1. ffmpeg
  2. Commit 55815edca038997ec283569a192a3eca7f2143bc
Browse code

prefer avio_check() over url_exist()

The problem with url_exist() is that it tries to open a resource in
RDONLY mode. If the file is a FIFO and there is already a reading
client, the open() call will hang.

By using avio_check() with access mode of 0, the second reading
process will check if the file exists without attempting to open it,
thus avoiding the lock.

Fix issue #1663.

Signed-off-by: Anton Khirnov <anton@khirnov.net>

Stefano Sabatini authored on 2011/04/09 08:32:37
Showing 3 changed files
ffmpeg.c
History View file @ 55815ed
... ... 
@@ -3733,7 +3733,7 @@ static void opt_output_file(const char *filename)
3733 3733 
             (strchr(filename, ':') == NULL ||
3734 3734 
              filename[1] == ':' ||
3735 3735 
              av_strstart(filename, "file:", NULL))) {
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-            if (url_exist(filename)) {
3736 
+            if (avio_check(filename, 0) == 0) {
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                 if (!using_stdin) {
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                     fprintf(stderr,"File '%s' already exists. Overwrite ? [y/N] ", filename);
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                     fflush(stderr);
ffserver.c
History View file @ 55815ed
... ... 
@@ -3679,7 +3679,7 @@ static void build_feed_streams(void)
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     for(feed = first_feed; feed != NULL; feed = feed->next_feed) {
3680 3680 
         int fd;
3681 3681
3682 
-        if (url_exist(feed->feed_filename)) {
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+        if (avio_check(feed->feed_filename, AVIO_FLAG_READ) > 0) {
3683 3683 
             /* See if it matches */
3684 3684 
             AVFormatContext *s;
3685 3685 
             int matches = 0;
... ... 
@@ -3752,7 +3752,7 @@ static void build_feed_streams(void)
3752 3752 
                 unlink(feed->feed_filename);
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             }
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         }
3755 
-        if (!url_exist(feed->feed_filename)) {
3755 
+        if (avio_check(feed->feed_filename, AVIO_FLAG_WRITE) <= 0) {
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             AVFormatContext s1 = {0}, *s = &s1;
3757 3757
3758 3758 
             if (feed->readonly) {
libavformat/img2.c
History View file @ 55815ed
... ... 
@@ -131,11 +131,11 @@ static int find_image_range(int *pfirst_index, int *plast_index,
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         if (av_get_frame_filename(buf, sizeof(buf), path, first_index) < 0){
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             *pfirst_index =
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             *plast_index = 1;
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-            if(url_exist(buf))
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+            if (avio_check(buf, AVIO_FLAG_READ) > 0)
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                 return 0;
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             return -1;
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         }
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-        if (url_exist(buf))
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+        if (avio_check(buf, AVIO_FLAG_READ) > 0)
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             break;
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     }
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     if (first_index == 5)
... ... 
@@ -153,7 +153,7 @@ static int find_image_range(int *pfirst_index, int *plast_index,
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             if (av_get_frame_filename(buf, sizeof(buf), path,
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                                       last_index + range1) < 0)
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                 goto fail;
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-            if (!url_exist(buf))
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+            if (avio_check(buf, AVIO_FLAG_READ) <= 0)
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                 break;
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             range = range1;
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             /* just in case... */