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libavformat/aviobuf.c

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00001 /*
00002  * Buffered I/O for ffmpeg system
00003  * Copyright (c) 2000,2001 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "libavutil/crc.h"
00023 #include "libavutil/intreadwrite.h"
00024 #include "avformat.h"
00025 #include "avio.h"
00026 #include <stdarg.h>
00027 
00028 #define IO_BUFFER_SIZE 32768
00029 
00035 #define SHORT_SEEK_THRESHOLD 4096
00036 
00037 static void fill_buffer(ByteIOContext *s);
00038 
00039 int init_put_byte(ByteIOContext *s,
00040                   unsigned char *buffer,
00041                   int buffer_size,
00042                   int write_flag,
00043                   void *opaque,
00044                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
00045                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
00046                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
00047 {
00048     s->buffer = buffer;
00049     s->buffer_size = buffer_size;
00050     s->buf_ptr = buffer;
00051     s->opaque = opaque;
00052     url_resetbuf(s, write_flag ? URL_WRONLY : URL_RDONLY);
00053     s->write_packet = write_packet;
00054     s->read_packet = read_packet;
00055     s->seek = seek;
00056     s->pos = 0;
00057     s->must_flush = 0;
00058     s->eof_reached = 0;
00059     s->error = 0;
00060     s->is_streamed = 0;
00061     s->max_packet_size = 0;
00062     s->update_checksum= NULL;
00063     if(!read_packet && !write_flag){
00064         s->pos = buffer_size;
00065         s->buf_end = s->buffer + buffer_size;
00066     }
00067     s->read_pause = NULL;
00068     s->read_seek  = NULL;
00069     return 0;
00070 }
00071 
00072 ByteIOContext *av_alloc_put_byte(
00073                   unsigned char *buffer,
00074                   int buffer_size,
00075                   int write_flag,
00076                   void *opaque,
00077                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
00078                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
00079                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
00080 {
00081     ByteIOContext *s = av_mallocz(sizeof(ByteIOContext));
00082     init_put_byte(s, buffer, buffer_size, write_flag, opaque,
00083                   read_packet, write_packet, seek);
00084     return s;
00085 }
00086 
00087 static void flush_buffer(ByteIOContext *s)
00088 {
00089     if (s->buf_ptr > s->buffer) {
00090         if (s->write_packet && !s->error){
00091             int ret= s->write_packet(s->opaque, s->buffer, s->buf_ptr - s->buffer);
00092             if(ret < 0){
00093                 s->error = ret;
00094             }
00095         }
00096         if(s->update_checksum){
00097             s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_ptr - s->checksum_ptr);
00098             s->checksum_ptr= s->buffer;
00099         }
00100         s->pos += s->buf_ptr - s->buffer;
00101     }
00102     s->buf_ptr = s->buffer;
00103 }
00104 
00105 void put_byte(ByteIOContext *s, int b)
00106 {
00107     *(s->buf_ptr)++ = b;
00108     if (s->buf_ptr >= s->buf_end)
00109         flush_buffer(s);
00110 }
00111 
00112 void put_buffer(ByteIOContext *s, const unsigned char *buf, int size)
00113 {
00114     int len;
00115 
00116     while (size > 0) {
00117         len = (s->buf_end - s->buf_ptr);
00118         if (len > size)
00119             len = size;
00120         memcpy(s->buf_ptr, buf, len);
00121         s->buf_ptr += len;
00122 
00123         if (s->buf_ptr >= s->buf_end)
00124             flush_buffer(s);
00125 
00126         buf += len;
00127         size -= len;
00128     }
00129 }
00130 
00131 void put_flush_packet(ByteIOContext *s)
00132 {
00133     flush_buffer(s);
00134     s->must_flush = 0;
00135 }
00136 
00137 int64_t url_fseek(ByteIOContext *s, int64_t offset, int whence)
00138 {
00139     int64_t offset1;
00140     int64_t pos;
00141 
00142     if(!s)
00143         return AVERROR(EINVAL);
00144 
00145     pos = s->pos - (s->write_flag ? 0 : (s->buf_end - s->buffer));
00146 
00147     if (whence != SEEK_CUR && whence != SEEK_SET)
00148         return AVERROR(EINVAL);
00149 
00150     if (whence == SEEK_CUR) {
00151         offset1 = pos + (s->buf_ptr - s->buffer);
00152         if (offset == 0)
00153             return offset1;
00154         offset += offset1;
00155     }
00156     offset1 = offset - pos;
00157     if (!s->must_flush &&
00158         offset1 >= 0 && offset1 < (s->buf_end - s->buffer)) {
00159         /* can do the seek inside the buffer */
00160         s->buf_ptr = s->buffer + offset1;
00161     } else if ((s->is_streamed ||
00162                offset1 <= s->buf_end + SHORT_SEEK_THRESHOLD - s->buffer) &&
00163                !s->write_flag && offset1 >= 0) {
00164         while(s->pos < offset && !s->eof_reached)
00165             fill_buffer(s);
00166         if (s->eof_reached)
00167             return AVERROR(EPIPE);
00168         s->buf_ptr = s->buf_end + offset - s->pos;
00169     } else {
00170         int64_t res = AVERROR(EPIPE);
00171 
00172 #if CONFIG_MUXERS || CONFIG_NETWORK
00173         if (s->write_flag) {
00174             flush_buffer(s);
00175             s->must_flush = 1;
00176         }
00177 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */
00178         if (!s->seek || (res = s->seek(s->opaque, offset, SEEK_SET)) < 0)
00179             return res;
00180         if (!s->write_flag)
00181             s->buf_end = s->buffer;
00182         s->buf_ptr = s->buffer;
00183         s->pos = offset;
00184     }
00185     s->eof_reached = 0;
00186     return offset;
00187 }
00188 
00189 void url_fskip(ByteIOContext *s, int64_t offset)
00190 {
00191     url_fseek(s, offset, SEEK_CUR);
00192 }
00193 
00194 int64_t url_ftell(ByteIOContext *s)
00195 {
00196     return url_fseek(s, 0, SEEK_CUR);
00197 }
00198 
00199 int64_t url_fsize(ByteIOContext *s)
00200 {
00201     int64_t size;
00202 
00203     if(!s)
00204         return AVERROR(EINVAL);
00205 
00206     if (!s->seek)
00207         return AVERROR(EPIPE);
00208     size = s->seek(s->opaque, 0, AVSEEK_SIZE);
00209     if(size<0){
00210         if ((size = s->seek(s->opaque, -1, SEEK_END)) < 0)
00211             return size;
00212         size++;
00213         s->seek(s->opaque, s->pos, SEEK_SET);
00214     }
00215     return size;
00216 }
00217 
00218 int url_feof(ByteIOContext *s)
00219 {
00220     if(!s)
00221         return 0;
00222     return s->eof_reached;
00223 }
00224 
00225 int url_ferror(ByteIOContext *s)
00226 {
00227     if(!s)
00228         return 0;
00229     return s->error;
00230 }
00231 
00232 void put_le32(ByteIOContext *s, unsigned int val)
00233 {
00234     put_byte(s, val);
00235     put_byte(s, val >> 8);
00236     put_byte(s, val >> 16);
00237     put_byte(s, val >> 24);
00238 }
00239 
00240 void put_be32(ByteIOContext *s, unsigned int val)
00241 {
00242     put_byte(s, val >> 24);
00243     put_byte(s, val >> 16);
00244     put_byte(s, val >> 8);
00245     put_byte(s, val);
00246 }
00247 
00248 void put_strz(ByteIOContext *s, const char *str)
00249 {
00250     if (str)
00251         put_buffer(s, (const unsigned char *) str, strlen(str) + 1);
00252     else
00253         put_byte(s, 0);
00254 }
00255 
00256 void put_le64(ByteIOContext *s, uint64_t val)
00257 {
00258     put_le32(s, (uint32_t)(val & 0xffffffff));
00259     put_le32(s, (uint32_t)(val >> 32));
00260 }
00261 
00262 void put_be64(ByteIOContext *s, uint64_t val)
00263 {
00264     put_be32(s, (uint32_t)(val >> 32));
00265     put_be32(s, (uint32_t)(val & 0xffffffff));
00266 }
00267 
00268 void put_le16(ByteIOContext *s, unsigned int val)
00269 {
00270     put_byte(s, val);
00271     put_byte(s, val >> 8);
00272 }
00273 
00274 void put_be16(ByteIOContext *s, unsigned int val)
00275 {
00276     put_byte(s, val >> 8);
00277     put_byte(s, val);
00278 }
00279 
00280 void put_le24(ByteIOContext *s, unsigned int val)
00281 {
00282     put_le16(s, val & 0xffff);
00283     put_byte(s, val >> 16);
00284 }
00285 
00286 void put_be24(ByteIOContext *s, unsigned int val)
00287 {
00288     put_be16(s, val >> 8);
00289     put_byte(s, val);
00290 }
00291 
00292 void put_tag(ByteIOContext *s, const char *tag)
00293 {
00294     while (*tag) {
00295         put_byte(s, *tag++);
00296     }
00297 }
00298 
00299 /* Input stream */
00300 
00301 static void fill_buffer(ByteIOContext *s)
00302 {
00303     uint8_t *dst= !s->max_packet_size && s->buf_end - s->buffer < s->buffer_size ? s->buf_ptr : s->buffer;
00304     int len= s->buffer_size - (dst - s->buffer);
00305 
00306     assert(s->buf_ptr == s->buf_end);
00307 
00308     /* no need to do anything if EOF already reached */
00309     if (s->eof_reached)
00310         return;
00311 
00312     if(s->update_checksum && dst == s->buffer){
00313         if(s->buf_end > s->checksum_ptr)
00314             s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_end - s->checksum_ptr);
00315         s->checksum_ptr= s->buffer;
00316     }
00317 
00318     if(s->read_packet)
00319         len = s->read_packet(s->opaque, dst, len);
00320     else
00321         len = 0;
00322     if (len <= 0) {
00323         /* do not modify buffer if EOF reached so that a seek back can
00324            be done without rereading data */
00325         s->eof_reached = 1;
00326         if(len<0)
00327             s->error= len;
00328     } else {
00329         s->pos += len;
00330         s->buf_ptr = dst;
00331         s->buf_end = dst + len;
00332     }
00333 }
00334 
00335 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
00336                                     unsigned int len)
00337 {
00338     return av_crc(av_crc_get_table(AV_CRC_32_IEEE), checksum, buf, len);
00339 }
00340 
00341 unsigned long get_checksum(ByteIOContext *s)
00342 {
00343     s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_ptr - s->checksum_ptr);
00344     s->update_checksum= NULL;
00345     return s->checksum;
00346 }
00347 
00348 void init_checksum(ByteIOContext *s,
00349                    unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
00350                    unsigned long checksum)
00351 {
00352     s->update_checksum= update_checksum;
00353     if(s->update_checksum){
00354         s->checksum= checksum;
00355         s->checksum_ptr= s->buf_ptr;
00356     }
00357 }
00358 
00359 /* XXX: put an inline version */
00360 int get_byte(ByteIOContext *s)
00361 {
00362     if (s->buf_ptr < s->buf_end) {
00363         return *s->buf_ptr++;
00364     } else {
00365         fill_buffer(s);
00366         if (s->buf_ptr < s->buf_end)
00367             return *s->buf_ptr++;
00368         else
00369             return 0;
00370     }
00371 }
00372 
00373 int url_fgetc(ByteIOContext *s)
00374 {
00375     if (s->buf_ptr < s->buf_end) {
00376         return *s->buf_ptr++;
00377     } else {
00378         fill_buffer(s);
00379         if (s->buf_ptr < s->buf_end)
00380             return *s->buf_ptr++;
00381         else
00382             return URL_EOF;
00383     }
00384 }
00385 
00386 int get_buffer(ByteIOContext *s, unsigned char *buf, int size)
00387 {
00388     int len, size1;
00389 
00390     size1 = size;
00391     while (size > 0) {
00392         len = s->buf_end - s->buf_ptr;
00393         if (len > size)
00394             len = size;
00395         if (len == 0) {
00396             if(size > s->buffer_size && !s->update_checksum){
00397                 if(s->read_packet)
00398                     len = s->read_packet(s->opaque, buf, size);
00399                 if (len <= 0) {
00400                     /* do not modify buffer if EOF reached so that a seek back can
00401                     be done without rereading data */
00402                     s->eof_reached = 1;
00403                     if(len<0)
00404                         s->error= len;
00405                     break;
00406                 } else {
00407                     s->pos += len;
00408                     size -= len;
00409                     buf += len;
00410                     s->buf_ptr = s->buffer;
00411                     s->buf_end = s->buffer/* + len*/;
00412                 }
00413             }else{
00414                 fill_buffer(s);
00415                 len = s->buf_end - s->buf_ptr;
00416                 if (len == 0)
00417                     break;
00418             }
00419         } else {
00420             memcpy(buf, s->buf_ptr, len);
00421             buf += len;
00422             s->buf_ptr += len;
00423             size -= len;
00424         }
00425     }
00426     return size1 - size;
00427 }
00428 
00429 int get_partial_buffer(ByteIOContext *s, unsigned char *buf, int size)
00430 {
00431     int len;
00432 
00433     if(size<0)
00434         return -1;
00435 
00436     len = s->buf_end - s->buf_ptr;
00437     if (len == 0) {
00438         fill_buffer(s);
00439         len = s->buf_end - s->buf_ptr;
00440     }
00441     if (len > size)
00442         len = size;
00443     memcpy(buf, s->buf_ptr, len);
00444     s->buf_ptr += len;
00445     return len;
00446 }
00447 
00448 unsigned int get_le16(ByteIOContext *s)
00449 {
00450     unsigned int val;
00451     val = get_byte(s);
00452     val |= get_byte(s) << 8;
00453     return val;
00454 }
00455 
00456 unsigned int get_le24(ByteIOContext *s)
00457 {
00458     unsigned int val;
00459     val = get_le16(s);
00460     val |= get_byte(s) << 16;
00461     return val;
00462 }
00463 
00464 unsigned int get_le32(ByteIOContext *s)
00465 {
00466     unsigned int val;
00467     val = get_le16(s);
00468     val |= get_le16(s) << 16;
00469     return val;
00470 }
00471 
00472 uint64_t get_le64(ByteIOContext *s)
00473 {
00474     uint64_t val;
00475     val = (uint64_t)get_le32(s);
00476     val |= (uint64_t)get_le32(s) << 32;
00477     return val;
00478 }
00479 
00480 unsigned int get_be16(ByteIOContext *s)
00481 {
00482     unsigned int val;
00483     val = get_byte(s) << 8;
00484     val |= get_byte(s);
00485     return val;
00486 }
00487 
00488 unsigned int get_be24(ByteIOContext *s)
00489 {
00490     unsigned int val;
00491     val = get_be16(s) << 8;
00492     val |= get_byte(s);
00493     return val;
00494 }
00495 unsigned int get_be32(ByteIOContext *s)
00496 {
00497     unsigned int val;
00498     val = get_be16(s) << 16;
00499     val |= get_be16(s);
00500     return val;
00501 }
00502 
00503 char *get_strz(ByteIOContext *s, char *buf, int maxlen)
00504 {
00505     int i = 0;
00506     char c;
00507 
00508     while ((c = get_byte(s))) {
00509         if (i < maxlen-1)
00510             buf[i++] = c;
00511     }
00512 
00513     buf[i] = 0; /* Ensure null terminated, but may be truncated */
00514 
00515     return buf;
00516 }
00517 
00518 uint64_t get_be64(ByteIOContext *s)
00519 {
00520     uint64_t val;
00521     val = (uint64_t)get_be32(s) << 32;
00522     val |= (uint64_t)get_be32(s);
00523     return val;
00524 }
00525 
00526 uint64_t ff_get_v(ByteIOContext *bc){
00527     uint64_t val = 0;
00528     int tmp;
00529 
00530     do{
00531         tmp = get_byte(bc);
00532         val= (val<<7) + (tmp&127);
00533     }while(tmp&128);
00534     return val;
00535 }
00536 
00537 int url_fdopen(ByteIOContext **s, URLContext *h)
00538 {
00539     uint8_t *buffer;
00540     int buffer_size, max_packet_size;
00541 
00542 
00543     max_packet_size = url_get_max_packet_size(h);
00544     if (max_packet_size) {
00545         buffer_size = max_packet_size; /* no need to bufferize more than one packet */
00546     } else {
00547         buffer_size = IO_BUFFER_SIZE;
00548     }
00549     buffer = av_malloc(buffer_size);
00550     if (!buffer)
00551         return AVERROR(ENOMEM);
00552 
00553     *s = av_mallocz(sizeof(ByteIOContext));
00554     if(!*s) {
00555         av_free(buffer);
00556         return AVERROR(ENOMEM);
00557     }
00558 
00559     if (init_put_byte(*s, buffer, buffer_size,
00560                       (h->flags & URL_WRONLY || h->flags & URL_RDWR), h,
00561                       url_read, url_write, url_seek) < 0) {
00562         av_free(buffer);
00563         av_freep(s);
00564         return AVERROR(EIO);
00565     }
00566     (*s)->is_streamed = h->is_streamed;
00567     (*s)->max_packet_size = max_packet_size;
00568     if(h->prot) {
00569         (*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
00570         (*s)->read_seek  = (int64_t (*)(void *, int, int64_t, int))h->prot->url_read_seek;
00571     }
00572     return 0;
00573 }
00574 
00575 int url_setbufsize(ByteIOContext *s, int buf_size)
00576 {
00577     uint8_t *buffer;
00578     buffer = av_malloc(buf_size);
00579     if (!buffer)
00580         return AVERROR(ENOMEM);
00581 
00582     av_free(s->buffer);
00583     s->buffer = buffer;
00584     s->buffer_size = buf_size;
00585     s->buf_ptr = buffer;
00586     url_resetbuf(s, s->write_flag ? URL_WRONLY : URL_RDONLY);
00587     return 0;
00588 }
00589 
00590 int url_resetbuf(ByteIOContext *s, int flags)
00591 {
00592     URLContext *h = s->opaque;
00593     if ((flags & URL_RDWR) || (h && h->flags != flags && !h->flags & URL_RDWR))
00594         return AVERROR(EINVAL);
00595 
00596     if (flags & URL_WRONLY) {
00597         s->buf_end = s->buffer + s->buffer_size;
00598         s->write_flag = 1;
00599     } else {
00600         s->buf_end = s->buffer;
00601         s->write_flag = 0;
00602     }
00603     return 0;
00604 }
00605 
00606 int url_fopen(ByteIOContext **s, const char *filename, int flags)
00607 {
00608     URLContext *h;
00609     int err;
00610 
00611     err = url_open(&h, filename, flags);
00612     if (err < 0)
00613         return err;
00614     err = url_fdopen(s, h);
00615     if (err < 0) {
00616         url_close(h);
00617         return err;
00618     }
00619     return 0;
00620 }
00621 
00622 int url_fclose(ByteIOContext *s)
00623 {
00624     URLContext *h = s->opaque;
00625 
00626     av_free(s->buffer);
00627     av_free(s);
00628     return url_close(h);
00629 }
00630 
00631 URLContext *url_fileno(ByteIOContext *s)
00632 {
00633     return s->opaque;
00634 }
00635 
00636 #if CONFIG_MUXERS
00637 int url_fprintf(ByteIOContext *s, const char *fmt, ...)
00638 {
00639     va_list ap;
00640     char buf[4096];
00641     int ret;
00642 
00643     va_start(ap, fmt);
00644     ret = vsnprintf(buf, sizeof(buf), fmt, ap);
00645     va_end(ap);
00646     put_buffer(s, buf, strlen(buf));
00647     return ret;
00648 }
00649 #endif //CONFIG_MUXERS
00650 
00651 char *url_fgets(ByteIOContext *s, char *buf, int buf_size)
00652 {
00653     int c;
00654     char *q;
00655 
00656     c = url_fgetc(s);
00657     if (c == EOF)
00658         return NULL;
00659     q = buf;
00660     for(;;) {
00661         if (c == EOF || c == '\n')
00662             break;
00663         if ((q - buf) < buf_size - 1)
00664             *q++ = c;
00665         c = url_fgetc(s);
00666     }
00667     if (buf_size > 0)
00668         *q = '\0';
00669     return buf;
00670 }
00671 
00672 int url_fget_max_packet_size(ByteIOContext *s)
00673 {
00674     return s->max_packet_size;
00675 }
00676 
00677 int av_url_read_fpause(ByteIOContext *s, int pause)
00678 {
00679     if (!s->read_pause)
00680         return AVERROR(ENOSYS);
00681     return s->read_pause(s->opaque, pause);
00682 }
00683 
00684 int64_t av_url_read_fseek(ByteIOContext *s, int stream_index,
00685                           int64_t timestamp, int flags)
00686 {
00687     URLContext *h = s->opaque;
00688     int64_t ret;
00689     if (!s->read_seek)
00690         return AVERROR(ENOSYS);
00691     ret = s->read_seek(h, stream_index, timestamp, flags);
00692     if(ret >= 0) {
00693         s->buf_ptr = s->buf_end; // Flush buffer
00694         s->pos = s->seek(h, 0, SEEK_CUR);
00695     }
00696     return ret;
00697 }
00698 
00699 /* url_open_dyn_buf and url_close_dyn_buf are used in rtp.c to send a response
00700  * back to the server even if CONFIG_MUXERS is false. */
00701 #if CONFIG_MUXERS || CONFIG_NETWORK
00702 /* buffer handling */
00703 int url_open_buf(ByteIOContext **s, uint8_t *buf, int buf_size, int flags)
00704 {
00705     int ret;
00706     *s = av_mallocz(sizeof(ByteIOContext));
00707     if(!*s)
00708         return AVERROR(ENOMEM);
00709     ret = init_put_byte(*s, buf, buf_size,
00710                         (flags & URL_WRONLY || flags & URL_RDWR),
00711                         NULL, NULL, NULL, NULL);
00712     if(ret != 0)
00713         av_freep(s);
00714     return ret;
00715 }
00716 
00717 int url_close_buf(ByteIOContext *s)
00718 {
00719     put_flush_packet(s);
00720     return s->buf_ptr - s->buffer;
00721 }
00722 
00723 /* output in a dynamic buffer */
00724 
00725 typedef struct DynBuffer {
00726     int pos, size, allocated_size;
00727     uint8_t *buffer;
00728     int io_buffer_size;
00729     uint8_t io_buffer[1];
00730 } DynBuffer;
00731 
00732 static int dyn_buf_write(void *opaque, uint8_t *buf, int buf_size)
00733 {
00734     DynBuffer *d = opaque;
00735     unsigned new_size, new_allocated_size;
00736 
00737     /* reallocate buffer if needed */
00738     new_size = d->pos + buf_size;
00739     new_allocated_size = d->allocated_size;
00740     if(new_size < d->pos || new_size > INT_MAX/2)
00741         return -1;
00742     while (new_size > new_allocated_size) {
00743         if (!new_allocated_size)
00744             new_allocated_size = new_size;
00745         else
00746             new_allocated_size += new_allocated_size / 2 + 1;
00747     }
00748 
00749     if (new_allocated_size > d->allocated_size) {
00750         d->buffer = av_realloc(d->buffer, new_allocated_size);
00751         if(d->buffer == NULL)
00752              return AVERROR(ENOMEM);
00753         d->allocated_size = new_allocated_size;
00754     }
00755     memcpy(d->buffer + d->pos, buf, buf_size);
00756     d->pos = new_size;
00757     if (d->pos > d->size)
00758         d->size = d->pos;
00759     return buf_size;
00760 }
00761 
00762 static int dyn_packet_buf_write(void *opaque, uint8_t *buf, int buf_size)
00763 {
00764     unsigned char buf1[4];
00765     int ret;
00766 
00767     /* packetized write: output the header */
00768     AV_WB32(buf1, buf_size);
00769     ret= dyn_buf_write(opaque, buf1, 4);
00770     if(ret < 0)
00771         return ret;
00772 
00773     /* then the data */
00774     return dyn_buf_write(opaque, buf, buf_size);
00775 }
00776 
00777 static int64_t dyn_buf_seek(void *opaque, int64_t offset, int whence)
00778 {
00779     DynBuffer *d = opaque;
00780 
00781     if (whence == SEEK_CUR)
00782         offset += d->pos;
00783     else if (whence == SEEK_END)
00784         offset += d->size;
00785     if (offset < 0 || offset > 0x7fffffffLL)
00786         return -1;
00787     d->pos = offset;
00788     return 0;
00789 }
00790 
00791 static int url_open_dyn_buf_internal(ByteIOContext **s, int max_packet_size)
00792 {
00793     DynBuffer *d;
00794     int ret;
00795     unsigned io_buffer_size = max_packet_size ? max_packet_size : 1024;
00796 
00797     if(sizeof(DynBuffer) + io_buffer_size < io_buffer_size)
00798         return -1;
00799     d = av_mallocz(sizeof(DynBuffer) + io_buffer_size);
00800     if (!d)
00801         return AVERROR(ENOMEM);
00802     *s = av_mallocz(sizeof(ByteIOContext));
00803     if(!*s) {
00804         av_free(d);
00805         return AVERROR(ENOMEM);
00806     }
00807     d->io_buffer_size = io_buffer_size;
00808     ret = init_put_byte(*s, d->io_buffer, io_buffer_size,
00809                         1, d, NULL,
00810                         max_packet_size ? dyn_packet_buf_write : dyn_buf_write,
00811                         max_packet_size ? NULL : dyn_buf_seek);
00812     if (ret == 0) {
00813         (*s)->max_packet_size = max_packet_size;
00814     } else {
00815         av_free(d);
00816         av_freep(s);
00817     }
00818     return ret;
00819 }
00820 
00821 int url_open_dyn_buf(ByteIOContext **s)
00822 {
00823     return url_open_dyn_buf_internal(s, 0);
00824 }
00825 
00826 int url_open_dyn_packet_buf(ByteIOContext **s, int max_packet_size)
00827 {
00828     if (max_packet_size <= 0)
00829         return -1;
00830     return url_open_dyn_buf_internal(s, max_packet_size);
00831 }
00832 
00833 int url_close_dyn_buf(ByteIOContext *s, uint8_t **pbuffer)
00834 {
00835     DynBuffer *d = s->opaque;
00836     int size;
00837 
00838     put_flush_packet(s);
00839 
00840     *pbuffer = d->buffer;
00841     size = d->size;
00842     av_free(d);
00843     av_free(s);
00844     return size;
00845 }
00846 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */

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