[PATCH 2/8] run-command: Call get_next_task with a clean child process.

[Stefan Beller <sbeller@google.com>]

If the `get_next_task` did not explicitly called child_process_init
and only filled in some fields, there may have been some stale data
in the child process. This is hard to debug and also adds a review
burden for each new user of that API. To improve the situation, we
pass only cleanly initialized child structs to the get_next_task.

As an invariant you can now assume any child not in use is
cleaned up and ready for its next reuse.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 run-command.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/run-command.c b/run-command.c
index b9363da..a5ef874 100644
--- a/run-command.c
+++ b/run-command.c
@@ -13,6 +13,12 @@ void child_process_init(struct child_process *child)
 	argv_array_init(&child->env_array);
 }
 
+void child_process_deinit(struct child_process *child)
+{
+	argv_array_clear(&child->args);
+	argv_array_clear(&child->env_array);
+}
+
 struct child_to_clean {
 	pid_t pid;
 	struct child_to_clean *next;
@@ -962,6 +968,7 @@ static struct parallel_processes *pp_init(int n,
 
 	for (i = 0; i < n; i++) {
 		strbuf_init(&pp->children[i].err, 0);
+		child_process_init(&pp->children[i].process);
 		pp->pfd[i].events = POLLIN;
 		pp->pfd[i].fd = -1;
 	}
@@ -973,8 +980,10 @@ static void pp_cleanup(struct parallel_processes *pp)
 {
 	int i;
 
-	for (i = 0; i < pp->max_processes; i++)
+	for (i = 0; i < pp->max_processes; i++) {
 		strbuf_release(&pp->children[i].err);
+		child_process_deinit(&pp->children[i].process);
+	}
 
 	free(pp->children);
 	free(pp->pfd);
@@ -1134,6 +1143,8 @@ static int pp_collect_finished(struct parallel_processes *pp)
 		pp->nr_processes--;
 		pp->children[i].in_use = 0;
 		pp->pfd[i].fd = -1;
+		child_process_deinit(&pp->children[i].process);
+		child_process_init(&pp->children[i].process);
 
 		if (i != pp->output_owner) {
 			strbuf_addbuf(&pp->buffered_output, &pp->children[i].err);
-- 
2.5.0.275.gbfc1651.dirty