#!SCRIPTSHELLCMD_MARKER
PROGNAME=`basename $0`

###############################################################################
#
#  TAPE LABELLER
#
###############################################################################

###############################################################################
#
#  CONFIGURABLE STUFF
#
###############################################################################

###############################################################################
#
#  CONFIGURABLE STUFF ENDS HERE
#
###############################################################################

#  Set a load of important variables
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/etc:/usr/etc:/usr/local/bin:/usr/local/sbin
VERBOSE_LEVEL=2				# verbosity level:3=info,warnings,errors
TMP_DIR=/var/tmp                        # where to stash temporary files
ERRORS_CAUSE_EXITS=true			# error() calls without options do exits
#  $Id: dailybackup-hpux10.in,v 1.1 1998/05/05 16:29:06 alexis Exp $
VERSION="PATCHLEVEL_MARKER"             #  version id
NEW_LABEL_SIZE=1k
NEW_LABEL_VERSION=1

###############################################################################
#
#  MAIN FUNCTION (called from very bottom of script)
#
###############################################################################

main()
{
    ###########################################################################
    #
    #  PROCESS OPTIONS
    #
    ###########################################################################

    #  default values for things modified by options
    MODE=unset
    TAPE_DEVICE=$TAPE
    FORCE=false

    debug 5 "before option processing"

    #  process command line REAL options
    while [ "X$1" != X ]; do
        debug 5 "considering $1"
        case $1 in
            -V) if expr "$VERSION" : 'P.*R$' > /dev/null; then
                    warning "this is development version; use 'ident'"
                    exit 1
                else
                    echo "$PROGNAME version $VERSION"
                    exit 0
                fi ;;
            -r) MODE=read ;;
            -s) MODE=skip ;;
            -w) MODE=write ;;
            -f) FORCE=true ;;
            -v) VERBOSE_LEVEL=3 ;;
            -d) [ "X$2" == X ] && usage
                VERBOSE_LEVEL=$2
                shift ;;
            -t) [ "X$2" == X ] && usage
                TAPE_DEVICE=$2
                shift ;;
            -*) usage ;;
            *)  break ;;
        esac
        shift
    done

    debug 5 "after option processing"

    case $MODE in
        unset) usage ;;
        read)  [ "X$1" != X ] && usage ;;
        skip)  [ "X$1" != X ] && usage ;;
        write) debug 5 "mode is write"
               [ "X$1" == X -o "X$2" != X ] && usage
               NEW_LABEL_TEXT="$1"
               shift ;;
    esac

    debug 5 "mode is $MODE, new label is $NEW_LABEL_TEXT"

    #  check device set
    [ "X$TAPE_DEVICE" = X ] && error -e "tape device unknown, use '-t' option"
    debug 5 "tape device is $TAPE_DEVICE"

    #  check the device file is valid
    debug 5 "checking device $TAPE_DEVICE is a valid backup device"
    if [ ! -c "$TAPE_DEVICE" -o ! -r "$TAPE_DEVICE" -o ! -w "$TAPE_DEVICE" ]; then
        error "$TAPE_DEVICE: invalid backup device (not character device)"
    fi

    #  try to open tape device for reading; open() can fail the first time!
    debug 5 "checking tape is present"
    mt -t $TAPE_DEVICE rewind 2>/dev/null || {
        warning "Cannot open tape device '$TAPE_DEVICE', retrying"
        sleep 1
        mt -t $TAPE_DEVICE 2>/dev/null || {
            error "$TAPE_DEVICE: unreadable (tape not inserted/wrong device?)"
        }
    }

    #  check if tape already has label
    delonexit /tmp/$PROGNAME.$$.label
    dd if=$TAPE_DEVICE bs=$NEW_LABEL_SIZE count=1 of=/tmp/$PROGNAME.$$.label 2>/dev/null
    OLD_LABEL_VERSION=`sed -n 's/^Version: //p' /tmp/$PROGNAME.$$.label`
    OLD_LABEL_TEXT=`sed -n 's/^Label: //p' /tmp/$PROGNAME.$$.label`
    rm /tmp/$PROGNAME.$$.label
    dontdelonexit /tmp/$PROGNAME.$$.label

    if [ $MODE != write -a "X$OLD_LABEL_TEXT" = X ]; then
        mt -t $TAPE_DEVICE rewind
        error "no label"
    elif [ $MODE = read ]; then
        echo "$OLD_LABEL_TEXT"
        mt -t $TAPE_DEVICE fsf
    elif [ $MODE = skip ]; then
        mt -t $TAPE_DEVICE fsf
    elif [ $MODE = write -a "X$OLD_LABEL_TEXT" != X -a $FORCE = false ]; then
        mt -t $TAPE_DEVICE rewind
        error "tape is labelled already, use '-f' to force"
    elif [ $MODE = write ]; then
        mt -t $TAPE_DEVICE rewind
        ( 
            echo "Version: $NEW_LABEL_VERSION"
            echo "Label: $NEW_LABEL_TEXT"
            dd if=/dev/zero 2>/dev/null
        ) | dd of=$TAPE_DEVICE bs=$NEW_LABEL_SIZE count=1 2>/dev/null
        info labelled
    fi
}

###############################################################################
#
#  RESILIANT MESSAGING FUNCTIONS 
#
###############################################################################

usage()
{
    {
        echo "Usage: $PROGNAME [ -t <device> ] [ -f ] { -r | -w <label> | -s }"
        echo "       $PROGNAME -V"
    } >&2
    exit 1
}

internal()
{
    MSG="INTERNAL ERROR: $*"
    DATE=`date`

    #  echo it so that the user can see it or cron can trap it (split line
    #  to avoid confusing 'ident')
    echo "$PROGNAME: \
$MSG" >&2

    #  try to write it into $LOG_FILE if that's defined - other message types
    #  treat unwritable but defined LOG_FILE as an error
    ( echo "$DATE: \
$MSG" >> ${LOG_FILE:-/dev/null} ) 2>/dev/null

    #  try to syslog it - other message types are only syslog'ed if there is
    #  no controlling terminal (as when run from 'at' or 'cron')
    logger -i -p local0.alert -t $PROGNAME "$MSG"

    #  try to log it on the console
    echo "$DATE: \
$MSG" > /dev/console

    exit 2
}

error()
{
    DO_EXIT=${ERRORS_CAUSE_EXITS:-true}
    STDIN=false

    while :; do
        case "$1" in
            -)  STDIN=true ;;
            -e) DO_EXIT=true ;;
            -ne) DO_EXIT=false ;;
            -*) internal "invalid option to error() '$1'" ;;
            *)  break ;;
        esac
        shift
    done

    if [ ${VERBOSE_LEVEL:-2} -ge 1 ]; then

        DATE=`date`

        { { [ $STDIN = false ] && echo "$@"; } || cat; } | while read LINE; do
            MSG="ERROR: $LINE"
            ( echo "$DATE: \
$MSG" >> ${LOG_FILE:-/dev/null} ) 2>/dev/null || internal "log file $LOG_FILE not writable!"
            { [ -t 2 ] && echo "$PROGNAME: \
$MSG" >&2; } || logger -i -p $FACILITY.err -t $PROGNAME "$MSG"
        done
    fi

    [ $DO_EXIT = false ] && return 1
    exitdel
    exit 1
}

warning()
{
    STDIN=false

    while :; do
        case "$1" in
            -)  STDIN=true ;;
            -*) internal "invalid option to error() '$1'" ;;
            *)  break ;;
        esac
        shift
    done

    if [ ${VERBOSE_LEVEL:-2} -ge 2 ]; then
        DATE=`date`

        { { [ $STDIN = false ] && echo "$@"; } || cat; } | while read LINE; do
            MSG="WARNING: $LINE"
            ( echo "$DATE: \
$MSG" >> ${LOG_FILE:-/dev/null} ) 2>/dev/null || internal "log file $LOG_FILE not writable!"
            { [ -t 2 ] && echo "$PROGNAME: \
$MSG" >&2; } || logger -i -p $FACILITY.warning -t $PROGNAME "$MSG"
        done
    fi

    return 0
}

debug()
{
    STDIN=false

    while :; do
        case "$1" in
            -)  STDIN=true ;;
            -*) internal "invalid option to error() '$1'" ;;
            *)  break ;;
        esac
        shift
    done

    LEVEL=$1
    shift

    if [ ${VERBOSE_LEVEL:-2} -ge $LEVEL ]; then
        DATE=`date`

        { { [ $STDIN = false ] && echo "$@"; } || cat; } | while read LINE; do
            MSG="DEBUG[$LEVEL]: $LINE"
            ( echo "$DATE: \
$MSG" >> ${LOG_FILE:-/dev/null} ) 2>/dev/null || internal "log file $LOG_FILE not writable!"
            { [ -t 2 ] && echo "$PROGNAME: \
$MSG" >&2; } || logger -i -p $FACILITY.debug -t $PROGNAME "$MSG"
        done
    fi

    return 0
}

info()
{
    STDIN=false

    while :; do
        case "$1" in
            -)  STDIN=true ;;
            -*) internal "invalid option to error() '$1'" ;;
            *)  break ;;
        esac
        shift
    done

    if [ ${VERBOSE_LEVEL:-2} -ge 3 ]; then
        DATE=`date`

        { { [ $STDIN = false ] && echo "$@"; } || cat; } | while read LINE; do
            MSG="INFO: $LINE"
            ( echo "$DATE: \
$MSG" >> ${LOG_FILE:-/dev/null} ) 2>/dev/null || internal "log file $LOG_FILE not writable!"
            { [ -t 2 ] && echo "$PROGNAME: \
$MSG" >&2; } || logger -i -p $FACILITY.info -t $PROGNAME "$MSG"
        done
    fi

    return 0
}

###############################################################################
#
#  GENERIC SUPPORT FUNCTIONS (not specifically related to backup task)
#
###############################################################################

locatecmd()
{
    for POSSCMD in $*; do
        [ X`whichcmd $POSSCMD` != X ] && { echo $POSSCMD; return 0; }
    done
    return 1
}

whichcmd()
{
    for DIR in `echo $PATH | sed 's/:/ /g'`; do
        [ -x $DIR/$1 ] && { echo $DIR/$1; return 0; }
    done
    return 1
}

###############################################################################
#
#  TEMPORARY FILE MANAGEMENT FUNCTIONS
#
###############################################################################

delonexit()
{
    DELONEXIT="$DELONEXIT $*"
}
 
dontdelonexit()
{
    for FILE in $*; do
        DELONEXIT=`echo $DELONEXIT | sed "s@$FILE@@g"`
    done
}
 
exitdel()
{
    debug 50 "cleaning up"
    rm -f $DELONEXIT
}

sighandler()
{
    warning "signal recieved, clearing up and exiting"
    exitdel
    exit 3
}

##############################################################################
#
#  LOCK FUNCTIONS
#
##############################################################################

gen_lock_file_name()
{
    TABLE=$1
    shift

    echo .$TABLE.lock
}

lock()
{
    debug 5 "lock: locking $1"
    LOCKFILE=`gen_lock_file_name $1`

    { echo $$ > $LOCKFILE.$$; } 2>/dev/null || error -e "can't create lock"
    ln $LOCKFILE.$$ $LOCKFILE 2>/dev/null && { rm $LOCKFILE.$$; return 0; }
    HOLDING_PID=`cat $LOCKFILE`
    [ "X$HOLDING_PID" = X ] && { rm $LOCKFILE.$$; error -e "empty lockfile: $LOCKFILE"; }
    [ -d /proc/$HOLDING_PID ] && { rm $LOCKFILE.$$; error -e "program running already! (pid=$HOLDING_PID)"; }
    info "removing stale lock (pid=$HOLDING_PID)"
    rm -f $LOCKFILE
    ln $LOCKFILE.$$ $LOCKFILE 2>/dev/null && { rm $LOCKFILE.$$; return 0; }
    rm $LOCKFILE.$$
    error -e "couldn't lock after removing stale lockfile"
}

unlock()
{
    debug 5 "unlock: unlocking $1"
    LOCKFILE=`gen_lock_file_name $1`

    rm -f $LOCKFILE
}

###############################################################################
#
#  ENTRY POINT
#
###############################################################################

#  ensure temporary files are private
umask 077
#  ensure temporary files are deleted if we get interrupted
trap sighandler 1 2 15
#  do the main thing!
main "$@"
#  yes, i know, this would be the default, but just for clarity
exit $?