On Sat, Apr 9, 2011 at 2:10 AM, Anton Khirnov <an...@khirnov.net> wrote:
> From: Stefano Sabatini <stefano.sabatini-l...@poste.it>
>
> The problem with url_exist() is that it tries to open a file in RDONLY
> mode. If the file is a FIFO and there is a reading client, the open()
> call will hang, and the ffmpeg process will get stuck.
>
> Using avio_check() with no access mode of ~0 check if the file simply
> exists without attempting to open it, thus avoiding locks.
>
> Fix issue #1663.
> ---
> ffmpeg.c | 2 +-
> ffserver.c | 4 ++--
> libavformat/avio.c | 2 ++
> libavformat/avio.h | 3 +++
> libavformat/img2.c | 6 +++---
> 5 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/ffmpeg.c b/ffmpeg.c
> index 46adb9a..3cd887b 100644
> --- a/ffmpeg.c
> +++ b/ffmpeg.c
> @@ -3733,7 +3733,7 @@ static void opt_output_file(const char *filename)
> (strchr(filename, ':') == NULL ||
> filename[1] == ':' ||
> av_strstart(filename, "file:", NULL))) {
> - if (url_exist(filename)) {
> + if (avio_check(filename, 0) != AVERROR(ENOENT)) {
> if (!using_stdin) {
> fprintf(stderr,"File '%s' already exists. Overwrite ?
> [y/N] ", filename);
> fflush(stderr);
> diff --git a/ffserver.c b/ffserver.c
> index eab8ae2..dd8ed23 100644
> --- a/ffserver.c
> +++ b/ffserver.c
> @@ -3684,7 +3684,7 @@ static void build_feed_streams(void)
> for(feed = first_feed; feed != NULL; feed = feed->next_feed) {
> int fd;
>
> - if (url_exist(feed->feed_filename)) {
> + if (avio_check(feed->feed_filename, URL_RDONLY) > 0) {
> /* See if it matches */
> AVFormatContext *s;
> int matches = 0;
> @@ -3757,7 +3757,7 @@ static void build_feed_streams(void)
> unlink(feed->feed_filename);
> }
> }
> - if (!url_exist(feed->feed_filename)) {
> + if (avio_check(feed->feed_filename, URL_RDONLY) <= 0) {
> AVFormatContext s1 = {0}, *s = &s1;
>
> if (feed->readonly) {
> diff --git a/libavformat/avio.c b/libavformat/avio.c
> index ecc7f27..f811073 100644
> --- a/libavformat/avio.c
> +++ b/libavformat/avio.c
> @@ -365,6 +365,7 @@ int ffurl_close(URLContext *h)
> return ret;
> }
>
> +#if FF_API_OLD_AVIO
> int url_exist(const char *filename)
> {
> URLContext *h;
> @@ -373,6 +374,7 @@ int url_exist(const char *filename)
> ffurl_close(h);
> return 1;
> }
> +#endif
>
> int avio_check(const char *url, int flags)
> {
> diff --git a/libavformat/avio.h b/libavformat/avio.h
> index 823aa97..806822c 100644
> --- a/libavformat/avio.h
> +++ b/libavformat/avio.h
> @@ -119,11 +119,14 @@ attribute_deprecated int64_t
> av_url_read_seek(URLContext *h, int stream_index,
> attribute_deprecated void url_set_interrupt_cb(int (*interrupt_cb)(void));
> #endif
>
> +#if FF_API_OLD_AVIO
> /**
> * Return a non-zero value if the resource indicated by url
> * exists, 0 otherwise.
> */
> +attribute_deprecated
> int url_exist(const char *url);
> +#endif
>
> /**
> * Return a positive value if the resource indicated by url can be
> diff --git a/libavformat/img2.c b/libavformat/img2.c
> index 2b5d63b..917bae6 100644
> --- a/libavformat/img2.c
> +++ b/libavformat/img2.c
> @@ -131,11 +131,11 @@ static int find_image_range(int *pfirst_index, int
> *plast_index,
> if (av_get_frame_filename(buf, sizeof(buf), path, first_index) <
> 0){
> *pfirst_index =
> *plast_index = 1;
> - if(url_exist(buf))
> + if (avio_check(buf, URL_RDONLY) != AVERROR(ENOENT))
> return 0;
> return -1;
> }
> - if (url_exist(buf))
> + if (avio_check(buf, URL_RDONLY) != AVERROR(ENOENT))
> break;
> }
> if (first_index == 5)
> @@ -153,7 +153,7 @@ static int find_image_range(int *pfirst_index, int
> *plast_index,
> if (av_get_frame_filename(buf, sizeof(buf), path,
> last_index + range1) < 0)
> goto fail;
> - if (!url_exist(buf))
> + if (avio_check(buf, URL_RDONLY) == AVERROR(ENOENT))
> break;
> range = range1;
> /* just in case... */
>
Couldn't avio_check() return other error values?
> --
> 1.7.4.1
>
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> libav-devel@libav.org
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>
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