| /* |
| * Copyright (c) 2014 Nicolas George |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public License |
| * as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public License |
| * along with FFmpeg; if not, write to the Free Software Foundation, Inc., |
| * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include "libavutil/avassert.h" |
| #include "libavutil/avstring.h" |
| #include "libavutil/opt.h" |
| #include "avformat.h" |
| #include "url.h" |
| |
| typedef struct SubfileContext { |
| const AVClass *class; |
| URLContext *h; |
| int64_t start; |
| int64_t end; |
| int64_t pos; |
| } SubfileContext; |
| |
| #define OFFSET(field) offsetof(SubfileContext, field) |
| #define D AV_OPT_FLAG_DECODING_PARAM |
| |
| static const AVOption subfile_options[] = { |
| { "start", "start offset", OFFSET(start), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D }, |
| { "end", "end offset", OFFSET(end), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D }, |
| { NULL } |
| }; |
| |
| #undef OFFSET |
| #undef D |
| |
| static const AVClass subfile_class = { |
| .class_name = "subfile", |
| .item_name = av_default_item_name, |
| .option = subfile_options, |
| .version = LIBAVUTIL_VERSION_INT, |
| }; |
| |
| static int slave_seek(URLContext *h) |
| { |
| SubfileContext *c = h->priv_data; |
| int64_t ret; |
| |
| if ((ret = ffurl_seek(c->h, c->pos, SEEK_SET)) != c->pos) { |
| if (ret >= 0) |
| ret = AVERROR_BUG; |
| av_log(h, AV_LOG_ERROR, "Impossible to seek in file: %s\n", |
| av_err2str(ret)); |
| return ret; |
| } |
| return 0; |
| } |
| |
| static int subfile_open(URLContext *h, const char *filename, int flags, |
| AVDictionary **options) |
| { |
| SubfileContext *c = h->priv_data; |
| int ret; |
| |
| if (!c->end) |
| c->end = INT64_MAX; |
| |
| if (c->end <= c->start) { |
| av_log(h, AV_LOG_ERROR, "end before start\n"); |
| return AVERROR(EINVAL); |
| } |
| av_strstart(filename, "subfile:", &filename); |
| ret = ffurl_open_whitelist(&c->h, filename, flags, &h->interrupt_callback, |
| options, h->protocol_whitelist, h->protocol_blacklist, h); |
| if (ret < 0) |
| return ret; |
| c->pos = c->start; |
| if ((ret = slave_seek(h)) < 0) { |
| ffurl_closep(&c->h); |
| return ret; |
| } |
| return 0; |
| } |
| |
| static int subfile_close(URLContext *h) |
| { |
| SubfileContext *c = h->priv_data; |
| return ffurl_closep(&c->h); |
| } |
| |
| static int subfile_read(URLContext *h, unsigned char *buf, int size) |
| { |
| SubfileContext *c = h->priv_data; |
| int64_t rest = c->end - c->pos; |
| int ret; |
| |
| if (rest <= 0) |
| return AVERROR_EOF; |
| size = FFMIN(size, rest); |
| ret = ffurl_read(c->h, buf, size); |
| if (ret >= 0) |
| c->pos += ret; |
| return ret; |
| } |
| |
| static int64_t subfile_seek(URLContext *h, int64_t pos, int whence) |
| { |
| SubfileContext *c = h->priv_data; |
| int64_t new_pos, end; |
| int ret; |
| |
| if (whence == AVSEEK_SIZE || whence == SEEK_END) { |
| end = c->end; |
| if (end == INT64_MAX && (end = ffurl_seek(c->h, 0, AVSEEK_SIZE)) < 0) |
| return end; |
| } |
| |
| if (whence == AVSEEK_SIZE) |
| return end - c->start; |
| switch (whence) { |
| case SEEK_SET: |
| new_pos = c->start + pos; |
| break; |
| case SEEK_CUR: |
| new_pos = c->pos + pos; |
| break; |
| case SEEK_END: |
| new_pos = end + pos; |
| break; |
| } |
| if (new_pos < c->start) |
| return AVERROR(EINVAL); |
| c->pos = new_pos; |
| if ((ret = slave_seek(h)) < 0) |
| return ret; |
| return c->pos - c->start; |
| } |
| |
| const URLProtocol ff_subfile_protocol = { |
| .name = "subfile", |
| .url_open2 = subfile_open, |
| .url_read = subfile_read, |
| .url_seek = subfile_seek, |
| .url_close = subfile_close, |
| .priv_data_size = sizeof(SubfileContext), |
| .priv_data_class = &subfile_class, |
| .default_whitelist = "file", |
| }; |