maintenance: use 'git config --fixed-value'

When a repository's leading directories contain regex metacharacters,
the config calls for 'git maintenance register' and 'git maintenance
unregister' are not careful enough. Use the new --fixed-value option
to direct the config machinery to use exact string matches. This is a
more robust option than escaping these arguments in a piecemeal fashion.

For the test, require that we are not running on Windows since the '+'
and '*' characters are not allowed on that filesystem.

Reported-by: Emily Shaffer <[email protected]>
Reported-by: Jonathan Nieder <[email protected]>
Signed-off-by: Derrick Stolee <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: derrickstolee

builtin/gc.c

@@ -1462,7 +1462,8 @@ static int maintenance_register(void)
 		git_config_set("maintenance.strategy", "incremental");
 
 	config_get.git_cmd = 1;
-	strvec_pushl(&config_get.args, "config", "--global", "--get", "maintenance.repo",
+	strvec_pushl(&config_get.args, "config", "--global", "--get",
+		     "--fixed-value", "maintenance.repo",
 		     the_repository->worktree ? the_repository->worktree
 					      : the_repository->gitdir,
 			 NULL);
@@ -1493,7 +1494,7 @@ static int maintenance_unregister(void)
 
 	config_unset.git_cmd = 1;
 	strvec_pushl(&config_unset.args, "config", "--global", "--unset",
-		     "maintenance.repo",
+		     "--fixed-value", "maintenance.repo",
 		     the_repository->worktree ? the_repository->worktree
 					      : the_repository->gitdir,
 		     NULL);

t/t7900-maintenance.sh

@@ -404,6 +404,18 @@ test_expect_success 'register and unregister' '
 	test_cmp before actual
 '
 
+test_expect_success !MINGW 'register and unregister with regex metacharacters' '
+	META="a+b*c" &&
+	git init "$META" &&
+	git -C "$META" maintenance register &&
+	git config --get-all --show-origin maintenance.repo &&
+	git config --get-all --global --fixed-value \
+		maintenance.repo "$(pwd)/$META" &&
+	git -C "$META" maintenance unregister &&
+	test_must_fail git config --get-all --global --fixed-value \
+		maintenance.repo "$(pwd)/$META"
+'
+
 test_expect_success 'start from empty cron table' '
 	GIT_TEST_CRONTAB="test-tool crontab cron.txt" git maintenance start &&