for-each-repo: do nothing on empty config

'git for-each-repo --config=X' should return success without calling any subcommands when the config key 'X' has no value. The current implementation instead segfaults. A user could run into this issue if they used 'git maintenance start' to initialize their cron schedule using 'git for-each-repo --config=maintenance.repo ...' but then using 'git maintenance unregister' to remove the config option. (Note: 'git maintenance stop' would remove the config _and_ remove the cron schedule.) Add a simple test to ensure this works. Use 'git help --no-such-option' as the potential subcommand to ensure that we will hit a failure if the subcommand is ever run. Reported-by: Andreas Bühmann <dev@uuml.de> Helped-by: Eric Sunshine <sunshine@sunshineco.com> Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Derrick Stolee committed Jan 8, 2021 at 02:30 UTC 6c62f015520eaecd94d93a7e8339b190f2c24bc6
2 files changed +13
builtin/for-each-repo.c
+7
@@ -51,6 +51,13 @@ int cmd_for_each_repo(int argc, const char **argv, const char *prefix)
51 values = repo_config_get_value_multi(the_repository,
52 config_key);
53
54 + /*
55 + * Do nothing on an empty list, which is equivalent to the case
56 + * where the config variable does not exist at all.
57 + */
58 + if (!values)
59 + return 0;
60 +
61 for (i = 0; !result && i < values->nr; i++)
62 result = run_command_on_repo(values->items[i].string, &args);
63
t/t0068-for-each-repo.sh
+6
@@ -27,4 +27,10 @@ test_expect_success 'run based on configured value' '
27 grep again message
28 '
29
30 +test_expect_success 'do nothing on empty config' '
31 + # the whole thing would fail if for-each-ref iterated even
32 + # once, because "git help --no-such-option" would fail
33 + git for-each-repo --config=bogus.config -- help --no-such-option
34 +'
35 +
36 test_done