#!/usr/bin/perl -w -U

#
# Possible improvements:
#
# - distinguish stdout and stderr output
# - add environment variable like assignments
# - run up to a specific line
# - resume at a specific line
#

use strict;
use FileHandle;
use Getopt::Std;
use POSIX qw(isatty setuid);
use vars qw($opt_v);

no warnings qw(taint);

getopts('v');

my ($OK, $FAILED) = ("ok", "failed");
if (isatty(fileno(STDOUT))) {
	$OK = "\033[32m" . $OK . "\033[m";
	$FAILED = "\033[31m\033[1m" . $FAILED . "\033[m";
}

sub exec_test($$);

my ($prog, $in, $out) = ([], [], []);
my $line_number = 0;
my $prog_line;
my ($tests, $failed) = (0,0);

for (;;) {
  my $line = <>; $line_number++;
  if (defined $line) {
    # Substitute %VAR and %{VAR} with environment variables.
    $line =~ s[%(?:(\w+)|\{(\w+)\})][$ENV{"$1$2"}]eg;
  }
  if (defined $line) {
    if ($line =~ s/^\s*< ?//) {
      push @$in, $line;
    } elsif ($line =~ s/^\s*> ?//) {
      push @$out, $line;
    } else {
      process_test($prog, $prog_line, $in, $out);

      $prog = [];
      $prog_line = 0;
    }
    if ($line =~ s/^\s*\$ ?//) {
      $line =~ s/\s+#.*//;  # remove comments here...
      $prog = [ map { s/\\(.)/$1/g; $_ } split /(?<!\\)\s+/, $line ];
      $prog_line = $line_number;
      $in = [];
      $out = [];
    }
  } else {
    process_test($prog, $prog_line, $in, $out);
    last;
  }
}

my $status = sprintf("%d commands (%d passed, %d failed)",
	$tests, $tests-$failed, $failed);
if (isatty(fileno(STDOUT))) {
	if ($failed) {
		$status = "\033[31m\033[1m" . $status . "\033[m";
	} else {
		$status = "\033[32m" . $status . "\033[m";
	}
}
print $status, "\n";
exit $failed ? 1 : 0;


sub process_test($$$$) {
  my ($prog, $prog_line, $in, $out) = @_;

  return unless @$prog;

       my $p = [ @$prog ];
       print "[$prog_line] \$ ", join(' ',
             map { s/\s/\\$&/g; $_ } @$p), " -- ";
       my $result = exec_test($prog, $in);
       my $good = 1;
       my $nmax = (@$out > @$result) ? @$out : @$result;
       for (my $n=0; $n < $nmax; $n++) {
	 if (!defined($out->[$n]) || !defined($result->[$n]) ||
	     $out->[$n] ne $result->[$n]) {
		 $good = 0;
	 }
       }
       $tests++;
       $failed++ unless $good;
       print $good ? $OK : $FAILED, "\n";
       if (!$good) {
         for (my $n=0; $n < $nmax; $n++) {
	   my $l = defined($out->[$n]) ? $out->[$n] : "~";
	   chomp $l;
	   my $r = defined($result->[$n]) ? $result->[$n] : "~";
	   chomp $r;
	   print sprintf("%-37s %s %-39s\n", $l, $l eq $r ? "|" : "?", $r);
         }
       } elsif ($opt_v) {
	 print join('', @$result);
       }
}


sub su($) {
  my ($user) = @_;

  $user ||= "root";

  my ($login, $pass, $uid, $gid) = getpwnam($user)
    or return [ "su: user $user does not exist\n" ];
  my @groups = ();
  my $fh = new FileHandle("/etc/group")
    or return [ "opening /etc/group: $!\n" ];
  while (<$fh>) {
    chomp;
    my ($group, $passwd, $gid, $users) = split /:/;
    foreach my $u (split /,/, $users) {
      push @groups, $gid
	if ($user eq $u);
    }
  }
  $fh->close;

  my $groups = join(" ", ($gid, $gid, @groups));
  #print STDERR "[[$groups]]\n";
  $! = 0;  # reset errno
  $> = 0;
  $( = $gid;
  $) = $groups;
  if ($!) {
    return [ "su: $!\n" ];
  }
  if ($uid != 0) {
    $> = $uid;
    #$< = $uid;
    if ($!) {
      return [ "su: $prog->[1]: $!\n" ];
    }
  }
  #print STDERR "[($>,$<)($(,$))]";
  return [];
}


sub sg($) {
  my ($group) = @_;

  my $gid = getgrnam($group)
    or return [ "sg: group $group does not exist\n" ];
  my %groups = map { $_ eq $gid ? () : ($_ => 1) } (split /\s/, $));
  
  #print STDERR "<<", join("/", keys %groups), ">>\n";
  my $groups = join(" ", ($gid, $gid, keys %groups));
  #print STDERR "[[$groups]]\n";
  $! = 0;  # reset errno
  if ($> != 0) {
	  my $uid = $>;
	  $> = 0;
	  $( = $gid;
	  $) = $groups;
	  $> = $uid;
  } else {
	  $( = $gid;
	  $) = $groups;
  }
  if ($!) {
    return [ "sg: $!\n" ];
  }
  print STDERR "[($>,$<)($(,$))]";
  return [];
}


sub exec_test($$) {
  my ($prog, $in) = @_;
  local (*IN, *IN_DUP, *IN2, *OUT_DUP, *OUT, *OUT2);
  my $needs_shell = (join('', @$prog) =~ /[][|<>"'`\$\*\?]/);

  if ($prog->[0] eq "umask") {
    umask oct $prog->[1];
    return [];
  } elsif ($prog->[0] eq "cd") {
    if (!chdir $prog->[1]) {
      return [ "chdir: $prog->[1]: $!\n" ];
    }
    return [];
  } elsif ($prog->[0] eq "su") {
    return su($prog->[1]);
  } elsif ($prog->[0] eq "sg") {
    return sg($prog->[1]);
  }

  pipe *IN2, *OUT
    or die "Can't create pipe for reading: $!";
  open *IN_DUP, "<&STDIN"
    or *IN_DUP = undef;
  open *STDIN, "<&IN2"
    or die "Can't duplicate pipe for reading: $!";
  close *IN2;

  open *OUT_DUP, ">&STDOUT"
    or die "Can't duplicate STDOUT: $!";
  pipe *IN, *OUT2
    or die "Can't create pipe for writing: $!";
  open *STDOUT, ">&OUT2"
    or die "Can't duplicate pipe for writing: $!";
  close *OUT2;

  *STDOUT->autoflush();
  *OUT->autoflush();

  if (fork()) {
    # Server
    if (*IN_DUP) {
      open *STDIN, "<&IN_DUP"
        or die "Can't duplicate STDIN: $!";
      close *IN_DUP
        or die "Can't close STDIN duplicate: $!";
    }
    open *STDOUT, ">&OUT_DUP"
      or die "Can't duplicate STDOUT: $!";
    close *OUT_DUP
      or die "Can't close STDOUT duplicate: $!";

    foreach my $line (@$in) {
      #print "> $line";
      print OUT $line;
    }
    close *OUT
      or die "Can't close pipe for writing: $!";

    my $result = [];
    while (<IN>) {
      #print "< $_";
      if ($needs_shell) {
	s#^/bin/sh: line \d+: ##;
      }
      push @$result, $_;
    }
    return $result;
  } else {
    # Client
    $< = $>;
    close IN
      or die "Can't close read end for input pipe: $!";
    close OUT
      or die "Can't close write end for output pipe: $!";
    close OUT_DUP
      or die "Can't close STDOUT duplicate: $!";
    local *ERR_DUP;
    open ERR_DUP, ">&STDERR"
      or die "Can't duplicate STDERR: $!";
    open STDERR, ">&STDOUT"
      or die "Can't join STDOUT and STDERR: $!";

    if ($needs_shell) {
      exec ('/bin/sh', '-c', join(" ", @$prog));
    } else {
      exec @$prog;
    }
    print STDERR $prog->[0], ": $!\n";
    exit;
  }
}