standardize and improve lookup rules for external local repos

When you specify a local repository on the command line of
clone, ls-remote, upload-pack, receive-pack, or upload-archive,
or in a request to git-daemon, we perform a little bit of
lookup magic, doing things like looking in working trees for
.git directories and appending ".git" for bare repos.

For clone, this magic happens in get_repo_path. For
everything else, it happens in enter_repo. In both cases,
there are some ambiguous or confusing cases that aren't
handled well, and there is one case that is not handled the
same by both methods.

This patch tries to provide (and test!) standard, sensible
lookup rules for both code paths. The intended changes are:

  1. When looking up "foo", we have always preferred
     a working tree "foo" (containing "foo/.git" over the
     bare "foo.git". But we did not prefer a bare "foo" over
     "foo.git". With this patch, we do so.

  2. We would select directories that existed but didn't
     actually look like git repositories. With this patch,
     we make sure a selected directory looks like a git
     repo. Not only is this more sensible in general, but it
     will help anybody who is negatively affected by change
     (1) negatively (e.g., if they had "foo.git" next to its
     separate work tree "foo", and expect to keep finding
     "foo.git" when they reference "foo").

  3. The enter_repo code path would, given "foo", look for
     "foo.git/.git" (i.e., do the ".git" append magic even
     for a repo with working tree). The clone code path did
     not; with this patch, they now behave the same.

In the unlikely case of a working tree overlaying a bare
repo (i.e., a ".git" directory _inside_ a bare repo), we
continue to treat it as a working tree (prefering the
"inner" .git over the bare repo). This is mainly because the
combination seems nonsensical, and I'd rather stick with
existing behavior on the off chance that somebody is relying
on it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

5 files changed, 109 insertions, 5 deletions

diff --git a/builtin/clone.c b/builtin/clone.c
index efe8b6cce5..b11dd6dd61 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -105,7 +105,7 @@ static const char *argv_submodule[] = {
 
 static char *get_repo_path(const char *repo, int *is_bundle)
 {
-	static char *suffix[] = { "/.git", ".git", "" };
+	static char *suffix[] = { "/.git", "", ".git/.git", ".git" };
 	static char *bundle_suffix[] = { ".bundle", "" };
 	struct stat st;
 	int i;
@@ -115,7 +115,7 @@ static char *get_repo_path(const char *repo, int *is_bundle)
 		path = mkpath("%s%s", repo, suffix[i]);
 		if (stat(path, &st))
 			continue;
-		if (S_ISDIR(st.st_mode)) {
+		if (S_ISDIR(st.st_mode) && is_git_directory(path)) {
 			*is_bundle = 0;
 			return xstrdup(absolute_path(path));
 		} else if (S_ISREG(st.st_mode) && st.st_size > 8) {
diff --git a/cache.h b/cache.h
index 2e6ad3604e..3dfb95d8aa 100644
--- a/cache.h
+++ b/cache.h
@@ -432,6 +432,7 @@ extern char *git_work_tree_cfg;
 extern int is_inside_work_tree(void);
 extern int have_git_dir(void);
 extern const char *get_git_dir(void);
+extern int is_git_directory(const char *path);
 extern char *get_object_directory(void);
 extern char *get_index_file(void);
 extern char *get_graft_file(void);
diff --git a/path.c b/path.c
index b6f71d1086..6f2aa699ad 100644
--- a/path.c
+++ b/path.c
@@ -293,7 +293,7 @@ const char *enter_repo(const char *path, int strict)
 
 	if (!strict) {
 		static const char *suffix[] = {
-			".git/.git", "/.git", ".git", "", NULL,
+			"/.git", "", ".git/.git", ".git", NULL,
 		};
 		const char *gitfile;
 		int len = strlen(path);
@@ -324,8 +324,11 @@ const char *enter_repo(const char *path, int strict)
 			return NULL;
 		len = strlen(used_path);
 		for (i = 0; suffix[i]; i++) {
+			struct stat st;
 			strcpy(used_path + len, suffix[i]);
-			if (!access(used_path, F_OK)) {
+			if (!stat(used_path, &st) &&
+			    (S_ISREG(st.st_mode) ||
+			    (S_ISDIR(st.st_mode) && is_git_directory(used_path)))) {
 				strcat(validated_path, suffix[i]);
 				break;
 			}
diff --git a/setup.c b/setup.c
index 61c22e6bec..7a3618fab7 100644
--- a/setup.c
+++ b/setup.c
@@ -247,7 +247,7 @@ const char **get_pathspec(const char *prefix, const char **pathspec)
  *    a proper "ref:", or a regular file HEAD that has a properly
  *    formatted sha1 object name.
  */
-static int is_git_directory(const char *suspect)
+int is_git_directory(const char *suspect)
 {
 	char path[PATH_MAX];
 	size_t len = strlen(suspect);
diff --git a/t/t5900-repo-selection.sh b/t/t5900-repo-selection.sh
new file mode 100755
index 0000000000..3d5b418bb4
--- /dev/null
+++ b/t/t5900-repo-selection.sh
@@ -0,0 +1,100 @@
+#!/bin/sh
+
+test_description='selecting remote repo in ambiguous cases'
+. ./test-lib.sh
+
+reset() {
+	rm -rf foo foo.git fetch clone
+}
+
+make_tree() {
+	git init "$1" &&
+	(cd "$1" && test_commit "$1")
+}
+
+make_bare() {
+	git init --bare "$1" &&
+	(cd "$1" &&
+	 tree=`git hash-object -w -t tree /dev/null` &&
+	 commit=$(echo "$1" | git commit-tree $tree) &&
+	 git update-ref HEAD $commit
+	)
+}
+
+get() {
+	git init --bare fetch &&
+	(cd fetch && git fetch "../$1") &&
+	git clone "$1" clone
+}
+
+check() {
+	echo "$1" >expect &&
+	(cd fetch && git log -1 --format=%s FETCH_HEAD) >actual.fetch &&
+	(cd clone && git log -1 --format=%s HEAD) >actual.clone &&
+	test_cmp expect actual.fetch &&
+	test_cmp expect actual.clone
+}
+
+test_expect_success 'find .git dir in worktree' '
+	reset &&
+	make_tree foo &&
+	get foo &&
+	check foo
+'
+
+test_expect_success 'automagically add .git suffix' '
+	reset &&
+	make_bare foo.git &&
+	get foo &&
+	check foo.git
+'
+
+test_expect_success 'automagically add .git suffix to worktree' '
+	reset &&
+	make_tree foo.git &&
+	get foo &&
+	check foo.git
+'
+
+test_expect_success 'prefer worktree foo over bare foo.git' '
+	reset &&
+	make_tree foo &&
+	make_bare foo.git &&
+	get foo &&
+	check foo
+'
+
+test_expect_success 'prefer bare foo over bare foo.git' '
+	reset &&
+	make_bare foo &&
+	make_bare foo.git &&
+	get foo &&
+	check foo
+'
+
+test_expect_success 'disambiguate with full foo.git' '
+	reset &&
+	make_bare foo &&
+	make_bare foo.git &&
+	get foo.git &&
+	check foo.git
+'
+
+test_expect_success 'we are not fooled by non-git foo directory' '
+	reset &&
+	make_bare foo.git &&
+	mkdir foo &&
+	get foo &&
+	check foo.git
+'
+
+test_expect_success 'prefer inner .git over outer bare' '
+	reset &&
+	make_tree foo &&
+	make_bare foo.git &&
+	mv foo/.git foo.git &&
+	get foo.git &&
+	check foo
+'
+
+test_done