#!/bin/sh
### Automatic build configuration script for Dinit.
### This script generates an "mconfig" file suitable for building on the current system.

## Initial preparation
set -eu
cd "$(dirname "$0")"

## Helper functions
# POSIX "echo" behaviour is unspecified behavior in some cases, for example
# when the first argument is "-n" or backslash ("\").
# So, replace the shell built-in echo with a printf based function.
# For more info see http://www.etalabs.net/sh_tricks.html
echo()
{
    IFS=" " printf %s\\n "$*"
}

info()
{
    echo "$*"
}

sub_info()
{
    echo "  ... $*"
}

error()
{
    >&2 echo "Error: $*"
    exit 1
}

sub_error()
{
    >&2 echo "  ... Error: $*"
    exit 1
}

# warning() have a built-in extra information feild which is optional
# $1: Info, $2: Extra info (Optional)
# NOTE: Always quote your warning() messages
warning()
{
    >&2 echo
    >&2 echo "Warning: $1"
    [ -n "${2:-}" ] && >&2 echo "  ... $2"
    >&2 echo
}

cxx_works()
{
    info Checking whether \""$1"\" is a working C++ compiler...
    if $CXX -o testfile.o testfile.cc; then
        rm -f testfile
        sub_info Yes.
    else
        rm -f testfile*
        sub_error It seems like \""$CXX"\" is not working a working C++ compiler. Please specify compiler.
    fi
}

# Test if the compiler accepts an argument (for compilation and link); if so add it to named variable.
# $1 - the name of the variable to potentially add the argument to
# $2 - the argument to add
# CXX - the name of the compiler
# CXXFLAGS, CXXFLAGS_EXTRA, LDFLAGS, LDFLAGS_EXTRA - any predetermined flags 
try_cxx_argument()
{
    info Checking whether the compiler accepts "$2"...
    if $CXX $CXXFLAGS $2 $CXXFLAGS_EXTRA $LDFLAGS $LDFLAGS_EXTRA testfile.cc -o testfile > /dev/null 2>&1; then
        rm testfile
        sub_info Yes.
        eval "$1=\"\${$1} \$2\""
        eval "$1=\${$1# }"
        return 0
    else
        sub_info No.
        return 1
    fi
}

try_ld_argument()
{
    info Checking whether "$2" is accepted as a link-time option...
    if $CXX $CXXFLAGS $CXXFLAGS_EXTRA $LDFLAGS $LDFLAGS_EXTRA $2 testfile.cc -o testfile > /dev/null 2>&1; then
        sub_info Yes.
        eval "$1=\"\${$1} \$2\""
        eval "$1=\${$1# }"
    else
        sub_info No.
    fi
}

try_both_argument()
{
    info Checking whether the compiler/linker accepts "$3"...
    if $CXX $CXXFLAGS $CXXFLAGS_EXTRA $LDFLAGS $LDFLAGS_EXTRA $3 testfile.cc -o testfile > /dev/null 2>&1; then
        sub_info Yes.
        eval "$1=\"\${$1} \$3\""
        eval "$1=\${$1# }"
        eval "$2=\"\${$2} \$3\""
        eval "$2=\${$2# }"
    else
        sub_info No.
    fi
}

usage()
{
    cat << _EOF
Usage: $0 [OPTION]...

Generates build configuration for Dinit.

Defaults for the options are specified in brackets.

  -h, --help                    This help message.
  -q, --quiet                   Don't print normal messages, just errors.
  -c, --clear                   Clear mconfig and configure's temporary files.

Target options:
  --platform=PLATFORM           Set the platform manually (Just for cross-platform cross-compile!) [autodetected]
                                  Note: for all cross-compiles please specify correct CXX and CXX_FOR_BUILD!

Installation directories:
  --prefix=PREFIX               Main installation prefix [/usr]
  --exec-prefix=EPREFIX         Main executables prefix  [/]
  --sbindir=SBINDIR             Dinit executables        [EPREFIX/sbin]
  --mandir=MANDIR               Dinit man-pages location [PREFIX/share/man]
  --syscontrolsocket=SOCKETPATH Dinitctl socket location [/run/dinitctl] on Linux systems
                                                         [/var/run/dinitctl] on other systems

Optional options:
  --enable-strip                Strip debug information in installation process [Enabled]
  --disable-strip               Don't strip debug information in installation process
  --shutdown-prefix=PREFIX      Name prefix for shutdown, poweroff, reboot, halt programs []
  --enable-shutdown             Build shutdown, poweroff, reboot, halt programs [Enabled only on Linux systems]
  --disable-shutdown            Don't build shutdown, poweroff, reboot, halt programs
  --enable-cgroups              Enable Cgroups support [Enabled only on Linux based systems]
  --disable-cgroups             Disable Cgroups support
  --enable-utmpx                Enable manipulating the utmp/utmpx database via the related POSIX functions [guessed]
  --disable-utmpx               Disable manipulating the utmp/utmpx database via the related POSIX functions
  --enable-initgroups           Enable initialization of supplementary groups for run-as [Enabled]
  --disable-initgroups          Disable initialization of supplementary groups for run-as
  --enable-auto-restart         Enable auto-restart for services by default [Enabled]
  --disable-auto-restart        Disable auto-restart for services by default
  --default-start-timeout=sec   Default start-timeout for services [60]
  --default-stop-timeout=sec    Default stop-timeout for services [10]

Build variables:
  Note: build variables can be passed in the environment, or as $0 argument (as "var=VALUE").
  Note: CXXFLAGS, TEST_CXXFLAGS, LDFLAGS and TEST_LDFLAGS by default will be set to options considered suitable
  for the platform, filtered to remove any options not supported by the  compiler/linker. To disable this,
  specify the values explicitly (an empty string is accepted). To add options without removing the defaults,
  set the variable with _EXTRA appended to the name (eg CXXFLAGS_EXTRA).

  CXX                           C++ compiler
  CXX_FOR_BUILD                 C++ compiler generating code for the build system (for cross-compiles).
  CXXFLAGS_FOR_BUILD            Flags to use when generating code for the build system.
                                  Defaults to the value of CXXFLAGS.
  CPPFLAGS_FOR_BUILD            Preprocessor flags to use when generating code for the build system.
                                  Defaults to the value of CPPFLAGS.
  LDFLAGS_FOR_BUILD             Link flags to use when generating code for the build system.
                                  Defaults to the value of LDFLAGS.
  CXXFLAGS                      Flags to use when compiling C++ code.
  CXXFLAGS_EXTRA                Additional flags to use when compiling C++ code.
  TEST_CXXFLAGS                 Flags to use when compiling C++ code in tests.
  TEST_CXXFLAGS_EXTRA           Additional flags to use when compiling C++ code in tests.
  CPPFLAGS                      Preprocessor flags to use when compiling C++ code.
  LDFLAGS                       Link flags.
  LDFLAGS_EXTRA                 Additional link flags.
  LDFLAGS_BASE                  Link flags to use in addition to any link-time optimisation
                                (LTO)-related options. Set this to control link options without
                                disabling LTO. Ignored if LDFLAGS is set.
  TEST_LDFLAGS                  Links flags when building test executables.
  TEST_LDFLAGS_EXTRA            Additional link flags when building test executables.
  TEST_LDFLAGS_BASE             Link flags to use when building test executables, in addition to
                                LTO-releated options.

Note: paths specified via --prefix/--exec-prefix/--sbindir/--mandir, and build variable values, must be
escaped for use in a makefile and in shell commands. If there are spaces in paths it is recommended to
prepend a backslash (\) to them.
For example: ./configure --prefix="/home/my\ home"

See BUILD file for more information.
_EOF
    exit 0
}

## Don't take values from environment for these variables:
for var in PREFIX \
           EPREFIX \
           SBINDIR \
           MANDIR \
           SHUTDOWN_PREFIX \
           BUILD_SHUTDOWN \
           SUPPORT_CGROUPS \
           USE_UTMPX \
           USE_INITGROUPS \
           SYSCONTROLSOCKET \
           STRIPOPTS
do
    unset $var
done

## Flag parser
for arg in "$@"; do
    case "$arg" in
        -h|--help) usage ;;
        -q|--quiet)
            info() { true; }
            sub_info() { true; }
            warning() { true; }
        ;;
        -c|--clear) rm -f test* & rm -f mconfig && exit 0 ;;
        --platform=*) PLATFORM="${arg#*=}" && shift ;;
        --prefix=*) PREFIX="${arg#*=}" && shift ;;
        --exec-prefix=*) EPREFIX="${arg#*=}" && shift;;
        --sbindir=*) SBINDIR="${arg#*=}" && shift ;;
        --mandir=*) MANDIR="${arg#*=}" && shift ;;
        --default-start-timeout=*) DEFAULT_START_TIMEOUT="${arg#*=}" && shift ;;
        --default-stop-timeout=*) DEFAULT_STOP_TIMEOUT="${arg#*=}" && shift ;;
        --syscontrolsocket=*) SYSCONTROLSOCKET="${arg#*=}" && shift ;;
        --shutdown-prefix=*) SHUTDOWN_PREFIX="${arg#*=}" && shift ;;
        --enable-shutdown|--enable-shutdown=yes) BUILD_SHUTDOWN=yes ;;
        --disable-shutdown|--enable-shutdown=no) BUILD_SHUTDOWN=no ;;
        --enable-cgroups|--enable-cgroups=yes) SUPPORT_CGROUPS=1 ;;
        --disable-cgroups|--enable-cgroups=no) SUPPORT_CGROUPS=0 ;;
        --enable-utmpx|--enable-utmpx=yes) USE_UTMPX=1 ;;
        --disable-utmpx|--enable-utmpx=no) USE_UTMPX=0 ;;
        --enable-initgroups|--enable-initgroups=yes) USE_INITGROUPS=1 ;;
        --disable-initgroups|--enable-initgroups=no) USE_INITGROUPS=0 ;;
        --enable-auto-restart|--enable-auto-restart=yes) DEFAULT_AUTO_RESTART=true ;;
        --disable-auto-restart|--enable-auto-restart=no) DEFAULT_AUTO_RESTART=false ;;
        --enable-strip|--enable-strip=yes) STRIPOPTS="-s" ;;
        --disable-strip|--enable-strip=no) STRIPOPTS="" ;;
        CXX=*|CXX_FOR_BUILD=*|CXXFLAGS_FOR_BUILD=*|CPPFLAGS_FOR_BUILD=*\
        |LDFLAGS_FOR_BUILD=*|CXXFLAGS=*|CXXFLAGS_EXTRA=*|TEST_CXXFLAGS=*\
        |TEST_CXXFLAGS_EXTRA=*|LDFLAGS=*|LDFLAGS_EXTRA=*|TEST_LDFLAGS=*\
        |TEST_LDFLAGS_EXTRA=*|CPPFLAGS=*|LDFLAGS_BASE=*|TEST_LDFLAGS_BASE=*) eval "${arg%%=*}=\${arg#*=}" ;;
        *=*) warning "Unknown variable: ${arg%%=*}" ;;
        *) warning "Unknown argument: $arg" ;;
    esac
done

## Defaults for variables not specified by user
: "${PLATFORM:=$(uname)}"
: "${PREFIX:="/usr"}"
: "${EPREFIX:="/"}"
: "${SBINDIR:="${EPREFIX%%/}/sbin"}"
: "${MANDIR:="${PREFIX%%/}/share/man"}"
: "${SHUTDOWN_PREFIX:=""}"
: "${CXXFLAGS_EXTRA:=""}"
: "${TEST_CXXFLAGS_EXTRA:=""}"
: "${CPPFLAGS:=""}"
: "${LDFLAGS_EXTRA:=""}"
: "${TEST_LDFLAGS_EXTRA:=""}"
: "${DEFAULT_AUTO_RESTART:="true"}"
: "${DEFAULT_START_TIMEOUT:="60"}"
: "${DEFAULT_STOP_TIMEOUT:="10"}"
: "${USE_INITGROUPS:="1"}"
if [ "$PLATFORM" = "Linux" ]; then
    : "${BUILD_SHUTDOWN:="yes"}"
    : "${SUPPORT_CGROUPS:="1"}"
    : "${SYSCONTROLSOCKET:="/run/dinitctl"}"
else
    : "${BUILD_SHUTDOWN:="no"}"
    : "${SUPPORT_CGROUPS:="0"}"
    : "${SYSCONTROLSOCKET:="/var/run/dinitctl"}"
fi

HAS_LTO=""

## Finalize $CXXFLAGS, $TEST_CXXFLAGS, $LDFLAGS, $TEST_LDFLAGS, $STRIPOPTS
if [ -z "${CXXFLAGS+IS_SET}" ]; then
    CXXFLAGS=""
    AUTO_CXXFLAGS="true"
else
    AUTO_CXXFLAGS="false"
fi
if [ -z "${TEST_CXXFLAGS+IS_SET}" ]; then
    TEST_CXXFLAGS=""
    AUTO_TEST_CXXFLAGS="true"
else
    AUTO_TEST_CXXFLAGS="false"
fi
if [ -z "${LDFLAGS+IS_SET}" ]; then
    LDFLAGS=""
    AUTO_LDFLAGS="true"
else
    AUTO_LDFLAGS="false"
fi
if [ -z "${TEST_LDFLAGS+IS_SET}" ]; then
    TEST_LDFLAGS=""
    AUTO_TEST_LDFLAGS="true"
else
    AUTO_TEST_LDFLAGS="false"
fi
if [ -z "${LDFLAGS_BASE+IS_SET}" ]; then
    LDFLAGS_BASE=""
    AUTO_LDFLAGS_BASE="true"
else
    AUTO_LDFLAGS=BASE="false"
fi
if [ -z "${TEST_LDFLAGS_BASE+IS_SET}" ]; then
    TEST_LDFLAGS_BASE=""
    AUTO_TEST_LDFLAGS_BASE="true"
else
    AUTO_TEST_LDFLAGS=BASE="false"
fi

[ -z "${STRIPOPTS+IS_SET}" ] && STRIPOPTS="-s"

## Verify PLATFORM value
if [ "$PLATFORM" != "Linux" ] && [ "$PLATFORM" != "FreeBSD" ] && \
[ "$PLATFORM" != "OpenBSD" ] && [ "$PLATFORM" != "Darwin" ]; then
    warning "$PLATFORM platform is unknown!" "Known Platforms are: Linux, FreeBSD, OpenBSD, Darwin"
fi

## Create testfile.cc to test c++ compiler
echo "int main(int argc, char **argv) { return 0; }" > testfile.cc || error Can\'t create temporary file

## Find and test C++ compiler
if [ -z "${CXX:-}" ]; then
    info Checking C++ compiler...
    for guess in g++ clang++ c++; do
        if type "$guess" > /dev/null 2>&1; then
            CXX="$guess"
            sub_info "$CXX"
            break # Found
        fi
    done
    if [ -z "${CXX:-}" ]; then
       sub_error No C++ compiler found! # Not found
    fi
fi
cxx_works "$CXX"
if [ -n "${CXX_FOR_BUILD:-}" ]; then
    cxx_works "$CXX_FOR_BUILD"
fi

## Test compiler/linker supported arguments
if [ "$AUTO_CXXFLAGS" = "true" ]; then
    if ! try_cxx_argument CXXFLAGS -std=c++11; then
        sub_error "The C++ compiler ($CXX) doesn't accept '-std=c++11' and may be too old."
    fi
    for argument in -Wall \
                    -Os \
                    -fno-plt
    do
        try_cxx_argument CXXFLAGS $argument || :
    done
    if [ "$PLATFORM" != "Darwin" ]; then
        try_cxx_argument CXXFLAGS -fno-rtti || :
    fi
fi
if [ "$AUTO_LDFLAGS" = "true" ] && [ "$AUTO_CXXFLAGS" = "true" ]; then
    if try_cxx_argument CXXFLAGS -flto; then
        HAS_LTO="true"
    else
        HAS_LTO="false"
    fi
fi
if [ "$AUTO_LDFLAGS_BASE" = true ] && [ "$PLATFORM" = FreeBSD ]; then
    try_ld_argument LDFLAGS_BASE -lrt
fi
if [ "$AUTO_TEST_LDFLAGS_BASE" = true ]; then
    TEST_LDFLAGS_BASE="\$(LDFLAGS_BASE)"
    established_TEST_LDFLAGS="$LDFLAGS_BASE"
else
    established_TEST_LDFLAGS="$TEST_LDFLAGS_BASE"
fi

# Determine LDFLAGS/TEST_LDFLAGS. In the case of TEST_LDFLAGS we may still add sanitisation
# options, shortly. 
if [ "$HAS_LTO" = true ]; then
    if [ "$AUTO_LDFLAGS" = true ]; then
        LDFLAGS="\$(LDFLAGS_BASE) \$(CXXFLAGS)"
    fi
    if [ "$AUTO_TEST_LDFLAGS" = true ]; then
        TEST_LDFLAGS="\$(TEST_LDFLAGS_BASE) \$(TEST_CXXFLAGS)"
        established_TEST_LDFLAGS="$established_TEST_LDFLAGS $TEST_CXXFLAGS"
    else
        established_TEST_LDFLAGS="$TEST_LDFLAGS"
    fi
else
    # default LDFLAGS are just $(LDFLAGS_BASE)
    if [ "$AUTO_LDFLAGS" = true ]; then
        LDFLAGS="\$(LDFLAGS_BASE)"
    fi
    if [ "$AUTO_TEST_LDFLAGS" = true ]; then
        TEST_LDFLAGS="\$(TEST_LDFLAGS_BASE)"
    else
        established_TEST_LDFLAGS="$TEST_LDFLAGS"
    fi
fi

# Default for test flags (TEST_CXXFLAGS, TEST_LDFLAGS) is to use the build flags
if [ "$AUTO_TEST_CXXFLAGS" = "true" ]; then
    TEST_CXXFLAGS="\$(CXXFLAGS)"
    established_TEST_CXXFLAGS="$CXXFLAGS"
else
    established_TEST_CXXFLAGS="$TEST_CXXFLAGS"
fi

# Check whether sanitizers can be used for tests
if [ "$AUTO_TEST_LDFLAGS" = "true" ] && [ "$AUTO_TEST_CXXFLAGS" = "true" ]; then
    if [ "$HAS_LTO" = true ]; then
        CXXFLAGS="$established_TEST_CXXFLAGS" CXXFLAGS_EXTRA="$TEST_CXXFLAGS_EXTRA" \
                LDFLAGS="$established_TEST_LDFLAGS" LDFLAGS_EXTRA="$TEST_LDFLAGS_EXTRA" \
                try_cxx_argument TEST_CXXFLAGS -fsanitize=address,undefined
    else
        CXXFLAGS="$established_TEST_CXXFLAGS" CXXFLAGS_EXTRA="$TEST_CXXFLAGS_EXTRA" \
                LDFLAGS="$established_TEST_LDFLAGS" LDFLAGS_EXTRA="$TEST_LDFLAGS_EXTRA" \
                try_both_argument TEST_CXXFLAGS TEST_LDFLAGS -fsanitize=address,undefined
    fi
fi

## Create mconfig
rm -f testfile*
info Creating mconfig...
cat << _EOF > mconfig
## Auto-generated by "$0" for "$PLATFORM"
# All changes will be lost if "$0" is re-run.

# See BUILD for help on all variables.

# Installation path options.

SBINDIR=$SBINDIR
MANDIR=$MANDIR
SYSCONTROLSOCKET=$SYSCONTROLSOCKET

# General build options.

CXX=$CXX
CXXFLAGS=$CXXFLAGS
CXXFLAGS_EXTRA=$CXXFLAGS_EXTRA
TEST_CXXFLAGS=$TEST_CXXFLAGS
TEST_CXXFLAGS_EXTRA=$TEST_CXXFLAGS_EXTRA
CPPFLAGS=$CPPFLAGS
LDFLAGS_BASE=$LDFLAGS_BASE
LDFLAGS=$LDFLAGS
LDFLAGS_EXTRA=$LDFLAGS_EXTRA
TEST_LDFLAGS_BASE=$TEST_LDFLAGS_BASE
TEST_LDFLAGS=$TEST_LDFLAGS
TEST_LDFLAGS_EXTRA=$TEST_LDFLAGS_EXTRA
BUILD_SHUTDOWN=$BUILD_SHUTDOWN
STRIPOPTS=$STRIPOPTS

# Feature settings
SUPPORT_CGROUPS=$SUPPORT_CGROUPS
USE_INITGROUPS=$USE_INITGROUPS

# Optional settings
SHUTDOWN_PREFIX=${SHUTDOWN_PREFIX:-}

# Service defaults
DEFAULT_AUTO_RESTART=$DEFAULT_AUTO_RESTART
DEFAULT_START_TIMEOUT=$DEFAULT_START_TIMEOUT
DEFAULT_STOP_TIMEOUT=$DEFAULT_STOP_TIMEOUT
_EOF
if [ -n "${USE_UTMPX:-}" ]; then
    echo "USE_UTMPX=$USE_UTMPX" >> mconfig
fi
if [ -n "${CXX_FOR_BUILD:-}" ]; then
    {
        echo ""
        echo "# For cross-compiling"
        echo "CXX_FOR_BUILD=$CXX_FOR_BUILD"
    } >> mconfig
fi
if [ -n "${CXXFLAGS_FOR_BUILD:-}" ]; then
    echo "CXXFLAGS_FOR_BUILD=$CXXFLAGS_FOR_BUILD" >> mconfig
fi
if [ -n "${CPPFLAGS_FOR_BUILD:-}" ]; then
    echo "CPPFLAGS_FOR_BUILD=$CPPFLAGS_FOR_BUILD" >> mconfig
fi
if [ -n "${LDFLAGS_FOR_BUILD:-}" ]; then
    echo "LDFLAGS_FOR_BUILD=$LDFLAGS_FOR_BUILD" >> mconfig
fi
sub_info done.
info Done!
exit 0