From 1be652b72fc6aee73a682dcc561072e308835498 Mon Sep 17 00:00:00 2001
From: Michael Kroes <michael@kroes.email>
Date: Wed, 16 Mar 2016 07:16:25 +0100
Subject: [PATCH] Add extra check when adding swap to see if swap would be
 allocated on next boot. Only activate swap on boot if initial activation
 succeeded. Refactor if statement for readability. Add comments on all checks
 performed.

---
 setup/system.sh | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/setup/system.sh b/setup/system.sh
index 05b0e2cb..40d498c2 100755
--- a/setup/system.sh
+++ b/setup/system.sh
@@ -14,16 +14,27 @@ source setup/functions.sh # load our functions
 # and buffers for the system. We will only allocate this file if there is more
 # than 5GB of disk space available
 
+# The following checks are performed:
+# - Check if swap is currently mountend by looking at /proc/mounts
+# - Check if the user intents to activate swap on next boot by checking fstab entries.
+# - Check if a swapfile already exists
+# - Check the memory requirements
+# - Check available diskspace
+
 # See https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04
 # for reference
 
 SWAP_MOUNTED=$(grep "swap" /proc/mounts)
+SWAP_IN_FSTAB=$(grep "swap" /etc/fstab)
 TOTAL_PHYSICAL_MEM=$(head -n 1 /proc/meminfo | awk '{print $2}')
 AVAILABLE_DISK_SPACE=$(df / --output=avail | tail -n 1)
-if [ $TOTAL_PHYSICAL_MEM -lt 1900000 ]; then
-if [ -z "$SWAP_MOUNTED" ]; then
-if [ ! -e /swapfile ]; then
-if [ $AVAILABLE_DISK_SPACE -gt 5242880 ]; then
+if
+	[ -z "$SWAP_MOUNTED" ] &&
+	[ -z "$SWAP_IN_FSTAB" ] &&
+	[ ! -e /swapfile ] &&
+	[ $TOTAL_PHYSICAL_MEM -lt 1900000 ] &&
+	[ $AVAILABLE_DISK_SPACE -gt 5242880 ]
+then
 	echo "Adding swap to the system..."
 
 	# Allocate and activate the swap file
@@ -32,11 +43,11 @@ if [ $AVAILABLE_DISK_SPACE -gt 5242880 ]; then
 	hide_output mkswap /swapfile
 	swapon /swapfile
 
-	# Make sure swap is activated on boot
-	echo "/swapfile   none    swap    sw    0   0" >> /etc/fstab
-fi
-fi
-fi
+	# Check if swap is mounted then activate on boot
+	ACTIVATED_SWAP=$(swapon -s | grep "\/swapfile")
+	if [ -n "$ACTIVATED_SWAP" ]; then
+		echo "/swapfile   none    swap    sw    0   0" >> /etc/fstab
+	fi
 fi
 
 # ### Add Mail-in-a-Box's PPA.