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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 
00030 static void fill_buffer(ByteIOContext *s);
00031 #if LIBAVFORMAT_VERSION_MAJOR >= 53
00032 static int url_resetbuf(ByteIOContext *s, int flags);
00033 #endif
00034 
00035 int init_put_byte(ByteIOContext *s,
00036                   unsigned char *buffer,
00037                   int buffer_size,
00038                   int write_flag,
00039                   void *opaque,
00040                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
00041                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
00042                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
00043 {
00044     s->buffer = buffer;
00045     s->buffer_size = buffer_size;
00046     s->buf_ptr = buffer;
00047     s->opaque = opaque;
00048     url_resetbuf(s, write_flag ? URL_WRONLY : URL_RDONLY);
00049     s->write_packet = write_packet;
00050     s->read_packet = read_packet;
00051     s->seek = seek;
00052     s->pos = 0;
00053     s->must_flush = 0;
00054     s->eof_reached = 0;
00055     s->error = 0;
00056     s->is_streamed = 0;
00057     s->max_packet_size = 0;
00058     s->update_checksum= NULL;
00059     if(!read_packet && !write_flag){
00060         s->pos = buffer_size;
00061         s->buf_end = s->buffer + buffer_size;
00062     }
00063     s->read_pause = NULL;
00064     s->read_seek  = NULL;
00065     return 0;
00066 }
00067 
00068 ByteIOContext *av_alloc_put_byte(
00069                   unsigned char *buffer,
00070                   int buffer_size,
00071                   int write_flag,
00072                   void *opaque,
00073                   int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
00074                   int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
00075                   int64_t (*seek)(void *opaque, int64_t offset, int whence))
00076 {
00077     ByteIOContext *s = av_mallocz(sizeof(ByteIOContext));
00078     init_put_byte(s, buffer, buffer_size, write_flag, opaque,
00079                   read_packet, write_packet, seek);
00080     return s;
00081 }
00082 
00083 static void flush_buffer(ByteIOContext *s)
00084 {
00085     if (s->buf_ptr > s->buffer) {
00086         if (s->write_packet && !s->error){
00087             int ret= s->write_packet(s->opaque, s->buffer, s->buf_ptr - s->buffer);
00088             if(ret < 0){
00089                 s->error = ret;
00090             }
00091         }
00092         if(s->update_checksum){
00093             s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_ptr - s->checksum_ptr);
00094             s->checksum_ptr= s->buffer;
00095         }
00096         s->pos += s->buf_ptr - s->buffer;
00097     }
00098     s->buf_ptr = s->buffer;
00099 }
00100 
00101 void put_byte(ByteIOContext *s, int b)
00102 {
00103     *(s->buf_ptr)++ = b;
00104     if (s->buf_ptr >= s->buf_end)
00105         flush_buffer(s);
00106 }
00107 
00108 void put_buffer(ByteIOContext *s, const unsigned char *buf, int size)
00109 {
00110     while (size > 0) {
00111         int len = FFMIN(s->buf_end - s->buf_ptr, size);
00112         memcpy(s->buf_ptr, buf, len);
00113         s->buf_ptr += len;
00114 
00115         if (s->buf_ptr >= s->buf_end)
00116             flush_buffer(s);
00117 
00118         buf += len;
00119         size -= len;
00120     }
00121 }
00122 
00123 void put_flush_packet(ByteIOContext *s)
00124 {
00125     flush_buffer(s);
00126     s->must_flush = 0;
00127 }
00128 
00129 int64_t url_fseek(ByteIOContext *s, int64_t offset, int whence)
00130 {
00131     int64_t offset1;
00132     int64_t pos;
00133     int force = whence & AVSEEK_FORCE;
00134     whence &= ~AVSEEK_FORCE;
00135 
00136     if(!s)
00137         return AVERROR(EINVAL);
00138 
00139     pos = s->pos - (s->write_flag ? 0 : (s->buf_end - s->buffer));
00140 
00141     if (whence != SEEK_CUR && whence != SEEK_SET)
00142         return AVERROR(EINVAL);
00143 
00144     if (whence == SEEK_CUR) {
00145         offset1 = pos + (s->buf_ptr - s->buffer);
00146         if (offset == 0)
00147             return offset1;
00148         offset += offset1;
00149     }
00150     offset1 = offset - pos;
00151     if (!s->must_flush &&
00152         offset1 >= 0 && offset1 <= (s->buf_end - s->buffer)) {
00153         /* can do the seek inside the buffer */
00154         s->buf_ptr = s->buffer + offset1;
00155     } else if(s->is_streamed && !s->write_flag && offset1 >= 0 &&
00156               (whence != SEEK_END || force)) {
00157         while(s->pos < offset && !s->eof_reached)
00158             fill_buffer(s);
00159         if (s->eof_reached)
00160             return AVERROR_EOF;
00161         s->buf_ptr = s->buf_end + offset - s->pos;
00162     } else {
00163         int64_t res;
00164 
00165 #if CONFIG_MUXERS || CONFIG_NETWORK
00166         if (s->write_flag) {
00167             flush_buffer(s);
00168             s->must_flush = 1;
00169         }
00170 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */
00171         if (!s->seek)
00172             return AVERROR(EPIPE);
00173         if ((res = s->seek(s->opaque, offset, SEEK_SET)) < 0)
00174             return res;
00175         if (!s->write_flag)
00176             s->buf_end = s->buffer;
00177         s->buf_ptr = s->buffer;
00178         s->pos = offset;
00179     }
00180     s->eof_reached = 0;
00181     return offset;
00182 }
00183 
00184 void url_fskip(ByteIOContext *s, int64_t offset)
00185 {
00186     url_fseek(s, offset, SEEK_CUR);
00187 }
00188 
00189 int64_t url_ftell(ByteIOContext *s)
00190 {
00191     return url_fseek(s, 0, SEEK_CUR);
00192 }
00193 
00194 int64_t url_fsize(ByteIOContext *s)
00195 {
00196     int64_t size;
00197 
00198     if(!s)
00199         return AVERROR(EINVAL);
00200 
00201     if (!s->seek)
00202         return AVERROR(ENOSYS);
00203     size = s->seek(s->opaque, 0, AVSEEK_SIZE);
00204     if(size<0){
00205         if ((size = s->seek(s->opaque, -1, SEEK_END)) < 0)
00206             return size;
00207         size++;
00208         s->seek(s->opaque, s->pos, SEEK_SET);
00209     }
00210     return size;
00211 }
00212 
00213 int url_feof(ByteIOContext *s)
00214 {
00215     if(!s)
00216         return 0;
00217     return s->eof_reached;
00218 }
00219 
00220 int url_ferror(ByteIOContext *s)
00221 {
00222     if(!s)
00223         return 0;
00224     return s->error;
00225 }
00226 
00227 void put_le32(ByteIOContext *s, unsigned int val)
00228 {
00229     put_byte(s, val);
00230     put_byte(s, val >> 8);
00231     put_byte(s, val >> 16);
00232     put_byte(s, val >> 24);
00233 }
00234 
00235 void put_be32(ByteIOContext *s, unsigned int val)
00236 {
00237     put_byte(s, val >> 24);
00238     put_byte(s, val >> 16);
00239     put_byte(s, val >> 8);
00240     put_byte(s, val);
00241 }
00242 
00243 void put_strz(ByteIOContext *s, const char *str)
00244 {
00245     if (str)
00246         put_buffer(s, (const unsigned char *) str, strlen(str) + 1);
00247     else
00248         put_byte(s, 0);
00249 }
00250 
00251 void put_le64(ByteIOContext *s, uint64_t val)
00252 {
00253     put_le32(s, (uint32_t)(val & 0xffffffff));
00254     put_le32(s, (uint32_t)(val >> 32));
00255 }
00256 
00257 void put_be64(ByteIOContext *s, uint64_t val)
00258 {
00259     put_be32(s, (uint32_t)(val >> 32));
00260     put_be32(s, (uint32_t)(val & 0xffffffff));
00261 }
00262 
00263 void put_le16(ByteIOContext *s, unsigned int val)
00264 {
00265     put_byte(s, val);
00266     put_byte(s, val >> 8);
00267 }
00268 
00269 void put_be16(ByteIOContext *s, unsigned int val)
00270 {
00271     put_byte(s, val >> 8);
00272     put_byte(s, val);
00273 }
00274 
00275 void put_le24(ByteIOContext *s, unsigned int val)
00276 {
00277     put_le16(s, val & 0xffff);
00278     put_byte(s, val >> 16);
00279 }
00280 
00281 void put_be24(ByteIOContext *s, unsigned int val)
00282 {
00283     put_be16(s, val >> 8);
00284     put_byte(s, val);
00285 }
00286 
00287 void put_tag(ByteIOContext *s, const char *tag)
00288 {
00289     while (*tag) {
00290         put_byte(s, *tag++);
00291     }
00292 }
00293 
00294 /* Input stream */
00295 
00296 static void fill_buffer(ByteIOContext *s)
00297 {
00298     uint8_t *dst= !s->max_packet_size && s->buf_end - s->buffer < s->buffer_size ? s->buf_ptr : s->buffer;
00299     int len= s->buffer_size - (dst - s->buffer);
00300     int max_buffer_size = s->max_packet_size ? s->max_packet_size : IO_BUFFER_SIZE;
00301 
00302     assert(s->buf_ptr == s->buf_end);
00303 
00304     /* no need to do anything if EOF already reached */
00305     if (s->eof_reached)
00306         return;
00307 
00308     if(s->update_checksum && dst == s->buffer){
00309         if(s->buf_end > s->checksum_ptr)
00310             s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_end - s->checksum_ptr);
00311         s->checksum_ptr= s->buffer;
00312     }
00313 
00314     /* make buffer smaller in case it ended up large after probing */
00315     if (s->buffer_size > max_buffer_size) {
00316         url_setbufsize(s, max_buffer_size);
00317 
00318         s->checksum_ptr = dst = s->buffer;
00319         len = s->buffer_size;
00320     }
00321 
00322     if(s->read_packet)
00323         len = s->read_packet(s->opaque, dst, len);
00324     else
00325         len = 0;
00326     if (len <= 0) {
00327         /* do not modify buffer if EOF reached so that a seek back can
00328            be done without rereading data */
00329         s->eof_reached = 1;
00330         if(len<0)
00331             s->error= len;
00332     } else {
00333         s->pos += len;
00334         s->buf_ptr = dst;
00335         s->buf_end = dst + len;
00336     }
00337 }
00338 
00339 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
00340                                     unsigned int len)
00341 {
00342     return av_crc(av_crc_get_table(AV_CRC_32_IEEE), checksum, buf, len);
00343 }
00344 
00345 unsigned long get_checksum(ByteIOContext *s)
00346 {
00347     s->checksum= s->update_checksum(s->checksum, s->checksum_ptr, s->buf_ptr - s->checksum_ptr);
00348     s->update_checksum= NULL;
00349     return s->checksum;
00350 }
00351 
00352 void init_checksum(ByteIOContext *s,
00353                    unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
00354                    unsigned long checksum)
00355 {
00356     s->update_checksum= update_checksum;
00357     if(s->update_checksum){
00358         s->checksum= checksum;
00359         s->checksum_ptr= s->buf_ptr;
00360     }
00361 }
00362 
00363 /* XXX: put an inline version */
00364 int get_byte(ByteIOContext *s)
00365 {
00366     if (s->buf_ptr < s->buf_end) {
00367         return *s->buf_ptr++;
00368     } else {
00369         fill_buffer(s);
00370         if (s->buf_ptr < s->buf_end)
00371             return *s->buf_ptr++;
00372         else
00373             return 0;
00374     }
00375 }
00376 
00377 int url_fgetc(ByteIOContext *s)
00378 {
00379     if (s->buf_ptr < s->buf_end) {
00380         return *s->buf_ptr++;
00381     } else {
00382         fill_buffer(s);
00383         if (s->buf_ptr < s->buf_end)
00384             return *s->buf_ptr++;
00385         else
00386             return URL_EOF;
00387     }
00388 }
00389 
00390 int get_buffer(ByteIOContext *s, unsigned char *buf, int size)
00391 {
00392     int len, size1;
00393 
00394     size1 = size;
00395     while (size > 0) {
00396         len = s->buf_end - s->buf_ptr;
00397         if (len > size)
00398             len = size;
00399         if (len == 0) {
00400             if(size > s->buffer_size && !s->update_checksum){
00401                 if(s->read_packet)
00402                     len = s->read_packet(s->opaque, buf, size);
00403                 if (len <= 0) {
00404                     /* do not modify buffer if EOF reached so that a seek back can
00405                     be done without rereading data */
00406                     s->eof_reached = 1;
00407                     if(len<0)
00408                         s->error= len;
00409                     break;
00410                 } else {
00411                     s->pos += len;
00412                     size -= len;
00413                     buf += len;
00414                     s->buf_ptr = s->buffer;
00415                     s->buf_end = s->buffer/* + len*/;
00416                 }
00417             }else{
00418                 fill_buffer(s);
00419                 len = s->buf_end - s->buf_ptr;
00420                 if (len == 0)
00421                     break;
00422             }
00423         } else {
00424             memcpy(buf, s->buf_ptr, len);
00425             buf += len;
00426             s->buf_ptr += len;
00427             size -= len;
00428         }
00429     }
00430     if (size1 == size) {
00431         if (url_ferror(s)) return url_ferror(s);
00432         if (url_feof(s))   return AVERROR_EOF;
00433     }
00434     return size1 - size;
00435 }
00436 
00437 int get_partial_buffer(ByteIOContext *s, unsigned char *buf, int size)
00438 {
00439     int len;
00440 
00441     if(size<0)
00442         return -1;
00443 
00444     len = s->buf_end - s->buf_ptr;
00445     if (len == 0) {
00446         fill_buffer(s);
00447         len = s->buf_end - s->buf_ptr;
00448     }
00449     if (len > size)
00450         len = size;
00451     memcpy(buf, s->buf_ptr, len);
00452     s->buf_ptr += len;
00453     if (!len) {
00454         if (url_ferror(s)) return url_ferror(s);
00455         if (url_feof(s))   return AVERROR_EOF;
00456     }
00457     return len;
00458 }
00459 
00460 unsigned int get_le16(ByteIOContext *s)
00461 {
00462     unsigned int val;
00463     val = get_byte(s);
00464     val |= get_byte(s) << 8;
00465     return val;
00466 }
00467 
00468 unsigned int get_le24(ByteIOContext *s)
00469 {
00470     unsigned int val;
00471     val = get_le16(s);
00472     val |= get_byte(s) << 16;
00473     return val;
00474 }
00475 
00476 unsigned int get_le32(ByteIOContext *s)
00477 {
00478     unsigned int val;
00479     val = get_le16(s);
00480     val |= get_le16(s) << 16;
00481     return val;
00482 }
00483 
00484 uint64_t get_le64(ByteIOContext *s)
00485 {
00486     uint64_t val;
00487     val = (uint64_t)get_le32(s);
00488     val |= (uint64_t)get_le32(s) << 32;
00489     return val;
00490 }
00491 
00492 unsigned int get_be16(ByteIOContext *s)
00493 {
00494     unsigned int val;
00495     val = get_byte(s) << 8;
00496     val |= get_byte(s);
00497     return val;
00498 }
00499 
00500 unsigned int get_be24(ByteIOContext *s)
00501 {
00502     unsigned int val;
00503     val = get_be16(s) << 8;
00504     val |= get_byte(s);
00505     return val;
00506 }
00507 unsigned int get_be32(ByteIOContext *s)
00508 {
00509     unsigned int val;
00510     val = get_be16(s) << 16;
00511     val |= get_be16(s);
00512     return val;
00513 }
00514 
00515 char *get_strz(ByteIOContext *s, char *buf, int maxlen)
00516 {
00517     int i = 0;
00518     char c;
00519 
00520     while ((c = get_byte(s))) {
00521         if (i < maxlen-1)
00522             buf[i++] = c;
00523     }
00524 
00525     buf[i] = 0; /* Ensure null terminated, but may be truncated */
00526 
00527     return buf;
00528 }
00529 
00530 uint64_t get_be64(ByteIOContext *s)
00531 {
00532     uint64_t val;
00533     val = (uint64_t)get_be32(s) << 32;
00534     val |= (uint64_t)get_be32(s);
00535     return val;
00536 }
00537 
00538 uint64_t ff_get_v(ByteIOContext *bc){
00539     uint64_t val = 0;
00540     int tmp;
00541 
00542     do{
00543         tmp = get_byte(bc);
00544         val= (val<<7) + (tmp&127);
00545     }while(tmp&128);
00546     return val;
00547 }
00548 
00549 int url_fdopen(ByteIOContext **s, URLContext *h)
00550 {
00551     uint8_t *buffer;
00552     int buffer_size, max_packet_size;
00553 
00554     max_packet_size = url_get_max_packet_size(h);
00555     if (max_packet_size) {
00556         buffer_size = max_packet_size; /* no need to bufferize more than one packet */
00557     } else {
00558         buffer_size = IO_BUFFER_SIZE;
00559     }
00560     buffer = av_malloc(buffer_size);
00561     if (!buffer)
00562         return AVERROR(ENOMEM);
00563 
00564     *s = av_mallocz(sizeof(ByteIOContext));
00565     if(!*s) {
00566         av_free(buffer);
00567         return AVERROR(ENOMEM);
00568     }
00569 
00570     if (init_put_byte(*s, buffer, buffer_size,
00571                       (h->flags & URL_WRONLY || h->flags & URL_RDWR), h,
00572                       url_read, url_write, url_seek) < 0) {
00573         av_free(buffer);
00574         av_freep(s);
00575         return AVERROR(EIO);
00576     }
00577     (*s)->is_streamed = h->is_streamed;
00578     (*s)->max_packet_size = max_packet_size;
00579     if(h->prot) {
00580         (*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
00581         (*s)->read_seek  = (int64_t (*)(void *, int, int64_t, int))h->prot->url_read_seek;
00582     }
00583     return 0;
00584 }
00585 
00586 int url_setbufsize(ByteIOContext *s, int buf_size)
00587 {
00588     uint8_t *buffer;
00589     buffer = av_malloc(buf_size);
00590     if (!buffer)
00591         return AVERROR(ENOMEM);
00592 
00593     av_free(s->buffer);
00594     s->buffer = buffer;
00595     s->buffer_size = buf_size;
00596     s->buf_ptr = buffer;
00597     url_resetbuf(s, s->write_flag ? URL_WRONLY : URL_RDONLY);
00598     return 0;
00599 }
00600 
00601 #if LIBAVFORMAT_VERSION_MAJOR < 53
00602 int url_resetbuf(ByteIOContext *s, int flags)
00603 #else
00604 static int url_resetbuf(ByteIOContext *s, int flags)
00605 #endif
00606 {
00607 #if LIBAVFORMAT_VERSION_MAJOR < 53
00608     URLContext *h = s->opaque;
00609     if ((flags & URL_RDWR) || (h && h->flags != flags && !h->flags & URL_RDWR))
00610         return AVERROR(EINVAL);
00611 #else
00612     assert(flags == URL_WRONLY || flags == URL_RDONLY);
00613 #endif
00614 
00615     if (flags & URL_WRONLY) {
00616         s->buf_end = s->buffer + s->buffer_size;
00617         s->write_flag = 1;
00618     } else {
00619         s->buf_end = s->buffer;
00620         s->write_flag = 0;
00621     }
00622     return 0;
00623 }
00624 
00625 int ff_rewind_with_probe_data(ByteIOContext *s, unsigned char *buf, int buf_size)
00626 {
00627     int64_t buffer_start;
00628     int buffer_size;
00629     int overlap, new_size;
00630 
00631     if (s->write_flag)
00632         return AVERROR(EINVAL);
00633 
00634     buffer_size = s->buf_end - s->buffer;
00635 
00636     /* the buffers must touch or overlap */
00637     if ((buffer_start = s->pos - buffer_size) > buf_size)
00638         return AVERROR(EINVAL);
00639 
00640     overlap = buf_size - buffer_start;
00641     new_size = buf_size + buffer_size - overlap;
00642 
00643     if (new_size > buf_size) {
00644         if (!(buf = av_realloc(buf, new_size)))
00645             return AVERROR(ENOMEM);
00646 
00647         memcpy(buf + buf_size, s->buffer + overlap, buffer_size - overlap);
00648         buf_size = new_size;
00649     }
00650 
00651     av_free(s->buffer);
00652     s->buf_ptr = s->buffer = buf;
00653     s->pos = s->buffer_size = buf_size;
00654     s->buf_end = s->buf_ptr + buf_size;
00655     s->eof_reached = 0;
00656     s->must_flush = 0;
00657 
00658     return 0;
00659 }
00660 
00661 int url_fopen(ByteIOContext **s, const char *filename, int flags)
00662 {
00663     URLContext *h;
00664     int err;
00665 
00666     err = url_open(&h, filename, flags);
00667     if (err < 0)
00668         return err;
00669     err = url_fdopen(s, h);
00670     if (err < 0) {
00671         url_close(h);
00672         return err;
00673     }
00674     return 0;
00675 }
00676 
00677 int url_fclose(ByteIOContext *s)
00678 {
00679     URLContext *h = s->opaque;
00680 
00681     av_free(s->buffer);
00682     av_free(s);
00683     return url_close(h);
00684 }
00685 
00686 URLContext *url_fileno(ByteIOContext *s)
00687 {
00688     return s->opaque;
00689 }
00690 
00691 #if CONFIG_MUXERS
00692 int url_fprintf(ByteIOContext *s, const char *fmt, ...)
00693 {
00694     va_list ap;
00695     char buf[4096];
00696     int ret;
00697 
00698     va_start(ap, fmt);
00699     ret = vsnprintf(buf, sizeof(buf), fmt, ap);
00700     va_end(ap);
00701     put_buffer(s, buf, strlen(buf));
00702     return ret;
00703 }
00704 #endif //CONFIG_MUXERS
00705 
00706 char *url_fgets(ByteIOContext *s, char *buf, int buf_size)
00707 {
00708     int c;
00709     char *q;
00710 
00711     c = url_fgetc(s);
00712     if (c == EOF)
00713         return NULL;
00714     q = buf;
00715     for(;;) {
00716         if (c == EOF || c == '\n')
00717             break;
00718         if ((q - buf) < buf_size - 1)
00719             *q++ = c;
00720         c = url_fgetc(s);
00721     }
00722     if (buf_size > 0)
00723         *q = '\0';
00724     return buf;
00725 }
00726 
00727 int url_fget_max_packet_size(ByteIOContext *s)
00728 {
00729     return s->max_packet_size;
00730 }
00731 
00732 int av_url_read_fpause(ByteIOContext *s, int pause)
00733 {
00734     if (!s->read_pause)
00735         return AVERROR(ENOSYS);
00736     return s->read_pause(s->opaque, pause);
00737 }
00738 
00739 int64_t av_url_read_fseek(ByteIOContext *s, int stream_index,
00740                           int64_t timestamp, int flags)
00741 {
00742     URLContext *h = s->opaque;
00743     int64_t ret;
00744     if (!s->read_seek)
00745         return AVERROR(ENOSYS);
00746     ret = s->read_seek(h, stream_index, timestamp, flags);
00747     if(ret >= 0) {
00748         int64_t pos;
00749         s->buf_ptr = s->buf_end; // Flush buffer
00750         pos = s->seek(h, 0, SEEK_CUR);
00751         if (pos >= 0)
00752             s->pos = pos;
00753         else if (pos != AVERROR(ENOSYS))
00754             ret = pos;
00755     }
00756     return ret;
00757 }
00758 
00759 /* url_open_dyn_buf and url_close_dyn_buf are used in rtp.c to send a response
00760  * back to the server even if CONFIG_MUXERS is false. */
00761 #if CONFIG_MUXERS || CONFIG_NETWORK
00762 /* buffer handling */
00763 int url_open_buf(ByteIOContext **s, uint8_t *buf, int buf_size, int flags)
00764 {
00765     int ret;
00766     *s = av_mallocz(sizeof(ByteIOContext));
00767     if(!*s)
00768         return AVERROR(ENOMEM);
00769     ret = init_put_byte(*s, buf, buf_size,
00770                         (flags & URL_WRONLY || flags & URL_RDWR),
00771                         NULL, NULL, NULL, NULL);
00772     if(ret != 0)
00773         av_freep(s);
00774     return ret;
00775 }
00776 
00777 int url_close_buf(ByteIOContext *s)
00778 {
00779     put_flush_packet(s);
00780     return s->buf_ptr - s->buffer;
00781 }
00782 
00783 /* output in a dynamic buffer */
00784 
00785 typedef struct DynBuffer {
00786     int pos, size, allocated_size;
00787     uint8_t *buffer;
00788     int io_buffer_size;
00789     uint8_t io_buffer[1];
00790 } DynBuffer;
00791 
00792 static int dyn_buf_write(void *opaque, uint8_t *buf, int buf_size)
00793 {
00794     DynBuffer *d = opaque;
00795     unsigned new_size, new_allocated_size;
00796 
00797     /* reallocate buffer if needed */
00798     new_size = d->pos + buf_size;
00799     new_allocated_size = d->allocated_size;
00800     if(new_size < d->pos || new_size > INT_MAX/2)
00801         return -1;
00802     while (new_size > new_allocated_size) {
00803         if (!new_allocated_size)
00804             new_allocated_size = new_size;
00805         else
00806             new_allocated_size += new_allocated_size / 2 + 1;
00807     }
00808 
00809     if (new_allocated_size > d->allocated_size) {
00810         d->buffer = av_realloc(d->buffer, new_allocated_size);
00811         if(d->buffer == NULL)
00812              return AVERROR(ENOMEM);
00813         d->allocated_size = new_allocated_size;
00814     }
00815     memcpy(d->buffer + d->pos, buf, buf_size);
00816     d->pos = new_size;
00817     if (d->pos > d->size)
00818         d->size = d->pos;
00819     return buf_size;
00820 }
00821 
00822 static int dyn_packet_buf_write(void *opaque, uint8_t *buf, int buf_size)
00823 {
00824     unsigned char buf1[4];
00825     int ret;
00826 
00827     /* packetized write: output the header */
00828     AV_WB32(buf1, buf_size);
00829     ret= dyn_buf_write(opaque, buf1, 4);
00830     if(ret < 0)
00831         return ret;
00832 
00833     /* then the data */
00834     return dyn_buf_write(opaque, buf, buf_size);
00835 }
00836 
00837 static int64_t dyn_buf_seek(void *opaque, int64_t offset, int whence)
00838 {
00839     DynBuffer *d = opaque;
00840 
00841     if (whence == SEEK_CUR)
00842         offset += d->pos;
00843     else if (whence == SEEK_END)
00844         offset += d->size;
00845     if (offset < 0 || offset > 0x7fffffffLL)
00846         return -1;
00847     d->pos = offset;
00848     return 0;
00849 }
00850 
00851 static int url_open_dyn_buf_internal(ByteIOContext **s, int max_packet_size)
00852 {
00853     DynBuffer *d;
00854     int ret;
00855     unsigned io_buffer_size = max_packet_size ? max_packet_size : 1024;
00856 
00857     if(sizeof(DynBuffer) + io_buffer_size < io_buffer_size)
00858         return -1;
00859     d = av_mallocz(sizeof(DynBuffer) + io_buffer_size);
00860     if (!d)
00861         return AVERROR(ENOMEM);
00862     *s = av_mallocz(sizeof(ByteIOContext));
00863     if(!*s) {
00864         av_free(d);
00865         return AVERROR(ENOMEM);
00866     }
00867     d->io_buffer_size = io_buffer_size;
00868     ret = init_put_byte(*s, d->io_buffer, io_buffer_size,
00869                         1, d, NULL,
00870                         max_packet_size ? dyn_packet_buf_write : dyn_buf_write,
00871                         max_packet_size ? NULL : dyn_buf_seek);
00872     if (ret == 0) {
00873         (*s)->max_packet_size = max_packet_size;
00874     } else {
00875         av_free(d);
00876         av_freep(s);
00877     }
00878     return ret;
00879 }
00880 
00881 int url_open_dyn_buf(ByteIOContext **s)
00882 {
00883     return url_open_dyn_buf_internal(s, 0);
00884 }
00885 
00886 int url_open_dyn_packet_buf(ByteIOContext **s, int max_packet_size)
00887 {
00888     if (max_packet_size <= 0)
00889         return -1;
00890     return url_open_dyn_buf_internal(s, max_packet_size);
00891 }
00892 
00893 int url_close_dyn_buf(ByteIOContext *s, uint8_t **pbuffer)
00894 {
00895     DynBuffer *d = s->opaque;
00896     int size;
00897 
00898     put_flush_packet(s);
00899 
00900     *pbuffer = d->buffer;
00901     size = d->size;
00902     av_free(d);
00903     av_free(s);
00904     return size;
00905 }
00906 #endif /* CONFIG_MUXERS || CONFIG_NETWORK */

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