Remove need for raspi-config to be installed on the image for resizing.

Closes #8

pishrink.sh

@@ -60,16 +60,51 @@ if [ "$should_skip_autoexpand" = false ]; then
   mountdir=`mktemp -d`
   mount $loopback $mountdir
 
-  if [ `md5sum $mountdir/etc/rc.local | cut -d ' ' -f 1` != "a27a4d8192ea6ba713d2ddd15a55b1df" ]; then
+  if [ `md5sum $mountdir/etc/rc.local | cut -d ' ' -f 1` != "c4eb22d9aa99915af319287d194d4529" ]; then
     echo Creating new /etc/rc.local
     mv $mountdir/etc/rc.local $mountdir/etc/rc.local.bak
     ###Do not touch the following 6 lines including EOF###
-cat <<\EOF > $mountdir/etc/rc.local
+cat <<\EOFE > $mountdir/etc/rc.local
 #!/bin/bash
-/usr/bin/raspi-config --expand-rootfs
-rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; reboot
-exit 0
+do_expand_rootfs() {
+  ROOT_PART=$(cat /proc/cmdline | tr -s ' ' '\n' | grep root= | cut -d '=' -f 2)
+  if [[ "$ROOT_PART" != /dev/mmcblk0* ]] ; then
+    echo $ROOT_PART is not an SD card...
+    return 0
+  fi
+  PART_NUM=$(echo $ROOT_PART | cut -d 'p' -f 2)
+
+  # Get the starting offset of the root partition
+  PART_START=$(fdisk -l /dev/mmcblk0 | grep $ROOT_PART | tr -s ' ' | cut -d ' ' -f 2)
+  [ "$PART_START" ] || return 1
+  # Return value will likely be error for fdisk as it fails to reload the
+  # partition table because the root fs is mounted
+  fdisk /dev/mmcblk0 <<EOF
+p
+d
+$PART_NUM
+n
+p
+$PART_NUM
+$PART_START
+
+w
+
 EOF
+
+cat <<EOF > /etc/rc.local &&
+#!/bin/sh
+resize2fs $ROOT_PART
+rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
+
+EOF
+reboot
+exit
+}
+do_expand_rootfs
+rm -f /etc/rc.local; cp -f /etc/rc.local.bak /etc/rc.local; /etc/rc.local
+exit 0
+EOFE
     ###End no touch zone###
     chmod +x $mountdir/etc/rc.local
   fi