kbuild: deb-pkg: split generating packaging and build

Move debian/ directory generation out of builddeb to a new script,
mkdebian. The package build commands are kept in builddeb, which
is now an internal command called from debian/rules.

With these changes in place, we can now use dpkg-buildpackage from
deb-pkg and bindeb-pkg removing need for handrolled source/changes
generation.

This patch is based on the criticism of the current state of builddeb
discussed on:

https://patchwork.kernel.org/patch/9656403/

Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/scripts/package/mkdebian b/scripts/package/mkdebian
new file mode 100755
index 0000000..6adb3a1
--- /dev/null
+++ b/scripts/package/mkdebian
@@ -0,0 +1,189 @@
+#!/bin/sh
+#
+# Copyright 2003 Wichert Akkerman <wichert@wiggy.net>
+#
+# Simple script to generate a debian/ directory for a Linux kernel.
+
+set -e
+
+set_debarch() {
+	# Attempt to find the correct Debian architecture
+	case "$UTS_MACHINE" in
+	i386|ia64|alpha)
+		debarch="$UTS_MACHINE" ;;
+	x86_64)
+		debarch=amd64 ;;
+	sparc*)
+		debarch=sparc ;;
+	s390*)
+		debarch=s390$(grep -q CONFIG_64BIT=y $KCONFIG_CONFIG && echo x || true) ;;
+	ppc*)
+		debarch=$(grep -q CPU_LITTLE_ENDIAN=y $KCONFIG_CONFIG && echo ppc64el || echo powerpc) ;;
+	parisc*)
+		debarch=hppa ;;
+	mips*)
+		debarch=mips$(grep -q CPU_LITTLE_ENDIAN=y $KCONFIG_CONFIG && echo el || true) ;;
+	aarch64|arm64)
+		debarch=arm64 ;;
+	arm*)
+		if grep -q CONFIG_AEABI=y $KCONFIG_CONFIG; then
+		    if grep -q CONFIG_VFP=y $KCONFIG_CONFIG; then
+			debarch=armhf
+		    else
+			debarch=armel
+		    fi
+		else
+		    debarch=arm
+		fi
+		;;
+	*)
+		debarch=$(dpkg --print-architecture)
+		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 using your current userspace instead!" >&2
+		echo "Please add support for $UTS_MACHINE to ${0} ..." >&2
+		echo "" >&2
+	esac
+	if [ -n "$KBUILD_DEBARCH" ] ; then
+		debarch="$KBUILD_DEBARCH"
+	fi
+}
+
+# Some variables and settings used throughout the script
+version=$KERNELRELEASE
+if [ -n "$KDEB_PKGVERSION" ]; then
+	packageversion=$KDEB_PKGVERSION
+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-$version
+fi
+
+# Try to determine maintainer and email values
+if [ -n "$DEBEMAIL" ]; then
+       email=$DEBEMAIL
+elif [ -n "$EMAIL" ]; then
+       email=$EMAIL
+else
+       email=$(id -nu)@$(hostname -f 2>/dev/null || hostname)
+fi
+if [ -n "$DEBFULLNAME" ]; then
+       name=$DEBFULLNAME
+elif [ -n "$NAME" ]; then
+       name=$NAME
+else
+       name="Anonymous"
+fi
+maintainer="$name <$email>"
+
+# Try to determine distribution
+if [ -n "$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/
+echo $debarch > debian/arch
+
+# Generate a simple changelog template
+cat <<EOF > debian/changelog
+$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, kmod, cpio
+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.
+
+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 $MAKE) -f
+
+build:
+	\$(MAKE) KERNELRELEASE=${version} ARCH=${ARCH} KBUILD_SRC=
+
+binary-arch:
+	\$(MAKE) KERNELRELEASE=${version} ARCH=${ARCH} KBUILD_SRC= intdeb-pkg
+
+clean:
+	rm -rf debian/*tmp debian/files
+	\$(MAKE) clean
+
+binary: binary-arch
+EOF
+
+exit 0