run-command: introduce function to prepare auto-maintenance process

The `run_auto_maintenance()` function is responsible for spawning a new
`git maintenance run --auto` process. To do so, it sets up the `sturct
child_process` and then runs it by executing `run_command()` directly.
This is rather inflexible in case callers want to modify the child
process somewhat, e.g. to redirect stderr or stdout.

Introduce a new `prepare_auto_maintenance()` function to plug this gap.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

run-command.c

@@ -1793,20 +1793,27 @@ void run_processes_parallel(const struct run_process_parallel_opts *opts)
 		trace2_region_leave(tr2_category, tr2_label, NULL);
 }
 
-int run_auto_maintenance(int quiet)
+int prepare_auto_maintenance(int quiet, struct child_process *maint)
 {
 	int enabled;
-	struct child_process maint = CHILD_PROCESS_INIT;
 
 	if (!git_config_get_bool("maintenance.auto", &enabled) &&
 	    !enabled)
 		return 0;
 
-	maint.git_cmd = 1;
-	maint.close_object_store = 1;
-	strvec_pushl(&maint.args, "maintenance", "run", "--auto", NULL);
-	strvec_push(&maint.args, quiet ? "--quiet" : "--no-quiet");
+	maint->git_cmd = 1;
+	maint->close_object_store = 1;
+	strvec_pushl(&maint->args, "maintenance", "run", "--auto", NULL);
+	strvec_push(&maint->args, quiet ? "--quiet" : "--no-quiet");
+
+	return 1;
+}
 
+int run_auto_maintenance(int quiet)
+{
+	struct child_process maint = CHILD_PROCESS_INIT;
+	if (!prepare_auto_maintenance(quiet, &maint))
+		return 0;
 	return run_command(&maint);
 }
 

run-command.h

@@ -217,6 +217,13 @@ int finish_command_in_signal(struct child_process *);
  */
 int run_command(struct child_process *);
 
+/*
+ * Prepare a `struct child_process` to run auto-maintenance. Returns 1 if the
+ * process has been prepared and is ready to run, or 0 in case auto-maintenance
+ * should be skipped.
+ */
+int prepare_auto_maintenance(int quiet, struct child_process *maint);
+
 /*
  * Trigger an auto-gc
  */