From: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Date: Mon, 30 Nov 2020 18:54:14 +0000 (-0500)
Subject: test: utils: lttng_pgrep performs lookup on non-existing pid
X-Git-Tag: v2.13.0-rc1~406
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=00d1ff64c4c7a19cd9e8bd705d76c5834d6dd822;p=lttng-tools.git

test: utils: lttng_pgrep performs lookup on non-existing pid

Observed issue
==============

 # Killing (signal SIGTERM) lttng-sessiond and lt-lttng-sessiond pids: 20962 20963
 ./tests/regression/tools/trigger/start-stop//../../../../utils/utils.sh: line 103: /proc/20963/cmdline: No such file or directory

Cause
=====

lttng_pgrep performs a two step search/validation for the pattern. Since
lttng_pgrep is used during tear-down of process (staged termination
signalling) a process returned by pgrep might exit before the second
check.

Solution
========

Simply silence the error. The code flow already acknowledges the
possibility of failure here.

Known drawbacks
=========

None

References
==========

Fixes: #1292

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I82cb9fd4754c10a5104af495a8a959f4fbd92664
---

diff --git a/tests/utils/utils.sh b/tests/utils/utils.sh
index 574495704..31087877d 100644
--- a/tests/utils/utils.sh
+++ b/tests/utils/utils.sh
@@ -100,7 +100,7 @@ function lttng_pgrep ()
 
 	while IFS= read -r pid ; do
 		# /proc/pid/cmdline is null separated.
-		if full_command_no_argument=$(cut -d '' -f 1 < /proc/"$pid"/cmdline); then
+		if full_command_no_argument=$(cut -d '' -f 1 2>/dev/null < /proc/"$pid"/cmdline); then
 			command_basename=$(basename "$full_command_no_argument")
 			if grep -q "$pattern" <<< "$command_basename"; then
 				echo "$pid"