#!/bin/ksh
# @(#) chuser.ksh 1.2.1 97/07/30
# 94/01/22 john h. dubois iii (john@armory.com)
# 94/09/09 Added check for non-matchable password.
# 94/10/11 Use % instead of - as sed separator, to guarantee that it cannot
#          appear in a user name.
# 94/10/13 Added -u option.  Added sanity checks.
# 94/10/22 Do not allow _ in login names.
# 94/11/14 Fixed regexp used for checking if login name is in use.
#          Fixed unsetting of old uid.
# 95/10/28 Added t option.
# 96/01/20 Create tempfile more carefully.
# 97/07/30 Added f option.

# todo: when changing uid, check for processes, ipc objects, etc. owned by
# the old uid and warn about them.

# @(#) mktempfile 1.0 96/05/22
# 96/01/20 jhdiii

# 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 "$@" || {
	# hopefully rm will have printed a more specific message.
	print -u2 "Could not remove pre-existing files."
	return 1
    }
    for file; do
	# Use >> to avoid 0'ing the file in case a symlink was just made from
	# the filename to something we don't want to truncate
	>> "$file" || {
	    print -u2 "Could not create temp file $file"
	    return 1
	}
	# These are very suspicious
	[ -s "$file" ] && {
	    print -u2 "New tempfile is not empty!!!"
	    return 1
	}
	[ -O "$file" ] || {
	    print -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$$"
    mkfiles "$file"
    mktempfile_ret="$TMP/#$1$$"
}

# Usage: Error [-f] message ...
# If -f is given, this is considered a fatal error even if tell is true
function Error {
    typeset warn

    if [ $# -gt 1 -a "$1" = -f ]; then
	warn=false
	shift
    else
	warn=$tell
    fi
    if $warn; then
	print -u2 "$name: Warning: $* (continuing)."
    else
	print -u2 "$name: Fatal error: $*.  Aborting."
	exit 1
    fi
}

### Start of main program

name=${0##*/}
unset newuid
tell=false
chkname=true

Usage="Usage: One of the following forms:
  $name -h
  $name [-ft] oldname newname
  $name [-ft] -u<uid> oldname [newname]"

while getopts :hftu: opt; do
    case $opt in
    h)
	print \
"$name: change a user's account name or uid.
$Usage
Either -u<uid> or [newname] or both may be given.  If -u<uid> is given, the
user's old uid is changed to <uid>.  If newname is given, the user's login name
is changed from oldname to newname and the user's home directory is renamed
($name assumes that the last component of the login directory is the same as
the user name).  In both cases, the user's protected password database
information is updated.  $name will fail if the named user is logged in, or if
newname or the new uid is already in use.
Other options:
-f: Force change even if newname is not a legal user name (for example, if
    newname starts with a digit).  Be very careful when using this option.
-h: Print this help.
-t: Tell what would be done, without doing it.  This changes some fatal errors
    to warnings."
	exit 0
	;;
    f)
	chkname=false
	;;
    t)
	tell=true
	;;
    u)
	newuid=$OPTARG
	if [[ "$newuid" != +([0-9]) || 
	"$newuid" -lt 1 || "$newuid" -gt 32767 ]]; then
	    Error -f "Bad value given for new uid"
	fi
	grep "^[^:]*:[^:]*:$newuid:" /etc/passwd > /dev/null &&
	Error "new uid '$newuid' is already in use"
	;;
    +?)
	Error -f "options should not be preceded by a '+'"
	;;
    :)
        Error -f "Option '$OPTARG' requires a value.  Use -h for help."
        ;;
    ?) 
	Error -f "$OPTARG: bad option.  Use -h for help"
	;;
    esac
done
 
# remove args that were options
let OPTIND=OPTIND-1
shift $OPTIND

# Must have 1 or 2 args; if only 1 arg, must have given -u option.
if [ $# -ne 1 -a $# -ne 2 -o $# -eq 1 -a -z "$newuid" ]; then
    Error -f "Not enough arguments.  Use -h for help.\n"
fi

oldname=$1
if [ $# -eq 1 ]; then
    newname=$1	# replace it with itself
else
    newname=$2
    egrep "^$newname:" /etc/passwd > /dev/null &&
    Error "$newname is already a user"
    # getty man page says _ should not be used in a login name,
    # and every other non-alphanum except - is used as a metachar
    # somewhere where a login name would be used.
    if $chkname &&
    [[ "$newname" != [a-z]+([-a-z0-9]) || "$newname" = ?????????* ]]; then
	Error "$newname: invalid user name"
    fi
fi

# Get olduid even if -u not given, since it is used as a check for whether
# a good username was given.
olduid=$(awk -F: "/^$oldname:/ { print \$3;}" /etc/passwd)

[ -z "$olduid" ] && Error -f "$oldname is not a user"

# If not changing uid, unset olduid, lest old uid be replaced with nothing
[ -z "$newuid" ] && unset olduid

# At this point:
# oldname is the name of the user whose account is being changed.
# newname is either the new name for the account, or is the same as oldname
#     if the name is not being changed.
# If the uid is being changed, olduid is the old uid and newuid is the new uid.
# If the uid isn't being changed, they are both null.

if who | egrep "^$oldname "; then
    Error "$oldname is logged in; cannot change account record"
fi

# ap output looks like this:
# stealth:x:1032:50:Jonathan D. Campbell:/u/stealth:/bin/ksh
# stealth:u_name=stealth:u_id#1032:\
#         :u_pwd=x:\
#         :u_type=general:u_lock@:chkent:
# ENDOFGROUPS::0:

# Save user account configuration, translated to new name
# Replace user name at start of line followed by a colon,
# and user name after an = or / followed by colon (u_name and home dir fields)
mktempfile chuser. || {
    print -u2 "$name: Exiting."
    exit 1
}
tmpfile=$mktempfile_ret

print "Saving account profile for $newname in $tmpfile"
# Line 1 subs passwd and tcb login name.
# Line 2 subs tcb u_name.
# Line 3 subs passwd directory name.
# Line 4 subs passwd uid.
# Line 5 subs passwd uid.
ap -gd "$oldname" | sed "
s/^$oldname:/$newname:/
s/=$oldname:/=$newname:/
s%/$oldname:%/$newname:%
s/:$olduid:/:$newuid:/
s/#$olduid:/#$newuid:/
" > $tmpfile

grep :u_pwd=x: $tmpfile && grep "^$newname:x:" $tmpfile &&
print -u2 "$name: Warning: account profile contains non-matchable password."

uhome=`awk -F: "\"$oldname"'" == $1 { print $6; }' /etc/passwd`

if $tell; then
    print "Would remove user $oldname."
else
    print "Removing user $oldname..."
    rmuser "$oldname"
    status=$?
    if [ $status -ne 0 ]; then
	# Do NOT remove tmpfile; rmuser may exit nonzero even if user is
	# mostly removed!
	#rm $tmpfile
	Error -f \
	"Removal of user $oldname failed (rmuser exited with status $status)"
    fi
fi

if $tell; then
    print "Would restore user $newname with account profile:"
    cat $tmpfile
else
    print "Restoring user $newname with account profile:"
    cat $tmpfile
    ap -r -f $tmpfile
fi

if [ $# -eq 2 ]; then
    # Replace /oldname$ with /newname
    newhome=`print -r -- $uhome|sed "s/\\/$oldname\\$/\\/$newname/"`

    if $tell; then
	print -r "Would move home dir $uhome to $newhome"
    else
	print -r "Moving home dir $uhome to $newhome"
    fi
    if [ -d $uhome ]; then
	$tell || mvdir $uhome $newhome
    else
	print -u2 \
	"$uhome is not a directory!  If it is a symlink, move it by hand."
    fi
fi

[ -n "$newuid" ] && print \
"Remember to change the ownership of any files
from $olduid to $newuid ($newname)."

[ "$oldname" != "$newname" ] && print \
"Remember to create a mail alias, if appropriate, to forward mail
from $oldname to $newname.  Here's an alias line to cut & paste:
$oldname	$newname"

rm $tmpfile