#!/bin/sh

  # SPDX-License-Identifier: GPL-2.0
  
  # This script generates an archive consisting of kernel headers

  # for CONFIG_IKHEADERS.

  set -e

  sfile="$(readlink -f "$0")"

  outdir="$(pwd)"
  tarfile=$1
  cpio_dir=$outdir/$tarfile.tmp

  dir_list="

  include/
  arch/$SRCARCH/include/
  "
  
  # Support incremental builds by skipping archive generation
  # if timestamps of files being archived are not changed.
  
  # This block is useful for debugging the incremental builds.
  # Uncomment it for debugging.

  # if [ ! -f /tmp/iter ]; then iter=1; echo 1 > /tmp/iter;
  # else iter=$(($(cat /tmp/iter) + 1)); echo $iter > /tmp/iter; fi

  # find $all_dirs -name "*.h" | xargs ls -l > /tmp/ls-$iter
  
  all_dirs=
  if [ "$building_out_of_srctree" ]; then
  	for d in $dir_list; do
  		all_dirs="$all_dirs $srctree/$d"
  	done
  fi
  all_dirs="$all_dirs $dir_list"

  
  # include/generated/compile.h is ignored because it is touched even when none

  # of the source files changed.
  #
  # When Kconfig regenerates include/generated/autoconf.h, its timestamp is
  # updated, but the contents might be still the same. When any CONFIG option is
  # changed, Kconfig touches the corresponding timestamp file include/config/*.h.
  # Hence, the md5sum detects the configuration change anyway. We do not need to
  # check include/generated/autoconf.h explicitly.
  #
  # Ignore them for md5 calculation to avoid pointless regeneration.

  headers_md5="$(find $all_dirs -name "*.h"			|
  		grep -v "include/generated/compile.h"	|
  		grep -v "include/generated/autoconf.h"	|

  		xargs ls -l | md5sum | cut -d ' ' -f1)"

  # Any changes to this script will also cause a rebuild of the archive.
  this_file_md5="$(ls -l $sfile | md5sum | cut -d ' ' -f1)"

  if [ -f $tarfile ]; then tarfile_md5="$(md5sum $tarfile | cut -d ' ' -f1)"; fi
  if [ -f kernel/kheaders.md5 ] &&

  	[ "$(head -n 1 kernel/kheaders.md5)" = "$headers_md5" ] &&
  	[ "$(head -n 2 kernel/kheaders.md5 | tail -n 1)" = "$this_file_md5" ] &&

  	[ "$(tail -n 1 kernel/kheaders.md5)" = "$tarfile_md5" ]; then

  		exit
  fi
  
  if [ "${quiet}" != "silent_" ]; then
         echo "  GEN     $tarfile"
  fi
  
  rm -rf $cpio_dir
  mkdir $cpio_dir

  if [ "$building_out_of_srctree" ]; then

  	(
  		cd $srctree
  		for f in $dir_list
  			do find "$f" -name "*.h";
  		done | cpio --quiet -pd $cpio_dir
  	)

  fi

  # The second CPIO can complain if files already exist which can happen with out
  # of tree builds having stale headers in srctree. Just silence CPIO for now.

  for f in $dir_list;
  	do find "$f" -name "*.h";

  done | cpio --quiet -pd $cpio_dir >/dev/null 2>&1
  
  # Remove comments except SDPX lines
  find $cpio_dir -type f -print0 |
  	xargs -0 -P8 -n1 perl -pi -e 'BEGIN {undef $/;}; s/\/\*((?!SPDX).)*?\*\///smg;'

  # Create archive and try to normalize metadata for reproducibility.
  # For compatibility with older versions of tar, files are fed to tar
  # pre-sorted, as --sort=name might not be available.
  find $cpio_dir -printf "./%P
  " | LC_ALL=C sort | \
      tar "${KBUILD_BUILD_TIMESTAMP:+--mtime=$KBUILD_BUILD_TIMESTAMP}" \
      --owner=0 --group=0 --numeric-owner --no-recursion \

      -I $XZ -cf $tarfile -C $cpio_dir/ -T - > /dev/null

  echo $headers_md5 > kernel/kheaders.md5

  echo "$this_file_md5" >> kernel/kheaders.md5

  echo "$(md5sum $tarfile | cut -d ' ' -f1)" >> kernel/kheaders.md5
  
  rm -rf $cpio_dir