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ffmpeg / libavformat / avio.c @ 0d9f8633

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/*
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 * Unbuffered io for ffmpeg system
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 * Copyright (c) 2001 Fabrice Bellard
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "avformat.h"
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static int default_interrupt_cb(void);
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URLProtocol *first_protocol = NULL;
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URLInterruptCB *url_interrupt_cb = default_interrupt_cb;
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int register_protocol(URLProtocol *protocol)
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{
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    URLProtocol **p;
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    p = &first_protocol;
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    while (*p != NULL) p = &(*p)->next;
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    *p = protocol;
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    protocol->next = NULL;
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    return 0;
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}
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int url_open(URLContext **puc, const char *filename, int flags)
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{
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    URLContext *uc;
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    URLProtocol *up;
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    const char *p;
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    char proto_str[128], *q;
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    int err;
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    p = filename;
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    q = proto_str;
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    while (*p != '\0' && *p != ':') {
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        /* protocols can only contain alphabetic chars */
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        if (!isalpha(*p))
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            goto file_proto;
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        if ((q - proto_str) < sizeof(proto_str) - 1)
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            *q++ = *p;
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        p++;
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    }
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    /* if the protocol has length 1, we consider it is a dos drive */
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    if (*p == '\0' || (q - proto_str) <= 1) {
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    file_proto:
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        strcpy(proto_str, "file");
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    } else {
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        *q = '\0';
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    }
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    up = first_protocol;
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    while (up != NULL) {
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        if (!strcmp(proto_str, up->name))
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            goto found;
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        up = up->next;
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    }
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    err = -ENOENT;
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    goto fail;
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 found:
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    uc = av_malloc(sizeof(URLContext) + strlen(filename) + 1);
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    if (!uc) {
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        err = -ENOMEM;
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        goto fail;
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    }
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#if LIBAVFORMAT_VERSION_INT >= (52<<16)
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    uc->filename = (char *) &uc[1];
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#endif
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    strcpy(uc->filename, filename);
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    uc->prot = up;
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    uc->flags = flags;
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    uc->is_streamed = 0; /* default = not streamed */
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    uc->max_packet_size = 0; /* default: stream file */
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    err = up->url_open(uc, filename, flags);
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    if (err < 0) {
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        av_free(uc);
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        *puc = NULL;
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        return err;
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    }
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    *puc = uc;
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    return 0;
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 fail:
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    *puc = NULL;
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    return err;
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}
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int url_read(URLContext *h, unsigned char *buf, int size)
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{
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    int ret;
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    if (h->flags & URL_WRONLY)
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        return AVERROR_IO;
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    ret = h->prot->url_read(h, buf, size);
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    return ret;
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}
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#if defined(CONFIG_MUXERS) || defined(CONFIG_PROTOCOLS)
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int url_write(URLContext *h, unsigned char *buf, int size)
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{
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    int ret;
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    if (!(h->flags & (URL_WRONLY | URL_RDWR)))
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        return AVERROR_IO;
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    /* avoid sending too big packets */
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    if (h->max_packet_size && size > h->max_packet_size)
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        return AVERROR_IO;
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    ret = h->prot->url_write(h, buf, size);
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    return ret;
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}
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#endif //CONFIG_MUXERS || CONFIG_PROTOCOLS
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offset_t url_seek(URLContext *h, offset_t pos, int whence)
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{
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    offset_t ret;
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    if (!h->prot->url_seek)
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        return -EPIPE;
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    ret = h->prot->url_seek(h, pos, whence);
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    return ret;
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}
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int url_close(URLContext *h)
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{
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    int ret;
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    ret = h->prot->url_close(h);
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    av_free(h);
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    return ret;
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}
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int url_exist(const char *filename)
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{
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    URLContext *h;
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    if (url_open(&h, filename, URL_RDONLY) < 0)
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        return 0;
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    url_close(h);
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    return 1;
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}
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offset_t url_filesize(URLContext *h)
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{
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    offset_t pos, size;
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    size= url_seek(h, 0, AVSEEK_SIZE);
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    if(size<0){
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        pos = url_seek(h, 0, SEEK_CUR);
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        if ((size = url_seek(h, -1, SEEK_END)) < 0)
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            return size;
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        size++;
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        url_seek(h, pos, SEEK_SET);
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    }
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    return size;
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}
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/*
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 * Return the maximum packet size associated to packetized file
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 * handle. If the file is not packetized (stream like http or file on
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 * disk), then 0 is returned.
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 *
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 * @param h file handle
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 * @return maximum packet size in bytes
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 */
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int url_get_max_packet_size(URLContext *h)
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{
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    return h->max_packet_size;
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}
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void url_get_filename(URLContext *h, char *buf, int buf_size)
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{
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    pstrcpy(buf, buf_size, h->filename);
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}
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static int default_interrupt_cb(void)
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{
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    return 0;
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}
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/**
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 * The callback is called in blocking functions to test regulary if
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 * asynchronous interruption is needed. -EINTR is returned in this
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 * case by the interrupted function. 'NULL' means no interrupt
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 * callback is given.
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 */
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void url_set_interrupt_cb(URLInterruptCB *interrupt_cb)
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{
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    if (!interrupt_cb)
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        interrupt_cb = default_interrupt_cb;
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    url_interrupt_cb = interrupt_cb;
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}