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 = FFMIN(s->buf_end - s->buf_ptr, size);
 111         memcpy(s->buf_ptr, buf, len);
 112         s->buf_ptr += len;
 113
 114         if (s->buf_ptr >= s->buf_end)
 115             flush_buffer(s);
 116
 117         buf += len;
 118         size -= len;
 119     }
 120 }
 121
 122 void put_flush_packet(ByteIOContext *s)
 123 {
 124     flush_buffer(s);
 125     s->must_flush = 0;
 126 }
 127
 128 int64_t url_fseek(ByteIOContext *s, int64_t offset, int whence)
 129 {
 130     int64_t offset1;
 131     int64_t pos;
 132
 133     if(!s)
 134         return AVERROR(EINVAL);
 135
 136     pos = s->pos - (s->write_flag ? 0 : (s->buf_end - s->buffer));
 137
 138     if (whence != SEEK_CUR && whence != SEEK_SET)
 139         return AVERROR(EINVAL);
 140
 141     if (whence == SEEK_CUR) {
 142         offset1 = pos + (s->buf_ptr - s->buffer);
 143         if (offset == 0)
 144             return offset1;
 145         offset += offset1;
 146     }
 147     offset1 = offset - pos;
 148     if (!s->must_flush &&
 149         offset1 >= 0 && offset1 <= (s->buf_end - s->buffer)) {
 150         /* can do the seek inside the buffer */
 151         s->buf_ptr = s->buffer + offset1;
 152     } else if(s->is_streamed && !s->write_flag &&
 153               offset1 >= 0 && offset1 < (s->buf_end - s->buffer) + (1<<16)){
 154         while(s->pos < offset && !s->eof_reached)
 155             fill_buffer(s);
 156         if (s->eof_reached)
 157             return AVERROR(EPIPE);
 158         s->buf_ptr = s->buf_end + offset - s->pos;
 159     } else {
 160         int64_t res = AVERROR(EPIPE);
 161
 162 #if CONFIG_MUXERS || CONFIG_NETWORK
 163         if (s->write_flag) {
 164             flush_buffer(s);
 165             s->must_flush = 1;
 166         }
 167 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */
 168         if (!s->seek || (res = s->seek(s->opaque, offset, SEEK_SET)) < 0)
 169             return res;
 170         if (!s->write_flag)
 171             s->buf_end = s->buffer;
 172         s->buf_ptr = s->buffer;
 173         s->pos = offset;
 174     }
 175     s->eof_reached = 0;
 176     return offset;
 177 }
 178
 179 void url_fskip(ByteIOContext *s, int64_t offset)
 180 {
 181     url_fseek(s, offset, SEEK_CUR);
 182 }
 183
 184 int64_t url_ftell(ByteIOContext *s)
 185 {
 186     return url_fseek(s, 0, SEEK_CUR);
 187 }
 188
 189 int64_t url_fsize(ByteIOContext *s)
 190 {
 191     int64_t size;
 192
 193     if(!s)
 194         return AVERROR(EINVAL);
 195
 196     if (!s->seek)
 197         return AVERROR(EPIPE);
 198     size = s->seek(s->opaque, 0, AVSEEK_SIZE);
 199     if(size<0){
 200         if ((size = s->seek(s->opaque, -1, SEEK_END)) < 0)
 201             return size;
 202         size++;
 203         s->seek(s->opaque, s->pos, SEEK_SET);
 204     }
 205     return size;
 206 }
 207
 208 int url_feof(ByteIOContext *s)
 209 {
 210     if(!s)
 211         return 0;
 212     return s->eof_reached;
 213 }
 214
 215 int url_ferror(ByteIOContext *s)
 216 {
 217     if(!s)
 218         return 0;
 219     return s->error;
 220 }
 221
 222 void put_le32(ByteIOContext *s, unsigned int val)
 223 {
 224     put_byte(s, val);
 225     put_byte(s, val >> 8);
 226     put_byte(s, val >> 16);
 227     put_byte(s, val >> 24);
 228 }
 229
 230 void put_be32(ByteIOContext *s, unsigned int val)
 231 {
 232     put_byte(s, val >> 24);
 233     put_byte(s, val >> 16);
 234     put_byte(s, val >> 8);
 235     put_byte(s, val);
 236 }
 237
 238 void put_strz(ByteIOContext *s, const char *str)
 239 {
 240     if (str)
 241         put_buffer(s, (const unsigned char *) str, strlen(str) + 1);
 242     else
 243         put_byte(s, 0);
 244 }
 245
 246 void put_le64(ByteIOContext *s, uint64_t val)
 247 {
 248     put_le32(s, (uint32_t)(val & 0xffffffff));
 249     put_le32(s, (uint32_t)(val >> 32));
 250 }
 251
 252 void put_be64(ByteIOContext *s, uint64_t val)
 253 {
 254     put_be32(s, (uint32_t)(val >> 32));
 255     put_be32(s, (uint32_t)(val & 0xffffffff));
 256 }
 257
 258 void put_le16(ByteIOContext *s, unsigned int val)
 259 {
 260     put_byte(s, val);
 261     put_byte(s, val >> 8);
 262 }
 263
 264 void put_be16(ByteIOContext *s, unsigned int val)
 265 {
 266     put_byte(s, val >> 8);
 267     put_byte(s, val);
 268 }
 269
 270 void put_le24(ByteIOContext *s, unsigned int val)
 271 {
 272     put_le16(s, val & 0xffff);
 273     put_byte(s, val >> 16);
 274 }
 275
 276 void put_be24(ByteIOContext *s, unsigned int val)
 277 {
 278     put_be16(s, val >> 8);
 279     put_byte(s, val);
 280 }
 281
 282 void put_tag(ByteIOContext *s, const char *tag)
 283 {
 284     while (*tag) {
 285         put_byte(s, *tag++);
 286     }
 287 }
 288
 289 /* Input stream */
 290
 291 static void fill_buffer(ByteIOContext *s)
 292 {
 293     uint8_t *dst= !s->max_packet_size && s->buf_end - s->buffer < s->buffer_size ? s->buf_ptr : s->buffer;
 294     int len= s->buffer_size - (dst - s->buffer);
 295
 296     assert(s->buf_ptr == s->buf_end);
 297
 298     /* no need to do anything if EOF already reached */
 299     if (s->eof_reached)
 300         return;
 301
 302     if(s->update_checksum && dst == s->buffer){
 303         if(s->buf_end > s->checksum_ptr)
 304             s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_end - s->checksum_ptr);
 305         s->checksum_ptr= s->buffer;
 306     }
 307
 308     if(s->read_packet)
 309         len = s->read_packet(s->opaque, dst, len);
 310     else
 311         len = 0;
 312     if (len <= 0) {
 313         /* do not modify buffer if EOF reached so that a seek back can
 314            be done without rereading data */
 315         s->eof_reached = 1;
 316         if(len<0)
 317             s->error= len;
 318     } else {
 319         s->pos += len;
 320         s->buf_ptr = dst;
 321         s->buf_end = dst + len;
 322     }
 323 }
 324
 325 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
 326                                     unsigned int len)
 327 {
 328     return av_crc(av_crc_get_table(AV_CRC_32_IEEE), checksum, buf, len);
 329 }
 330
 331 unsigned long get_checksum(ByteIOContext *s)
 332 {
 333     s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_ptr - s->checksum_ptr);
 334     s->update_checksum= NULL;
 335     return s->checksum;
 336 }
 337
 338 void init_checksum(ByteIOContext *s,
 339                    unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
 340                    unsigned long checksum)
 341 {
 342     s->update_checksum= update_checksum;
 343     if(s->update_checksum){
 344         s->checksum= checksum;
 345         s->checksum_ptr= s->buf_ptr;
 346     }
 347 }
 348
 349 /* XXX: put an inline version */
 350 int get_byte(ByteIOContext *s)
 351 {
 352     if (s->buf_ptr < s->buf_end) {
 353         return *s->buf_ptr++;
 354     } else {
 355         fill_buffer(s);
 356         if (s->buf_ptr < s->buf_end)
 357             return *s->buf_ptr++;
 358         else
 359             return 0;
 360     }
 361 }
 362
 363 int url_fgetc(ByteIOContext *s)
 364 {
 365     if (s->buf_ptr < s->buf_end) {
 366         return *s->buf_ptr++;
 367     } else {
 368         fill_buffer(s);
 369         if (s->buf_ptr < s->buf_end)
 370             return *s->buf_ptr++;
 371         else
 372             return URL_EOF;
 373     }
 374 }
 375
 376 int get_buffer(ByteIOContext *s, unsigned char *buf, int size)
 377 {
 378     int len, size1;
 379
 380     size1 = size;
 381     while (size > 0) {
 382         len = s->buf_end - s->buf_ptr;
 383         if (len > size)
 384             len = size;
 385         if (len == 0) {
 386             if(size > s->buffer_size && !s->update_checksum){
 387                 if(s->read_packet)
 388                     len = s->read_packet(s->opaque, buf, size);
 389                 if (len <= 0) {
 390                     /* do not modify buffer if EOF reached so that a seek back can
 391                     be done without rereading data */
 392                     s->eof_reached = 1;
 393                     if(len<0)
 394                         s->error= len;
 395                     break;
 396                 } else {
 397                     s->pos += len;
 398                     size -= len;
 399                     buf += len;
 400                     s->buf_ptr = s->buffer;
 401                     s->buf_end = s->buffer/* + len*/;
 402                 }
 403             }else{
 404                 fill_buffer(s);
 405                 len = s->buf_end - s->buf_ptr;
 406                 if (len == 0)
 407                     break;
 408             }
 409         } else {
 410             memcpy(buf, s->buf_ptr, len);
 411             buf += len;
 412             s->buf_ptr += len;
 413             size -= len;
 414         }
 415     }
 416     if (size1 == size) {
 417         if (url_ferror(s)) return url_ferror(s);
 418         if (url_feof(s))   return AVERROR_EOF;
 419     }
 420     return size1 - size;
 421 }
 422
 423 int get_partial_buffer(ByteIOContext *s, unsigned char *buf, int size)
 424 {
 425     int len;
 426
 427     if(size<0)
 428         return -1;
 429
 430     len = s->buf_end - s->buf_ptr;
 431     if (len == 0) {
 432         fill_buffer(s);
 433         len = s->buf_end - s->buf_ptr;
 434     }
 435     if (len > size)
 436         len = size;
 437     memcpy(buf, s->buf_ptr, len);
 438     s->buf_ptr += len;
 439     if (!len) {
 440         if (url_ferror(s)) return url_ferror(s);
 441         if (url_feof(s))   return AVERROR_EOF;
 442     }
 443     return len;
 444 }
 445
 446 unsigned int get_le16(ByteIOContext *s)
 447 {
 448     unsigned int val;
 449     val = get_byte(s);
 450     val |= get_byte(s) << 8;
 451     return val;
 452 }
 453
 454 unsigned int get_le24(ByteIOContext *s)
 455 {
 456     unsigned int val;
 457     val = get_le16(s);
 458     val |= get_byte(s) << 16;
 459     return val;
 460 }
 461
 462 unsigned int get_le32(ByteIOContext *s)
 463 {
 464     unsigned int val;
 465     val = get_le16(s);
 466     val |= get_le16(s) << 16;
 467     return val;
 468 }
 469
 470 uint64_t get_le64(ByteIOContext *s)
 471 {
 472     uint64_t val;
 473     val = (uint64_t)get_le32(s);
 474     val |= (uint64_t)get_le32(s) << 32;
 475     return val;
 476 }
 477
 478 unsigned int get_be16(ByteIOContext *s)
 479 {
 480     unsigned int val;
 481     val = get_byte(s) << 8;
 482     val |= get_byte(s);
 483     return val;
 484 }
 485
 486 unsigned int get_be24(ByteIOContext *s)
 487 {
 488     unsigned int val;
 489     val = get_be16(s) << 8;
 490     val |= get_byte(s);
 491     return val;
 492 }
 493 unsigned int get_be32(ByteIOContext *s)
 494 {
 495     unsigned int val;
 496     val = get_be16(s) << 16;
 497     val |= get_be16(s);
 498     return val;
 499 }
 500
 501 char *get_strz(ByteIOContext *s, char *buf, int maxlen)
 502 {
 503     int i = 0;
 504     char c;
 505
 506     while ((c = get_byte(s))) {
 507         if (i < maxlen-1)
 508             buf[i++] = c;
 509     }
 510
 511     buf[i] = 0; /* Ensure null terminated, but may be truncated */
 512
 513     return buf;
 514 }
 515
 516 uint64_t get_be64(ByteIOContext *s)
 517 {
 518     uint64_t val;
 519     val = (uint64_t)get_be32(s) << 32;
 520     val |= (uint64_t)get_be32(s);
 521     return val;
 522 }
 523
 524 uint64_t ff_get_v(ByteIOContext *bc){
 525     uint64_t val = 0;
 526     int tmp;
 527
 528     do{
 529         tmp = get_byte(bc);
 530         val= (val<<7) + (tmp&127);
 531     }while(tmp&128);
 532     return val;
 533 }
 534
 535 int url_fdopen(ByteIOContext **s, URLContext *h)
 536 {
 537     uint8_t *buffer;
 538     int buffer_size, max_packet_size;
 539
 540
 541     max_packet_size = url_get_max_packet_size(h);
 542     if (max_packet_size) {
 543         buffer_size = max_packet_size; /* no need to bufferize more than one packet */
 544     } else {
 545         buffer_size = IO_BUFFER_SIZE;
 546     }
 547     buffer = av_malloc(buffer_size);
 548     if (!buffer)
 549         return AVERROR(ENOMEM);
 550
 551     *s = av_mallocz(sizeof(ByteIOContext));
 552     if(!*s) {
 553         av_free(buffer);
 554         return AVERROR(ENOMEM);
 555     }
 556
 557     if (init_put_byte(*s, buffer, buffer_size,
 558                       (h->flags & URL_WRONLY || h->flags & URL_RDWR), h,
 559                       url_read, url_write, url_seek) < 0) {
 560         av_free(buffer);
 561         av_freep(s);
 562         return AVERROR(EIO);
 563     }
 564     (*s)->is_streamed = h->is_streamed;
 565     (*s)->max_packet_size = max_packet_size;
 566     if(h->prot) {
 567         (*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
 568         (*s)->read_seek  = (int64_t (*)(void *, int, int64_t, int))h->prot->url_read_seek;
 569     }
 570     return 0;
 571 }
 572
 573 int url_setbufsize(ByteIOContext *s, int buf_size)
 574 {
 575     uint8_t *buffer;
 576     buffer = av_malloc(buf_size);
 577     if (!buffer)
 578         return AVERROR(ENOMEM);
 579
 580     av_free(s->buffer);
 581     s->buffer = buffer;
 582     s->buffer_size = buf_size;
 583     s->buf_ptr = buffer;
 584     url_resetbuf(s, s->write_flag ? URL_WRONLY : URL_RDONLY);
 585     return 0;
 586 }
 587
 588 int url_resetbuf(ByteIOContext *s, int flags)
 589 {
 590     URLContext *h = s->opaque;
 591     if ((flags & URL_RDWR) || (h && h->flags != flags && !h->flags & URL_RDWR))
 592         return AVERROR(EINVAL);
 593
 594     if (flags & URL_WRONLY) {
 595         s->buf_end = s->buffer + s->buffer_size;
 596         s->write_flag = 1;
 597     } else {
 598         s->buf_end = s->buffer;
 599         s->write_flag = 0;
 600     }
 601     return 0;
 602 }
 603
 604 int url_fopen(ByteIOContext **s, const char *filename, int flags)
 605 {
 606     URLContext *h;
 607     int err;
 608
 609     err = url_open(&h, filename, flags);
 610     if (err < 0)
 611         return err;
 612     err = url_fdopen(s, h);
 613     if (err < 0) {
 614         url_close(h);
 615         return err;
 616     }
 617     return 0;
 618 }
 619
 620 int url_fclose(ByteIOContext *s)
 621 {
 622     URLContext *h = s->opaque;
 623
 624     av_free(s->buffer);
 625     av_free(s);
 626     return url_close(h);
 627 }
 628
 629 URLContext *url_fileno(ByteIOContext *s)
 630 {
 631     return s->opaque;
 632 }
 633
 634 #if CONFIG_MUXERS
 635 int url_fprintf(ByteIOContext *s, const char *fmt, ...)
 636 {
 637     va_list ap;
 638     char buf[4096];
 639     int ret;
 640
 641     va_start(ap, fmt);
 642     ret = vsnprintf(buf, sizeof(buf), fmt, ap);
 643     va_end(ap);
 644     put_buffer(s, buf, strlen(buf));
 645     return ret;
 646 }
 647 #endif //CONFIG_MUXERS
 648
 649 char *url_fgets(ByteIOContext *s, char *buf, int buf_size)
 650 {
 651     int c;
 652     char *q;
 653
 654     c = url_fgetc(s);
 655     if (c == EOF)
 656         return NULL;
 657     q = buf;
 658     for(;;) {
 659         if (c == EOF || c == '\n')
 660             break;
 661         if ((q - buf) < buf_size - 1)
 662             *q++ = c;
 663         c = url_fgetc(s);
 664     }
 665     if (buf_size > 0)
 666         *q = '\0';
 667     return buf;
 668 }
 669
 670 int url_fget_max_packet_size(ByteIOContext *s)
 671 {
 672     return s->max_packet_size;
 673 }
 674
 675 int av_url_read_fpause(ByteIOContext *s, int pause)
 676 {
 677     if (!s->read_pause)
 678         return AVERROR(ENOSYS);
 679     return s->read_pause(s->opaque, pause);
 680 }
 681
 682 int64_t av_url_read_fseek(ByteIOContext *s, int stream_index,
 683                           int64_t timestamp, int flags)
 684 {
 685     URLContext *h = s->opaque;
 686     int64_t ret;
 687     if (!s->read_seek)
 688         return AVERROR(ENOSYS);
 689     ret = s->read_seek(h, stream_index, timestamp, flags);
 690     if(ret >= 0) {
 691         s->buf_ptr = s->buf_end; // Flush buffer
 692         s->pos = s->seek(h, 0, SEEK_CUR);
 693     }
 694     return ret;
 695 }
 696
 697 /* url_open_dyn_buf and url_close_dyn_buf are used in rtp.c to send a response
 698  * back to the server even if CONFIG_MUXERS is false. */
 699 #if CONFIG_MUXERS || CONFIG_NETWORK
 700 /* buffer handling */
 701 int url_open_buf(ByteIOContext **s, uint8_t *buf, int buf_size, int flags)
 702 {
 703     int ret;
 704     *s = av_mallocz(sizeof(ByteIOContext));
 705     if(!*s)
 706         return AVERROR(ENOMEM);
 707     ret = init_put_byte(*s, buf, buf_size,
 708                         (flags & URL_WRONLY || flags & URL_RDWR),
 709                         NULL, NULL, NULL, NULL);
 710     if(ret != 0)
 711         av_freep(s);
 712     return ret;
 713 }
 714
 715 int url_close_buf(ByteIOContext *s)
 716 {
 717     put_flush_packet(s);
 718     return s->buf_ptr - s->buffer;
 719 }
 720
 721 /* output in a dynamic buffer */
 722
 723 typedef struct DynBuffer {
 724     int pos, size, allocated_size;
 725     uint8_t *buffer;
 726     int io_buffer_size;
 727     uint8_t io_buffer[1];
 728 } DynBuffer;
 729
 730 static int dyn_buf_write(void *opaque, uint8_t *buf, int buf_size)
 731 {
 732     DynBuffer *d = opaque;
 733     unsigned new_size, new_allocated_size;
 734
 735     /* reallocate buffer if needed */
 736     new_size = d->pos + buf_size;
 737     new_allocated_size = d->allocated_size;
 738     if(new_size < d->pos || new_size > INT_MAX/2)
 739         return -1;
 740     while (new_size > new_allocated_size) {
 741         if (!new_allocated_size)
 742             new_allocated_size = new_size;
 743         else
 744             new_allocated_size += new_allocated_size / 2 + 1;
 745     }
 746
 747     if (new_allocated_size > d->allocated_size) {
 748         d->buffer = av_realloc(d->buffer, new_allocated_size);
 749         if(d->buffer == NULL)
 750              return AVERROR(ENOMEM);
 751         d->allocated_size = new_allocated_size;
 752     }
 753     memcpy(d->buffer + d->pos, buf, buf_size);
 754     d->pos = new_size;
 755     if (d->pos > d->size)
 756         d->size = d->pos;
 757     return buf_size;
 758 }
 759
 760 static int dyn_packet_buf_write(void *opaque, uint8_t *buf, int buf_size)
 761 {
 762     unsigned char buf1[4];
 763     int ret;
 764
 765     /* packetized write: output the header */
 766     AV_WB32(buf1, buf_size);
 767     ret= dyn_buf_write(opaque, buf1, 4);
 768     if(ret < 0)
 769         return ret;
 770
 771     /* then the data */
 772     return dyn_buf_write(opaque, buf, buf_size);
 773 }
 774
 775 static int64_t dyn_buf_seek(void *opaque, int64_t offset, int whence)
 776 {
 777     DynBuffer *d = opaque;
 778
 779     if (whence == SEEK_CUR)
 780         offset += d->pos;
 781     else if (whence == SEEK_END)
 782         offset += d->size;
 783     if (offset < 0 || offset > 0x7fffffffLL)
 784         return -1;
 785     d->pos = offset;
 786     return 0;
 787 }
 788
 789 static int url_open_dyn_buf_internal(ByteIOContext **s, int max_packet_size)
 790 {
 791     DynBuffer *d;
 792     int ret;
 793     unsigned io_buffer_size = max_packet_size ? max_packet_size : 1024;
 794
 795     if(sizeof(DynBuffer) + io_buffer_size < io_buffer_size)
 796         return -1;
 797     d = av_mallocz(sizeof(DynBuffer) + io_buffer_size);
 798     if (!d)
 799         return AVERROR(ENOMEM);
 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     ret = init_put_byte(*s, d->io_buffer, io_buffer_size,
 807                         1, d, NULL,
 808                         max_packet_size ? dyn_packet_buf_write : dyn_buf_write,
 809                         max_packet_size ? NULL : dyn_buf_seek);
 810     if (ret == 0) {
 811         (*s)->max_packet_size = max_packet_size;
 812     } else {
 813         av_free(d);
 814         av_freep(s);
 815     }
 816     return ret;
 817 }
 818
 819 int url_open_dyn_buf(ByteIOContext **s)
 820 {
 821     return url_open_dyn_buf_internal(s, 0);
 822 }
 823
 824 int url_open_dyn_packet_buf(ByteIOContext **s, int max_packet_size)
 825 {
 826     if (max_packet_size <= 0)
 827         return -1;
 828     return url_open_dyn_buf_internal(s, max_packet_size);
 829 }
 830
 831 int url_close_dyn_buf(ByteIOContext *s, uint8_t **pbuffer)
 832 {
 833     DynBuffer *d = s->opaque;
 834     int size;
 835
 836     put_flush_packet(s);
 837
 838     *pbuffer = d->buffer;
 839     size = d->size;
 840     av_free(d);
 841     av_free(s);
 842     return size;
 843 }
 844 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */