#! /bin/sh -e
# Script to grab a given kernel version (stolen from Virtual Anton).

barf()
{
    echo "$@" >&2
    exit 1
}

PATCHDIR=~/devel/kernel/kernel-patches
MIRRORS="rsync://kernel::kernel http://kernel.linux.pacific.net.au/linux/kernel/ rsync://master.kernel.org:/pub/linux/kernel"
#MIRRORS="rsync.planetmirror.com::ftp.kernel.org/pub/linux/kernel master.kernel.org:/pub/linux/kernel"

# Takes destination directory, and filename, tries each mirror.
get_file()
{
    get_file_dir=$1
    get_file_name=$2

    # Patch there already?
    if [ -f "$get_file_dir"/"$(basename "$get_file_name")" ]; then
	echo " Already have patch..."
	return 0
    fi

    for get_file_server in $MIRRORS; do
	echo Trying $get_file_server...
	case $get_file_server in
	rsync://*) get_file_s=`echo $get_file_server | cut -c9-`;
		  rsync $get_file_s/$get_file_name $get_file_dir && return 0
		  ;;
	http://*) get_file_s=`echo $get_file_server | cut -c8-`;
		wget -O $get_file_dir/`basename $get_file_name` $get_file_s/$get_file_name && return 0
		# Leaves a zero-len file on failure 8(
		rm -f $get_file_dir/`basename $get_file_name`
		;;
	esac
    done
    return 1
}

if [ $# -ne 2 ]; then
    echo Usage: $0 version kerneldir >&2
    exit 1
fi

VERSION=$1
KDIR=$2

if [ -d $KDIR/linux-$VERSION ]; then exit 0; fi
MAJOR=`echo $VERSION | cut -d. -f1-2`

# Given vanity kernel name, major version, and previous version, produce pathname
vanity_source()
{
    case "$1" in
    *-ac*)
	echo people/alan/linux-$2/$3/patch-$1.bz2;;
    *-dj*)
	echo people/davej/patches/$2/$3/patch-$1.bz2;;
    *-mm*)
	echo people/akpm/patches/$2/$3/$1/$1.bz2;;
    *)
	barf "Unknown kernel series $1";;
    esac
}

# Given base name, new name and patch, do patch application.
apply_patch()
{
    rm -rf $KDIR/.linux-$2
    cp -al $KDIR/linux-$1 $KDIR/.linux-$2 ||
	    barf "Couldn't clone $1 dir"
    bunzip2 -t $3 || barf "Corrupt patch $3"
    bzcat $3 | patch -s -d $KDIR/.linux-$2 -p1 ||
	    barf "Problem patching new kernel $2"
    mv $KDIR/.linux-$2 $KDIR/linux-$2
}

echo Grabbing $VERSION
case "$VERSION" in
    # Bitkeeper snapshot
    *-bk*)
	if [ -d $KDIR/linux-$VERSION ]; then exit 0; fi

	PREVIOUS=`echo "$VERSION" | sed 's/-bk.*//'`
	$0 "$PREVIOUS" $KDIR || barf "Couldn't get $PREVIOUS to build $VERSION"

	# Grab patch
	get_file $PATCHDIR v$MAJOR/snapshots/patch-$VERSION.bz2  || barf "Couldn't get v$MAJOR/snapshots/patch-$VERSION.bz2"
	apply_patch $PREVIOUS $VERSION $PATCHDIR/patch-$VERSION.bz2
	;;

    # Various vanity patches
    *-mm[0-9]*|*-ac[0-9]*|*-dj[0-9]*)
	# First make sure we have base tree
	BASE_KERNEL=`echo "$VERSION" | sed -e 's/-[a-z][a-z][0-9]*$//'`
	$0 "$BASE_KERNEL" $KDIR	||
	    barf "Couldn't get $BASE_KERNEL to build $VERSION"
	VANITY=`vanity_source $VERSION $MAJOR $BASE_KERNEL`
	get_file $PATCHDIR $VANITY ||
		barf "Couldn't fetch $VANITY"

	apply_patch $BASE_KERNEL $VERSION $PATCHDIR/`basename $VANITY`
	;;

    # *-pre*: This refers to the Linus or Marcelo pre-patches.
    *-pre*|*-rc*)
	# Linus or Marcelo pre-patch.
	if [ -d $KDIR/linux-$VERSION ]; then exit 0; fi

	PREVIOUS=`echo "$VERSION" | sed 's/-\(pre\|rc\).*//'`
	LAST_VER=`echo "$PREVIOUS" | cut -d. -f3`
	PREVIOUS=`echo "$PREVIOUS" | cut -d. -f1,2`.`expr $LAST_VER - 1 || true`
	$0 "$PREVIOUS" $KDIR || barf "Couldn't get $PREVIOUS to build $VERSION"

	# Grab patch
	get_file $PATCHDIR v$MAJOR/testing/patch-$VERSION.bz2 ||
	    get_file $PATCHDIR v$MAJOR/testing/old/patch-$VERSION.bz2 ||
	    barf "Couldn't get v$MAJOR/testing/patch-$VERSION.bz2"
	apply_patch $PREVIOUS $VERSION $PATCHDIR/patch-$VERSION.bz2
	;;

    # Linus 2.6.0 test patch.
    2.6.0-test*)
	VER=`echo "$VERSION" | sed 's/.*test//'`
	PREVIOUS=2.6.0-test`expr $VER - 1 || true`

	if [ $PREVIOUS = 2.6.0-test0 ]; then
	    PREVIOUS=2.5.75
	fi

	$0 "$PREVIOUS" $KDIR || barf "Couldn't get $PREVIOUS to build $VERSION"

	# Grab patch
	get_file $PATCHDIR v$MAJOR/patch-$VERSION.bz2 ||
	    get_file $PATCHDIR v$MAJOR/old/patch-$VERSION.bz2 ||
	    barf "Couldn't get v$MAJOR/patch-$VERSION.bz2"
	apply_patch $PREVIOUS $VERSION $PATCHDIR/patch-$VERSION.bz2
	;;

    2.6.0)
	PREVIOUS=2.6.0-test11

	$0 "$PREVIOUS" $KDIR || barf "Couldn't get $PREVIOUS to build $VERSION"

	# Grab patch
	get_file $PATCHDIR v$MAJOR/patch-$VERSION.bz2 ||
	    get_file $PATCHDIR v$MAJOR/old/patch-$VERSION.bz2 ||
	    barf "Couldn't get v$MAJOR/patch-$VERSION.bz2"
	apply_patch $PREVIOUS $VERSION $PATCHDIR/patch-$VERSION.bz2
	;;

    # *.0: This refers to the base of the Linus kernels, fetched whole.
    *.0)
	# Linus' root of all trees.
	get_file $PATCHDIR v$MAJOR/linux-$VERSION.tar.bz2 || barf "Couldn't get  v$MAJOR/linux-$VERSION.tar.bz2"
	bzcat $PATCHDIR/linux-$VERSION.tar.bz2 | (cd $KDIR && tar xf -) ||
	    barf "Problem unpacking linux-$VERSION.tar.bz2"
	mv $KDIR/linux $KDIR/linux-$VERSION
	;;

    #   [1-9].*.*: This refers to the any other Linus kernel.
    [1-9].*.*[0-9])
	# Linus standard ?
	if [ -d $KDIR/linux-$VERSION ]; then exit 0; fi

	LAST_VER=`echo "$VERSION" | cut -d. -f3`
	PREVIOUS=`echo "$VERSION" | cut -d. -f1,2`.`expr $LAST_VER - 1 || true`
	$0 "$PREVIOUS" $KDIR || barf "Couldn't get $PREVIOUS to build $VERSION"

	# Grab patch
	get_file $PATCHDIR v$MAJOR/patch-$VERSION.bz2 || barf "Couldn't get v$MAJOR/patch-$VERSION.bz2"
	trap "rm -rf $KDIR/.linux-$VERSION" 0
	apply_patch $PREVIOUS $VERSION $PATCHDIR/patch-$VERSION.bz2
	;;
    *)
	barf "Unknown kernel version $VERSION"
	;;
esac