libtestbed.pm.in 10.7 KB
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#!/usr/bin/perl -w
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#
# EMULAB-COPYRIGHT
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# Copyright (c) 2000-2005 University of Utah and the Flux Group.
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# All rights reserved.
#

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package libtestbed;
use Exporter;

@ISA = "Exporter";
@EXPORT =
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    qw ( SENDMAIL OPENMAIL TBTimeStamp TBBackGround TBDateTimeFSSafe
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	 TBMakeLogname TB_BOSSNODE TB_OPSEMAIL TBGenSecretKey TBDebugTimeStamp
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	 TBDebugTimeStampsOn TBForkCmd TB_BOSSEVENTPORT TB_EVENTSERVER
	 TBScriptLock TBScriptUnlock
	 TBSCRIPTLOCK_OKAY TBSCRIPTLOCK_TIMEDOUT
	 TBSCRIPTLOCK_IGNORE TBSCRIPTLOCK_FAILED);
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# After package decl.
use English;
use POSIX qw(strftime);
use POSIX qw(setsid);
use Fcntl;
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use Fcntl ':flock';
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use IO::Handle;
use File::Basename;
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use Time::HiRes qw(gettimeofday);
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#my $MAILTAG  = "@OURDOMAIN@";
my $MAILTAG  = "@THISHOMEBASE@";
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my $BOSSNODE = "@BOSSNODE@";
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my $TIMESTAMPS = "@TIMESTAMPS@";
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my $TBOPSEMAIL = "@TBOPSEMAIL@";
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my $SCRIPTNAME = "Unknown";
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# Hostname of our boss node
sub TB_BOSSNODE()	{ $BOSSNODE; }
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# Testbed ops email address
sub TB_OPSEMAIL()	{ $TBOPSEMAIL; }

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# This is for the swigged event library which includes this file.
sub TB_BOSSEVENTPORT()  { "@BOSSEVENTPORT@"; }
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sub TB_EVENTSERVER()    { "@EVENTSERVER@" . "." . "@OURDOMAIN@"; }
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# Untainted scriptname for email below.
if ($PROGRAM_NAME =~ /^([-\w\.\/]+)$/) {
    $SCRIPTNAME = basename($1);
}
else {
    $SCRIPTNAME = "Tainted";
}

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#
# Turn off line buffering on output
#
STDOUT->autoflush(1);
STDERR->autoflush(1);

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# A library of useful stuff.

# Send an email message via sendmail -t.
#
# I am mimicking the PHP mail interface, only because I'm old and its
# hard to remember new things. I did add a From arg since thats basically
# required to make the mail look nice (not generated by root or daemon!).
#
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# SENDMAIL(To, Subject, Message, [From], [More Headers], [files to append])
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#
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sub SENDMAIL($$$;$$@)
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{
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    my($To, $Subject, $Message, $From, $Headers, @Files) = @_;
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    my $tag = uc($MAILTAG);
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    if (! open(MAIL, "|/usr/sbin/sendmail -t")) {
	print STDERR "SENDMAIL: Could not start sendmail: $!\n";
	return 0;
    }

    #
    # Sendmail will figure this out if not given.
    # 
    if (defined($From) && $From) {
	print MAIL "From: $From\n";
    }
    if (defined($Headers)) {
	print MAIL "$Headers\n";
    }
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    print MAIL "X-NetBed: $SCRIPTNAME\n";
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    print MAIL "To: $To\n";
    print MAIL "Subject: $tag: $Subject\n";
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    print MAIL "\n";
    print MAIL "$Message\n";
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    print MAIL "\n";

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    if (@Files) {
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	foreach my $file ( @Files ) {
	    if (open(IN, "$file")) {
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		print MAIL "\n--------- $file --------\n";
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		while (<IN>) {
		    print MAIL "$_";
		}
		close(IN);
	    }
	}
    }
    
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    print MAIL "\n";
    if (! close(MAIL)) {
	print STDERR "SENDMAIL: Could not finish sendmail: $!\n";
	return 0;
    }
    return 1;
}

#
# Fire up a sendmail process, and return the handle for the caller
# to print the body of the message into. This is easer in many places.
#
# OPENMAIL(To, Subject, [From], [More Headers])
#
sub OPENMAIL($$;$$)
{
    my($To, $Subject, $From, $Headers) = @_;
    local *MAIL;

    if (! open(MAIL, "|/usr/sbin/sendmail -t")) {
	print STDERR "OPENMAIL: Could not start sendmail: $!\n";
	return 0;
    }

    #
    # Sendmail will figure this out if not given.
    # 
    if (defined($From) && $From) {
	print MAIL "From: $From\n";
    }
    print MAIL "To: $To\n";
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    print MAIL "Subject: $tag: $Subject\n";
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    if (defined($Headers)) {
	print MAIL "$Headers\n";
    }
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    print MAIL "X-NetBed: $SCRIPTNAME\n";
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    print MAIL "\n";

    return(*MAIL);
}

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#
# Return a timestamp. We don't care about day/date/year. Just the time mam.
# 
# TBTimeStamp()
#
sub TBTimeStamp()
{
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    my ($seconds, $microseconds) = gettimeofday();
    
    return POSIX::strftime("%H:%M:%S", localtime($seconds)) . ":$microseconds";
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}

#
# Another routine for creating a file name based on the current date and
# time. The format is slightly different so that it can be a proper filename.
#
# usage: char *TBDateTimeFSSafe()
#
sub TBDateTimeFSSafe()
{
    return POSIX::strftime("20%y%m%d-%H.%M.%S", localtime());
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}

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#
# Print out a timestamp if the TIMESTAMPS configure variable was set.
# 
# usage: void TBDebugTimeStamp(@)
#
sub TBDebugTimeStamp(@)
{
    my @strings = @_;
    if ($TIMESTAMPS) {
	print "TIMESTAMP: ", TBTimeStamp(), " ", join("",@strings), "\n";
    }
}

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#
# Turn on timestamps locally. We could do this globally by using an
# env variable to pass it along, but lets see if we need that.
# 
sub TBDebugTimeStampsOn()
{
    $TIMESTAMPS = 1;
}
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#
# Put ourselves into the background, directing output to the log file.
# The caller provides the logfile name, which should have been created
# with mktemp, just to be safe. Returns the usual return of fork. 
#
# usage int TBBackGround(char *filename).
# 
sub TBBackGround($)
{
    my($logname) = @_;
    
    my $mypid = fork();
    if ($mypid) {
	return $mypid;
    }
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    select(undef, undef, undef, 0.2);
    
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    #
    # We have to disconnect from the caller by redirecting both STDIN and
    # STDOUT away from the pipe. Otherwise the caller (the web server) will
    # continue to wait even though the parent has exited. 
    #
    open(STDIN, "< /dev/null") or
	die("opening /dev/null for STDIN: $!");

    # Note different taint check (allow /).
    if ($logname =~ /^([-\@\w.\/]+)$/) {
	$logname = $1;
    } else {
	die "Bad data in logfile name: $logname";
    }

    open(STDERR, ">> $logname") or die("opening $logname for STDERR: $!");
    open(STDOUT, ">> $logname") or die("opening $logname for STDOUT: $!");

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    #
    # Turn off line buffering on output
    #
    STDOUT->autoflush(1);
    STDERR->autoflush(1);

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    #
    # Create a new session to ensure we are clear of any process group
    #
    POSIX::setsid() or
	die("setsid failed: $!");

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    return 0;
}

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#
# Create a logname and untaint it!
#
sub TBMakeLogname($)
{
    my($prefix) = @_;
    my $logname;
    
    $logname = `mktemp /tmp/${prefix}.XXXXXX`;

    if ($logname =~ /^([-\@\w\.\/]+)$/) {
	$logname = $1;
    }
    else {
	die("Bad data in logfile name: $logname");
    }

    return $logname;
}

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#
# Get me a secret key!
#
sub TBGenSecretKey()
{
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    my $key=`/bin/dd if=/dev/urandom count=128 bs=1 2> /dev/null | /sbin/md5`;
    chomp($key);
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    return $key;
}

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#
# Fork+exec a command and return its exit value.  This is similar to
# system(), but does not use a shell to invoke the command.  The function
# exits with the return value from wait().
#
# If the second optional param is passed and true, then
# a signal handler for TERM will be installed, and the
# child process will be sent a SIGTERM if this (the calling)
# process gets one. The handler exits with the exit status returned by 
# wait() after sending the signal.
#
sub TBForkCmd($;$) {
    my ($cmd, $dokill) = @_;

    my $childpid = fork();
        
    if ($childpid) {
        my $handler = sub {
            kill("TERM", $childpid);
            my $exstat = wait();
            print STDERR "*** $0:\n".
                "    Command terminated: $cmd.\n"; 
            exit($exstat);
        };
        local $SIG{TERM} = \&$handler if (defined($dokill) && $dokill);

        my $waitpid = wait();
        my $exitstatus = $?;
        if ($waitpid < 0) {
            die("*** $0:\n".
                "    Uh oh, wait() returned a negative number");
        }
        elsif ($waitpid != $childpid) {
            warn("*** $0:\n".
                "    pid returned by wait() != pid ".
                "from fork(): $waitpid $childpid");
        }
        return $exitstatus;
    }
    else {
        exec($cmd);
        die("*** $0:\n".
            "    exec of $cmd failed!\n");
    }

    # NOTREACHED
    return(0);
}

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#
# Serialize an operation (script).
#
my $lockname;
my $lockhandle;

# Return Values.
sub TBSCRIPTLOCK_OKAY()		{ 0;  }
sub TBSCRIPTLOCK_TIMEDOUT()	{ 1;  }
sub TBSCRIPTLOCK_IGNORE()	{ 2;  }
sub TBSCRIPTLOCK_FAILED()	{ -1; }

# 
# There are two kinds of serialization.
#
#   * Usual Kind: Each party just waits for a chance to go.
#   * Other Kind: Only the first party really needs to run; the others just
#                 need to wait. For example; exports_setup operates globally,
#                 so there is no reason to run it more then once. We just
#                 need to make sure that everyone waits for the one that is
#		  running to finish. Use the global option for this.
#
sub TBScriptLock($;$$)
{
    my ($token, $global, $waittime) = @_;
    local *LOCK;

    $waittime = 30
	if (!defined($waittime));
    $global = 0
	if (!defined($global));
    $lockname = "/var/tmp/testbed_${token}_lockfile";

    if (! open(LOCK, ">>$lockname")) {
	print STDERR "Could not open $lockname!\n";
	return TBSCRIPTLOCK_FAILED();
    }

    if (! $global) {
	#
	# A plain old serial lock.
	#
	while (flock(LOCK, LOCK_EX|LOCK_NB) == 0) {
	    print "Another $token is in progress. Waiting a moment ...\n";

	    $waittime--;
	    if ($waittime == 0) {
		print STDERR "Could not get the lock after a long time!\n";
		return TBSCRIPTLOCK_TIMEDOUT();
	    }
	    sleep(1);
	}
	# Okay, got the lock. Save the handle. We need it below.
	$lockhandle = *LOCK;
	return TBSCRIPTLOCK_OKAY();
    }

    #
    # Okay, a global lock.
    #
    # If we don't get it the first time, we wait for:
    # 1) The lock to become free, in which case we do our thing
    # 2) The time on the lock to change, in which case we wait for that 
    #    process to finish, and then we are done since there is no
    #    reason to duplicate what the just finished process did.
    #
    if (flock(LOCK, LOCK_EX|LOCK_NB) == 0) {
	my $oldlocktime = (stat(LOCK))[9];
	my $gotlock = 0;
	
	while (1) {
	    print "Another $token in progress. Waiting a moment ...\n";
	    
	    if (flock(LOCK, LOCK_EX|LOCK_NB) != 0) {
		# OK, got the lock
		$gotlock = 1;
		last;
	    }
	    my $locktime = (stat(LOCK))[9];
	    if ($locktime != $oldlocktime) {
		$oldlocktime = $locktime;
		last;
	    }
	    
	    $waittime--;
	    if ($waittime <= 0) {
		print STDERR "Could not get the lock after a long time!\n";
		return TBSCRIPTLOCK_TIMEDOUT();
	    }
	    sleep(1);
	}

	$count = 0;
	#
	# If we did not get the lock, wait for the process that did to finish.
	#
	if (!$gotlock) {
	    while (1) {
		if ((stat(LOCK))[9] != $oldlocktime) {
		    return TBSCRIPTLOCK_IGNORE();
		}
		if (flock(LOCK, LOCK_EX|LOCK_NB) != 0) {
		    close(LOCK);
		    return TBSCRIPTLOCK_IGNORE();
		}

		$waittime--;
		if ($waittime <= 0) {
		    print STDERR
			"Process with the lock did not finish after ".
			"a long time!\n";
		    return TBSCRIPTLOCK_TIMEDOUT();
		}
		sleep(1); 
	    }
	}
    }
    #
    # Perl-style touch(1)
    #
    my $now = time;
    utime $now, $now, $lockname;
    
    $lockhandle = *LOCK;
    return TBSCRIPTLOCK_OKAY();
}

#
# Unlock; Just need to close the file (releasing the lock).
#
sub TBScriptUnlock()
{
    close($lockhandle)
	if defined($lockhandle);
}

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