#!/bin/sh
# SPDX-License-Identifier: GPL-2.0

TARGET=$1
ARCH=$2
SMP=$3
PREEMPT=$4
PREEMPT_DYNAMIC=$5
PREEMPT_RT=$6
CC_VERSION="$7"
LD=$8

# Do not expand names
set -f

# Fix the language to get consistent output
LC_ALL=C
export LC_ALL

if [ -z "$KBUILD_BUILD_VERSION" ]; then
	VERSION=$(cat .version 2>/dev/null || echo 1)
else
	VERSION=$KBUILD_BUILD_VERSION
fi

if [ -z "$KBUILD_BUILD_TIMESTAMP" ]; then
	TIMESTAMP=`date`
else
	TIMESTAMP=$KBUILD_BUILD_TIMESTAMP
fi
if test -z "$KBUILD_BUILD_USER"; then
	LINUX_COMPILE_BY=$(whoami | sed 's/\\/\\\\/')
else
	LINUX_COMPILE_BY=$KBUILD_BUILD_USER
fi
if test -z "$KBUILD_BUILD_HOST"; then
	LINUX_COMPILE_HOST=`uname -n`
else
	LINUX_COMPILE_HOST=$KBUILD_BUILD_HOST
fi

UTS_VERSION="#$VERSION"
CONFIG_FLAGS=""
if [ -n "$SMP" ] ; then CONFIG_FLAGS="SMP"; fi

if [ -n "$PREEMPT_RT" ] ; then
	CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT_RT"
elif [ -n "$PREEMPT_DYNAMIC" ] ; then
	CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT_DYNAMIC"
elif [ -n "$PREEMPT" ] ; then
	CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT"
fi

# Truncate to maximum length
UTS_LEN=64
UTS_VERSION="$(echo $UTS_VERSION $CONFIG_FLAGS $TIMESTAMP | cut -b -$UTS_LEN)"

# Generate a temporary compile.h

{ echo /\* This file is auto generated, version $VERSION \*/
  if [ -n "$CONFIG_FLAGS" ] ; then echo "/* $CONFIG_FLAGS */"; fi

  echo \#define UTS_MACHINE \"$ARCH\"

  echo \#define UTS_VERSION \"$UTS_VERSION\"

  printf '#define LINUX_COMPILE_BY "%s"\n' "$LINUX_COMPILE_BY"
  echo \#define LINUX_COMPILE_HOST \"$LINUX_COMPILE_HOST\"

  LD_VERSION=$($LD -v | head -n1 | sed 's/(compatible with [^)]*)//' \
		      | sed 's/[[:space:]]*$//')
  printf '#define LINUX_COMPILER "%s"\n' "$CC_VERSION, $LD_VERSION"
} > .tmpcompile

# Only replace the real compile.h if the new one is different,
# in order to preserve the timestamp and avoid unnecessary
# recompilations.
# We don't consider the file changed if only the date/time changed,
# unless KBUILD_BUILD_TIMESTAMP was explicitly set (e.g. for
# reproducible builds with that value referring to a commit timestamp).
# A kernel config change will increase the generation number, thus
# causing compile.h to be updated (including date/time) due to the
# changed comment in the
# first line.

if [ -z "$KBUILD_BUILD_TIMESTAMP" ]; then
   IGNORE_PATTERN="UTS_VERSION"
else
   IGNORE_PATTERN="NOT_A_PATTERN_TO_BE_MATCHED"
fi

if [ -r $TARGET ] && \
      grep -v $IGNORE_PATTERN $TARGET > .tmpver.1 && \
      grep -v $IGNORE_PATTERN .tmpcompile > .tmpver.2 && \
      cmp -s .tmpver.1 .tmpver.2; then
   rm -f .tmpcompile
else
   echo "  UPD     $TARGET"
   mv -f .tmpcompile $TARGET
fi
rm -f .tmpver.1 .tmpver.2