avformat/file: seek back to initial position for fd protocol

So user's fd can be passed to libavformat multiple times in sequence
without changing the position.

Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
This commit is contained in:
Zhao Zhili 2023-12-19 00:42:39 +08:00
parent 287e22f745
commit 5c3d2177e7

View File

@ -98,6 +98,7 @@ typedef struct FileContext {
#if HAVE_DIRENT_H
DIR *dir;
#endif
int64_t initial_pos;
} FileContext;
static const AVOption file_options[] = {
@ -218,7 +219,12 @@ static int fd_dup(URLContext *h, int oldfd)
static int file_close(URLContext *h)
{
FileContext *c = h->priv_data;
int ret = close(c->fd);
int ret;
if (c->initial_pos >= 0 && !h->is_streamed)
lseek(c->fd, c->initial_pos, SEEK_SET);
ret = close(c->fd);
return (ret == -1) ? AVERROR(errno) : 0;
}
@ -286,6 +292,7 @@ static int file_open(URLContext *h, const char *filename, int flags)
av_strstart(filename, "file:", &filename);
c->initial_pos = -1;
if (flags & AVIO_FLAG_WRITE && flags & AVIO_FLAG_READ) {
access = O_CREAT | O_RDWR;
if (c->trunc)
@ -494,6 +501,11 @@ static int fd_open(URLContext *h, const char *filename, int flags)
if (c->fd == -1)
return AVERROR(errno);
if (h->is_streamed)
c->initial_pos = -1;
else
c->initial_pos = lseek(c->fd, 0, SEEK_CUR);
return 0;
}