[PATCH v3] Disallow empty section and variable names

[Libor Pechacek <lpechacek@suse.cz>]

It is possible to break your repository config by creating an invalid key.  The
config parser in turn chokes on it.

$ git init
Initialized empty Git repository in /tmp/gittest/.git/
$ git config .foo false
$ git config core.bare
fatal: bad config file line 6 in .git/config

This patch makes git-config reject keys which start or end with a dot, adds
tests for these cases and also fixes a typo in t5526-fetch-submodules, which
was exposed by the new check.

Signed-off-by: Libor Pechacek <lpechacek@suse.cz>
Cc: Johannes Sixt <j.sixt@viscovery.net>
---

Incoporated feedback from Johannes, introduced keylen local variable to improve
readability of the code.  Applies on top "Sanity-check config variable names".

 config.c                    |   10 ++++++++--
 t/t1300-repo-config.sh      |    4 ++++
 t/t5526-fetch-submodules.sh |    2 +-
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/config.c b/config.c
index fde91f5..5eb89a7 100644
--- a/config.c
+++ b/config.c
@@ -1113,6 +1113,7 @@ int git_config_set(const char *key, const char *value)
 int git_config_parse_key(const char *key, char **store_key, int *baselen_)
 {
 	int i, dot, baselen;
+	int keylen = strlen(key);
 	const char *last_dot = strrchr(key, '.');
 
 	/*
@@ -1120,11 +1121,16 @@ int git_config_parse_key(const char *key, char **store_key, int *baselen_)
 	 * key name separated by a dot, we have to know where the dot is.
 	 */
 
-	if (last_dot == NULL) {
+	if (last_dot == NULL || *key == '.') {
 		error("key does not contain a section: %s", key);
 		return -2;
 	}
 
+	if (keylen && key[keylen-1] == '.') {
+		error("key does not contain variable name: %s", key);
+		return -2;
+	}
+
 	baselen = last_dot - key;
 	if (baselen_)
 		*baselen_ = baselen;
@@ -1132,7 +1138,7 @@ int git_config_parse_key(const char *key, char **store_key, int *baselen_)
 	/*
 	 * Validate the key and while at it, lower case it for matching.
 	 */
-	*store_key = xmalloc(strlen(key) + 1);
+	*store_key = xmalloc(keylen + 1);
 
 	dot = 0;
 	for (i = 0; key[i]; i++) {
diff --git a/t/t1300-repo-config.sh b/t/t1300-repo-config.sh
index c3d91d1..53fb822 100755
--- a/t/t1300-repo-config.sh
+++ b/t/t1300-repo-config.sh
@@ -889,6 +889,10 @@ test_expect_success 'key sanity-checking' '
 	test_must_fail git config foo.1bar &&
 	test_must_fail git config foo."ba
 				z".bar &&
+	test_must_fail git config . false &&
+	test_must_fail git config .foo false &&
+	test_must_fail git config foo. false &&
+	test_must_fail git config .foo. false &&
 	git config foo.bar true &&
 	git config foo."ba =z".bar false
 '
diff --git a/t/t5526-fetch-submodules.sh b/t/t5526-fetch-submodules.sh
index 884a5e5..7106c6c 100755
--- a/t/t5526-fetch-submodules.sh
+++ b/t/t5526-fetch-submodules.sh
@@ -124,7 +124,7 @@ test_expect_success "--recurse-submodules overrides fetchRecurseSubmodules setti
 	(
 		cd downstream &&
 		git fetch --recurse-submodules >../actual.out 2>../actual.err &&
-		git config -f --unset .gitmodules submodule.submodule.fetchRecurseSubmodules true &&
+		git config -f .gitmodules --unset submodule.submodule.fetchRecurseSubmodules true &&
 		git config --unset submodule.submodule.fetchRecurseSubmodules
 	) &&
 	test_cmp expect.out actual.out &&
-- 
1.7.4.rc3.11.g863f7