[brasero] One more safety test not to get a negative value for the position in the stream

[Philippe Rouquier <philippr src gnome org>]

commit 9f58acec014d2b78098e0829d975ecb2543dab66
Author: Philippe Rouquier <bonfire-app wanadoo fr>
Date:   Mon Sep 28 14:50:26 2009 +0200

    One more safety test not to get a negative value for the position in the stream
    That will avoid an infinite loop in some rare cases.

 libbrasero-utils/brasero-metadata.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/libbrasero-utils/brasero-metadata.c b/libbrasero-utils/brasero-metadata.c
index 1c81133..fb463f5 100644
--- a/libbrasero-utils/brasero-metadata.c
+++ b/libbrasero-utils/brasero-metadata.c
@@ -437,9 +437,12 @@ brasero_metadata_thumbnail (BraseroMetadata *self)
 
 	/* find the right position and move forward */
 	position = 15 * GST_SECOND;
-	while (position >= priv->info->len)
+	while (position > 0 && position >= priv->info->len)
 		position -= 5 * GST_SECOND;
 
+	if (position <= 0)
+		return FALSE;
+
 	gst_element_set_state (priv->pipeline, GST_STATE_PAUSED);
 
 	priv->snapshot_started = 1;