[PATCH] setup: avoid double slashes when looking for HEAD

Johannes Schindelin· Nov 3, 2017, 12:58 UTC · lore

From: Jeff King <peff@peff.net>

Andrew Baumann reported that when called outside of any Git worktree, `git rev-parse --is-inside-work-tree` eventually tries to access `//HEAD`, i.e. any `HEAD` file in the root directory, but with a double slash.

This double slash is not only unintentional, but is allowed by the POSIX standard to have a special meaning. And most notably on Windows, it does, where it refers to a UNC path of the form `//server/share/`.

As a consequence, afore-mentioned `rev-parse` call not only looks for the wrong thing, but it also causes serious delays, as Windows will try to access a server called `HEAD`. Let's simply avoid the unintended double slash.

Signed-off-by: Jeff King <peff@peff.net>
Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
Published-As: https://github.com/dscho/git/releases/tag/double-slash-HEAD-v1
Fetch-It-Via: git fetch https://github.com/dscho/git double-slash-HEAD-v1

	And here it is, as a proper, easy-to-pull branch, and also in the
	form Junio prefers.

 setup.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Show changes to setup.c +3 −1

diff --git a/setup.c b/setup.c
index 03f51e056cd..94768512b79 100644
--- a/setup.c
+++ b/setup.c
@@ -312,7 +312,9 @@ int is_git_directory(const char *suspect)
 	size_t len;
 
 	/* Check worktree-related signatures */
-	strbuf_addf(&path, "%s/HEAD", suspect);
+	strbuf_addstr(&path, suspect);
+	strbuf_complete(&path, '/');
+	strbuf_addstr(&path, "HEAD");
 	if (validate_headref(path.buf))
 		goto done;
 

base-commit: cb5918aa0d50f50e83787f65c2ddc3dcb10159fe

-- 
2.15.0.windows.1

Jeff King· Nov 3, 2017, 18:38 UTC · re: Johannes Schindelin · lore

Re: [PATCH] setup: avoid double slashes when looking for HEAD

On Fri, Nov 03, 2017 at 01:58:02PM +0100, Johannes Schindelin wrote:

Show 18 quoted lines

> From: Jeff King <peff@peff.net>
> 
> Andrew Baumann reported that when called outside of any Git worktree,
> `git rev-parse --is-inside-work-tree` eventually tries to access
> `//HEAD`, i.e.  any `HEAD` file in the root directory, but with a double
> slash.
> 
> This double slash is not only unintentional, but is allowed by the POSIX
> standard to have a special meaning. And most notably on Windows, it
> does, where it refers to a UNC path of the form `//server/share/`.
> 
> As a consequence, afore-mentioned `rev-parse` call not only looks for
> the wrong thing, but it also causes serious delays, as Windows will try
> to access a server called `HEAD`.  Let's simply avoid the unintended
> double slash.
> 
> Signed-off-by: Jeff King <peff@peff.net>
> Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Thanks, this explanation looks good to me (and the patch is flawless, of course ;) ).

-Peff

patchsetup: avoid double slashes when looking for HEAD