remote: add meaningful exit code on missing/existing

Change the exit code for the likes of "git remote add/rename" to exit
with 2 if the remote in question doesn't exist, and 3 if it
does. Before we'd just die() and exit with the general 128 exit code.

This changes the output message from e.g.:

    fatal: remote origin already exists.

To:

    error: remote origin already exists.

Which I believe is a feature, since we generally use "fatal" for the
generic errors, and "error" for the more specific ones with a custom
exit code, but this part of the change may break code that already
relies on stderr parsing (not that we ever supported that...).

The motivation for this is a discussion around some code in GitLab's
gitaly which wanted to check this, and had to parse stderr to do so:
https://gitlab.com/gitlab-org/gitaly/-/merge_requests/2695

It's worth noting as an aside that a method of checking this that
doesn't rely on that is to check with "git config" whether the value
in question does or doesn't exist. That introduces a TOCTOU race
condition, but on the other hand this code (e.g. "git remote add")
already has a TOCTOU race.

We go through the config.lock for the actual setting of the config,
but the pseudocode logic is:

    read_config();
    check_config_and_arg_sanity();
    save_config();

So e.g. if a sleep() is added right after the remote_is_configured()
check in add() we'll clobber remote.NAME.url, and add another (usually
duplicate) remote.NAME.fetch entry (and other values, depending on
invocation).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/t/t5505-remote.sh b/t/t5505-remote.sh
index 8d62edd98b..c99659d39e 100755
--- a/t/t5505-remote.sh
+++ b/t/t5505-remote.sh
@@ -145,8 +145,8 @@ test_expect_success 'remove remote protects local branches' '
 test_expect_success 'remove errors out early when deleting non-existent branch' '
 	(
 		cd test &&
-		echo "fatal: No such remote: '\''foo'\''" >expect &&
-		test_must_fail git remote rm foo 2>actual &&
+		echo "error: No such remote: '\''foo'\''" >expect &&
+		test_expect_code 2 git remote rm foo 2>actual &&
 		test_i18ncmp expect actual
 	)
 '
@@ -173,24 +173,24 @@ test_expect_success 'remove remote with a branch without configured merge' '
 test_expect_success 'rename errors out early when deleting non-existent branch' '
 	(
 		cd test &&
-		echo "fatal: No such remote: '\''foo'\''" >expect &&
-		test_must_fail git remote rename foo bar 2>actual &&
+		echo "error: No such remote: '\''foo'\''" >expect &&
+		test_expect_code 2 git remote rename foo bar 2>actual &&
 		test_i18ncmp expect actual
 	)
 '
 
 test_expect_success 'add existing foreign_vcs remote' '
 	test_config remote.foo.vcs bar &&
-	echo "fatal: remote foo already exists." >expect &&
-	test_must_fail git remote add foo bar 2>actual &&
+	echo "error: remote foo already exists." >expect &&
+	test_expect_code 3 git remote add foo bar 2>actual &&
 	test_i18ncmp expect actual
 '
 
 test_expect_success 'add existing foreign_vcs remote' '
 	test_config remote.foo.vcs bar &&
 	test_config remote.bar.vcs bar &&
-	echo "fatal: remote bar already exists." >expect &&
-	test_must_fail git remote rename foo bar 2>actual &&
+	echo "error: remote bar already exists." >expect &&
+	test_expect_code 3 git remote rename foo bar 2>actual &&
 	test_i18ncmp expect actual
 '