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symbolic ref: refuse non-ref targets in HEAD

When calling "git symbolic-ref" it is easy to forget that the target must be a fully qualified ref. E.g., you might accidentally do: $ git symbolic-ref HEAD master Unfortunately, this is very difficult to recover from, because the bogus contents of HEAD make git believe we are no longer in a git repository (as is_git_dir explicitly checks for "^refs/heads/" in the HEAD target). So immediately trying to fix the situation doesn't work: $ git symbolic-ref HEAD refs/heads/master fatal: Not a git repository and one is left editing the .git/HEAD file manually. Furthermore, one might be tempted to use symbolic-ref to set up a detached HEAD: $ git symbolic-ref HEAD `git rev-parse HEAD` which sets up an even more bogus HEAD: $ cat .git/HEAD ref: 1a9ace4f2ad4176148e61b5a85cd63d5604aac6d This patch introduces a small safety valve to prevent the specific case of anything not starting with refs/heads/ to go into HEAD. The scope of the safety valve is intentionally very limited, to make sure that we are not preventing any behavior that would otherwise be valid (like pointing a different symref than HEAD outside of refs/heads/). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Jan 29, 2009 at 03:33 UTC afe5d3d516114f08d3c4289682a704f5a7889909
2 files changed +44
builtin-symbolic-ref.c
+3
@@ -44,6 +44,9 @@ int cmd_symbolic_ref(int argc, const char **argv, const char *prefix)
44 check_symref(argv[0], quiet);
45 break;
46 case 2:
47 + if (!strcmp(argv[0], "HEAD") &&
48 + prefixcmp(argv[1], "refs/heads/"))
49 + die("Refusing to point HEAD outside of refs/heads/");
50 create_symref(argv[0], argv[1], msg);
51 break;
52 default:
t/t1401-symbolic-ref.sh new
+41
@@ -0,0 +1,41 @@
1 +#!/bin/sh
2 +
3 +test_description='basic symbolic-ref tests'
4 +. ./test-lib.sh
5 +
6 +# If the tests munging HEAD fail, they can break detection of
7 +# the git repo, meaning that further tests will operate on
8 +# the surrounding git repo instead of the trash directory.
9 +reset_to_sane() {
10 + echo ref: refs/heads/foo >.git/HEAD
11 +}
12 +
13 +test_expect_success 'symbolic-ref writes HEAD' '
14 + git symbolic-ref HEAD refs/heads/foo &&
15 + echo ref: refs/heads/foo >expect &&
16 + test_cmp expect .git/HEAD
17 +'
18 +
19 +test_expect_success 'symbolic-ref reads HEAD' '
20 + echo refs/heads/foo >expect &&
21 + git symbolic-ref HEAD >actual &&
22 + test_cmp expect actual
23 +'
24 +
25 +test_expect_success 'symbolic-ref refuses non-ref for HEAD' '
26 + test_must_fail git symbolic-ref HEAD foo
27 +'
28 +reset_to_sane
29 +
30 +test_expect_success 'symbolic-ref refuses non-branch for HEAD' '
31 + test_must_fail git symbolic-ref HEAD refs/foo
32 +'
33 +reset_to_sane
34 +
35 +test_expect_success 'symbolic-ref refuses bare sha1' '
36 + echo content >file && git add file && git commit -m one
37 + test_must_fail git symbolic-ref HEAD `git rev-parse HEAD`
38 +'
39 +reset_to_sane
40 +
41 +test_done