stream: don't try to read from all-sparse/no-data files

 ```
 dd if=/dev/zero of=/tmp/10g.empty bs=1 seek=10G count=0
 dd if=/dev/zero of=/tmp/10m.empty bs=1 seek=10M count=0
 time mpv /tmp/10{g,m}.empty
 ```

 I keep files with the name format `${name}-${hash}.${ext}.empty`
 around, where the original is removed, and a sparse file with
 the size of the original is created instead.

 A lot of time is wasted on such files when going through
 playlists/directories that include some of them.

 This admittedly may not be that common of a use-case.

Signed-off-by: Mohammad AlSaleh <CE.Mohammad.AlSaleh@gmail.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/stream/stream_file.c b/stream/stream_file.c
index 1744fc13a4..0a6a697ff6 100644
--- a/stream/stream_file.c
+++ b/stream/stream_file.c
@@ -358,6 +358,17 @@ static int open_f(stream_t *stream, const struct stream_open_args *args)
     setmode(p->fd, O_BINARY);
 #endif
 
+#if HAVE_SEEK_DATA
+    if (stream->mode == STREAM_READ) {
+        off_t first_data = lseek(p->fd, 0, SEEK_DATA);
+        if (first_data == (off_t)-1 && errno == ENXIO) {
+            MP_ERR(stream, "File is empty or all sparse (has no data).\n");
+            s_close(stream);
+            return STREAM_ERROR;
+        }
+    }
+#endif
+
     off_t len = lseek(p->fd, 0, SEEK_END);
     lseek(p->fd, 0, SEEK_SET);
     if (len != (off_t)-1) {