[PATCH] revision.c: fix possible null pointer access

[Stefan Naewe <stefan.naewe@gmail.com>]

Two functions dereference a tree pointer before checking
if the pointer is valid. Fix that by doing the check first.

Signed-off-by: Stefan Naewe <stefan.naewe@gmail.com>
---
This has been reported through the CppHints newsletter (http://cpphints.com/hints/40)
but doesn't seem to have made its way to the ones who care (the git list
that is...)

 revision.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/revision.c b/revision.c
index 0fbb684..bb40179 100644
--- a/revision.c
+++ b/revision.c
@@ -104,7 +104,12 @@ static void mark_tree_contents_uninteresting(struct tree *tree)
 {
 	struct tree_desc desc;
 	struct name_entry entry;
-	struct object *obj = &tree->object;
+	struct object *obj;
+
+	if (!tree)
+		return;
+
+	obj = &tree->object;
 
 	if (!has_sha1_file(obj->sha1))
 		return;
@@ -135,10 +140,13 @@ static void mark_tree_contents_uninteresting(struct tree *tree)
 
 void mark_tree_uninteresting(struct tree *tree)
 {
-	struct object *obj = &tree->object;
+	struct object *obj;
 
 	if (!tree)
 		return;
+
+	obj = &tree->object;
+
 	if (obj->flags & UNINTERESTING)
 		return;
 	obj->flags |= UNINTERESTING;
-- 
2.6.3