#!/bin/ksh
# @(#) chkbackup.ksh 2.1 96/06/21
# 95/05/28 john h. dubois iii (john@armory.com)
# 95/06/26 Added all options.
# 96/04/08 Try /dev/nrStp0 in addition to /dev/nrct0.  Added t option.
# 96/06/16 Added uN options.
# 96/06/21 Write status to logfile.  Added L option.  Print tape amount info.

# Usage: mkfiles name ...
# Creates the named files with some attempt at security.
# This will be more reliable if user do not have chown authority.
# Any file that contains no / characters is created in the user's tempdir.
# If TMP was not set, it is set by this function (but not exported).
# Returns 0 on success; prints a diagnostic message & returns 1 on failure.
function mkfiles {
    typeset file files
    typeset -i i=0

    : ${TMP:=$TMPDIR}
    : ${TMP:=/tmp}
    for file; do
	[[ "$file" != */* ]] && file="$TMP/$file"
	files[i]=$file
	let i+=1
    done
    set -- "${files[@]}"

    rm -f "$@" || {
	# hopefully rm will have printed a more specific message.
	print -r -u2 "Could not remove pre-existing files."
	return 1
    }
    for file; do
	# Use >> to avoid 0'ing the file in case a symlink was just made from
	# the filename to something we don't want to truncate
	>> "$file" || {
	    print -r -u2 "Could not create temp file $file"
	    return 1
	}
	# These are very suspicious
	[ -s "$file" ] && {
	    print -r -u2 "New tempfile is not empty!!!"
	    return 1
	}
	[ -O "$file" ] || {
	    print -r -u2 "Do not own $file!!!"
	    return 1
	}
    done
    # Could do some more stuff here, but anyone concerned with security should
    # have chown authorization off for most users.
    return 0
}

# Usage: mktempfile name
# Creates a tempfile name tempdir/#name$$, and sets the global mktempfile_ret
# to that name.  tempdir is a temp directory in $TMP, $TMPDIR, or /tmp, and $$
# is the PID of the current process.
# name should be 8 characters or less, so that the resulting filename will
# not be more than 14 characters long (a limit on some machines).
# Returns 0 on success, prints a diagnostic message & returns 1 on failure.
function mktempfile {
    typeset file="#$1$$"
    mkfiles "$file"
    mktempfile_ret="$TMP/#$1$$"
}

function lprint {
    print -r -- "$*"
    $log && print -r -- "$*" >> "$logfile"
}

function Rewind {
    if $rewind; then
	print -r "*** Rewinding..."
	tape rewind $nr_device || {
	    print -ru2 -- "$longname: Rewind of $nr_device failed.  Exiting."
	    exit 1
	}
    fi
}

function check {
    typeset -i status

    let extent+=1
    lprint "*** `date`  Checking extent $extent"
    $debug && set -x
    if [ -n "$Uncompress" ]; then
	nice -n $nice $Uncompress | nice -$nice "${cmd[@]}"
    else
	nice -n $nice "${cmd[@]}"
    fi < $nr_device >&3
    status=$?
    $debug && set +x
    return $status
}

nr_device1=/dev/nrct0
nr_device2=/dev/nrStp0
nr_device=
longname=${0##*/}
rewind=true
debug=false
log=true
defaultCommand="cpio -it -C 65536"
def_nice=15
typeset -i nice=$def_nice
typeset -i maxExtent=0
Usage=\
"Usage: $longname [-hLnv] [-e<extents>] [-d<device>] [-u<uncompress-command>]
       [archive listing command]"
exec 3>/dev/null	# default dest for file lists

while getopts :hLnN:e:d:vxu: opt; do
    case $opt in
    h)
	print -r -- \
"$longname: Check tape backups.
$Usage
$longname reads all of the file extents (tape sections between filemarks) on a
tape and passes them through a command to test the archive integrity of each
backup.  The default command is \"$defaultCommand\".  An alternate command can
be given at the end of the command line that $longname is invoked with.  It
will be run for each file extent in turn, with the tape device passed as its
input and it standard output (which would typically be a listing of the
archive) discarded so that only errors will be displayed.  The archive listing
command should not actually extract files onto disk.  The command will be
repeatedly invoked, either as many times as specified with the -e option (if
given) or until it exits nonzero, whichever comes first.  If -e is not given,
the report produced by $longname should give a good status for the number of
archives stored on the tape, and then one failure when it tries to read beyond
the end of the last position on the tape that has been written to.  
For each extent successfully read, a status line and a report of the amount of
data read from tape is printed.  The same information is written to a logfile
named /tmp/#chkback.pid, where pid is the process ID of the program.  To get
the tape amount information, the tape control device is used.  The name of the
control device is determined by replacing everything up through a leading 'r'
in the trailing component of the device name with 'x'.  For example, the
control device for /dev/nrStp0 would be /dev/xStp0.
Options:
-h: Print this help.
-n: Do not rewind the tape device before or after checking the backups.
-e<extents>: Check only the number of extents specified.
-d<device>: Use <device> instead of the default of $nr_device1 or (if it does
    not exist) $nr_device2.  <device> should be a no-rewind device.
-L: Do not create or write to the logfile.
-N<nice-increment>: Use <nice-increment> when running uncompressing and archive
    listing commands.  The default is $def_nice.
-u<uncompress-command>: Pass the archive data through <uncompress-command>
    before giving it to the archiving listing command.  This could also be done
    by making the uncompress-command part of the archive listing command.
    However, if the default archive listing command is correct, using -u avoids
    the need to give the archive listing command explicitly.
-v: Verbose.  Print files found."
	exit 0
	;;
    N)
	nice=$OPTARG || exit 1
	;;
    n)
	rewind=false
	;;
    d)
	nr_device=$OPTARG
	[[ "$nr_device" != */* ]] && nr_device=/dev/$nr_device
	;;
    e)
	maxExtent=$OPTARG || {
	    print -ru2 -- "$longname: Bad number given with -e.  Exiting."
	    exit 1
	}
	;;
    u)
	Uncompress=$OPTARG
	;;
    L)
	log=false;;
    v)
	exec 3>&1
	;;
    x)
	debug=true
	;;
    +?)
	print -ru2 -- "$longname: options should not be preceded by a '+'."
	exit 1
	;;
    :)
        print -r -u2 -- \
        "$longname: Option '$OPTARG' requires a value.  Use -h for help."
        exit 1
        ;;
    ?) 
	print -ru2 -- "$longname: $OPTARG: bad option.  Use -h for help."
	exit 1
	;;
    esac
done
 
# remove args that were options
let OPTIND=OPTIND-1
shift $OPTIND

if [ $# -lt 1 ]; then
    set -A cmd $defaultCommand
else
    set -A cmd "$@"
fi

# Find which device to use
if [ -z "$nr_device" ]; then
    if [ -c $nr_device1 ]; then
	nr_device=$nr_device1
    elif [ -c $nr_device2 ]; then
	nr_device=$nr_device2
    else
	print -ru2 -- \
    "$longname: Neither $nr_device1 nor $nr_device2 exists.  Exiting."
	exit 1
    fi
elif [ ! -c "$nr_device" ]; then
    print -ru2 -- \
    "$longname: $nr_device does not exist or is not a tape device.  Exiting."
    exit 1
fi

tail=${nr_device##*/}
xdev="${nr_device%/*}/x${tail#*r}"
if [ ! -c "$xdev" ]; then
    print -ru2 -- \
    "$longname: Cannot access control device $xdev; skipping tape amounts."
    unset xdev
fi

if $debug; then
    if [ -n "$xdev" ]; then
	print -ru2 "Using device $nr_device and control device $xdev"
    else
	print -ru2 "Using device $nr_device"
    fi
fi

typeset -i extent=0

Rewind

if $log; then
    TMP=/tmp	# for mkfiles
    mktempfile chkback. || {
	print -ru2 -- "$longname: exiting."
	exit 1
    }
    logfile=$mktempfile_ret
    print -r -- "Writing status information to log file $logfile"
fi

while [ maxExtent -eq 0 -o extent -lt maxExtent ] && check; do
    [ -n "$xdev" ] && lprint "$(tape amount "$xdev")"
    lprint "*** `date`  Extent $extent OK"
    sleep 5
done

Rewind