# Copyright 2010, 2011 Kevin Ryde
# This file is part of Filter-gunzip.
#
# Filter-gunzip is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 3, or (at your option) any later
# version.
#
# Filter-gunzip is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License along
# with Filter-gunzip. If not, see <http://www.gnu.org/licenses/>.
package Filter::Gunzip;
use strict;
use warnings;
use Carp;
use Filter::Util::Call;
use Compress::Zlib;
our $VERSION = 4;
use constant DEBUG => 1;
sub import {
my ($class) = @_;
filter_add ($class->new);
}
sub new {
my ($class) = @_;
my ($inf, $zerr) = inflateInit
(-WindowBits => MAX_WBITS() + WANT_GZIP_OR_ZLIB());
$inf or croak "Gunzip cannot create inflator: $zerr";
return bless { inf => $inf, input => '' }, $class;
}
sub filter {
my ($self) = @_;
if (DEBUG) { print STDERR "filter\n"; }
unless ($self->{'input_eof'} || length ($self->{'input'})) {
$_ = '';
my $status = filter_read(5);
if (DEBUG) { print " filter_read() $status\n"; }
if ($status < 0) {
delete $self->{'inf'};
return ($self->{'final_status'} = $status);
}
if ($status == 0) {
$self->{'input_eof'} = 1;
}
$self->{'input'} = $_;
}
my $inf = $self->{'inf'} || do {
if (! $self->{'input_eof'}) {
carp "Gunzip spurious extra input bytes";
$self->{'input_eof'} = 1;
$self->{'final_status'} = -1;
}
return $self->{'final_status'};
};
my ($output, $zerr) = $inf->inflate($_);
if (DEBUG) { print " inflate() \"$zerr\" leaving ",length($_),"\n"; }
if ($zerr == Z_STREAM_END) {
delete $self->{'inf'};
$self->{'final_status'} = 0;
if ($self->{'input_eof'}) {
# 0 for eof if no output
return length($_);
}
# return this output, next call will check for input eof
return 1;
}
if ($zerr == Z_OK) {
if ($self->{'input_eof'}) {
# got to EOF on filter_read(), but $inf not at Z_STREAM_END
carp "Gunzip incomplete input";
delete $self->{'inf'};
return ($self->{'final_status'} = -1);
}
# might have empty string $output here, but that's ok, we'll be called
# again immediately
return 1;
}
carp "Gunzip error: $zerr";
delete $self->{'inf'};
return ($self->{'final_status'} = -1);
}
1;
__END__
# require POSIX;
# require Scalar::Util;
# $! = Scalar::Util::dualvar (POSIX::EINVAL(),
# 'Gunzip spurious extra input bytes');