Merge branch 'jk/run-command-capture'

The run-command interface was easy to abuse and make a pipe for us
to read from the process, wait for the process to finish and then
attempt to read its output, which is a pattern that lead to a
deadlock.  Fix such uses by introducing a helper to do this
correctly (i.e. we need to read first and then wait the process to
finish) and also add code to prevent such abuse in the run-command
helper.

* jk/run-command-capture:
  run-command: forbid using run_command with piped output
  trailer: use capture_command
  submodule: use capture_command
  wt-status: use capture_command
  run-command: introduce capture_command helper
  wt_status: fix signedness mismatch in strbuf_read call
  wt-status: don't flush before running "submodule status"

1 files changed, 3 insertions, 7 deletions

diff --git a/wt-status.c b/wt-status.c
index 7036fa28dc..853419f05f 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -729,7 +729,6 @@ static void wt_status_print_submodule_summary(struct wt_status *s, int uncommitt
 	struct strbuf cmd_stdout = STRBUF_INIT;
 	struct strbuf summary = STRBUF_INIT;
 	char *summary_content;
-	size_t len;
 
 	argv_array_pushf(&sm_summary.env_array, "GIT_INDEX_FILE=%s",
 			 s->index_file);
@@ -745,15 +744,11 @@ static void wt_status_print_submodule_summary(struct wt_status *s, int uncommitt
 
 	sm_summary.git_cmd = 1;
 	sm_summary.no_stdin = 1;
-	fflush(s->fp);
-	sm_summary.out = -1;
 
-	run_command(&sm_summary);
-
-	len = strbuf_read(&cmd_stdout, sm_summary.out, 1024);
+	capture_command(&sm_summary, &cmd_stdout, 1024);
 
 	/* prepend header, only if there's an actual output */
-	if (len) {
+	if (cmd_stdout.len) {
 		if (uncommitted)
 			strbuf_addstr(&summary, _("Submodules changed but not updated:"));
 		else
@@ -764,6 +759,7 @@ static void wt_status_print_submodule_summary(struct wt_status *s, int uncommitt
 	strbuf_release(&cmd_stdout);
 
 	if (s->display_comment_prefix) {
+		size_t len;
 		summary_content = strbuf_detach(&summary, &len);
 		strbuf_add_commented_lines(&summary, summary_content, len);
 		free(summary_content);