[tracker] NB#185950 - Crash in gif extractor.

[Carlos Garnacho <carlosg src gnome org>]

commit 56877e9c7c53acf0ac5d90498909a0393da91e9d
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Aug 17 14:57:03 2010 +0200

    NB#185950 - Crash in gif extractor.
    
    Check for the first char before assuming the second is valid memory.

 src/tracker-extract/tracker-extract-gif.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/tracker-extract/tracker-extract-gif.c b/src/tracker-extract/tracker-extract-gif.c
index 7759489..c5a7693 100644
--- a/src/tracker-extract/tracker-extract-gif.c
+++ b/src/tracker-extract/tracker-extract-gif.c
@@ -138,7 +138,7 @@ read_metadata (TrackerSparqlBuilder *preupdate,
 					return;
 				}
 #if defined(HAVE_EXEMPI)
-				if (ExtData &&
+				if (ExtData && *ExtData &&
 				    strncmp(&ExtData[1],"XMP Data",8) == 0) {
 					while (ExtData != NULL && status == GIF_OK ) {
 						if ((status = DGifGetExtensionNext(gifFile, &ExtData)) == GIF_OK) {