symbolic-ref -d: do not allow removal of HEAD

If you delete the symbolic-ref HEAD from a repository, Git no longer considers the repository valid, and even "git symbolic-ref HEAD refs/heads/master" would not be able to recover from that state (although "git init" can, but that is a sure sign that you are talking about a "broken" repository). In the spirit similar to afe5d3d5 ("symbolic ref: refuse non-ref targets in HEAD", 2009-01-29), forbid removal of HEAD to avoid corrupting a repository. Signed-off-by: Junio C Hamano <gitster@pobox.com>

Junio C Hamano committed Sep 1, 2016 at 15:38 UTC 12cfa792b8657cfd37523df83df0a83d987570a5
2 files changed +16 -7
builtin/symbolic-ref.c
+2
@@ -56,6 +56,8 @@ int cmd_symbolic_ref(int argc, const char **argv, const char *prefix)
56 ret = check_symref(argv[0], 1, 0, 0);
57 if (ret)
58 die("Cannot delete %s, not a symbolic ref", argv[0]);
59 + if (!strcmp(argv[0], "HEAD"))
60 + die("deleting '%s' is not allowed", argv[0]);
61 return delete_ref(argv[0], NULL, REF_NODEREF);
62 }
63
t/t1401-symbolic-ref.sh
+14 -7
@@ -33,18 +33,25 @@ test_expect_success 'symbolic-ref refuses bare sha1' '
33 '
34 reset_to_sane
35
36 -test_expect_success 'symbolic-ref deletes HEAD' '
37 - git symbolic-ref -d HEAD &&
36 +test_expect_success 'HEAD cannot be removed' '
37 + test_must_fail git symbolic-ref -d HEAD
38 +'
39 +
40 +reset_to_sane
41 +
42 +test_expect_success 'symbolic-ref can be deleted' '
43 + git symbolic-ref NOTHEAD refs/heads/foo &&
44 + git symbolic-ref -d NOTHEAD &&
45 test_path_is_file .git/refs/heads/foo &&
39 - test_path_is_missing .git/HEAD
46 + test_path_is_missing .git/NOTHEAD
47 '
48 reset_to_sane
49
43 -test_expect_success 'symbolic-ref deletes dangling HEAD' '
44 - git symbolic-ref HEAD refs/heads/missing &&
45 - git symbolic-ref -d HEAD &&
50 +test_expect_success 'symbolic-ref can delete dangling symref' '
51 + git symbolic-ref NOTHEAD refs/heads/missing &&
52 + git symbolic-ref -d NOTHEAD &&
53 test_path_is_missing .git/refs/heads/missing &&
47 - test_path_is_missing .git/HEAD
54 + test_path_is_missing .git/NOTHEAD
55 '
56 reset_to_sane
57