#!/bin/bash
#
# Build script that compiles a DVB driver tarball and slipstreams it into
# an matching Debian kernel package. Can compile for non-running kernels.
# Configured by variables set in the header section below.
# Outputs a kernel package with -dvb added to the package name and
# -YYYYMMDD.HHMM added to the version number.
#
# You'll need a V4L/DVB driver tarball, a linux-image-*.deb package file,
# matching linux-headers *installed*
#
# !!!CAUTION!!!
# Always keep another kernel installed for backup, in case of an emergency.
# The built kernel package will OVERWRITE its original package on install,
# so you might want to install an -486 package for safety if you're modifying
# the -686 package.
#
# Script (c) by Udo Richter <udo_richter@gmx.de>, 
# http://www.udo-richter.de/scripts.en.html#builddvb
# Released under the GNU GPL license

# Directory name of this script file:
DIR="$(dirname "$(readlink -f "$(which "$0")")")"

# DVB driver source file:
DRIVER="$DIR/v4l-dvb-saa716x-218f3fbbb434.tar.bz2"

# Patches to apply to driver:
PATCH=(
    "-p1 -i $DIR/saa716x_ff_demux_tasklet.diff"
)

# Kernel release number, eg. uname -r
KERNELRELEASE="2.6.32-5-686"

# Original kernel package version number:
KERNELVERSION="2.6.32-31"

# Debian distribution:
PLATFORM="i386"

# Version number to attach to kernel version:
NEWKERNELVERSION="$KERNELVERSION-"$(date +%Y%m%d.%H%M)

# Source deb file of matching kernel package
DEBSRCKERNEL="${DIR}/linux-image-${KERNELRELEASE}_${KERNELVERSION}_${PLATFORM}.deb"

# Target deb file for modified kernel package
DEBDSTKERNEL="${DIR}/linux-image-${KERNELRELEASE}-dvb_${NEWKERNELVERSION}_${PLATFORM}.deb"

# Paths to kernel source and kernel header, as installed
OUTDIR="/lib/modules/${KERNELRELEASE}/build"
SRCDIR="/lib/modules/${KERNELRELEASE}/source"

# Temporary folder for building and assembling:
BUILD="/tmp/dvb-build/$$"


# ----------------------------------------

ask-delete-folder() {
  if [ -d "$1" ] ; then
    echo -n "Delete folder $1 (y/n)?"
    read yesno
    if [ "$yesno" = "y" ] ; then
      rm -r $1
    else
      exit 1
    fi
  fi
}

set -e

MAKEPARAMS=(
	KERNELRELEASE="$KERNELRELEASE"
	OUTDIR="$OUTDIR"
	SRCDIR="$SRCDIR"
	DESTDIR="$BUILD/deb"
)

ask-delete-folder "$BUILD"

# Prepare the driver source

mkdir -p "$BUILD/dvb"
mkdir -p "$BUILD/deb"
cd "$BUILD/dvb"
echo "Extracting $DRIVER"
tar xf "$DRIVER" --strip-components=1
for ((i=0; i<${#PATCH[@]}; i++)) do
	echo "Patching ${PATCH[i]}"
	patch ${PATCH[i]}
done

# Build the driver

make "${MAKEPARAMS[@]}" all

# Extract the kernel package and install driver

fakeroot dpkg -x "$DEBSRCKERNEL" "$BUILD/deb"
fakeroot dpkg -e "$DEBSRCKERNEL" "$BUILD/deb/DEBIAN"
fakeroot make "${MAKEPARAMS[@]}" media-install

# Files that will be rebuilt on package install:

rm "$BUILD/deb/lib/modules/${KERNELRELEASE}/modules.alias"
rm "$BUILD/deb/lib/modules/${KERNELRELEASE}/modules.alias.bin"
rm "$BUILD/deb/lib/modules/${KERNELRELEASE}/modules.dep"
rm "$BUILD/deb/lib/modules/${KERNELRELEASE}/modules.dep.bin"
rm "$BUILD/deb/lib/modules/${KERNELRELEASE}/modules.devname"
rm "$BUILD/deb/lib/modules/${KERNELRELEASE}/modules.softdep"
rm "$BUILD/deb/lib/modules/${KERNELRELEASE}/modules.symbols"
rm "$BUILD/deb/lib/modules/${KERNELRELEASE}/modules.symbols.bin"

# Modify DEBIAN/control file

# old package name:
package=`sed -n -e "/^Package: /s/Package: //p" "$BUILD/deb/DEBIAN/control"`

# driver source file name:
driverfile=$(basename "$DRIVER")

sed -e "/^Package:/s/.*/Package: linux-image-$KERNELRELEASE-dvb/" \
    -e "/^Version:/s/.*/Version: $NEWKERNELVERSION\\nReplaces: $package/" \
    -e "$ a \\ Repacked with DVB drivers from $driverfile\n made with builddvb script from http://www.udo-richter.de/vdr/scripts.html#builddvb" \
    -i "$BUILD/deb/DEBIAN/control"

# Build new kernel file:

fakeroot dpkg -b "$BUILD/deb" "$DEBDSTKERNEL"

echo "Kernel package built into $DEBDSTKERNEL"

ask-delete-folder "$BUILD"