setup: avoid double slashes when looking for HEAD

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/setup.c b/setup.c
index 98b8dee8b822f200c283085c36ea36b4ad54e354..600410777beea715c8d5c94279ef1efa532c1686 100644 (file)
--- a/setup.c
+++ b/setup.c
@@ -283,7 +283,9 @@ 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;