maintenance: add custom config to background jobs

At the moment, some background jobs are getting blocked on credentials
during the 'prefetch' task. This leads to other tasks, such as
incremental repacks, getting blocked. Further, if a user manages to fix
their credentials, then they still need to cancel the background process
before their background maintenance can continue working.

Update the background schedules for our four scheduler integrations to
include these config options via '-c' options:

 * 'credential.interactive=false' will stop Git and some credential
   helpers from prompting in the UI (assuming the '-c' parameters are
   carried through and respected by GCM).

 * 'core.askPass=true' will replace the text fallback for a username
   and password into the 'true' command, which will return a success in
   its exit code, but Git will treat the empty string returned as an
   invalid password and move on.

We can do some testing that the credentials are passed, at least in the
systemd case due to writing the service files.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>

builtin/gc.c

@@ -1685,6 +1685,42 @@ static const char *get_frequency(enum schedule_priority schedule)
 	}
 }
 
+static const char *extraconfig[] = {
+	"credential.interactive=false",
+	"core.askPass=true", /* 'true' returns success, but no output. */
+	NULL
+};
+
+static const char *get_extra_config_parameters(void) {
+	static const char *result = NULL;
+	struct strbuf builder = STRBUF_INIT;
+
+	if (result)
+		return result;
+
+	for (const char **s = extraconfig; s && *s; s++)
+		strbuf_addf(&builder, "-c %s ", *s);
+
+	result = strbuf_detach(&builder, NULL);
+	return result;
+}
+
+static const char *get_extra_launchctl_strings(void) {
+	static const char *result = NULL;
+	struct strbuf builder = STRBUF_INIT;
+
+	if (result)
+		return result;
+
+	for (const char **s = extraconfig; s && *s; s++) {
+		strbuf_addstr(&builder, "<string>-c</string>\n");
+		strbuf_addf(&builder, "<string>%s</string>\n", *s);
+	}
+
+	result = strbuf_detach(&builder, NULL);
+	return result;
+}
+
 /*
  * get_schedule_cmd` reads the GIT_TEST_MAINT_SCHEDULER environment variable
  * to mock the schedulers that `git maintenance start` rely on.
@@ -1891,6 +1927,7 @@ static int launchctl_schedule_plist(const char *exec_path, enum schedule_priorit
 		   "<array>\n"
 		   "<string>%s/git</string>\n"
 		   "<string>--exec-path=%s</string>\n"
+		   "%s" /* For extra config parameters. */
 		   "<string>for-each-repo</string>\n"
 		   "<string>--keep-going</string>\n"
 		   "<string>--config=maintenance.repo</string>\n"
@@ -1900,7 +1937,8 @@ static int launchctl_schedule_plist(const char *exec_path, enum schedule_priorit
 		   "</array>\n"
 		   "<key>StartCalendarInterval</key>\n"
 		   "<array>\n";
-	strbuf_addf(&plist, preamble, name, exec_path, exec_path, frequency);
+	strbuf_addf(&plist, preamble, name, exec_path, exec_path,
+		    get_extra_launchctl_strings(), frequency);
 
 	switch (schedule) {
 	case SCHEDULE_HOURLY:
@@ -2135,11 +2173,12 @@ static int schtasks_schedule_task(const char *exec_path, enum schedule_priority
 	      "<Actions Context=\"Author\">\n"
 	      "<Exec>\n"
 	      "<Command>\"%s\\headless-git.exe\"</Command>\n"
-	      "<Arguments>--exec-path=\"%s\" for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%s</Arguments>\n"
+	      "<Arguments>--exec-path=\"%s\" %s for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%s</Arguments>\n"
 	      "</Exec>\n"
 	      "</Actions>\n"
 	      "</Task>\n";
-	fprintf(tfile->fp, xml, exec_path, exec_path, frequency);
+	fprintf(tfile->fp, xml, exec_path, exec_path,
+		get_extra_config_parameters(), frequency);
 	strvec_split(&child.args, cmd);
 	strvec_pushl(&child.args, "/create", "/tn", name, "/f", "/xml",
 				  get_tempfile_path(tfile), NULL);
@@ -2280,8 +2319,8 @@ static int crontab_update_schedule(int run_maintenance, int fd)
 			"# replaced in the future by a Git command.\n\n");
 
 		strbuf_addf(&line_format,
-			    "%%d %%s * * %%s \"%s/git\" --exec-path=\"%s\" for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%%s\n",
-			    exec_path, exec_path);
+			    "%%d %%s * * %%s \"%s/git\" --exec-path=\"%s\" %s for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%%s\n",
+			    exec_path, exec_path, get_extra_config_parameters());
 		fprintf(cron_in, line_format.buf, minute, "1-23", "*", "hourly");
 		fprintf(cron_in, line_format.buf, minute, "0", "1-6", "daily");
 		fprintf(cron_in, line_format.buf, minute, "0", "0", "weekly");
@@ -2481,7 +2520,7 @@ static int systemd_timer_write_service_template(const char *exec_path)
 	       "\n"
 	       "[Service]\n"
 	       "Type=oneshot\n"
-	       "ExecStart=\"%s/git\" --exec-path=\"%s\" for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%%i\n"
+	       "ExecStart=\"%s/git\" --exec-path=\"%s\" %s for-each-repo --keep-going --config=maintenance.repo maintenance run --schedule=%%i\n"
 	       "LockPersonality=yes\n"
 	       "MemoryDenyWriteExecute=yes\n"
 	       "NoNewPrivileges=yes\n"
@@ -2491,7 +2530,7 @@ static int systemd_timer_write_service_template(const char *exec_path)
 	       "RestrictSUIDSGID=yes\n"
 	       "SystemCallArchitectures=native\n"
 	       "SystemCallFilter=@system-service\n";
-	if (fprintf(file, unit, exec_path, exec_path) < 0) {
+	if (fprintf(file, unit, exec_path, exec_path, get_extra_config_parameters()) < 0) {
 		error(_("failed to write to '%s'"), filename);
 		fclose(file);
 		goto error;

t/t7900-maintenance.sh

@@ -800,6 +800,9 @@ test_expect_success 'start and stop Linux/systemd maintenance' '
 	test_systemd_analyze_verify "systemd/user/git-maintenance@daily.service" &&
 	test_systemd_analyze_verify "systemd/user/git-maintenance@weekly.service" &&
 
+	grep "core.askPass=true" "systemd/user/git-maintenance@.service" &&
+	grep "credential.interactive=false" "systemd/user/git-maintenance@.service" &&
+
 	printf -- "--user enable --now git-maintenance@%s.timer\n" hourly daily weekly >expect &&
 	test_cmp expect args &&