gen_OPALrevision

#!/bin/bash
#
# create/rewrite 'src/OPALrevision.h'
#

print () {
    echo '#define GIT_VERSION '\"$1\" > src/OPALrevision-new.h
    if [[ -e  src/OPALrevision.h ]] && cmp -s src/OPALrevision.h src/OPALrevision-new.h; then
        rm src/OPALrevision-new.h
    else
        mv src/OPALrevision-new.h src/OPALrevision.h
    fi
}

# if git(1) is not in $PATH
if ! which -a git &> /dev/null; then
    if  [[ -e  src/OPALrevision.h ]]; then
        # do nothing if file exist
        exit 0
    else
        # otherwise create file
        print unknown
        exit $?
    fi
fi

# if we are in a work-tree
if git rev-parse --is-inside-work-tree &> /dev/null; then
    # create/rewrite file
    revision=$(git rev-parse HEAD)
    print ${revision}
    exit $?
fi

# if we are not in a work tree and the file does not exist
if [[ ! -e  src/OPALrevision.h ]]; then
    # create file
    print unknown
    exit $?
fi

exit 0