[PATCH] fsck: warn about ".git" in trees

[Jeff King <peff@peff.net>]

On Wed, Nov 28, 2012 at 01:25:05PM -0800, Junio C Hamano wrote:

> >> * jk/fsck-dot-in-trees (2012-11-28) 1 commit
> >>  - fsck: warn about '.' and '..' in trees
> >> 
> >>  Will merge to 'next'.
> >
> > Do you have an opinion on warning about '.git', as well? It probably
> > would make more sense as a patch on top, but I thought I'd ask before
> > this got merged to next.
> 
> Yeah, it would make sense to reject what we would not record
> ourselves when the tools are used in a sane manner.

Here's the patch on top of jk/fsck-dot-in-trees.

-- >8 --
Subject: [PATCH] fsck: warn about ".git" in trees

Having a ".git" entry inside a tree can cause confusing
results on checkout. At the top-level, you could not
checkout such a tree, as it would complain about overwriting
the real ".git" directory. In a subdirectory, you might
check it out, but performing operations in the subdirectory
would confusingly consider the in-tree ".git" directory as
the repository.

The regular git tools already make it hard to accidentally
add such an entry to a tree, and do not allow such entries
to enter the index at all. Teaching fsck about it provides
an additional safety check, and let's us avoid propagating
any such bogosity when transfer.fsckObjects is on.

Signed-off-by: Jeff King <peff@peff.net>
---
 fsck.c          |  5 +++++
 t/t1450-fsck.sh | 15 +++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/fsck.c b/fsck.c
index 31c9a51..99c0497 100644
--- a/fsck.c
+++ b/fsck.c
@@ -144,6 +144,7 @@ static int fsck_tree(struct tree *item, int strict, fsck_error error_func)
 	int has_empty_name = 0;
 	int has_dot = 0;
 	int has_dotdot = 0;
+	int has_dotgit = 0;
 	int has_zero_pad = 0;
 	int has_bad_modes = 0;
 	int has_dup_entries = 0;
@@ -174,6 +175,8 @@ static int fsck_tree(struct tree *item, int strict, fsck_error error_func)
 			has_dot = 1;
 		if (!strcmp(name, ".."))
 			has_dotdot = 1;
+		if (!strcmp(name, ".git"))
+			has_dotgit = 1;
 		has_zero_pad |= *(char *)desc.buffer == '0';
 		update_tree_entry(&desc);
 
@@ -227,6 +230,8 @@ static int fsck_tree(struct tree *item, int strict, fsck_error error_func)
 		retval += error_func(&item->object, FSCK_WARN, "contains '.'");
 	if (has_dotdot)
 		retval += error_func(&item->object, FSCK_WARN, "contains '..'");
+	if (has_dotgit)
+		retval += error_func(&item->object, FSCK_WARN, "contains '.git'");
 	if (has_zero_pad)
 		retval += error_func(&item->object, FSCK_WARN, "contains zero-padded file modes");
 	if (has_bad_modes)
diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh
index 0b5c30b..d730734 100755
--- a/t/t1450-fsck.sh
+++ b/t/t1450-fsck.sh
@@ -253,4 +253,19 @@ test_expect_success 'fsck notices "." and ".." in trees' '
 	)
 '
 
+test_expect_success 'fsck notices ".git" in trees' '
+	(
+		git init dotgit &&
+		cd dotgit &&
+		blob=$(echo foo | git hash-object -w --stdin) &&
+		tab=$(printf "\\t") &&
+		git mktree <<-EOF &&
+		100644 blob $blob$tab.git
+		EOF
+		git fsck 2>out &&
+		cat out &&
+		grep "warning.*\\.git" out
+	)
+'
+
 test_done
-- 
1.8.0.207.gdf2154c