wt-status: use capture_command

When we spawn "git submodule status" to read its output, we
use run_command() followed by strbuf_read() read from the
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 capture_command
helper.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/wt-status.c b/wt-status.c
index 05b69dc4d3f2e4e825dd87b3ba8c0d0a14bb43bb..ef232a74beb7121e176da692a893a7cd66dbdd85 100644 (file)
--- 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);
+       capture_command(&sm_summary, &cmd_stdout, 1024);
 
        /* prepend header, only if there's an actual output */
        if (cmd_stdout.len) {