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#
# This file is part of Log-Dispatch-FileRotate
#
# This software is copyright (c) 2005 by Mark Pfeiffer.
#
# This is free software; you can redistribute it and/or modify it under
# the same terms as the Perl 5 programming language system itself.
#
package Log::Dispatch::FileRotate::Flock;
$Log::Dispatch::FileRotate::Flock::VERSION = '1.38';
# ABSTRACT: File Locking Functions for L<Log::Dispatch::FileRotate>
use strict;
use warnings;
use base 'Exporter';
use Fcntl ':flock';
our @EXPORT_OK = qw(safe_flock flopen);
sub safe_flock {
my ($fh, $flags) = @_;
while (1) {
unless (flock $fh, $flags) {
# retry if we were interrupted or we are in non-blocking and the file is locked
next if $!{EAGAIN} or $!{EWOULDBLOCK};
return 0;
}
else {
return 1;
}
}
}
sub flopen {
my $path = shift;
my $flags = LOCK_EX; my $fh;
while (1) {
unless (open $fh, '>>', $path) {
return;
}
unless (safe_flock($fh, $flags)) {
return;
}
my @path_stat = stat $path;
unless (@path_stat) {
# file disappeared fron under our feet
close $fh;
next;
}
my @fh_stat = stat $fh;
unless (@fh_stat) {
# This should never happen
return;
}
unless ($^O =~ /^MSWin/) {
# stat on a filehandle and path return different "dev" and "rdev"
# fields on windows
if ($path_stat[0] != $fh_stat[0]) {
# file was changed under our feet. try again;
close $fh;
next;
}
}
# check that inode are the same for the path and fh
if ($path_stat[1] != $fh_stat[1])
{
# file was changed under our feet. try again;
close $fh;
next;
}
return ($fh, $fh_stat[1]);
}
}
1;
__END__
=pod
=encoding UTF-8
=head1 NAME
Log::Dispatch::FileRotate::Flock - File Locking Functions for L<Log::Dispatch::FileRotate>
=head1 VERSION
version 1.38
=head1 SYNOPSIS
Internal Use Only!
=head2 DESCRIPTION
Internal Use Only!
=head1 METHODS
=head2 safe_flock($filehandle, $flags): boolean
This is a wrapper around C<flock()> that handles things such as interruption of
the call by a signal automatically.
=head2 flopen($path): ($filehandle, $inode)
This function is similar to BSD's C<flopen()> function. It opens a file,
obtiains an exclusive lock on it using C<flock()>, and handles a bunch of race
conditions that can happen. It returns the opened filehandle and the inode of
the file on success, nothing on failure.
=head1 SOURCE
The development version is on github at L<https://https://github.com/mschout/perl-log-dispatch-filerotate>
and may be cloned from L<git://https://github.com/mschout/perl-log-dispatch-filerotate.git>
=head1 BUGS
Please report any bugs or feature requests on the bugtracker website
L<https://github.com/mschout/perl-log-dispatch-filerotate/issues>
When submitting a bug or request, please include a test-file or a
patch to an existing test-file that illustrates the bug or desired
feature.
=head1 AUTHOR
Michael Schout <mschout@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2005 by Mark Pfeiffer.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut
|
