Option to expand partition and rootfs on first boot

Initial version from vknecht

2 files changed, 70 insertions, 2 deletions

diff --git a/README.md b/README.md
index 998c534..9afe18b 100644
--- a/README.md
+++ b/README.md
@@ -43,6 +43,9 @@ Set default system locale. This setting can also be changed inside the running O
 ##### `TIMEZONE`="Europe/Berlin"
 Set default system timezone. All available timezones can be found in the `/usr/share/zoneinfo/` directory. This setting can also be changed inside the running OS using the `dpkg-reconfigure tzdata` command.
 
+##### `EXPANDROOT`=true
+Expand the root partition and filesystem automatically on first boot.
+
 #### Keyboard settings:
 These options are used to configure keyboard layout in `/etc/default/keyboard` for console and Xorg. These settings can also be changed inside the running OS using the `dpkg-reconfigure keyboard-configuration` command.
 ##### `XKBMODEL`=""
diff --git a/rpi2-gen-image.sh b/rpi2-gen-image.sh
index 4a2ba7d..391c870 100755
--- a/rpi2-gen-image.sh
+++ b/rpi2-gen-image.sh
@@ -55,6 +55,7 @@ XKBMODEL=${XKBMODEL:=""}
 XKBLAYOUT=${XKBLAYOUT:=""}
 XKBVARIANT=${XKBVARIANT:=""}
 XKBOPTIONS=${XKBOPTIONS:=""}
+EXPANDROOT=${EXPANDROOT:=true}
 
 # Network settings
 ENABLE_DHCP=${ENABLE_DHCP:=true}
@@ -158,6 +159,11 @@ else
   APT_INCLUDES="${APT_INCLUDES},locales,keyboard-configuration,console-setup"
 fi
 
+# Add parted package, required to get partprobe utility
+if [ "$EXPANDROOT" = true ] ; then
+  APT_INCLUDES="${APT_INCLUDES},parted"
+fi
+
 # Add dbus package, recommended if using systemd
 if [ "$ENABLE_DBUS" = true ] ; then
   APT_INCLUDES="${APT_INCLUDES},dbus"
@@ -602,14 +608,73 @@ ssh-keygen -q -t ed25519 -N "" -f /etc/ssh/ssh_host_ed25519_key
 sync
 
 systemctl restart sshd
-sed -i 's/.*rc.firstboot.*/exit 0/g' /etc/rc.local
+sed -i '/.*rc.firstboot/d' /etc/rc.local
 rm -f /etc/rc.firstboot
 EOM
   chmod +x $R/etc/rc.firstboot
-  sed -i 's,exit 0,/etc/rc.firstboot,g' $R/etc/rc.local
+  sed -i '/exit 0/d' $R/etc/rc.local
+  echo /etc/rc.firstboot >> $R/etc/rc.local
   rm -f $R/etc/ssh/ssh_host_*
 fi
 
+if [ "$EXPANDROOT" = true ] ; then
+  cat <<EOF > $R/etc/rc.expandroot
+#!/bin/sh
+
+ROOT_PART=\$(mount | sed -n 's|^/dev/\(.*\) on / .*|\1|p')
+PART_NUM=\$(echo \${ROOT_PART} | grep -o '[1-9][0-9]*$')
+case "\${ROOT_PART}" in
+  mmcblk0*) ROOT_DEV=mmcblk0 ;;
+  sda*)     ROOT_DEV=sda ;;
+esac
+if [ "\$PART_NUM" = "\$ROOT_PART" ]; then
+  logger -t "rc.expandroot" "\$ROOT_PART is not an SD card. Don't know how to expand"
+  return 0
+fi
+# NOTE: the NOOBS partition layout confuses parted. For now, let's only
+# agree to work with a sufficiently simple partition layout
+if [ "\$PART_NUM" -gt 2 ]; then
+  logger -t "rc.expandroot" "Your partition layout is not currently supported by this tool."
+  return 0
+fi
+LAST_PART_NUM=\$(parted /dev/\${ROOT_DEV} -ms unit s p | tail -n 1 | cut -f 1 -d:)
+if [ \$LAST_PART_NUM -ne \$PART_NUM ]; then
+  logger -t "rc.expandroot" "\$ROOT_PART is not the last partition. Don't know how to expand"
+  return 0
+fi
+# Get the starting offset of the root partition
+PART_START=\$(parted /dev/\${ROOT_DEV} -ms unit s p | grep "^\${PART_NUM}" | cut -f 2 -d: | sed 's/[^0-9]//g')
+[ "\$PART_START" ] || return 1
+# Get the possible last sector for the root partition
+PART_LAST=\$(fdisk -l /dev/\${ROOT_DEV} | grep '^Disk.*sectors' | awk '{ print \$7 - 1 }')
+[ "\$PART_LAST" ] || return 1
+# Return value will likely be error for fdisk as it fails to reload the
+# partition table because the root fs is mounted
+### Since rc.local is run with "sh -e", let's add "|| true" to prevent premature exit
+fdisk /dev/\${ROOT_DEV} <<EOF2 || true
+p
+d
+\$PART_NUM
+n
+p
+\$PART_NUM
+\$PART_START
+\$PART_LAST
+p
+w
+EOF2
+  # Reload the partition table, resize root filesystem then remove resizing code from this file
+  partprobe &&
+    resize2fs /dev/\${ROOT_PART} &&
+    logger -t "rc.expandroot" "Root partition successfuly resized." &&
+    sed -i '/.*rc.expandroot/d' /etc/rc.local
+    rm -f /etc/rc.expandroot
+EOF
+  chmod +x $R/etc/rc.expandroot
+  sed -i '/exit 0/d' $R/etc/rc.local
+  echo /etc/rc.expandroot >> $R/etc/rc.local
+fi
+
 # Disable rsyslog
 if [ "$ENABLE_RSYSLOG" = false ]; then
   sed -i 's|[#]*ForwardToSyslog=yes|ForwardToSyslog=no|g' $R/etc/systemd/journald.conf