s->read_packet = read_packet;
  48     s->seek = seek;
  49     s->pos = 0;
  50     s->must_flush = 0;
  51     s->eof_reached = 0;
  52     s->error = 0;
  53     s->is_streamed = 0;
  54     s->max_packet_size = 0;
  55     s->update_checksum= NULL;
  56     if(!read_packet && !write_flag){
  57         s->pos = buffer_size;
  58         s->buf_end = s->buffer + buffer_size;
  59     }
  60     s->read_pause = NULL;
  61     s->read_seek  = NULL;
  62     return 0;
  63 }
  64
  65 ByteIOContext *av_alloc_put_byte(
  66                   unsigned char *buffer,
  67                   int buffer_size,
  68                   int write_flag,
  69                   void *opaque,
  70                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
  71                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
  72                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
  73 {
  74     ByteIOContext *s = av_mallocz(sizeof(ByteIOContext));
  75     init_put_byte(s, buffer, buffer_size, write_flag, opaque,
  76                   read_packet, write_packet, seek);
  77     return s;
  78 }
  79
  80 static void flush_buffer(ByteIOContext *s)
  81 {
  82     if (s->buf_ptr > s->buffer) {
  83         if (s->write_packet && !s->error){
  84             int ret= s->write_packet(s->opaque, s->buffer, s->buf_ptr - s->buffer);
  85             if(ret < 0){
  86                 s->error = ret;
  87             }
  88         }
  89         if(s->update_checksum){
  90             s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_ptr - s->checksum_ptr);
  91             s->checksum_ptr= s->buffer;
  92         }
  93         s->pos += s->buf_ptr - s->buffer;
  94     }
  95     s->buf_ptr = s->buffer;
  96 }
  97
  98 void put_byte(ByteIOContext *s, int b)
  99 {
 100     *(s->buf_ptr)++ = b;
 101     if (s->buf_ptr >= s->buf_end)
 102         flush_buffer(s);
 103 }
 104
 105 void put_buffer(ByteIOContext *s, const unsigned char *buf, int size)
 106 {
 107     int len;
 108
 109     while (size > 0) {
 110         len = (s->buf_end - s->buf_ptr);
 111         if (len > size)
 112             len = size;
 113         memcpy(s->buf_ptr, buf, len);
 114         s->buf_ptr += len;
 115
 116         if (s->buf_ptr >= s->buf_end)
 117             flush_buffer(s);
 118
 119         buf += len;
 120         size -= len;
 121     }
 122 }
 123
 124 void put_flush_packet(ByteIOContext *s)
 125 {
 126     flush_buffer(s);
 127     s->must_flush = 0;
 128 }
 129
 130 int64_t url_fseek(ByteIOContext *s, int64_t offset, int whence)
 131 {
 132     int64_t offset1;
 133     int64_t pos;
 134
 135     if(!s)
 136         return AVERROR(EINVAL);
 137
 138     pos = s->pos - (s->write_flag ? 0 : (s->buf_end - s->buffer));
 139
 140     if (whence != SEEK_CUR && whence != SEEK_SET)
 141         return AVERROR(EINVAL);
 142
 143     if (whence == SEEK_CUR) {
 144         offset1 = pos + (s->buf_ptr - s->buffer);
 145         if (offset == 0)
 146             return offset1;
 147         offset += offset1;
 148     }
 149     offset1 = offset - pos;
 150     if (!s->must_flush &&
 151         offset1 >= 0 && offset1 < (s->buf_end - s->buffer)) {
 152         /* can do the seek inside the buffer */
 153         s->buf_ptr = s->buffer + offset1;
 154     } else if(s->is_streamed && !s->write_flag &&
 155               offset1 >= 0 && offset1 < (s->buf_end - s->buffer) + (1<<16)){
 156         while(s->pos < offset && !s->eof_reached)
 157             fill_buffer(s);
 158         if (s->eof_reached)
 159             return AVERROR(EPIPE);
 160         s->buf_ptr = s->buf_end + offset - s->pos;
 161     } else {
 162         int64_t res = AVERROR(EPIPE);
 163
 164 #if CONFIG_MUXERS || CONFIG_NETWORK
 165         if (s->write_flag) {
 166             flush_buffer(s);
 167             s->must_flush = 1;
 168         }
 169 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */
 170         if (!s->seek || (res = s->seek(s->opaque, offset, SEEK_SET)) < 0)
 171             return res;
 172         if (!s->write_flag)
 173             s->buf_end = s->buffer;
 174         s->buf_ptr = s->buffer;
 175         s->pos = offset;
 176     }
 177     s->eof_reached = 0;
 178     return offset;
 179 }
 180
 181 void url_fskip(ByteIOContext *s, int64_t offset)
 182 {
 183     url_fseek(s, offset, SEEK_CUR);
 184 }
 185
 186 int64_t url_ftell(ByteIOContext *s)
 187 {
 188     return url_fseek(s, 0, SEEK_CUR);
 189 }
 190
 191 int64_t url_fsize(ByteIOContext *s)
 192 {
 193     int64_t size;
 194
 195     if(!s)
 196         return AVERROR(EINVAL);
 197
 198     if (!s->seek)
 199         return AVERROR(EPIPE);
 200     size = s->seek(s->opaque, 0, AVSEEK_SIZE);
 201     if(size<0){
 202         if ((size = s->seek(s->opaque, -1, SEEK_END)) < 0)
 203             return size;
 204         size++;
 205         s->seek(s->opaque, s->pos, SEEK_SET);
 206     }
 207     return size;
 208 }
 209
 210 int url_feof(ByteIOContext *s)
 211 {
 212     if(!s)
 213         return 0;
 214     return s->eof_reached;
 215 }
 216
 217 int url_ferror(ByteIOContext *s)
 218 {
 219     if(!s)
 220         return 0;
 221     return s->error;
 222 }
 223
 224 void put_le32(ByteIOContext *s, unsigned int val)
 225 {
 226     put_byte(s, val);
 227     put_byte(s, val >> 8);
 228     put_byte(s, val >> 16);
 229     put_byte(s, val >> 24);
 230 }
 231
 232 void put_be32(ByteIOContext *s, unsigned int val)
 233 {
 234     put_byte(s, val >> 24);
 235     put_byte(s, val >> 16);
 236     put_byte(s, val >> 8);
 237     put_byte(s, val);
 238 }
 239
 240 void put_strz(ByteIOContext *s, const char *str)
 241 {
 242     if (str)
 243         put_buffer(s, (const unsigned char *) str, strlen(str) + 1);
 244     else
 245         put_byte(s, 0);
 246 }
 247
 248 void put_le64(ByteIOContext *s, uint64_t val)
 249 {
 250     put_le32(s, (uint32_t)(val & 0xffffffff));
 251     put_le32(s, (uint32_t)(val >> 32));
 252 }
 253
 254 void put_be64(ByteIOContext *s, uint64_t val)
 255 {
 256     put_be32(s, (uint32_t)(val >> 32));
 257     put_be32(s, (uint32_t)(val & 0xffffffff));
 258 }
 259
 260 void put_le16(ByteIOContext *s, unsigned int val)
 261 {
 262     put_byte(s, val);
 263     put_byte(s, val >> 8);
 264 }
 265
 266 void put_be16(ByteIOContext *s, unsigned int val)
 267 {
 268     put_byte(s, val >> 8);
 269     put_byte(s, val);
 270 }
 271
 272 void put_le24(ByteIOContext *s, unsigned int val)
 273 {
 274     put_le16(s, val & 0xffff);
 275     put_byte(s, val >> 16);
 276 }
 277
 278 void put_be24(ByteIOContext *s, unsigned int val)
 279 {
 280     put_be16(s, val >> 8);
 281     put_byte(s, val);
 282 }
 283
 284 void put_tag(ByteIOContext *s, const char *tag)
 285 {
 286     while (*tag) {
 287         put_byte(s, *tag++);
 288     }
 289 }
 290
 291 /* Input stream */
 292
 293 static void fill_buffer(ByteIOContext *s)
 294 {
 295     uint8_t *dst= !s->max_packet_size && s->buf_end - s->buffer < s->buffer_size ? s->buf_ptr : s->buffer;
 296     int len= s->buffer_size - (dst - s->buffer);
 297
 298     assert(s->buf_ptr == s->buf_end);
 299
 300     /* no need to do anything if EOF already reached */
 301     if (s->eof_reached)
 302         return;
 303
 304     if(s->update_checksum && dst == s->buffer){
 305         if(s->buf_end > s->checksum_ptr)
 306             s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_end - s->checksum_ptr);
 307         s->checksum_ptr= s->buffer;
 308     }
 309
 310     if(s->read_packet)
 311         len = s->read_packet(s->opaque, dst, len);
 312     else
 313         len = 0;
 314     if (len <= 0) {
 315         /* do not modify buffer if EOF reached so that a seek back can
 316            be done without rereading data */
 317         s->eof_reached = 1;
 318         if(len<0)
 319             s->error= len;
 320     } else {
 321         s->pos += len;
 322         s->buf_ptr = dst;
 323         s->buf_end = dst + len;
 324     }
 325 }
 326
 327 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
 328                                     unsigned int len)
 329 {
 330     return av_crc(av_crc_get_table(AV_CRC_32_IEEE), checksum, buf, len);
 331 }
 332
 333 unsigned long get_checksum(ByteIOContext *s)
 334 {
 335     s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_ptr - s->checksum_ptr);
 336     s->update_checksum= NULL;
 337     return s->checksum;
 338 }
 339
 340 void init_checksum(ByteIOContext *s,
 341                    unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
 342                    unsigned long checksum)
 343 {
 344     s->update_checksum= update_checksum;
 345     if(s->update_checksum){
 346         s->checksum= checksum;
 347         s->checksum_ptr= s->buf_ptr;
 348     }
 349 }
 350
 351 /* XXX: put an inline version */
 352 int get_byte(ByteIOContext *s)
 353 {
 354     if (s->buf_ptr < s->buf_end) {
 355         return *s->buf_ptr++;
 356     } else {
 357         fill_buffer(s);
 358         if (s->buf_ptr < s->buf_end)
 359             return *s->buf_ptr++;
 360         else
 361             return 0;
 362     }
 363 }
 364
 365 int url_fgetc(ByteIOContext *s)
 366 {
 367     if (s->buf_ptr < s->buf_end) {
 368         return *s->buf_ptr++;
 369     } else {
 370         fill_buffer(s);
 371         if (s->buf_ptr < s->buf_end)
 372             return *s->buf_ptr++;
 373         else
 374             return URL_EOF;
 375     }
 376 }
 377
 378 int get_buffer(ByteIOContext *s, unsigned char *buf, int size)
 379 {
 380     int len, size1;
 381
 382     size1 = size;
 383     while (size > 0) {
 384         len = s->buf_end - s->buf_ptr;
 385         if (len > size)
 386             len = size;
 387         if (len == 0) {
 388             if(size > s->buffer_size && !s->update_checksum){
 389                 if(s->read_packet)
 390                     len = s->read_packet(s->opaque, buf, size);
 391                 if (len <= 0) {
 392                     /* do not modify buffer if EOF reached so that a seek back can
 393                     be done without rereading data */
 394                     s->eof_reached = 1;
 395                     if(len<0)
 396                         s->error= len;
 397                     break;
 398                 } else {
 399                     s->pos += len;
 400                     size -= len;
 401                     buf += len;
 402                     s->buf_ptr = s->buffer;
 403                     s->buf_end = s->buffer/* + len*/;
 404                 }
 405             }else{
 406                 fill_buffer(s);
 407                 len = s->buf_end - s->buf_ptr;
 408                 if (len == 0)
 409                     break;
 410             }
 411         } else {
 412             memcpy(buf, s->buf_ptr, len);
 413             buf += len;
 414             s->buf_ptr += len;
 415             size -= len;
 416         }
 417     }
 418     return size1 - size;
 419 }
 420
 421 int get_partial_buffer(ByteIOContext *s, unsigned char *buf, int size)
 422 {
 423     int len;
 424
 425     if(size<0)
 426         return -1;
 427
 428     len = s->buf_end - s->buf_ptr;
 429     if (len == 0) {
 430         fill_buffer(s);
 431         len = s->buf_end - s->buf_ptr;
 432     }
 433     if (len > size)
 434         len = size;
 435     memcpy(buf, s->buf_ptr, len);
 436     s->buf_ptr += len;
 437     return len;
 438 }
 439
 440 unsigned int get_le16(ByteIOContext *s)
 441 {
 442     unsigned int val;
 443     val = get_byte(s);
 444     val |= get_byte(s) << 8;
 445     return val;
 446 }
 447
 448 unsigned int get_le24(ByteIOContext *s)
 449 {
 450     unsigned int val;
 451     val = get_le16(s);
 452     val |= get_byte(s) << 16;
 453     return val;
 454 }
 455
 456 unsigned int get_le32(ByteIOContext *s)
 457 {
 458     unsigned int val;
 459     val = get_le16(s);
 460     val |= get_le16(s) << 16;
 461     return val;
 462 }
 463
 464 uint64_t get_le64(ByteIOContext *s)
 465 {
 466     uint64_t val;
 467     val = (uint64_t)get_le32(s);
 468     val |= (uint64_t)get_le32(s) << 32;
 469     return val;
 470 }
 471
 472 unsigned int get_be16(ByteIOContext *s)
 473 {
 474     unsigned int val;
 475     val = get_byte(s) << 8;
 476     val |= get_byte(s);
 477     return val;
 478 }
 479
 480 unsigned int get_be24(ByteIOContext *s)
 481 {
 482     unsigned int val;
 483     val = get_be16(s) << 8;
 484     val |= get_byte(s);
 485     return val;
 486 }
 487 unsigned int get_be32(ByteIOContext *s)
 488 {
 489     unsigned int val;
 490     val = get_be16(s) << 16;
 491     val |= get_be16(s);
 492     return val;
 493 }
 494
 495 char *get_strz(ByteIOContext *s, char *buf, int maxlen)
 496 {
 497     int i = 0;
 498     char c;
 499
 500     while ((c = get_byte(s))) {
 501         if (i < maxlen-1)
 502             buf[i++] = c;
 503     }
 504
 505     buf[i] = 0; /* Ensure null terminated, but may be truncated */
 506
 507     return buf;
 508 }
 509
 510 uint64_t get_be64(ByteIOContext *s)
 511 {
 512     uint64_t val;
 513     val = (uint64_t)get_be32(s) << 32;
 514     val |= (uint64_t)get_be32(s);
 515     return val;
 516 }
 517
 518 uint64_t ff_get_v(ByteIOContext *bc){
 519     uint64_t val = 0;
 520     int tmp;
 521
 522     do{
 523         tmp = get_byte(bc);
 524         val= (val<<7) + (tmp&127);
 525     }while(tmp&128);
 526     return val;
 527 }
 528
 529 int url_fdopen(ByteIOContext **s, URLContext *h)
 530 {
 531     uint8_t *buffer;
 532     int buffer_size, max_packet_size;
 533
 534
 535     max_packet_size = url_get_max_packet_size(h);
 536     if (max_packet_size) {
 537         buffer_size = max_packet_size; /* no need to bufferize more than one packet */
 538     } else {
 539         buffer_size = IO_BUFFER_SIZE;
 540     }
 541     buffer = av_malloc(buffer_size);
 542     if (!buffer)
 543         return AVERROR(ENOMEM);
 544
 545     *s = av_mallocz(sizeof(ByteIOContext));
 546     if(!*s) {
 547         av_free(buffer);
 548         return AVERROR(ENOMEM);
 549     }
 550
 551     if (init_put_byte(*s, buffer, buffer_size,
 552                       (h->flags & URL_WRONLY || h->flags & URL_RDWR), h,
 553                       url_read, url_write, url_seek) < 0) {
 554         av_free(buffer);
 555         av_freep(s);
 556         return AVERROR(EIO);
 557     }
 558     (*s)->is_streamed = h->is_streamed;
 559     (*s)->max_packet_size = max_packet_size;
 560     if(h->prot) {
 561         (*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
 562         (*s)->read_seek  = (int64_t (*)(void *, int, int64_t, int))h->prot->url_read_seek;
 563     }
 564     return 0;
 565 }
 566
 567 int url_setbufsize(ByteIOContext *s, int buf_size)
 568 {
 569     uint8_t *buffer;
 570     buffer = av_malloc(buf_size);
 571     if (!buffer)
 572         return AVERROR(ENOMEM);
 573
 574     av_free(s->buffer);
 575     s->buffer = buffer;
 576     s->buffer_size = buf_size;
 577     s->buf_ptr = buffer;
 578     url_resetbuf(s, s->write_flag ? URL_WRONLY : URL_RDONLY);
 579     return 0;
 580 }
 581
 582 int url_resetbuf(ByteIOContext *s, int flags)
 583 {
 584     URLContext *h = s->opaque;
 585     if ((flags & URL_RDWR) || (h && h->flags != flags && !h->flags & URL_RDWR))
 586         return AVERROR(EINVAL);
 587
 588     if (flags & URL_WRONLY) {
 589         s->buf_end = s->buffer + s->buffer_size;
 590         s->write_flag = 1;
 591     } else {
 592         s->buf_end = s->buffer;
 593         s->write_flag = 0;
 594     }
 595     return 0;
 596 }
 597
 598 int url_fopen(ByteIOContext **s, const char *filename, int flags)
 599 {
 600     URLContext *h;
 601     int err;
 602
 603     err = url_open(&h, filename, flags);
 604     if (err < 0)
 605         return err;
 606     err = url_fdopen(s, h);
 607     if (err < 0) {
 608         url_close(h);
 609         return err;
 610     }
 611     return 0;
 612 }
 613
 614 int url_fclose(ByteIOContext *s)
 615 {
 616     URLContext *h = s->opaque;
 617
 618     av_free(s->buffer);
 619     av_free(s);
 620     return url_close(h);
 621 }
 622
 623 URLContext *url_fileno(ByteIOContext *s)
 624 {
 625     return s->opaque;
 626 }
 627
 628 #if CONFIG_MUXERS
 629 int url_fprintf(ByteIOContext *s, const char *fmt, ...)
 630 {
 631     va_list ap;
 632     char buf[4096];
 633     int ret;
 634
 635     va_start(ap, fmt);
 636     ret = vsnprintf(buf, sizeof(buf), fmt, ap);
 637     va_end(ap);
 638     put_buffer(s, buf, strlen(buf));
 639     return ret;
 640 }
 641 #endif //CONFIG_MUXERS
 642
 643 char *url_fgets(ByteIOContext *s, char *buf, int buf_size)
 644 {
 645     int c;
 646     char *q;
 647
 648     c = url_fgetc(s);
 649     if (c == EOF)
 650         return NULL;
 651     q = buf;
 652     for(;;) {
 653         if (c == EOF || c == '\n')
 654             break;
 655         if ((q - buf) < buf_size - 1)
 656             *q++ = c;
 657         c = url_fgetc(s);
 658     }
 659     if (buf_size > 0)
 660         *q = '\0';
 661     return buf;
 662 }
 663
 664 int url_fget_max_packet_size(ByteIOContext *s)
 665 {
 666     return s->max_packet_size;
 667 }
 668
 669 int av_url_read_fpause(ByteIOContext *s, int pause)
 670 {
 671     if (!s->read_pause)
 672         return AVERROR(ENOSYS);
 673     return s->read_pause(s->opaque, pause);
 674 }
 675
 676 int64_t av_url_read_fseek(ByteIOContext *s, int stream_index,
 677                           int64_t timestamp, int flags)
 678 {
 679     URLContext *h = s->opaque;
 680     int64_t ret;
 681     if (!s->read_seek)
 682         return AVERROR(ENOSYS);
 683     ret = s->read_seek(h, stream_index, timestamp, flags);
 684     if(ret >= 0) {
 685         s->buf_ptr = s->buf_end; // Flush buffer
 686         s->pos = s->seek(h, 0, SEEK_CUR);
 687     }
 688     return ret;
 689 }
 690
 691 /* url_open_dyn_buf and url_close_dyn_buf are used in rtp.c to send a response
 692  * back to the server even if CONFIG_MUXERS is false. */
 693 #if CONFIG_MUXERS || CONFIG_NETWORK
 694 /* buffer handling */
 695 int url_open_buf(ByteIOContext **s, uint8_t *buf, int buf_size, int flags)
 696 {
 697     int ret;
 698     *s = av_mallocz(sizeof(ByteIOContext));
 699     if(!*s)
 700         return AVERROR(ENOMEM);
 701     ret = init_put_byte(*s, buf, buf_size,
 702                         (flags & URL_WRONLY || flags & URL_RDWR),
 703                         NULL, NULL, NULL, NULL);
 704     if(ret != 0)
 705         av_freep(s);
 706     return ret;
 707 }
 708
 709 int url_close_buf(ByteIOContext *s)
 710 {
 711     put_flush_packet(s);
 712     return s->buf_ptr - s->buffer;
 713 }
 714
 715 /* output in a dynamic buffer */
 716
 717 typedef struct DynBuffer {
 718     int pos, size, allocated_size;
 719     uint8_t *buffer;
 720     int io_buffer_size;
 721     uint8_t io_buffer[1];
 722 } DynBuffer;
 723
 724 static int dyn_buf_write(void *opaque, uint8_t *buf, int buf_size)
 725 {
 726     DynBuffer *d = opaque;
 727     unsigned new_size, new_allocated_size;
 728
 729     /* reallocate buffer if needed */
 730     new_size = d->pos + buf_size;
 731     new_allocated_size = d->allocated_size;
 732     if(new_size < d->pos || new_size > INT_MAX/2)
 733         return -1;
 734     while (new_size > new_allocated_size) {
 735         if (!new_allocated_size)
 736             new_allocated_size = new_size;
 737         else
 738             new_allocated_size += new_allocated_size / 2 + 1;
 739     }
 740
 741     if (new_allocated_size > d->allocated_size) {
 742         d->buffer = av_realloc(d->buffer, new_allocated_size);
 743         if(d->buffer == NULL)
 744              return AVERROR(ENOMEM);
 745         d->allocated_size = new_allocated_size;
 746     }
 747     memcpy(d->buffer + d->pos, buf, buf_size);
 748     d->pos = new_size;
 749     if (d->pos > d->size)
 750         d->size = d->pos;
 751     return buf_size;
 752 }
 753
 754 static int dyn_packet_buf_write(void *opaque, uint8_t *buf, int buf_size)
 755 {
 756     unsigned char buf1[4];
 757     int ret;
 758
 759     /* packetized write: output the header */
 760     AV_WB32(buf1, buf_size);
 761     ret= dyn_buf_write(opaque, buf1, 4);
 762     if(ret < 0)
 763         return ret;
 764
 765     /* then the data */
 766     return dyn_buf_write(opaque, buf, buf_size);
 767 }
 768
 769 static int64_t dyn_buf_seek(void *opaque, int64_t offset, int whence)
 770 {
 771     DynBuffer *d = opaque;
 772
 773     if (whence == SEEK_CUR)
 774         offset += d->pos;
 775     else if (whence == SEEK_END)
 776         offset += d->size;
 777     if (offset < 0 || offset > 0x7fffffffLL)
 778         return -1;
 779     d->pos = offset;
 780     return 0;
 781 }
 782
 783 static int url_open_dyn_buf_internal(ByteIOContext **s, int max_packet_size)
 784 {
 785     DynBuffer *d;
 786     int ret;
 787     unsigned io_buffer_size = max_packet_size ? max_packet_size : 1024;
 788
 789     if(sizeof(DynBuffer) + io_buffer_size < io_buffer_size)
 790         return -1;
 791     d = av_mallocz(sizeof(DynBuffer) + io_buffer_size);
 792     if (!d)
 793         return AVERROR(ENOMEM);
 794     *s = av_mallocz(sizeof(ByteIOContext));
 795     if(!*s) {
 796         av_free(d);
 797         return AVERROR(ENOMEM);
 798     }
 799     d->io_buffer_size = io_buffer_size;
 800     ret = init_put_byte(*s, d->io_buffer, io_buffer_size,
 801                         1, d, NULL,
 802                         max_packet_size ? dyn_packet_buf_write : dyn_buf_write,
 803                         max_packet_size ? NULL : dyn_buf_seek);
 804     if (ret == 0) {
 805         (*s)->max_packet_size = max_packet_size;
 806     } else {
 807         av_free(d);
 808         av_freep(s);
 809     }
 810     return ret;
 811 }
 812
 813 int url_open_dyn_buf(ByteIOContext **s)
 814 {
 815     return url_open_dyn_buf_internal(s, 0);
 816 }
 817
 818 int url_open_dyn_packet_buf(ByteIOContext **s, int max_packet_size)
 819 {
 820     if (max_packet_size <= 0)
 821         return -1;
 822     return url_open_dyn_buf_internal(s, max_packet_size);
 823 }
 824
 825 int url_close_dyn_buf(ByteIOContext *s, uint8_t **pbuffer)
 826 {
 827     DynBuffer *d = s->opaque;
 828     int size;
 829
 830     put_flush_packet(s);
 831
 832     *pbuffer = d->buffer;
 833     size = d->size;
 834     av_free(d);
 835     av_free(s);
 836     return size;
 837 }
 838 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */