#!/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

  
  if [ "$ARCH" = "um" ] ; then

  	packagename=user-mode-linux
  else
  	packagename=linux-image

  fi

  debarch=
  set_debarch

  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:native)"

  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

  Rules-Requires-Root: no

  Build-Depends: bc, rsync, kmod, cpio, bison, flex | flex:native $extra_build_depends

  Homepage: https://www.kernel.org/

  Package: $packagename-$version

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

  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

  EOF

  if is_enabled CONFIG_MODULES; then
  cat <<EOF >> debian/control

  Package: linux-headers-$version

  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
  EOF
  fi

  if is_enabled CONFIG_DEBUG_INFO; then
  cat <<EOF >> debian/control

  Package: linux-image-$version-dbg

  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

  fi

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

  srctree ?= .

  build-indep:
  build-arch:

  	\$(MAKE) KERNELRELEASE=${version} ARCH=${ARCH} \

  	KBUILD_BUILD_VERSION=${revision} -f \$(srctree)/Makefile

  build: build-arch
  
  binary-indep:
  binary-arch: build-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