From 6a4ea132ac61a74e6c066d44cdb077ec47164d4b Mon Sep 17 00:00:00 2001
From: Jeremy Katz <katzj@redhat.com>
Date: Thu, 6 Mar 2008 19:35:47 -0500
Subject: [PATCH] Fixes to avoid problems on VFAT usb sticks

If we're using a VFAT formatted stick, don't allow an overlay > 2 GB to avoid
corruption.  Also, VFAT doesn't really allow for sparse files and the kernel
gets unhappy when you try to make one.
---
 tools/livecd-iso-to-disk.sh | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/livecd-iso-to-disk.sh b/tools/livecd-iso-to-disk.sh
index 00465e3..5aeeca7 100644
--- a/tools/livecd-iso-to-disk.sh
+++ b/tools/livecd-iso-to-disk.sh
@@ -197,6 +197,11 @@ checkPartActive $USBDEV
 checkMBR $USBDEV
 [ -n $resetmbr ] && resetMBR $USBDEV
 
+if [ -n "$overlaysizemb" -a "$USBFS" = "vfat" -a "$overlaysizemb" -gt 2047 ]; then
+    echo "Can't have an overlay greater than 2048MB on VFAT"
+    exitclean
+fi
+
 # FIXME: would be better if we had better mountpoints
 CDMNT=$(mktemp -d /media/cdtmp.XXXXXX)
 mount -o loop $ISO $CDMNT || exitclean
@@ -238,8 +243,12 @@ sed -i -e "s/CDLABEL=[^ ]*/$USBLABEL/" -e "s/rootfstype=[^ ]*/rootfstype=$USBFS/
 if [ -n "$overlaysizemb" ]; then
     echo "Initializing persistent overlay file"
     OVERFILE="overlay-$( /lib/udev/vol_id -l $USBDEV )-$( /lib/udev/vol_id -u $USBDEV )"
-    dd if=/dev/null of=$USBMNT/LiveOS/$OVERFILE \
-	count=1 bs=1M seek=$overlaysizemb
+    if [ "$USBFS" = "vfat" ]; then
+	# vfat can't handle sparse files
+	dd if=/dev/zero of=$USBMNT/LiveOS/$OVERFILE count=$overlaysizemb bs=1M
+    else
+	dd if=/dev/null of=$USBMNT/LiveOS/$OVERFILE count=1 bs=1M seek=$overlaysizemb
+    fi
     sed -i -e "s/liveimg/liveimg overlay=${USBLABEL}/" \
 	$USBMNT/$SYSLINUXPATH/isolinux.cfg
     sed -i -e "s/\ ro\ /\ rw\ /" \
-- 
2.11.4.GIT