[PATCH 2/3] Clean up builtin-update-ref's option parsing

["Karl Hasselström" <kha@treskal.com>]

builtin-update-ref's option parsing was somewhat tricky to follow,
especially if the -d option was given. This patch cleans it upp a bit
(including fixing an out-of-bounds argv access), at the expense of
making it a bit longer.

Signed-off-by: Karl Hasselström <kha@treskal.com>

---

 builtin-update-ref.c |   30 +++++++++++++++++-------------
 1 files changed, 17 insertions(+), 13 deletions(-)


diff --git a/builtin-update-ref.c b/builtin-update-ref.c
index e90737c..0d3eb8e 100644
--- a/builtin-update-ref.c
+++ b/builtin-update-ref.c
@@ -27,25 +27,29 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 	if (msg && !*msg)
 		die("Refusing to perform update with empty message.");
 
-	if (argc < 2 || argc > 3)
-		usage_with_options(git_update_ref_usage, options);
-	refname = argv[0];
-	value   = argv[1];
-	oldval  = argv[2];
-
-	if (get_sha1(value, sha1))
-		die("%s: not a valid SHA1", value);
-
 	if (delete) {
-		if (oldval)
+		if (argc != 2)
 			usage_with_options(git_update_ref_usage, options);
-		return delete_ref(refname, sha1);
+		refname = argv[0];
+		value = NULL;
+		oldval = argv[1];
+	} else {
+		if (argc < 2 || argc > 3)
+			usage_with_options(git_update_ref_usage, options);
+		refname = argv[0];
+		value = argv[1];
+		oldval = argc > 2 ? argv[2] : NULL;
 	}
 
+	if (value && *value && get_sha1(value, sha1))
+		die("%s: not a valid SHA1", value);
 	hashclr(oldsha1);
 	if (oldval && *oldval && get_sha1(oldval, oldsha1))
 		die("%s: not a valid old SHA1", oldval);
 
-	return update_ref(msg, refname, sha1, oldval ? oldsha1 : NULL,
-			  no_deref ? REF_NODEREF : 0, DIE_ON_ERR);
+	if (delete)
+		return delete_ref(refname, oldsha1);
+	else
+		return update_ref(msg, refname, sha1, oldval ? oldsha1 : NULL,
+				  no_deref ? REF_NODEREF : 0, DIE_ON_ERR);
 }