[qarsh] Fix double-free and command hang

We need to test all exit conditions at once so we fall back into the
hbeat code.  I was falling into a case when running "reboot -fin &"
where the command would exit, but the sockets would not close and we
weren't getting to hbeat() to detect the reboot.

In another case which I can't completely explain, we were getting a
double-free error from glibc in the qpfree() at the end of
run_remote_cmd().  Instead of waiting until the very end to read the
exit status, save it off as soon as we get the packet and use
cmd_exitted to determine if we have an exit code or if something went
horribly wrong.

1 files changed, 14 insertions, 11 deletions

diff --git a/qarsh.c b/qarsh.c
index fce6ad2..31ff36a 100644
--- a/qarsh.c
+++ b/qarsh.c
@@ -292,14 +292,16 @@ run_remote_cmd(char *cmdline)
 				&pselect_sigmask);
 
 		if (nset == 0) {
-			if (cmd_finished) {
-				/* we don't want to check the heartbeat, just
-				 * the output sockets */
-				if (c_out == 0 && c_err == 0) break;
+			if (cmd_finished && c_out == 0 && c_err == 0) {
+				/* If the command is complete and both output
+				 * sockets are closed, we can exit now.  We need
+				 * to test all conditions at once so if none are
+				 * true, we'll still check for heartbeat. */
+				break;
 			} else if (!hbeat(qarsh_hb)) {
-				/* Set our return packet as NULL so we exit 
-				 * with unknown error. */
-				qp = NULL;
+				/* If the heartbeat fails, we should exit now.
+				 * The hbeat state will take precedence over the
+				 * exit status of the command. */
 				break;
 			} else {
 				/* No output to process, the command is
@@ -374,7 +376,10 @@ run_remote_cmd(char *cmdline)
 				/* dump_qp(qp); */
 				if (qp && qp->qp_type == QP_CMDEXIT) {
 					cmd_finished = 1;
-					/* break; */
+					rc = qp->qp_cmdexit.qp_status;
+					qpfree(qp);
+					/* Don't break yet, we need to make
+					 * sure all output is read. */
 				}
 				nset--;
 			}
@@ -391,12 +396,10 @@ run_remote_cmd(char *cmdline)
 		fprintf(stderr, "Remote host rebooted\n");
 		return W_EXITCODE(127, 0);
 	}
-	if (qp == NULL) {
+	if (!cmd_finished) {
 		fprintf(stderr, "Remote command exited with unknown state\n");
 		return W_EXITCODE(127, 0);
 	}
-	rc = qp->qp_cmdexit.qp_status;
-	qpfree(qp);
 	return rc;
 }