source: branches/samba-3.0/packaging/SGI/sambalp@ 1036

#!/bin/perl
#
# Hacked by Alan Stebbens <aks@sgi.com> to setuid to the username if 
# valid on this system.  Written as a secure Perl script.  To enable,
#
#       chown root /usr/samba/bin/sambalp
#       chmod u+s,+x /usr/samba/bin/sambalp
#
# If setuidshells is not enabled on your system, you must also do this:
#
#       systune -i
#       nosuidshells = 0
#       y
#       quit
#
#       reboot
#
# This script will still work as a normal user; it will not try
# to setuid in this case.
#
# If the "$PSFIX" variable is set below...
#
# Workaround Win95 printer driver/Impressario bug by removing
# the PS check for available virtual memory.  Note that this
# bug appears to be in all Win95 print drivers that generate
# PostScript; but is for certain there with a QMS-PS 810 (the
# printer type I configure on the Win95-side for printing with
# Samba).
#
# the perl script fixes 3 different bugs. 
# 1. remove the JCL statements added by some HP printer drivers to the
# beginning of the postscript output. 
# 2. Fix a bug in output from word files with long filenames. A non-printing
# character added to the end of the title comment by word is 
# removed. 
# 3. The VM fix described above.
#
#
# Modified for Perl4 compatibility.
#

$PROG = "sambalp";

$PSFIX = 1;                     # set to 0 if you don't want to run
                                # the "psfix" portion

# Untaint the PATH variable
@PATH = split(' ',<<EOF);
        /usr/sbin /usr/bsd /sbin /usr/bin /bin /usr/lib /usr/local/bin
EOF
$ENV{'PATH'} = join(':',@PATH);

        print "$#ARGV ".scalar(@ARGV)."\n";
if (scalar(@ARGV) < 2) {
    print STDERR "usage: $PROG printer file [user] [system]\n";
    exit;
}

$printer = $ARGV[0];
$file    = $ARGV[1];
$user    = $ARGV[2];
$system  = $ARGV[3];

$user = "nobody" unless($user);
$system = `hostname` unless($system);

open(LPSTAT,"/usr/bin/lpstat -t|") || die("Can't get printer list.\n");
@printers = ();
while (<LPSTAT>) {
    next unless /^printer (\w+)/;
    push(@printers,$1);
}
close LPSTAT;
# Create a hash list
@printers{@printers} = @printers;
    
# Untaint the printer name
if (defined($prtname = $printers{$printer})) {
    $printer = $prtname;
} else {
    die("Unknown printer: \"$printer\"\n");
}

if ($> == 0) {          # are we root?
    # yes -- then perform a taint checks and possibly do a suid check

    # Untaint the file and system names (pretend to filter them)
    $file   =   $file =~ /^(.*)/ ? $1 : die("Bad file: $file\n");
    $system = $system =~ /^(.*)/ ? $1 : die("Bad system: $system\n");

    # Get the valid users
    setpwent;
    %users = ();
    while (@pwe = getpwent()) { 
        $uids{$pwe[0]} = $pwe[2];
        $users{$pwe[2]} = $pwe[0];
    }
    endpwent();

    # Check out the user -- if the user is a real user on this system,
    # then become that user so that the  printer header page looks right
    # otherwise, remain as the default user (probably "nobody").

    if (defined($uid = $uids{$user})) {

        # before we change UID, we must ensure that the file is still
        # readable after the UID change.
        chown($uid, 9, $file);  # make the file owned by the user

        # Now, go ahead and become the user
        $name = $users{$uid};
        $> = $uid;              # become the user
        $< = $uid;
    } else {                    # do untaint filtering
        $name = $user =~ /^(\w+)/ ? $1 : die("Bad user: $user\n");
    }
} else {                        # otherwise, just be me
    $name = $user;              # whomever that is
}

$lpcommand = "/usr/bin/lp -c -d$printer -t'$name on $system'";

# This code is from the original "psfix" but it has been completely
# rewritten for speed.

if ($PSFIX) {                   # are we running a "psfix"?
    open(FILE, $file)           || die("Can't read $file: $!\n");
    open(LP, "|$lpcommand -")   || die("Can't open pipe to \"lp\": $!\n");
    select(LP);
    while (<FILE>) {            # 
        $_ =~ s/^\004//;                # strip any ctrl-d's
        if (/^\e%/) {           # get rid of any non-postscript commands
            while (<FILE>) {    # remove text until next %!PS
                s/^\001M//;     # lenmark driver prefixes Ctrl-A M to %!PS
                last if /^%!PS/;
            }
            last if eof(FILE);
        } elsif (/^%%Title:/) { # fix bug in long titles from MS Word
            s/.\r$/\r/;         # remove trailing character on the title
        } elsif (/^\/VM\?/) {   # remove VM test
            print "/VM? { pop } bind def\r\n";
            while (<FILE>) { last if /def\r/; }
            next;               # don't print
        }
        print;
    }
    close FILE;
    close LP;
} else {                        # we're not running psfix?
    system("$lpcommand $file");
}

if ($file =~ m(^/)) {
        # $file is a fully specified path
        # Remove the file only if it lives in a directory ending in /tmp.
        unlink($file) if ($file =~ m(/tmp/[^/]+$));
} else {
        # $file is NOT a fully specified path
        # Remove the file only if current directory ends in /tmp.
        unlink($file) if (`pwd` =~ m(/tmp$));
}