From: Martin Schwenke <martin@meltin.net>
Date: Mon, 11 Jul 2016 10:53:56 +0000 (+1000)
Subject: ctdb-scripts: Avoid shellcheck warning SC2094 (read/write same file)
X-Git-Tag: tdb-1.3.10~262
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=524eac92347a8adc6745f0cca04358a6f3fb581f;p=thirdparty%2Fsamba.git

ctdb-scripts: Avoid shellcheck warning SC2094 (read/write same file)

SC2094: Make sure not to read and write the same file in the same pipeline.

The semantics here are unclear, so use a separate flock file in each
case for clarity.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
---

diff --git a/ctdb/config/events.d/13.per_ip_routing b/ctdb/config/events.d/13.per_ip_routing
index cfb8348078e..f0e4609a01d 100755
--- a/ctdb/config/events.d/13.per_ip_routing
+++ b/ctdb/config/events.d/13.per_ip_routing
@@ -36,6 +36,8 @@ if ! have_link_local_config && [ ! -r "$CTDB_PER_IP_ROUTING_CONF" ] ; then
     die "error: CTDB_PER_IP_ROUTING_CONF=$CTDB_PER_IP_ROUTING_CONF file not found"
 fi
 
+service_state_dir=$(ctdb_setup_service_state_dir) || exit $?
+
 ######################################################################
 
 ipv4_is_valid_addr()
@@ -103,6 +105,7 @@ ipv4_host_addr_to_net ()
 ensure_rt_tables ()
 {
     rt_tables="$CTDB_SYS_ETCDIR/iproute2/rt_tables"
+    rt_tables_lock="${service_state_dir}/rt_tables_lock"
 
     # This file should always exist.  Even if this didn't exist on the
     # system, adding a route will have created it.  What if we startup
@@ -131,7 +134,7 @@ ensure_table_id_for_ip ()
     # range).
     (
 	# Note that die() just gets us out of the subshell...
-	flock --timeout 30 0 || \
+	flock --timeout 30 9 || \
 	    die "ensure_table_id_for_ip: failed to lock file $rt_tables"
 
 	_new="$CTDB_PER_IP_ROUTING_TABLE_ID_LOW"
@@ -150,7 +153,7 @@ ensure_table_id_for_ip ()
 		"$_t" -le "$CTDB_PER_IP_ROUTING_TABLE_ID_HIGH" ] 2>/dev/null ; then
 		_new=$((_t + 1))
 	    fi
-	done
+	done <"$rt_tables"
 
 	# If the new table id is legal then add it to the file and
 	# print it.
@@ -160,7 +163,7 @@ ensure_table_id_for_ip ()
 	else
 	    return 1
 	fi
-    ) <"$rt_tables"
+    ) 9>"$rt_tables_lock"
 }
 
 # Clean up all the table ids that we might own.
@@ -170,7 +173,7 @@ clean_up_table_ids ()
 
     (
 	# Note that die() just gets us out of the subshell...
-	flock --timeout 30 0 || \
+	flock --timeout 30 9 || \
 	    die "clean_up_table_ids: failed to lock file $rt_tables"
 
 	# Delete any items from the file that have a table id in our
@@ -185,8 +188,7 @@ clean_up_table_ids ()
 	     { print $0 }' "$rt_tables" >"$_tmp"
 
 	mv "$_tmp" "$rt_tables"
-	# The lock is gone - don't do anything else here
-    ) <"$rt_tables"
+    ) 9>"$rt_tables_lock"
 }
 
 ######################################################################
diff --git a/ctdb/config/functions b/ctdb/config/functions
index 603cbf0a490..3b9d1dbbfa2 100755
--- a/ctdb/config/functions
+++ b/ctdb/config/functions
@@ -864,29 +864,32 @@ service_reconfigure ()
 
 ctdb_reconfigure_take_lock ()
 {
-    _ctdb_service_reconfigure_common
-    _lock="${_d}/reconfigure_lock"
-    mkdir -p "${_lock%/*}" # dirname
-    touch "$_lock"
-
-    (
-	flock 0
-	# This is overkill but will work if we need to extend this to
-	# allow certain events to run multiple times in parallel
-	# (e.g. takeip) and write multiple PIDs to the file.
-	read _locker_event 
-	if [ -n "$_locker_event" ] ; then
-	    while read _pid ; do
-		if [ -n "$_pid" -a "$_pid" != $$ ] && \
-		    kill -0 "$_pid" 2>/dev/null ; then
-		    exit 1
-		fi
-	    done
-	fi
+	_ctdb_service_reconfigure_common
+	_lock="${_d}/reconfigure_lock"
+	mkdir -p "${_lock%/*}" # dirname
+	touch "$_lock"
 
-	printf "%s\n%s\n" "$event_name" $$ >"$_lock"
-	exit 0
-    ) <"$_lock"
+	(
+		flock 9
+		# This is overkill but will work if we need to extend
+		# this to allow certain events to run multiple times
+		# in parallel (e.g. takeip) and write multiple PIDs to
+		# the file.
+		{
+			read _locker_event
+			if [ -n "$_locker_event" ] ; then
+				while read _pid ; do
+					if [ -n "$_pid" -a "$_pid" != $$ ] && \
+					   kill -0 "$_pid" 2>/dev/null ; then
+						exit 1
+					fi
+				done
+			fi
+		} <"$_lock"
+
+		printf "%s\n%s\n" "$event_name" $$ >"$_lock"
+		exit 0
+    ) 9>"${_lock}.flock"
 }
 
 ctdb_reconfigure_release_lock ()