[PATCH 4/7] wt-status: use strbuf_read_cmd

[Jeff King <peff@peff.net>]

When we spawn "git submodule status" to read its output, we
use run_command() followed by a strbuf_read() from a pipe.
This can deadlock if the subprocess output is larger than
the system pipe buffer.

Furthermore, if start_command() fails, we'll try to read
from a bogus descriptor (probably "-1" or a descriptor we
just closed, but it is a bad idea for us to make assumptions
about how start_command implements its error handling). And
if start_command succeeds, we leak the file descriptor for
the pipe to the child.

All of these can be solved by using the strbuf_read_cmd
helper.

Signed-off-by: Jeff King <peff@peff.net>
---
 wt-status.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/wt-status.c b/wt-status.c
index b47f6d9..fd85d61 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -744,11 +744,8 @@ static void wt_status_print_submodule_summary(struct wt_status *s, int uncommitt
 
 	sm_summary.git_cmd = 1;
 	sm_summary.no_stdin = 1;
-	sm_summary.out = -1;
 
-	run_command(&sm_summary);
-
-	strbuf_read(&cmd_stdout, sm_summary.out, 1024);
+	strbuf_read_cmd(&cmd_stdout, &sm_summary, 1024);
 
 	/* prepend header, only if there's an actual output */
 	if (cmd_stdout.len) {
-- 
2.3.3.618.ga041503