#!/bin/sh
#
# Copyright 2003 Wichert Akkerman <wichert@wiggy.net>
#
# Simple script to generate a debian/ directory for a Linux kernel.

set -e

is_enabled() {
	grep -q "^$1=y" include/config/auto.conf
}

if_enabled_echo() {
	if is_enabled "$1"; then
		echo -n "$2"
	elif [ $# -ge 3 ]; then
		echo -n "$3"
	fi
}

set_debarch() {
	if [ -n "$KBUILD_DEBARCH" ] ; then
		debarch="$KBUILD_DEBARCH"
		return
	fi

	# Attempt to find the correct Debian architecture
	case "$UTS_MACHINE" in
	i386|ia64|alpha|m68k|riscv*)
		debarch="$UTS_MACHINE" ;;
	x86_64)
		debarch=amd64 ;;
	sparc*)
		debarch=sparc$(if_enabled_echo CONFIG_64BIT 64) ;;
	s390*)
		debarch=s390x ;;
	ppc*)
		if is_enabled CONFIG_64BIT; then
			debarch=ppc64$(if_enabled_echo CONFIG_CPU_LITTLE_ENDIAN el)
		else
			debarch=powerpc$(if_enabled_echo CONFIG_SPE spe)
		fi
		;;
	parisc*)
		debarch=hppa ;;
	mips*)
		if is_enabled CONFIG_CPU_LITTLE_ENDIAN; then
			debarch=mips$(if_enabled_echo CONFIG_64BIT 64)$(if_enabled_echo CONFIG_CPU_MIPSR6 r6)el
		elif is_enabled CONFIG_CPU_MIPSR6; then
			debarch=mips$(if_enabled_echo CONFIG_64BIT 64)r6
		else
			debarch=mips
		fi
		;;
	aarch64|arm64)
		debarch=arm64 ;;
	arm*)
		if is_enabled CONFIG_AEABI; then
			debarch=arm$(if_enabled_echo CONFIG_VFP hf el)
		else
			debarch=arm
		fi
		;;
	openrisc)
		debarch=or1k ;;
	sh)
		if is_enabled CONFIG_CPU_SH3; then
			debarch=sh3$(if_enabled_echo CONFIG_CPU_BIG_ENDIAN eb)
		elif is_enabled CONFIG_CPU_SH4; then
			debarch=sh4$(if_enabled_echo CONFIG_CPU_BIG_ENDIAN eb)
		fi
		;;
	esac
	if [ -z "$debarch" ]; then
		debarch=$(dpkg-architecture -qDEB_HOST_ARCH)
		echo "" >&2
		echo "** ** **  WARNING  ** ** **" >&2
		echo "" >&2
		echo "Your architecture doesn't have its equivalent" >&2
		echo "Debian userspace architecture defined!" >&2
		echo "Falling back to the current host architecture ($debarch)." >&2
		echo "Please add support for $UTS_MACHINE to ${0} ..." >&2
		echo "" >&2
	fi
}

# Some variables and settings used throughout the script
version=$KERNELRELEASE
if [ -n "$KDEB_PKGVERSION" ]; then
	packageversion=$KDEB_PKGVERSION
	revision=${packageversion##*-}
else
	revision=$(cat .version 2>/dev/null||echo 1)
	packageversion=$version-$revision
fi
sourcename=$KDEB_SOURCENAME
packagename=linux-image-$version
kernel_headers_packagename=linux-headers-$version
dbg_packagename=$packagename-dbg
debarch=
set_debarch

if [ "$ARCH" = "um" ] ; then
	packagename=user-mode-linux-$version
fi

email=${DEBEMAIL-$EMAIL}

# use email string directly if it contains <email>
if echo $email | grep -q '<.*>'; then
	maintainer=$email
else
	# or construct the maintainer string
	user=${KBUILD_BUILD_USER-$(id -nu)}
	name=${DEBFULLNAME-$user}
	if [ -z "$email" ]; then
		buildhost=${KBUILD_BUILD_HOST-$(hostname -f 2>/dev/null || hostname)}
		email="$user@$buildhost"
	fi
	maintainer="$name <$email>"
fi

# Try to determine distribution
if [ -n "$KDEB_CHANGELOG_DIST" ]; then
        distribution=$KDEB_CHANGELOG_DIST
# In some cases lsb_release returns the codename as n/a, which breaks dpkg-parsechangelog
elif distribution=$(lsb_release -cs 2>/dev/null) && [ -n "$distribution" ] && [ "$distribution" != "n/a" ]; then
        : # nothing to do in this case
else
        distribution="unstable"
        echo >&2 "Using default distribution of 'unstable' in the changelog"
        echo >&2 "Install lsb-release or set \$KDEB_CHANGELOG_DIST explicitly"
fi

mkdir -p debian/source/
echo "1.0" > debian/source/format

echo $debarch > debian/arch
extra_build_depends=", $(if_enabled_echo CONFIG_UNWINDER_ORC libelf-dev)"
extra_build_depends="$extra_build_depends, $(if_enabled_echo CONFIG_SYSTEM_TRUSTED_KEYRING libssl-dev:native)"

# Generate a simple changelog template
cat <<EOF > debian/changelog
$sourcename ($packageversion) $distribution; urgency=low

  * Custom built Linux kernel.

 -- $maintainer  $(date -R)
EOF

# Generate copyright file
cat <<EOF > debian/copyright
This is a packacked upstream version of the Linux kernel.

The sources may be found at most Linux archive sites, including:
https://www.kernel.org/pub/linux/kernel

Copyright: 1991 - 2018 Linus Torvalds and others.

The git repository for mainline kernel development is at:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; version 2 dated June, 1991.

On Debian GNU/Linux systems, the complete text of the GNU General Public
License version 2 can be found in \`/usr/share/common-licenses/GPL-2'.
EOF

# Generate a control file
cat <<EOF > debian/control
Source: $sourcename
Section: kernel
Priority: optional
Maintainer: $maintainer
Build-Depends: bc, rsync, kmod, cpio, bison, flex | flex:native $extra_build_depends
Homepage: http://www.kernel.org/

Package: $packagename
Architecture: $debarch
Description: Linux kernel, version $version
 This package contains the Linux kernel, modules and corresponding other
 files, version: $version.

Package: $kernel_headers_packagename
Architecture: $debarch
Description: Linux kernel headers for $version on $debarch
 This package provides kernel header files for $version on $debarch
 .
 This is useful for people who need to build external modules

Package: linux-libc-dev
Section: devel
Provides: linux-kernel-headers
Architecture: $debarch
Description: Linux support headers for userspace development
 This package provides userspaces headers from the Linux kernel.  These headers
 are used by the installed headers for GNU glibc and other system libraries.
Multi-Arch: same

Package: $dbg_packagename
Section: debug
Architecture: $debarch
Description: Linux kernel debugging symbols for $version
 This package will come in handy if you need to debug the kernel. It provides
 all the necessary debug symbols for the kernel and its modules.
EOF

cat <<EOF > debian/rules
#!$(command -v $MAKE) -f

srctree ?= .

build:
	\$(MAKE) KERNELRELEASE=${version} ARCH=${ARCH} \
	KBUILD_BUILD_VERSION=${revision} -f \$(srctree)/Makefile

binary-arch:
	\$(MAKE) KERNELRELEASE=${version} ARCH=${ARCH} \
	KBUILD_BUILD_VERSION=${revision} -f \$(srctree)/Makefile intdeb-pkg

clean:
	rm -rf debian/*tmp debian/files
	\$(MAKE) clean

binary: binary-arch
EOF
chmod +x debian/rules

exit 0