git checkout: do not allow switching to a tree-ish that is not a commit

diff --git a/builtin-merge-base.c b/builtin-merge-base.c
index 0108e22adee8b4de922a2b00b514dd4d4cf23c55..3382b1382a7dcbd525126a35209072da4b4d8041 100644 (file)
--- a/builtin-merge-base.c
+++ b/builtin-merge-base.c
@@ -20,15 +20,28 @@ static int show_merge_base(struct commit *rev1, struct commit *rev2, int show_al
 }
 
 static const char merge_base_usage[] =
-"git-merge-base [--all] <commit-id> <commit-id>";
+"git merge-base [--all] <commit-id> <commit-id>";
+
+static struct commit *get_commit_reference(const char *arg)
+{
+       unsigned char revkey[20];
+       struct commit *r;
+
+       if (get_sha1(arg, revkey))
+               die("Not a valid object name %s", arg);
+       r = lookup_commit_reference(revkey);
+       if (!r)
+               die("Not a valid commit name %s", arg);
+
+       return r;
+}
 
 int cmd_merge_base(int argc, const char **argv, const char *prefix)
 {
        struct commit *rev1, *rev2;
-       unsigned char rev1key[20], rev2key[20];
        int show_all = 0;
 
-       git_config(git_default_config);
+       git_config(git_default_config, NULL);
 
        while (1 < argc && argv[1][0] == '-') {
                const char *arg = argv[1];
@@ -40,13 +53,8 @@ int cmd_merge_base(int argc, const char **argv, const char *prefix)
        }
        if (argc != 3)
                usage(merge_base_usage);
-       if (get_sha1(argv[1], rev1key))
-               die("Not a valid object name %s", argv[1]);
-       if (get_sha1(argv[2], rev2key))
-               die("Not a valid object name %s", argv[2]);
-       rev1 = lookup_commit_reference(rev1key);
-       rev2 = lookup_commit_reference(rev2key);
-       if (!rev1 || !rev2)
-               return 1;
+       rev1 = get_commit_reference(argv[1]);
+       rev2 = get_commit_reference(argv[2]);
+
        return show_merge_base(rev1, rev2, show_all);
 }