
use strict;

package Mail::Box::Locker::POSIX;
use vars '$VERSION';
$VERSION = '2.055';
use base 'Mail::Box::Locker';

use POSIX;
use Fcntl;
use IO::File;


#-------------------------------------------

sub name() {'POSIX'}

#-------------------------------------------

sub _try_lock($)
{   my ($self, $file) = @_;
    $? = fcntl($file, F_SETLK, pack('s @256', F_WRLCK)) || 0;
    $?==0;
}

sub _unlock($)
{   my ($self, $file) = @_;
    fcntl($file, F_SETLK, pack('s @256', F_UNLCK));
    delete $self->{MBL_has_lock};
    $self;
}

#-------------------------------------------


sub lock()
{   my $self  = shift;
    return 1 if $self->hasLock;

    my $filename = $self->filename;

    my $file   = IO::File->new($filename, 'r+');
    unless(defined $file)
    {   $self->log(ERROR =>
           "Unable to open POSIX lock file $filename for $self->{MBL_folder}: $!");
        return 0;
    }

    my $end = $self->{MBL_timeout} eq 'NOTIMEOUT' ? -1 : $self->{MBL_timeout};

    while(1)
    {   if($self->_try_lock($file))
        {   $self->{MBL_has_lock}    = 1;
            $self->{MBLF_filehandle} = $file;
            return 1;
        }

        if($? != EAGAIN)
        {   $self->log(ERROR =>
            "Will never get a POSIX lock on $filename for $self->{MBL_folder}: $!");
            last;
        }

        last unless --$end;
        sleep 1;
    }

    return 0;
}

#-------------------------------------------


sub isLocked()
{   my $self     = shift;
    my $filename = $self->filename;

    my $file     = IO::File->new($filename, "r");
    unless($file)
    {   $self->log(ERROR =>
               "Unable to check lock file $filename for $self->{MBL_folder}: $!");
        return 0;
    }

    $self->_try_lock($file) or return 0;
    $self->_unlock($file);
    $file->close;

    1;
}

#-------------------------------------------

sub unlock()
{   my $self = shift;

    $self->_unlock(delete $self->{MBLF_filehandle})
       if $self->hasLock;

    $self;
}

#-------------------------------------------

1;
