From 5c8d8203303c84fba038af753a5f675d3899be7c Mon Sep 17 00:00:00 2001
From: Stefan Saraev <stefan@saraev.ca>
Date: Sat, 30 Nov 2013 18:19:16 +0200
Subject: [PATCH] busybox: init: check for zero-size *.md5 files

busybox's md5sum applet does not fail if sizeof .md5 file is 0, so
in some rare cases (impropper shutdown before update / broken RPi sdcard)
we may updateto 0byte KERNEL/SYSTEM because md5 check didn't fail

closes #2788
---
 .../sysutils/busybox-initramfs/scripts/init   | 20 +++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/packages/initramfs/sysutils/busybox-initramfs/scripts/init b/packages/initramfs/sysutils/busybox-initramfs/scripts/init
index b2badd7201..746447a399 100755
--- a/packages/initramfs/sysutils/busybox-initramfs/scripts/init
+++ b/packages/initramfs/sysutils/busybox-initramfs/scripts/init
@@ -477,14 +477,22 @@
       # check md5 sums if .nocheck doesn't exist
       if [ "$MD5_NOCHECK" -eq "0" ] ; then
         if [ -f "$UPDATE_DIR/${UPDATE_KERNEL}.md5" -a -f "$UPDATE_DIR/${UPDATE_SYSTEM}.md5" ] ; then
-          sed  -i 's#target#/storage/.update#g' "$UPDATE_DIR/${UPDATE_KERNEL}.md5"
-          sed  -i 's#target#/storage/.update#g' "$UPDATE_DIR/${UPDATE_SYSTEM}.md5"
+          # *.md5 size-check
+          SYSTEM_MD5_SIZE=$(stat -t "$UPDATE_DIR/${UPDATE_KERNEL}.md5" | awk '{print $2}')
+          KERNEL_MD5_SIZE=$(stat -t "$UPDATE_DIR/${UPDATE_SYSTEM}.md5" | awk '{print $2}')
+          if [ "$SYSTEM_MD5_SIZE" -eq 0 -o "$KERNEL_MD5_SIZE" -eq 0 ] ; then
+            echo "zero-sized .md5 file..."
+            MD5_FAILED="1"
+          else
+            sed  -i 's#target#/storage/.update#g' "$UPDATE_DIR/${UPDATE_KERNEL}.md5"
+            sed  -i 's#target#/storage/.update#g' "$UPDATE_DIR/${UPDATE_SYSTEM}.md5"
 
-          echo "Checking ${UPDATE_KERNEL}.md5..."
-          md5sum -c "$UPDATE_DIR/${UPDATE_KERNEL}.md5" || MD5_FAILED="1"
+            echo "Checking ${UPDATE_KERNEL}.md5..."
+            md5sum -c "$UPDATE_DIR/${UPDATE_KERNEL}.md5" || MD5_FAILED="1"
 
-          echo "Checking ${UPDATE_SYSTEM}.md5..."
-          md5sum -c "$UPDATE_DIR/${UPDATE_SYSTEM}.md5" || MD5_FAILED="1"
+            echo "Checking ${UPDATE_SYSTEM}.md5..."
+            md5sum -c "$UPDATE_DIR/${UPDATE_SYSTEM}.md5" || MD5_FAILED="1"
+          fi
         else
           echo "missing ${UPDATE_KERNEL}.md5 or ${UPDATE_SYSTEM}.md5..."
           MD5_FAILED="1"