last-modified: verify revision argument is a commit-ish

Passing a non-committish revision to git-last-modified(1) triggers the
following BUG:

    git last-modified HEAD^{tree}
    BUG: builtin/last-modified.c:456: paths remaining beyond boundary in last-modified

Fix this error by ensuring that the given revision peels to a commit.

Reported-by: Gusted <[email protected]>
Signed-off-by: Toon Claes <[email protected]>

Author: To1ne

builtin/last-modified.c

@@ -150,6 +150,11 @@ static int populate_paths_from_revs(struct last_modified *lm)
 			goto out;
 		}
 
+		if (!repo_peel_to_type(lm->rev.repo, obj->path, 0, obj->item, OBJ_COMMIT)) {
+			ret = error(_("revision argument '%s' is a %s, not a commit-ish"), obj->name, type_name(obj->item->type));
+			goto out;
+		}
+
 		diff_tree_oid(lm->rev.repo->hash_algo->empty_tree,
 			      &obj->item->oid, "", &diffopt);
 		diff_flush(&diffopt);

t/t8020-last-modified.sh

@@ -8,6 +8,7 @@ test_expect_success 'setup' '
 	test_commit 1 file &&
 	mkdir a &&
 	test_commit 2 a/file &&
+	git tag -mA t2 2 &&
 	mkdir a/b &&
 	test_commit 3 a/b/file
 '
@@ -51,6 +52,13 @@ test_expect_success 'last-modified recursive' '
 	EOF
 '
 
+test_expect_success 'last-modified on annotated tag' '
+	check_last_modified t2 <<-\EOF
+	2 a
+	1 file
+	EOF
+'
+
 test_expect_success 'last-modified recursive with show-trees' '
 	check_last_modified -r -t <<-\EOF
 	3 a/b
@@ -236,4 +244,9 @@ test_expect_success 'last-modified complains about unknown arguments' '
 	test_grep "unknown last-modified argument: --foo" err
 '
 
+test_expect_success 'last-modified expects commit-ish' '
+	test_must_fail git last-modified HEAD^{tree} 2>err &&
+	grep "revision argument '"'"'HEAD^{tree}'"'"' is a tree, not a commit-ish" err
+'
+
 test_done