clone

#!/bin/bash

usage() {
    echo
    echo "Usage: `basename $0` <source> <dest>"
    exit 1
}

samefs() {
    FS1=`stat -c %d $1`
    FS2=`stat -c %d $2`

    [ "${FS1}" == "${FS2}" ] && return 0
}

cderror() {
    echo "Could not cd into $1."
    exit 1
}

toucherror() {
    echo "Write test failed on $1."
    exit 1
}

mkdirerror() {
    echo "Error creating $1."
    exit 1
}

copyerror() {
    echo "Error during copy."
    exit 1
}

docopy() {
    SOURCE=$1
    DEST=$2
    SOURCETYPE=''
    DESTTYPE=''

    if [ -e ${SOURCE} ]; then
        SOURCETYPE=$(stat -c %F ${SOURCE})
    else
        echo "${SOURCE} does not exist."
        exit 1
    fi

    if [ -e ${DEST} ]; then
        DESTTYPE=$(stat -c %F ${DEST})
        if [ "${DESTTYPE}" == 'directory' ]; then
            if ! samefs ${SOURCE} ${DEST}; then
                echo "$(basename $0) will only work if ${SOURCE} and ${DEST} are in the same filesystem."
                exit 1
            fi
        else
            echo 'Destination exists. Aborting.'
            exit 1
        fi
    fi

    if [ "${SOURCETYPE}" == 'directory' ]; then
        [ -e "${DEST}" ] && DEST="${DEST}/$(basename ${SOURCE})"

        if mkdir -p ${DEST}; then
            if ! samefs ${SOURCE} ${DEST}; then
                echo "$(basename $0) will only work if ${SOURCE} and ${DEST} are in the same filesystem."
                \rmdir ${DEST}
                exit 1
            fi
        else
            mkdirerror ${DEST}
            exit 1
        fi

        TESTFILE=${DEST}/$(basename $(mktemp))
        if touch ${TESTFILE}; then
            \rm ${TESTFILE}
        else
            toucherror ${DEST}
        fi

        CWD=$(pwd)
        cd ${DEST} || cderror ${DEST}
        DEST=$(pwd)
        cd ${CWD}
        cd ${SOURCE} || cderror ${SOURCE}

        find -type d -exec mkdir -p ${DEST}/{} \;
        if [ $? -ne 0 ]; then
            cd ${CWD}
            copyerror
        fi

        find ! -type d -exec \ln -f {} ${DEST}/{} \;
        if [ $? -ne 0 ]; then
            cd ${CWD}
            copyerror
        fi

        cd ${CWD}
    else
        \ln -f ${SOURCE} ${DEST}
    fi
}

[ $# -lt 2 ] && usage

if [ $# -gt 2 ]; then
    eval LASTARG=\$$#

    if [ "$(stat -c %F ${LASTARG})" != "directory" ]; then
        echo "$LASTARG must be a directory."
        exit 1
    fi

    while [ "$#" -gt 1 ]; do
        docopy $1 ${LASTARG}
        shift
    done
else
    docopy $1 $2
fi