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 "avformat.h"
  24 #include "avio.h"
  25 #include <stdarg.h>
  26
  27 #define IO_BUFFER_SIZE 32768
  28
  29 static void fill_buffer(ByteIOContext *s);
  30
  31 int init_put_byte(ByteIOContext *s,
  32                   unsigned char *buffer,
  33                   int buffer_size,
  34                   int write_flag,
  35                   void *opaque,
  36                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
  37                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
  38                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
  39 {
  40     s->buffer = buffer;
  41     s->buffer_size = buffer_size;
  42     s->buf_ptr = buffer;
  43     s->opaque = opaque;
  44     url_resetbuf(s, write_flag ? URL_WRONLY : URL_RDONLY);
  45     s->write_packet = write_packet;
  46     s->read_packet = read_packet;
  47     s->seek = seek;
  48     s->pos = 0;
  49     s->must_flush = 0;
  50     s->eof_reached = 0;
  51     s->error = 0;
  52     s->is_streamed = 0;
  53     s->max_packet_size = 0;
  54     s->update_checksum= NULL;
  55     if(!read_packet && !write_flag){
  56         s->pos = buffer_size;
  57         s->buf_end = s->buffer + buffer_size;
  58     }
  59     s->read_pause = NULL;
  60     s->read_seek  = NULL;
  61     return 0;
  62 }
  63
  64 ByteIOContext *av_alloc_put_byte(
  65                   unsigned char *buffer,
  66                   int buffer_size,
  67                   int write_flag,
  68                   void *opaque,
  69                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
  70                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
  71                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
  72 {
  73     ByteIOContext *s = av_mallocz(sizeof(ByteIOContext));
  74     init_put_byte(s, buffer, buffer_size, write_flag, opaque,
  75                   read_packet, write_packet, seek);
  76     return s;
  77 }
  78
  79 static void flush_buffer(ByteIOContext *s)
  80 {
  81     if (s->buf_ptr > s->buffer) {
  82         if (s->write_packet && !s->error){
  83             int ret= s->write_packet(s->opaque, s->buffer, s->buf_ptr - s->buffer);
  84             if(ret < 0){
  85                 s->error = ret;
  86             }
  87         }
  88         if(s->update_checksum){
  89             s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_ptr - s->checksum_ptr);
  90             s->checksum_ptr= s->buffer;
  91         }
  92         s->pos += s->buf_ptr - s->buffer;
  93     }
  94     s->buf_ptr = s->buffer;
  95 }
  96
  97 void put_byte(ByteIOContext *s, int b)
  98 {
  99     *(s->buf_ptr)++ = b;
 100     if (s->buf_ptr >= s->buf_end)
 101         flush_buffer(s);
 102 }
 103
 104 void put_buffer(ByteIOContext *s, const unsigned char *buf, int size)
 105 {
 106     int len;
 107
 108     while (size > 0) {
 109         len = (s->buf_end - s->buf_ptr);
 110         if (len > size)
 111             len = size;
 112         memcpy(s->buf_ptr, buf, len);
 113         s->buf_ptr += len;
 114
 115         if (s->buf_ptr >= s->buf_end)
 116             flush_buffer(s);
 117
 118         buf += len;
 119         size -= len;
 120     }
 121 }
 122
 123 void put_flush_packet(ByteIOContext *s)
 124 {
 125     flush_buffer(s);
 126     s->must_flush = 0;
 127 }
 128
 129 int64_t url_fseek(ByteIOContext *s, int64_t offset, int whence)
 130 {
 131     int64_t offset1;
 132     int64_t pos;
 133
 134     if(!s)
 135         return AVERROR(EINVAL);
 136
 137     pos = s->pos - (s->write_flag ? 0 : (s->buf_end - s->buffer));
 138
 139     if (whence != SEEK_CUR && whence != SEEK_SET)
 140         return AVERROR(EINVAL);
 141
 142     if (whence == SEEK_CUR) {
 143         offset1 = pos + (s->buf_ptr - s->buffer);
 144         if (offset == 0)
 145             return offset1;
 146         offset += offset1;
 147     }
 148     offset1 = offset - pos;
 149     if (!s->must_flush &&
 150         offset1 >= 0 && offset1 < (s->buf_end - s->buffer)) {
 151         /* can do the seek inside the buffer */
 152         s->buf_ptr = s->buffer + offset1;
 153     } else if(s->is_streamed && !s->write_flag &&
 154               offset1 >= 0 && offset1 < (s->buf_end - s->buffer) + (1<<16)){
 155         while(s->pos < offset && !s->eof_reached)
 156             fill_buffer(s);
 157         if (s->eof_reached)
 158             return AVERROR(EPIPE);
 159         s->buf_ptr = s->buf_end + offset - s->pos;
 160     } else {
 161         int64_t res = AVERROR(EPIPE);
 162
 163 #if CONFIG_MUXERS || CONFIG_NETWORK
 164         if (s->write_flag) {
 165             flush_buffer(s);
 166             s->must_flush = 1;
 167         }
 168 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */
 169         if (!s->seek || (res = s->seek(s->opaque, offset, SEEK_SET)) < 0)
 170             return res;
 171         if (!s->write_flag)
 172             s->buf_end = s->buffer;
 173         s->buf_ptr = s->buffer;
 174         s->pos = offset;
 175     }
 176     s->eof_reached = 0;
 177     return offset;
 178 }
 179
 180 void url_fskip(ByteIOContext *s, int64_t offset)
 181 {
 182     url_fseek(s, offset, SEEK_CUR);
 183 }
 184
 185 int64_t url_ftell(ByteIOContext *s)
 186 {
 187     return url_fseek(s, 0, SEEK_CUR);
 188 }
 189
 190 int64_t url_fsize(ByteIOContext *s)
 191 {
 192     int64_t size;
 193
 194     if(!s)
 195         return AVERROR(EINVAL);
 196
 197     if (!s->seek)
 198         return AVERROR(EPIPE);
 199     size = s->seek(s->opaque, 0, AVSEEK_SIZE);
 200     if(size<0){
 201         if ((size = s->seek(s->opaque, -1, SEEK_END)) < 0)
 202             return size;
 203         size++;
 204         s->seek(s->opaque, s->pos, SEEK_SET);
 205     }
 206     return size;
 207 }
 208
 209 int url_feof(ByteIOContext *s)
 210 {
 211     if(!s)
 212         return 0;
 213     return s->eof_reached;
 214 }
 215
 216 int url_ferror(ByteIOContext *s)
 217 {
 218     if(!s)
 219         return 0;
 220     return s->error;
 221 }
 222
 223 void put_le32(ByteIOContext *s, unsigned int val)
 224 {
 225     put_byte(s, val);
 226     put_byte(s, val >> 8);
 227     put_byte(s, val >> 16);
 228     put_byte(s, val >> 24);
 229 }
 230
 231 void put_be32(ByteIOContext *s, unsigned int val)
 232 {
 233     put_byte(s, val >> 24);
 234     put_byte(s, val >> 16);
 235     put_byte(s, val >> 8);
 236     put_byte(s, val);
 237 }
 238
 239 void put_strz(ByteIOContext *s, const char *str)
 240 {
 241     if (str)
 242         put_buffer(s, (const unsigned char *) str, strlen(str) + 1);
 243     else
 244         put_byte(s, 0);
 245 }
 246
 247 void put_le64(ByteIOContext *s, uint64_t val)
 248 {
 249     put_le32(s, (uint32_t)(val & 0xffffffff));
 250     put_le32(s, (uint32_t)(val >> 32));
 251 }
 252
 253 void put_be64(ByteIOContext *s, uint64_t val)
 254 {
 255     put_be32(s, (uint32_t)(val >> 32));
 256     put_be32(s, (uint32_t)(val & 0xffffffff));
 257 }
 258
 259 void put_le16(ByteIOContext *s, unsigned int val)
 260 {
 261     put_byte(s, val);
 262     put_byte(s, val >> 8);
 263 }
 264
 265 void put_be16(ByteIOContext *s, unsigned int val)
 266 {
 267     put_byte(s, val >> 8);
 268     put_byte(s, val);
 269 }
 270
 271 void put_le24(ByteIOContext *s, unsigned int val)
 272 {
 273     put_le16(s, val & 0xffff);
 274     put_byte(s, val >> 16);
 275 }
 276
 277 void put_be24(ByteIOContext *s, unsigned int val)
 278 {
 279     put_be16(s, val >> 8);
 280     put_byte(s, val);
 281 }
 282
 283 void put_tag(ByteIOContext *s, const char *tag)
 284 {
 285     while (*tag) {
 286         put_byte(s, *tag++);
 287     }
 288 }
 289
 290 /* Input stream */
 291
 292 static void fill_buffer(ByteIOContext *s)
 293 {
 294     uint8_t *dst= !s->max_packet_size && s->buf_end - s->buffer < s->buffer_size ? s->buf_ptr : s->buffer;
 295     int len= s->buffer_size - (dst - s->buffer);
 296
 297     assert(s->buf_ptr == s->buf_end);
 298
 299     /* no need to do anything if EOF already reached */
 300     if (s->eof_reached)
 301         return;
 302
 303     if(s->update_checksum && dst == s->buffer){
 304         if(s->buf_end > s->checksum_ptr)
 305             s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_end - s->checksum_ptr);
 306         s->checksum_ptr= s->buffer;
 307     }
 308
 309     if(s->read_packet)
 310         len = s->read_packet(s->opaque, dst, len);
 311     else
 312         len = 0;
 313     if (len <= 0) {
 314         /* do not modify buffer if EOF reached so that a seek back can
 315            be done without rereading data */
 316         s->eof_reached = 1;
 317         if(len<0)
 318             s->error= len;
 319     } else {
 320         s->pos += len;
 321         s->buf_ptr = dst;
 322         s->buf_end = dst + len;
 323     }
 324 }
 325
 326 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
 327                                     unsigned int len)
 328 {
 329     return av_crc(av_crc_get_table(AV_CRC_32_IEEE), checksum, buf, len);
 330 }
 331
 332 unsigned long get_checksum(ByteIOContext *s)
 333 {
 334     s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_ptr - s->checksum_ptr);
 335     s->update_checksum= NULL;
 336     return s->checksum;
 337 }
 338
 339 void init_checksum(ByteIOContext *s,
 340                    unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
 341                    unsigned long checksum)
 342 {
 343     s->update_checksum= update_checksum;
 344     if(s->update_checksum){
 345         s->checksum= checksum;
 346         s->checksum_ptr= s->buf_ptr;
 347     }
 348 }
 349
 350 /* XXX: put an inline version */
 351 int get_byte(ByteIOContext *s)
 352 {
 353     if (s->buf_ptr < s->buf_end) {
 354         return *s->buf_ptr++;
 355     } else {
 356         fill_buffer(s);
 357         if (s->buf_ptr < s->buf_end)
 358             return *s->buf_ptr++;
 359         else
 360             return 0;
 361     }
 362 }
 363
 364 int url_fgetc(ByteIOContext *s)
 365 {
 366     if (s->buf_ptr < s->buf_end) {
 367         return *s->buf_ptr++;
 368     } else {
 369         fill_buffer(s);
 370         if (s->buf_ptr < s->buf_end)
 371             return *s->buf_ptr++;
 372         else
 373             return URL_EOF;
 374     }
 375 }
 376
 377 int get_buffer(ByteIOContext *s, unsigned char *buf, int size)
 378 {
 379     int len, size1;
 380
 381     size1 = size;
 382     while (size > 0) {
 383         len = s->buf_end - s->buf_ptr;
 384         if (len > size)
 385             len = size;
 386         if (len == 0) {
 387             if(size > s->buffer_size && !s->update_checksum){
 388                 if(s->read_packet)
 389                     len = s->read_packet(s->opaque, buf, size);
 390                 if (len <= 0) {
 391                     /* do not modify buffer if EOF reached so that a seek back can
 392                     be done without rereading data */
 393                     s->eof_reached = 1;
 394                     if(len<0)
 395                         s->error= len;
 396                     break;
 397                 } else {
 398                     s->pos += len;
 399                     size -= len;
 400                     buf += len;
 401                     s->buf_ptr = s->buffer;
 402                     s->buf_end = s->buffer/* + len*/;
 403                 }
 404             }else{
 405                 fill_buffer(s);
 406                 len = s->buf_end - s->buf_ptr;
 407                 if (len == 0)
 408                     break;
 409             }
 410         } else {
 411             memcpy(buf, s->buf_ptr, len);
 412             buf += len;
 413             s->buf_ptr += len;
 414             size -= len;
 415         }
 416     }
 417     return size1 - size;
 418 }
 419
 420 int get_partial_buffer(ByteIOContext *s, unsigned char *buf, int size)
 421 {
 422     int len;
 423
 424     if(size<0)
 425         return -1;
 426
 427     len = s->buf_end - s->buf_ptr;
 428     if (len == 0) {
 429         fill_buffer(s);
 430         len = s->buf_end - s->buf_ptr;
 431     }
 432     if (len > size)
 433         len = size;
 434     memcpy(buf, s->buf_ptr, len);
 435     s->buf_ptr += len;
 436     return len;
 437 }
 438
 439 unsigned int get_le16(ByteIOContext *s)
 440 {
 441     unsigned int val;
 442     val = get_byte(s);
 443     val |= get_byte(s) << 8;
 444     return val;
 445 }
 446
 447 unsigned int get_le24(ByteIOContext *s)
 448 {
 449     unsigned int val;
 450     val = get_le16(s);
 451     val |= get_byte(s) << 16;
 452     return val;
 453 }
 454
 455 unsigned int get_le32(ByteIOContext *s)
 456 {
 457     unsigned int val;
 458     val = get_le16(s);
 459     val |= get_le16(s) << 16;
 460     return val;
 461 }
 462
 463 uint64_t get_le64(ByteIOContext *s)
 464 {
 465     uint64_t val;
 466     val = (uint64_t)get_le32(s);
 467     val |= (uint64_t)get_le32(s) << 32;
 468     return val;
 469 }
 470
 471 unsigned int get_be16(ByteIOContext *s)
 472 {
 473     unsigned int val;
 474     val = get_byte(s) << 8;
 475     val |= get_byte(s);
 476     return val;
 477 }
 478
 479 unsigned int get_be24(ByteIOContext *s)
 480 {
 481     unsigned int val;
 482     val = get_be16(s) << 8;
 483     val |= get_byte(s);
 484     return val;
 485 }
 486 unsigned int get_be32(ByteIOContext *s)
 487 {
 488     unsigned int val;
 489     val = get_be16(s) << 16;
 490     val |= get_be16(s);
 491     return val;
 492 }
 493
 494 char *get_strz(ByteIOContext *s, char *buf, int maxlen)
 495 {
 496     int i = 0;
 497     char c;
 498
 499     while ((c = get_byte(s))) {
 500         if (i < maxlen-1)
 501             buf[i++] = c;
 502     }
 503
 504     buf[i] = 0; /* Ensure null terminated, but may be truncated */
 505
 506     return buf;
 507 }
 508
 509 uint64_t get_be64(ByteIOContext *s)
 510 {
 511     uint64_t val;
 512     val = (uint64_t)get_be32(s) << 32;
 513     val |= (uint64_t)get_be32(s);
 514     return val;
 515 }
 516
 517 uint64_t ff_get_v(ByteIOContext *bc){
 518     uint64_t val = 0;
 519     int tmp;
 520
 521     do{
 522         tmp = get_byte(bc);
 523         val= (val<<7) + (tmp&127);
 524     }while(tmp&128);
 525     return val;
 526 }
 527
 528 int url_fdopen(ByteIOContext **s, URLContext *h)
 529 {
 530     uint8_t *buffer;
 531     int buffer_size, max_packet_size;
 532
 533
 534     max_packet_size = url_get_max_packet_size(h);
 535     if (max_packet_size) {
 536         buffer_size = max_packet_size; /* no need to bufferize more than one packet */
 537     } else {
 538         buffer_size = IO_BUFFER_SIZE;
 539     }
 540     buffer = av_malloc(buffer_size);
 541     if (!buffer)
 542         return AVERROR(ENOMEM);
 543
 544     *s = av_mallocz(sizeof(ByteIOContext));
 545     if(!*s) {
 546         av_free(buffer);
 547         return AVERROR(ENOMEM);
 548     }
 549
 550     if (init_put_byte(*s, buffer, buffer_size,
 551                       (h->flags & URL_WRONLY || h->flags & URL_RDWR), h,
 552                       url_read, url_write, url_seek) < 0) {
 553         av_free(buffer);
 554         av_freep(s);
 555         return AVERROR(EIO);
 556     }
 557     (*s)->is_streamed = h->is_streamed;
 558     (*s)->max_packet_size = max_packet_size;
 559     if(h->prot) {
 560         (*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
 561         (*s)->read_seek  = (int64_t (*)(void *, int, int64_t, int))h->prot->url_read_seek;
 562     }
 563     return 0;
 564 }
 565
 566 int url_setbufsize(ByteIOContext *s, int buf_size)
 567 {
 568     uint8_t *buffer;
 569     buffer = av_malloc(buf_size);
 570     if (!buffer)
 571         return AVERROR(ENOMEM);
 572
 573     av_free(s->buffer);
 574     s->buffer = buffer;
 575     s->buffer_size = buf_size;
 576     s->buf_ptr = buffer;
 577     url_resetbuf(s, s->write_flag ? URL_WRONLY : URL_RDONLY);
 578     return 0;
 579 }
 580
 581 int url_resetbuf(ByteIOContext *s, int flags)
 582 {
 583     URLContext *h = s->opaque;
 584     if ((flags & URL_RDWR) || (h && h->flags != flags && !h->flags & URL_RDWR))
 585         return AVERROR(EINVAL);
 586
 587     if (flags & URL_WRONLY) {
 588         s->buf_end = s->buffer + s->buffer_size;
 589         s->write_flag = 1;
 590     } else {
 591         s->buf_end = s->buffer;
 592         s->write_flag = 0;
 593     }
 594     return 0;
 595 }
 596
 597 int url_fopen(ByteIOContext **s, const char *filename, int flags)
 598 {
 599     URLContext *h;
 600     int err;
 601
 602     err = url_open(&h, filename, flags);
 603     if (err < 0)
 604         return err;
 605     err = url_fdopen(s, h);
 606     if (err < 0) {
 607         url_close(h);
 608         return err;
 609     }
 610     return 0;
 611 }
 612
 613 int url_fclose(ByteIOContext *s)
 614 {
 615     URLContext *h = s->opaque;
 616
 617     av_free(s->buffer);
 618     av_free(s);
 619     return url_close(h);
 620 }
 621
 622 URLContext *url_fileno(ByteIOContext *s)
 623 {
 624     return s->opaque;
 625 }
 626
 627 #if CONFIG_MUXERS
 628 int url_fprintf(ByteIOContext *s, const char *fmt, ...)
 629 {
 630     va_list ap;
 631     char buf[4096];
 632     int ret;
 633
 634     va_start(ap, fmt);
 635     ret = vsnprintf(buf, sizeof(buf), fmt, ap);
 636     va_end(ap);
 637     put_buffer(s, buf, strlen(buf));
 638     return ret;
 639 }
 640 #endif //CONFIG_MUXERS
 641
 642 char *url_fgets(ByteIOContext *s, char *buf, int buf_size)
 643 {
 644     int c;
 645     char *q;
 646
 647     c = url_fgetc(s);
 648     if (c == EOF)
 649         return NULL;
 650     q = buf;
 651     for(;;) {
 652         if (c == EOF || c == '\n')
 653             break;
 654         if ((q - buf) < buf_size - 1)
 655             *q++ = c;
 656         c = url_fgetc(s);
 657     }
 658     if (buf_size > 0)
 659         *q = '\0';
 660     return buf;
 661 }
 662
 663 int url_fget_max_packet_size(ByteIOContext *s)
 664 {
 665     return s->max_packet_size;
 666 }
 667
 668 int av_url_read_fpause(ByteIOContext *s, int pause)
 669 {
 670     if (!s->read_pause)
 671         return AVERROR(ENOSYS);
 672     return s->read_pause(s->opaque, pause);
 673 }
 674
 675 int64_t av_url_read_fseek(ByteIOContext *s, int stream_index,
 676                           int64_t timestamp, int flags)
 677 {
 678     URLContext *h = s->opaque;
 679     int64_t ret;
 680     if (!s->read_seek)
 681         return AVERROR(ENOSYS);
 682     ret = s->read_seek(h, stream_index, timestamp, flags);
 683     if(ret >= 0) {
 684         s->buf_ptr = s->buf_end; // Flush buffer
 685         s->pos = s->seek(h, 0, SEEK_CUR);
 686     }
 687     return ret;
 688 }
 689
 690 /* url_open_dyn_buf and url_close_dyn_buf are used in rtp.c to send a response
 691  * back to the server even if CONFIG_MUXERS is false. */
 692 #if CONFIG_MUXERS || CONFIG_NETWORK
 693 /* buffer handling */
 694 int url_open_buf(ByteIOContext **s, uint8_t *buf, int buf_size, int flags)
 695 {
 696     int ret;
 697     *s = av_mallocz(sizeof(ByteIOContext));
 698     if(!*s)
 699         return AVERROR(ENOMEM);
 700     ret = init_put_byte(*s, buf, buf_size,
 701                         (flags & URL_WRONLY || flags & URL_RDWR),
 702                         NULL, NULL, NULL, NULL);
 703     if(ret != 0)
 704         av_freep(s);
 705     return ret;
 706 }
 707
 708 int url_close_buf(ByteIOContext *s)
 709 {
 710     put_flush_packet(s);
 711     return s->buf_ptr - s->buffer;
 712 }
 713
 714 /* output in a dynamic buffer */
 715
 716 typedef struct DynBuffer {
 717     int pos, size, allocated_size;
 718     uint8_t *buffer;
 719     int io_buffer_size;
 720     uint8_t io_buffer[1];
 721 } DynBuffer;
 722
 723 static int dyn_buf_write(void *opaque, uint8_t *buf, int buf_size)
 724 {
 725     DynBuffer *d = opaque;
 726     unsigned new_size, new_allocated_size;
 727
 728     /* reallocate buffer if needed */
 729     new_size = d->pos + buf_size;
 730     new_allocated_size = d->allocated_size;
 731     if(new_size < d->pos || new_size > INT_MAX/2)
 732         return -1;
 733     while (new_size > new_allocated_size) {
 734         if (!new_allocated_size)
 735             new_allocated_size = new_size;
 736         else
 737             new_allocated_size += new_allocated_size / 2 + 1;
 738     }
 739
 740     if (new_allocated_size > d->allocated_size) {
 741         d->buffer = av_realloc(d->buffer, new_allocated_size);
 742         if(d->buffer == NULL)
 743              return AVERROR(ENOMEM);
 744         d->allocated_size = new_allocated_size;
 745     }
 746     memcpy(d->buffer + d->pos, buf, buf_size);
 747     d->pos = new_size;
 748     if (d->pos > d->size)
 749         d->size = d->pos;
 750     return buf_size;
 751 }
 752
 753 static int dyn_packet_buf_write(void *opaque, uint8_t *buf, int buf_size)
 754 {
 755     unsigned char buf1[4];
 756     int ret;
 757
 758     /* packetized write: output the header */
 759     buf1[0] = (buf_size >> 24);
 760     buf1[1] = (buf_size >> 16);
 761     buf1[2] = (buf_size >> 8);
 762     buf1[3] = (buf_size);
 763     ret= dyn_buf_write(opaque, buf1, 4);
 764     if(ret < 0)
 765         return ret;
 766
 767     /* then the data */
 768     return dyn_buf_write(opaque, buf, buf_size);
 769 }
 770
 771 static int64_t dyn_buf_seek(void *opaque, int64_t offset, int whence)
 772 {
 773     DynBuffer *d = opaque;
 774
 775     if (whence == SEEK_CUR)
 776         offset += d->pos;
 777     else if (whence == SEEK_END)
 778         offset += d->size;
 779     if (offset < 0 || offset > 0x7fffffffLL)
 780         return -1;
 781     d->pos = offset;
 782     return 0;
 783 }
 784
 785 static int url_open_dyn_buf_internal(ByteIOContext **s, int max_packet_size)
 786 {
 787     DynBuffer *d;
 788     int io_buffer_size, ret;
 789
 790     if (max_packet_size)
 791         io_buffer_size = max_packet_size;
 792     else
 793         io_buffer_size = 1024;
 794
 795     if(sizeof(DynBuffer) + io_buffer_size < io_buffer_size)
 796         return -1;
 797     d = av_malloc(sizeof(DynBuffer) + io_buffer_size);
 798     if (!d)
 799         return -1;
 800     *s = av_mallocz(sizeof(ByteIOContext));
 801     if(!*s) {
 802         av_free(d);
 803         return AVERROR(ENOMEM);
 804     }
 805     d->io_buffer_size = io_buffer_size;
 806     d->buffer = NULL;
 807     d->pos = 0;
 808     d->size = 0;
 809     d->allocated_size = 0;
 810     ret = init_put_byte(*s, d->io_buffer, io_buffer_size,
 811                         1, d, NULL,
 812                         max_packet_size ? dyn_packet_buf_write : dyn_buf_write,
 813                         max_packet_size ? NULL : dyn_buf_seek);
 814     if (ret == 0) {
 815         (*s)->max_packet_size = max_packet_size;
 816     } else {
 817         av_free(d);
 818         av_freep(s);
 819     }
 820     return ret;
 821 }
 822
 823 int url_open_dyn_buf(ByteIOContext **s)
 824 {
 825     return url_open_dyn_buf_internal(s, 0);
 826 }
 827
 828 int url_open_dyn_packet_buf(ByteIOContext **s, int max_packet_size)
 829 {
 830     if (max_packet_size <= 0)
 831         return -1;
 832     return url_open_dyn_buf_internal(s, max_packet_size);
 833 }
 834
 835 int url_close_dyn_buf(ByteIOContext *s, uint8_t **pbuffer)
 836 {
 837     DynBuffer *d = s->opaque;
 838     int size;
 839
 840     put_flush_packet(s);
 841
 842     *pbuffer = d->buffer;
 843     size = d->size;
 844     av_free(d);
 845     av_free(s);
 846     return size;
 847 }
 848 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */