#!/bin/bash -e

# debirf module: install-kernel
# install a kernel package, indicated by the expected environment
# variables:
#  DEBIRF_PATH
#  DEBIRF_ROOT
#  DEBIRF_KERNEL_PACKAGE
#  DEBIRF_KERNEL_FLAVOR
#
# *** REQUIRED MODULE ***
# WARNING: this module is necessary for proper functioning of debirf.
#
# The debirf scripts were written by
# Jameson Rollins <jrollins@fifthhorseman.net>
# and
# Daniel Kahn Gillmor <dkg@fifthhorseman.net>.
#
# They are Copyright 2007, and are all released under the GPL,
# version 3 or later.

# clear out old modules if they exist, to avoid confusion
rm -rf "$DEBIRF_ROOT/lib/modules"

# download/copy in kernel package
if [ -z "$DEBIRF_KERNEL_PACKAGE" ] ; then
    # determine kernel to install. assume arch of build host.

    # determine kernel arch.  need everything after the kernel version
    # and debian version
    KARCH=${DEBIRF_KERNEL_FLAVOR:-$(uname -r | cut -d- -f3-)}

    # determine the full kernel version from the dependency of the
    # generic linux-image-ARCH package in the debirf root (since it
    # may be different than what is installed on the build host)
    KNAME=$(debirf_exec apt-cache show linux-image-"$KARCH" | grep '^Depends: ' | sed 's/^Depends: //' | tr ',' '\n' | tr -d ' ' | grep ^linux-image | sort -r | head -n1)

    # download only the desired kernel package for later dpkg
    # extraction.  this also downloads the kernel dependencies, but
    # they will not be installed, and the downloaded packages will all
    # be purged in the end by the clean-root module.  it would be nice
    # to just use "apt-get download", but that's only supported since
    # wheezy.
    debirf_exec apt-get install -d -y "$KNAME"

else
    # install kernel deb if given at command line
    cp "$DEBIRF_KERNEL_PACKAGE" "$DEBIRF_ROOT"/var/cache/apt/archives/
fi

KPKG=$(basename "$DEBIRF_ROOT"/var/cache/apt/archives/linux-image-*)

echo "extracting kernel package $KPKG..."
debirf_exec dpkg --extract /var/cache/apt/archives/"$KPKG" /

# install the module init tools, since they are needed for depmod
debirf_exec apt-get --assume-yes install module-init-tools

# depmod to create module list
KVERS=$(ls -1 -t "$DEBIRF_ROOT/lib/modules" | head -n1)
echo "generating modules.dep..."
debirf_exec depmod -a "$KVERS"

# extract kernel and debian stock initrd from the build root:
mv "$DEBIRF_ROOT"/boot/vmlinu* "$DEBIRF_BUILDD"

# remove kernel symlinks
if [ -L "$DEBIRF_ROOT"/vmlinuz ] ; then
    rm "$DEBIRF_BUILDD"/vmlinuz
fi
