--- embedaddon/rsync/support/lsh	2012/02/17 15:09:30	1.1.1.1
+++ embedaddon/rsync/support/lsh	2013/10/14 07:51:15	1.1.1.2
@@ -1,33 +1,81 @@
-#!/bin/sh
+#!/usr/bin/perl
 # This script can be used as a "remote shell" command that is only
 # capable of pretending to connect to "localhost".  This is useful
 # for testing or for running a local copy where the sender and the
 # receiver needs to use different options (e.g. --fake-super).  If
-# we get a -l USER option, we try to use "sudo -u USER" to run the
-# command.
+# we get -l USER, we try to become the USER, either directly (must
+# be root) or by using "sudo -H -u USER" (requires --sudo option).
 
-user=''
-do_cd=y # Default path is user's home dir, just like ssh.
+use strict;
+use warnings;
+use Getopt::Long;
+use English '-no_match_vars';
 
-while : ; do
-    case "$1" in
-    -l) user="$2"; shift; shift ;;
-    -l*) user=`echo "$1" | sed 's/^-l//'`; shift ;;
-    --no-cd) do_cd=n; shift ;;
-    -*) shift ;;
-    localhost) shift; break ;;
-    *) echo "lsh: unable to connect to host $1" 1>&2; exit 1 ;;
-    esac
-done
+&Getopt::Long::Configure('bundling');
+&Getopt::Long::Configure('require_order');
+GetOptions(
+    'l=s' => \( my $login_name ),
+    '1|2|4|6|A|a|C|f|g|k|M|N|n|q|s|T|t|V|v|X|x|Y' => sub { }, # Ignore
+    'b|c|D|e|F|i|L|m|O|o|p|R|S|w=s' => sub { }, # Ignore
+    'no-cd' => \( my $no_chdir ),
+    'sudo' => \( my $use_sudo ),
+) or &usage;
+&usage unless @ARGV > 1;
 
-if [ "$user" ]; then
-    prefix=''
-    if [ $do_cd = y ]; then
-	home=`perl -e "print((getpwnam('$user'))[7])"`
-	prefix="cd '$home' ;"
-    fi
-    sudo -H -u "$user" sh -c "$prefix $*"
-else
-    [ $do_cd = y ] && cd
-    eval "${@}"
-fi
+my $host = shift;
+if ($host =~ s/^([^@]+)\@//) {
+    $login_name = $1;
+}
+if ($host ne 'localhost') {
+    die "lsh: unable to connect to host $host\n";
+}
+
+my ($home_dir, @cmd);
+if ($login_name) {
+    my ($uid, $gid);
+    if ($login_name =~ /\D/) {
+	$uid = getpwnam($login_name);
+	die "Unknown user: $login_name\n" unless defined $uid;
+    } else {
+	$uid = $login_name;
+    }
+    ($login_name, $gid, $home_dir) = (getpwuid($uid))[0,3,7];
+    if ($use_sudo) {
+	unshift @ARGV, "cd '$home_dir' &&" unless $no_chdir;
+	unshift @cmd, qw( sudo -H -u ), $login_name;
+	$no_chdir = 1;
+    } else {
+	my $groups = "$gid $gid";
+	while (my ($grgid, $grmembers) = (getgrent)[2,3]) {
+	    if ($grgid != $gid && $grmembers =~ /(^|\s)\Q$login_name\E(\s|$)/o) {
+		$groups .= " $grgid";
+	    }
+	}
+
+	my ($ruid, $euid) = ($UID, $EUID);
+	$GID = $EGID = $groups;
+	$UID = $EUID = $uid;
+	die "Cannot set ruid: $! (use --sudo?)\n" if $UID == $ruid && $ruid != $uid;
+	die "Cannot set euid: $! (use --sudo?)\n" if $EUID == $euid && $euid != $uid;
+
+	$ENV{USER} = $ENV{USERNAME} = $login_name;
+	$ENV{HOME} = $home_dir;
+    }
+} else {
+    $home_dir = (getpwuid($UID))[7];
+}
+
+unless ($no_chdir) {
+    chdir $home_dir or die "Unable to chdir to $home_dir: $!\n";
+}
+
+push @cmd, '/bin/sh', '-c', "@ARGV";
+exec @cmd;
+die "Failed to exec: $!\n";
+
+sub usage
+{
+    die <<EOT;
+Usage: lsh [-l user] [--sudo] [--no-cd] localhost COMMAND [...]
+EOT
+}