[Buildroot] [git commit] package/dnsmasq: Fix init script restart command

[Yann E. MORIN]

commit: https://git.buildroot.net/buildroot/commit/?id=507caef3ddf5ab7d933e14303508db057c4b9501
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/master

Restarting dnsmasq can cause constant issues: stop works, but start
fails because the new instance can't bind the socket. Another restart
immediately after works just fine:

    # /etc/init.d/S80dnsmasq restart
    Stopping dnsmasq: OK
    Starting dnsmasq:
    dnsmasq: failed to create listening socket for 192.168.128.1: Address in use
    FAIL
    # /etc/init.d/S80dnsmasq restart
    Stopping dnsmasq: FAIL
    Starting dnsmasq: OK

Solve this by waiting for process to actually stop before returning
from the stop command. Clean up the PID file after to avoid potential
issues with the PID being reused after stop. The wait could also be
placed inside the restart block, but putting it into the stop block
has the advantage that it also avoids similar issues for any other
callers.

Signed-off-by: Fiona Klute <fiona.klute+wiwa at gmx.de>
[yann.morin.1998 at free.fr:
  - fix shellcheck
  - reflow commit log
]
Signed-off-by: Yann E. MORIN <yann.morin.1998 at free.fr>
---
 .checkpackageignore        | 1 -
 package/dnsmasq/S80dnsmasq | 9 +++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/.checkpackageignore b/.checkpackageignore
index 846cd8e1ec..914f3b5bb5 100644
--- a/.checkpackageignore
+++ b/.checkpackageignore
@@ -552,7 +552,6 @@ package/dmalloc/0004-Makefile-use-the-configure-detected-or-user-supplied.patch
 package/dmalloc/0005-configure-use-LD-instead-of-hard-coding-ld.patch lib_patch.Upstream
 package/dmraid/0001-fix-compilation-under-musl.patch lib_patch.Upstream
 package/dmraid/S20dmraid lib_sysv.Variables
-package/dnsmasq/S80dnsmasq Shellcheck
 package/docker-engine/S60dockerd Shellcheck lib_sysv.Indent lib_sysv.Variables
 package/docopt-cpp/0001-only-build-one-target-use-BUILD_SHARED_LIBS-where-appropriate.patch lib_patch.Upstream
 package/domoticz/S99domoticz Shellcheck
diff --git a/package/dnsmasq/S80dnsmasq b/package/dnsmasq/S80dnsmasq
index 175daf9d26..f1e1a68585 100644
--- a/package/dnsmasq/S80dnsmasq
+++ b/package/dnsmasq/S80dnsmasq
@@ -10,12 +10,21 @@ case "$1" in
 		printf "Starting dnsmasq: "
 		start-stop-daemon -S -p "$PIDFILE" -x "/usr/sbin/$DAEMON" -- \
 			--pid-file="$PIDFILE"
+		# shellcheck disable=SC2181
 		[ $? = 0 ] && echo "OK" || echo "FAIL"
 		;;
 	stop)
 		printf "Stopping dnsmasq: "
 		start-stop-daemon -K -q -p "$PIDFILE" -x "/usr/sbin/$DAEMON"
+		# shellcheck disable=SC2181
 		[ $? = 0 ] && echo "OK" || echo "FAIL"
+		# wait for dnsmasq process to be gone
+		while true; do
+			pid="$( cat "${PIDFILE}" 2>/dev/null || true )"
+			{ [ -n "${pid}" ] && [ -d "/proc/${pid}" ]; } || break
+			sleep 0.1
+		done
+		rm -f "$PIDFILE"
 		;;
 	restart|reload)
 		$0 stop