forked from KolibriOS/kolibrios
148 lines
3.9 KiB
C
148 lines
3.9 KiB
C
/*
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* Copyright (c) 2014 Nicolas George
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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 License
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* 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
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* GNU 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 License
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* along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/avassert.h"
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#include "libavutil/avstring.h"
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#include "libavutil/opt.h"
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#include "avformat.h"
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#include "url.h"
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typedef struct SubfileContext {
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const AVClass *class;
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URLContext *h;
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int64_t start;
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int64_t end;
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int64_t pos;
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} SubfileContext;
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#define OFFSET(field) offsetof(SubfileContext, field)
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#define D AV_OPT_FLAG_DECODING_PARAM
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static const AVOption subfile_options[] = {
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{ "start", "start offset", OFFSET(start), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D },
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{ "end", "end offset", OFFSET(end), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D },
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{ NULL }
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};
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#undef OFFSET
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#undef D
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static const AVClass subfile_class = {
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.class_name = "subfile",
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.item_name = av_default_item_name,
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.option = subfile_options,
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.version = LIBAVUTIL_VERSION_INT,
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};
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static int slave_seek(URLContext *h)
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{
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SubfileContext *c = h->priv_data;
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int64_t ret;
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if ((ret = ffurl_seek(c->h, c->pos, SEEK_SET)) != c->pos) {
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if (ret >= 0)
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ret = AVERROR_BUG;
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av_log(h, AV_LOG_ERROR, "Impossible to seek in file: %s\n",
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av_err2str(ret));
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return ret;
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}
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return 0;
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}
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static int subfile_open(URLContext *h, const char *filename, int flags,
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AVDictionary **options)
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{
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SubfileContext *c = h->priv_data;
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int ret;
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if (c->end <= c->start) {
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av_log(h, AV_LOG_ERROR, "end before start\n");
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return AVERROR(EINVAL);
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}
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av_strstart(filename, "subfile:", &filename);
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ret = ffurl_open(&c->h, filename, flags, &h->interrupt_callback, options);
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if (ret < 0)
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return ret;
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c->pos = c->start;
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if ((ret = slave_seek(h)) < 0) {
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ffurl_close(c->h);
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return ret;
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}
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return 0;
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}
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static int subfile_close(URLContext *h)
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{
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SubfileContext *c = h->priv_data;
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return ffurl_close(c->h);
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}
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static int subfile_read(URLContext *h, unsigned char *buf, int size)
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{
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SubfileContext *c = h->priv_data;
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int64_t rest = c->end - c->pos;
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int ret;
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if (rest <= 0)
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return 0;
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size = FFMIN(size, rest);
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ret = ffurl_read(c->h, buf, size);
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if (ret >= 0)
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c->pos += ret;
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return ret;
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}
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static int64_t subfile_seek(URLContext *h, int64_t pos, int whence)
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{
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SubfileContext *c = h->priv_data;
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int64_t new_pos = -1;
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int ret;
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if (whence == AVSEEK_SIZE)
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return c->end - c->start;
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switch (whence) {
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case SEEK_SET:
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new_pos = c->start + pos;
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break;
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case SEEK_CUR:
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new_pos += pos;
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break;
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case SEEK_END:
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new_pos = c->end + c->pos;
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break;
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}
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if (new_pos < c->start)
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return AVERROR(EINVAL);
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c->pos = new_pos;
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if ((ret = slave_seek(h)) < 0)
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return ret;
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return c->pos - c->start;
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}
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URLProtocol ff_subfile_protocol = {
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.name = "subfile",
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.url_open2 = subfile_open,
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.url_read = subfile_read,
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.url_seek = subfile_seek,
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.url_close = subfile_close,
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.priv_data_size = sizeof(SubfileContext),
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.priv_data_class = &subfile_class,
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};
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