git-cat-file: Make option parsing a little more flexible

This will make it easier to add newer options later.

Signed-off-by: Adam Roben <aroben@apple.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-cat-file.c

@@ -143,23 +143,41 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
 	return 0;
 }
 
+static const char cat_file_usage[] = "git-cat-file [-t|-s|-e|-p|<type>] <sha1>";
+
 int cmd_cat_file(int argc, const char **argv, const char *prefix)
 {
-	int opt;
-	const char *exp_type, *obj_name;
+	int i, opt = 0;
+	const char *exp_type = NULL, *obj_name = NULL;
 
 	git_config(git_default_config);
-	if (argc != 3)
-		usage("git-cat-file [-t|-s|-e|-p|<type>] <sha1>");
-	exp_type = argv[1];
-	obj_name = argv[2];
-
-	opt = 0;
-	if ( exp_type[0] == '-' ) {
-		opt = exp_type[1];
-		if ( !opt || exp_type[2] )
-			opt = -1; /* Not a single character option */
+
+	for (i = 1; i < argc; ++i) {
+		const char *arg = argv[i];
+
+		if (!strcmp(arg, "-t") || !strcmp(arg, "-s") || !strcmp(arg, "-e") || !strcmp(arg, "-p")) {
+			exp_type = arg;
+			opt = exp_type[1];
+			continue;
+		}
+
+		if (arg[0] == '-')
+			usage(cat_file_usage);
+
+		if (!exp_type) {
+			exp_type = arg;
+			continue;
+		}
+
+		if (obj_name)
+			usage(cat_file_usage);
+
+		obj_name = arg;
+		break;
 	}
 
+	if (!exp_type || !obj_name)
+		usage(cat_file_usage);
+
 	return cat_one_file(opt, exp_type, obj_name);
 }