#!/bin/sh

# A script to configure the musl C library

# This is intended to provide you with a way to use the musl C library
# with modern compilers such that you will be able to use most C23
# features that such compilers already provide.
#
# Note that this script not suited for cross compilation.
#
# You need
#
# - a native Linux system, with musl or glibc, regardless
#
# - a modern C compiler with good support for C23 features such as gcc
#   (starting with version 13) or clang (starting with 17).

# - a directory (denoted by sourceDir in the following) with the musl
#   source plus C23 patches as provided here:
#
#   https://forge.icube.unistra.fr/icps/musl/-/branches
#
#   As these patches will hopefully be integrated more and more into
#   musl's main line this is a moving target and you should make sure
#   that you always grab the latest c23 branch. As of this writing
#   this is c23-v11.
#
# - Root rights (so-called sudoer rights in Linux slang) to be able to
#   install the compiled library and wrappers in a system wide
#   directory, "/usr/local" per default.
#
# To configure, compile and install
#
#    cd sourceDir
#    path/to/this/directory/build-musl COMPILER [FLAG] [LOGFILE]
#
# where
#
# - COMPILER is the name of the compiler, for example "gcc-13" or
#   "clang-17".
#
# (FLAG and LOGFILE are optional and not interesting in general.)
#
# For example with
#
#    path/to/this/directory/build-musl clang-18
#
# the LOGFILE is musl-log-clang-18.txt in sourceDir, and the
# installation is in /usr/local/musl-clang-18. Note that to be able to
# install, it is usually necessary to collect your password, which is
# done by a program referred to by the SUDO_ASKPASS variable
# below. Per default this will result in a popup at the end of
# compilation that blocks your screen.

# The interface that you then should use is bin/cc, for the example
# above that would be
#
#        /usr/local/musl-clang-18/bin/cc
#
# You should be able to use this just as any other compiler
# interface. To use this interface to compile in C23 mode you probably
# have to add an option "-std=c23" or "-std=c2x".


PREFIXDIR="${PREFIXDIR:-/usr/local}"
LOGFILE="${LOGFILE:-musl-log}"
SUDO_ASKPASS="${SUDO_ASKPASS:-/usr/bin/ssh-askpass}"

export SUDO_ASKPASS

COMMANDLINE="$*"

if [ $# -gt 0 ] ; then
    export CC="$1"
    PREFIXDIR="${PREFIXDIR}/musl-$1"
    LOGFILE="${LOGFILE}-$1"
    shift
fi

if [ $# -gt 0 ] ; then
    export CFLAGS="-std=$1"
    PREFIXDIR="${PREFIXDIR}-$1"
    LOGFILE="${LOGFILE}-$1"
    shift
fi

if [ $# -gt 0 ] ; then
    export CFLAGS="${CFLAGS} $*"
    PREFIXDIR="${PREFIXDIR}-$1"
    LOGFILE="${LOGFILE}-$1"
fi

LOGFILE="${LOGFILE}.txt"

echo > "${LOGFILE}"

echo "command line: ${COMMANDLINE}"                                           | tee -a "${LOGFILE}"
echo "building musl with prefix '${PREFIXDIR}', ask-pass '${SUDO_ASKPASS}'"   | tee -a "${LOGFILE}"
echo "	compiler '${CC}' and flags '${CFLAGS}'"                               | tee -a "${LOGFILE}"
echo "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++" | tee -a "${LOGFILE}"
./configure "--prefix=${PREFIXDIR}"                                            2>&1 1>>"${LOGFILE}"
if [ $? -ne 0 ] ; then
    echo "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++" | tee -a "${LOGFILE}"
    echo "configuration failed"                                                   | tee -a "${LOGFILE}"
    cat "${LOGFILE}"
    exit 1
fi
echo "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++" | tee -a "${LOGFILE}"
make clean                                                               2>&1 | tee -a "${LOGFILE}"
echo "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++" | tee -a "${LOGFILE}"
make -j 8                                                                2>&1 | tee -a "${LOGFILE}"
echo "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++" | tee -a "${LOGFILE}"
sudo -A make install                                                     2>&1 | tee -a "${LOGFILE}"
echo "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++" | tee -a "${LOGFILE}"

if [ -x "${PREFIXDIR}/bin/musl-gcc" ] ; then
    sudo -A ln -sf "musl-gcc" "${PREFIXDIR}/bin/cc"                      2>&1 | tee -a "${LOGFILE}"
elif [ -x "${PREFIXDIR}/bin/musl-clang" ] ; then
    sudo -A ln -sf "musl-clang" "${PREFIXDIR}/bin/cc"                    2>&1 | tee -a "${LOGFILE}"
fi