[p5sagit/p5-mst-13.2.git] / ext / IO_Compress_Base / lib / IO / Uncompress / Base.pm


package IO::Uncompress::Base ;

use strict ;
use warnings;
use bytes;

our (@ISA, $VERSION, @EXPORT_OK, %EXPORT_TAGS);
#@ISA    = qw(Exporter IO::File);
@ISA    = qw(Exporter );


$VERSION = '2.004';

use constant G_EOF => 0 ;
use constant G_ERR => -1 ;

use IO::Compress::Base::Common 2.004 ;
#use Parse::Parameters ;

use IO::File ;
use Symbol;
use Scalar::Util qw(readonly);
use List::Util qw(min);
use Carp ;

%EXPORT_TAGS = ( );
push @{ $EXPORT_TAGS{all} }, @EXPORT_OK ;
#Exporter::export_ok_tags('all') ;


sub smartRead
{
    my $self = $_[0];
    my $out = $_[1];
    my $size = $_[2];
    $$out = "" ;

    my $offset = 0 ;


    if (defined *$self->{InputLength}) {
        return 0
            if *$self->{InputLengthRemaining} <= 0 ;
        $size = min($size, *$self->{InputLengthRemaining});
    }

    if ( length *$self->{Prime} ) {
        #$$out = substr(*$self->{Prime}, 0, $size, '') ;
        $$out = substr(*$self->{Prime}, 0, $size) ;
        substr(*$self->{Prime}, 0, $size) =  '' ;
        if (length $$out == $size) {
            *$self->{InputLengthRemaining} -= length $$out
                if defined *$self->{InputLength};

            return length $$out ;
        }
        $offset = length $$out ;
    }

    my $get_size = $size - $offset ;

    #if ( defined *$self->{InputLength} ) {
    #    $get_size = min($get_size, *$self->{InputLengthRemaining});
    #}

    if (defined *$self->{FH})
      { *$self->{FH}->read($$out, $get_size, $offset) }
    elsif (defined *$self->{InputEvent}) {
        my $got = 1 ;
        while (length $$out < $size) {
            last 
                if ($got = *$self->{InputEvent}->($$out, $get_size)) <= 0;
        }

        if (length $$out > $size ) {
            #*$self->{Prime} = substr($$out, $size, length($$out), '');
            *$self->{Prime} = substr($$out, $size, length($$out));
            substr($$out, $size, length($$out)) =  '';
        }

       *$self->{EventEof} = 1 if $got <= 0 ;
    }
    else {
       no warnings 'uninitialized';
       my $buf = *$self->{Buffer} ;
       $$buf = '' unless defined $$buf ;
       #$$out = '' unless defined $$out ;
       substr($$out, $offset) = substr($$buf, *$self->{BufferOffset}, $get_size);
       if (*$self->{ConsumeInput})
         { substr($$buf, 0, $get_size) = '' }
       else  
         { *$self->{BufferOffset} += length($$out) - $offset }
    }

    *$self->{InputLengthRemaining} -= length($$out) #- $offset 
        if defined *$self->{InputLength};
        
    $self->saveStatus(length $$out < 0 ? STATUS_ERROR : STATUS_OK) ;

    return length $$out;
}

sub pushBack
{
    my $self = shift ;

    return if ! defined $_[0] || length $_[0] == 0 ;

    if (defined *$self->{FH} || defined *$self->{InputEvent} ) {
        *$self->{Prime} = $_[0] . *$self->{Prime} ;
        *$self->{InputLengthRemaining} += length($_[0]);
    }
    else {
        my $len = length $_[0];

        if($len > *$self->{BufferOffset}) {
            *$self->{Prime} = substr($_[0], 0, $len - *$self->{BufferOffset}) . *$self->{Prime} ;
            *$self->{InputLengthRemaining} = *$self->{InputLength};
            *$self->{BufferOffset} = 0
        }
        else {
            *$self->{InputLengthRemaining} += length($_[0]);
            *$self->{BufferOffset} -= length($_[0]) ;
        }
    }
}

sub smartSeek
{
    my $self   = shift ;
    my $offset = shift ;
    my $truncate = shift;
    #print "smartSeek to $offset\n";

    # TODO -- need to take prime into account
    if (defined *$self->{FH})
      { *$self->{FH}->seek($offset, SEEK_SET) }
    else {
        *$self->{BufferOffset} = $offset ;
        substr(${ *$self->{Buffer} }, *$self->{BufferOffset}) = ''
            if $truncate;
        return 1;
    }
}

sub smartWrite
{
    my $self   = shift ;
    my $out_data = shift ;

    if (defined *$self->{FH}) {
        # flush needed for 5.8.0 
        defined *$self->{FH}->write($out_data, length $out_data) &&
        defined *$self->{FH}->flush() ;
    }
    else {
       my $buf = *$self->{Buffer} ;
       substr($$buf, *$self->{BufferOffset}, length $out_data) = $out_data ;
       *$self->{BufferOffset} += length($out_data) ;
       return 1;
    }
}

sub smartReadExact
{
    return $_[0]->smartRead($_[1], $_[2]) == $_[2];
}

sub smartEof
{
    my ($self) = $_[0];
    local $.; 

    return 0 if length *$self->{Prime} || *$self->{PushMode};

    if (defined *$self->{FH})
     { *$self->{FH}->eof() }
    elsif (defined *$self->{InputEvent})
     { *$self->{EventEof} }
    else 
     { *$self->{BufferOffset} >= length(${ *$self->{Buffer} }) }
}

sub clearError
{
    my $self   = shift ;

    *$self->{ErrorNo}  =  0 ;
    ${ *$self->{Error} } = '' ;
}

sub saveStatus
{
    my $self   = shift ;
    my $errno = shift() + 0 ;
    #return $errno unless $errno || ! defined *$self->{ErrorNo};
    #return $errno unless $errno ;

    *$self->{ErrorNo}  = $errno;
    ${ *$self->{Error} } = '' ;

    return *$self->{ErrorNo} ;
}


sub saveErrorString
{
    my $self   = shift ;
    my $retval = shift ;

    #return $retval if ${ *$self->{Error} };

    ${ *$self->{Error} } = shift ;
    *$self->{ErrorNo} = shift() + 0 if @_ ;

    #warn "saveErrorString: " . ${ *$self->{Error} } . " " . *$self->{Error} . "\n" ;
    return $retval;
}

sub croakError
{
    my $self   = shift ;
    $self->saveErrorString(0, $_[0]);
    croak $_[0];
}


sub closeError
{
    my $self = shift ;
    my $retval = shift ;

    my $errno = *$self->{ErrorNo};
    my $error = ${ *$self->{Error} };

    $self->close();

    *$self->{ErrorNo} = $errno ;
    ${ *$self->{Error} } = $error ;

    return $retval;
}

sub error
{
    my $self   = shift ;
    return ${ *$self->{Error} } ;
}

sub errorNo
{
    my $self   = shift ;
    return *$self->{ErrorNo};
}

sub HeaderError
{
    my ($self) = shift;
    return $self->saveErrorString(undef, "Header Error: $_[0]", STATUS_ERROR);
}

sub TrailerError
{
    my ($self) = shift;
    return $self->saveErrorString(G_ERR, "Trailer Error: $_[0]", STATUS_ERROR);
}

sub TruncatedHeader
{
    my ($self) = shift;
    return $self->HeaderError("Truncated in $_[0] Section");
}

sub TruncatedTrailer
{
    my ($self) = shift;
    return $self->TrailerError("Truncated in $_[0] Section");
}

sub postCheckParams
{
    return 1;
}

sub checkParams
{
    my $self = shift ;
    my $class = shift ;

    my $got = shift || IO::Compress::Base::Parameters::new();
    
    my $Valid = {
                    'BlockSize'     => [1, 1, Parse_unsigned, 16 * 1024],
                    'AutoClose'     => [1, 1, Parse_boolean,  0],
                    'Strict'        => [1, 1, Parse_boolean,  0],
                    'Append'        => [1, 1, Parse_boolean,  0],
                    'Prime'         => [1, 1, Parse_any,      undef],
                    'MultiStream'   => [1, 1, Parse_boolean,  0],
                    'Transparent'   => [1, 1, Parse_any,      1],
                    'Scan'          => [1, 1, Parse_boolean,  0],
                    'InputLength'   => [1, 1, Parse_unsigned, undef],
                    'BinModeOut'    => [1, 1, Parse_boolean,  0],
                    #'Encode'        => [1, 1, Parse_any,       undef],

                   #'ConsumeInput'  => [1, 1, Parse_boolean,  0],

                    $self->getExtraParams(),

                    #'Todo - Revert to ordinary file on end Z_STREAM_END'=> 0,
                    # ContinueAfterEof
                } ;

    $Valid->{TrailingData} = [1, 1, Parse_writable_scalar, undef]
        if  *$self->{OneShot} ;
        
    $got->parse($Valid, @_ ) 
        or $self->croakError("${class}: $got->{Error}")  ;

    $self->postCheckParams($got) 
        or $self->croakError("${class}: " . $self->error())  ;

    return $got;
}

sub _create
{
    my $obj = shift;
    my $got = shift;
    my $append_mode = shift ;

    my $class = ref $obj;
    $obj->croakError("$class: Missing Input parameter")
        if ! @_ && ! $got ;

    my $inValue = shift ;

    *$obj->{OneShot}           = 0 ;

    if (! $got)
    {
        $got = $obj->checkParams($class, undef, @_)
            or return undef ;
    }

    my $inType  = whatIsInput($inValue, 1);

    $obj->ckInputParam($class, $inValue, 1) 
        or return undef ;

    *$obj->{InNew} = 1;

    $obj->ckParams($got)
        or $obj->croakError("${class}: " . *$obj->{Error});

    if ($inType eq 'buffer' || $inType eq 'code') {
        *$obj->{Buffer} = $inValue ;        
        *$obj->{InputEvent} = $inValue 
           if $inType eq 'code' ;
    }
    else {
        if ($inType eq 'handle') {
            *$obj->{FH} = $inValue ;
            *$obj->{Handle} = 1 ;

            # Need to rewind for Scan
            *$obj->{FH}->seek(0, SEEK_SET) 
                if $got->value('Scan');
        }  
        else {    
            my $mode = '<';
            $mode = '+<' if $got->value('Scan');
            *$obj->{StdIO} = ($inValue eq '-');
            *$obj->{FH} = new IO::File "$mode $inValue"
                or return $obj->saveErrorString(undef, "cannot open file '$inValue': $!", $!) ;
        }
        
        *$obj->{LineNo} = $. = 0;
        setBinModeInput(*$obj->{FH}) ;

        my $buff = "" ;
        *$obj->{Buffer} = \$buff ;
    }

    if ($got->parsed('Encode')) { 
        my $want_encoding = $got->value('Encode');
        *$obj->{Encoding} = getEncoding($obj, $class, $want_encoding);
    }


    *$obj->{InputLength}       = $got->parsed('InputLength') 
                                    ? $got->value('InputLength')
                                    : undef ;
    *$obj->{InputLengthRemaining} = $got->value('InputLength');
    *$obj->{BufferOffset}      = 0 ;
    *$obj->{AutoClose}         = $got->value('AutoClose');
    *$obj->{Strict}            = $got->value('Strict');
    *$obj->{BlockSize}         = $got->value('BlockSize');
    *$obj->{Append}            = $got->value('Append');
    *$obj->{AppendOutput}      = $append_mode || $got->value('Append');
    *$obj->{ConsumeInput}      = $got->value('ConsumeInput');
    *$obj->{Transparent}       = $got->value('Transparent');
    *$obj->{MultiStream}       = $got->value('MultiStream');

    # TODO - move these two into RawDeflate
    *$obj->{Scan}              = $got->value('Scan');
    *$obj->{ParseExtra}        = $got->value('ParseExtra') 
                                  || $got->value('Strict')  ;
    *$obj->{Type}              = '';
    *$obj->{Prime}             = $got->value('Prime') || '' ;
    *$obj->{Pending}           = '';
    *$obj->{Plain}             = 0;
    *$obj->{PlainBytesRead}    = 0;
    *$obj->{InflatedBytesRead} = 0;
    *$obj->{UnCompSize}        = new U64;
    *$obj->{CompSize}          = new U64;
    *$obj->{TotalInflatedBytesRead} = 0;
    *$obj->{NewStream}         = 0 ;
    *$obj->{EventEof}          = 0 ;
    *$obj->{ClassName}         = $class ;
    *$obj->{Params}            = $got ;

    if (*$obj->{ConsumeInput}) {
        *$obj->{InNew} = 0;
        *$obj->{Closed} = 0;
        return $obj
    }

    my $status = $obj->mkUncomp($class, $got);

    return undef
        unless defined $status;

    if ( !  $status) {
        return undef 
            unless *$obj->{Transparent};

        $obj->clearError();
        *$obj->{Type} = 'plain';
        *$obj->{Plain} = 1;
        #$status = $obj->mkIdentityUncomp($class, $got);
        $obj->pushBack(*$obj->{HeaderPending})  ;
    }

    push @{ *$obj->{InfoList} }, *$obj->{Info} ;

    $obj->saveStatus(STATUS_OK) ;
    *$obj->{InNew} = 0;
    *$obj->{Closed} = 0;

    return $obj;
}

sub ckInputParam
{
    my $self = shift ;
    my $from = shift ;
    my $inType = whatIsInput($_[0], $_[1]);

    $self->croakError("$from: input parameter not a filename, filehandle, array ref or scalar ref")
        if ! $inType ;

    if ($inType  eq 'filename' )
    {
        $self->croakError("$from: input filename is undef or null string")
            if ! defined $_[0] || $_[0] eq ''  ;

        if ($_[0] ne '-' && ! -e $_[0] )
        {
            return $self->saveErrorString(undef, 
                            "input file '$_[0]' does not exist", STATUS_ERROR);
        }
    }

    return 1;
}


sub _inf
{
    my $obj = shift ;

    my $class = (caller)[0] ;
    my $name = (caller(1))[3] ;

    $obj->croakError("$name: expected at least 1 parameters\n")
        unless @_ >= 1 ;

    my $input = shift ;
    my $haveOut = @_ ;
    my $output = shift ;


    my $x = new Validator($class, *$obj->{Error}, $name, $input, $output)
        or return undef ;
    
    push @_, $output if $haveOut && $x->{Hash};

    *$obj->{OneShot} = 1 ;
    
    my $got = $obj->checkParams($name, undef, @_)
        or return undef ;

    if ($got->parsed('TrailingData'))
    {
        *$obj->{TrailingData} = $got->value('TrailingData');
    }

    *$obj->{MultiStream} = $got->value('MultiStream');
    $got->value('MultiStream', 0);

    $x->{Got} = $got ;

#    if ($x->{Hash})
#    {
#        while (my($k, $v) = each %$input)
#        {
#            $v = \$input->{$k} 
#                unless defined $v ;
#
#            $obj->_singleTarget($x, $k, $v, @_)
#                or return undef ;
#        }
#
#        return keys %$input ;
#    }
    
    if ($x->{GlobMap})
    {
        $x->{oneInput} = 1 ;
        foreach my $pair (@{ $x->{Pairs} })
        {
            my ($from, $to) = @$pair ;
            $obj->_singleTarget($x, $from, $to, @_)
                or return undef ;
        }

        return scalar @{ $x->{Pairs} } ;
    }

    if (! $x->{oneOutput} )
    {
        my $inFile = ($x->{inType} eq 'filenames' 
                        || $x->{inType} eq 'filename');

        $x->{inType} = $inFile ? 'filename' : 'buffer';
        
        foreach my $in ($x->{oneInput} ? $input : @$input)
        {
            my $out ;
            $x->{oneInput} = 1 ;

            $obj->_singleTarget($x, $in, $output, @_)
                or return undef ;
        }

        return 1 ;
    }

    # finally the 1 to 1 and n to 1
    return $obj->_singleTarget($x, $input, $output, @_);

    croak "should not be here" ;
}

sub retErr
{
    my $x = shift ;
    my $string = shift ;

    ${ $x->{Error} } = $string ;

    return undef ;
}

sub _singleTarget
{
    my $self      = shift ;
    my $x         = shift ;
    my $input     = shift;
    my $output    = shift;
    
    my $buff = '';
    $x->{buff} = \$buff ;

    my $fh ;
    if ($x->{outType} eq 'filename') {
        my $mode = '>' ;
        $mode = '>>'
            if $x->{Got}->value('Append') ;
        $x->{fh} = new IO::File "$mode $output" 
            or return retErr($x, "cannot open file '$output': $!") ;
        binmode $x->{fh} if $x->{Got}->valueOrDefault('BinModeOut');

    }

    elsif ($x->{outType} eq 'handle') {
        $x->{fh} = $output;
        binmode $x->{fh} if $x->{Got}->valueOrDefault('BinModeOut');
        if ($x->{Got}->value('Append')) {
                seek($x->{fh}, 0, SEEK_END)
                    or return retErr($x, "Cannot seek to end of output filehandle: $!") ;
            }
    }

    
    elsif ($x->{outType} eq 'buffer' )
    {
        $$output = '' 
            unless $x->{Got}->value('Append');
        $x->{buff} = $output ;
    }

    if ($x->{oneInput})
    {
        defined $self->_rd2($x, $input, $output)
            or return undef; 
    }
    else
    {
        for my $element ( ($x->{inType} eq 'hash') ? keys %$input : @$input)
        {
            defined $self->_rd2($x, $element, $output) 
                or return undef ;
        }
    }


    if ( ($x->{outType} eq 'filename' && $output ne '-') || 
         ($x->{outType} eq 'handle' && $x->{Got}->value('AutoClose'))) {
        $x->{fh}->close() 
            or return retErr($x, $!); 
        delete $x->{fh};
    }

    return 1 ;
}

sub _rd2
{
    my $self      = shift ;
    my $x         = shift ;
    my $input     = shift;
    my $output    = shift;
        
    my $z = createSelfTiedObject($x->{Class}, *$self->{Error});
    
    $z->_create($x->{Got}, 1, $input, @_)
        or return undef ;

    my $status ;
    my $fh = $x->{fh};
    
    while (1) {

        while (($status = $z->read($x->{buff})) > 0) {
            if ($fh) {
                print $fh ${ $x->{buff} }
                    or return $z->saveErrorString(undef, "Error writing to output file: $!", $!);
                ${ $x->{buff} } = '' ;
            }
        }

        if (! $x->{oneOutput} ) {
            my $ot = $x->{outType} ;

            if ($ot eq 'array') 
              { push @$output, $x->{buff} }
            elsif ($ot eq 'hash') 
              { $output->{$input} = $x->{buff} }

            my $buff = '';
            $x->{buff} = \$buff;
        }

        last 
            unless *$self->{MultiStream};

        $status = $z->nextStream();

        last 
            unless $status == 1 ;
    }

    return $z->closeError(undef)
        if $status < 0 ;

    ${ *$self->{TrailingData} } = $z->trailingData()
        if defined *$self->{TrailingData} ;

    $z->close() 
        or return undef ;

    return 1 ;
}

sub TIEHANDLE
{
    return $_[0] if ref($_[0]);
    die "OOPS\n" ;

}
  
sub UNTIE
{
    my $self = shift ;
}


sub getHeaderInfo
{
    my $self = shift ;
    wantarray ? @{ *$self->{InfoList} } : *$self->{Info};
}

sub readBlock
{
    my $self = shift ;
    my $buff = shift ;
    my $size = shift ;

    if (defined *$self->{CompressedInputLength}) {
        if (*$self->{CompressedInputLengthRemaining} == 0) {
            delete *$self->{CompressedInputLength};
            *$self->{CompressedInputLengthDone} = 1;
            return STATUS_OK ;
        }
        $size = min($size, *$self->{CompressedInputLengthRemaining} );
        *$self->{CompressedInputLengthRemaining} -= $size ;
    }
    
    my $status = $self->smartRead($buff, $size) ;
    return $self->saveErrorString(STATUS_ERROR, "Error Reading Data")
        if $status < 0  ;

    if ($status == 0 ) {
        *$self->{Closed} = 1 ;
        *$self->{EndStream} = 1 ;
        return $self->saveErrorString(STATUS_ERROR, "unexpected end of file", STATUS_ERROR);
    }

    return STATUS_OK;
}

sub postBlockChk
{
    return STATUS_OK;
}

sub _raw_read
{
    # return codes
    # >0 - ok, number of bytes read
    # =0 - ok, eof
    # <0 - not ok
    
    my $self = shift ;

    return G_EOF if *$self->{Closed} ;
    #return G_EOF if !length *$self->{Pending} && *$self->{EndStream} ;
    return G_EOF if *$self->{EndStream} ;

    my $buffer = shift ;
    my $scan_mode = shift ;

    if (*$self->{Plain}) {
        my $tmp_buff ;
        my $len = $self->smartRead(\$tmp_buff, *$self->{BlockSize}) ;
        
        return $self->saveErrorString(G_ERR, "Error reading data: $!", $!) 
                if $len < 0 ;

        if ($len == 0 ) {
            *$self->{EndStream} = 1 ;
        }
        else {
            *$self->{PlainBytesRead} += $len ;
            $$buffer .= $tmp_buff;
        }

        return $len ;
    }

    if (*$self->{NewStream}) {

        $self->gotoNextStream() > 0
            or return G_ERR;

        # For the headers that actually uncompressed data, put the
        # uncompressed data into the output buffer.
        $$buffer .=  *$self->{Pending} ;
        my $len = length  *$self->{Pending} ;
        *$self->{Pending} = '';
        return $len; 
    }

    my $temp_buf = '';
    my $outSize = 0;
    my $status = $self->readBlock(\$temp_buf, *$self->{BlockSize}, $outSize) ;
    return G_ERR
        if $status == STATUS_ERROR  ;

    my $buf_len = 0;
    if ($status == STATUS_OK) {
        my $beforeC_len = length $temp_buf;
        my $before_len = defined $$buffer ? length $$buffer : 0 ;
        $status = *$self->{Uncomp}->uncompr(\$temp_buf, $buffer,
                                    defined *$self->{CompressedInputLengthDone} ||
                                                $self->smartEof(), $outSize);

        return $self->saveErrorString(G_ERR, *$self->{Uncomp}{Error}, *$self->{Uncomp}{ErrorNo})
            if $self->saveStatus($status) == STATUS_ERROR;

        $self->postBlockChk($buffer, $before_len) == STATUS_OK
            or return G_ERR;

        $buf_len = length($$buffer) - $before_len;
    
        *$self->{CompSize}->add($beforeC_len - length $temp_buf) ;

        *$self->{InflatedBytesRead} += $buf_len ;
        *$self->{TotalInflatedBytesRead} += $buf_len ;
        *$self->{UnCompSize}->add($buf_len) ;

        $self->filterUncompressed($buffer);

        if (*$self->{Encoding}) {
            $$buffer = *$self->{Encoding}->decode($$buffer);
        }
    }

    if ($status == STATUS_ENDSTREAM) {

        *$self->{EndStream} = 1 ;
        $self->pushBack($temp_buf)  ;
        $temp_buf = '';

        my $trailer;
        my $trailer_size = *$self->{Info}{TrailerLength} ;
        my $got = 0;
        if (*$self->{Info}{TrailerLength})
        {
            $got = $self->smartRead(\$trailer, $trailer_size) ;
        }

        if ($got == $trailer_size) {
            $self->chkTrailer($trailer) == STATUS_OK
                or return G_ERR;
        }
        else {
            return $self->TrailerError("trailer truncated. Expected " . 
                                      "$trailer_size bytes, got $got")
                if *$self->{Strict};
            $self->pushBack($trailer)  ;
        }

        # TODO - if want to file file pointer, do it here

        if (! $self->smartEof()) {
            *$self->{NewStream} = 1 ;

            if (*$self->{MultiStream}) {
                *$self->{EndStream} = 0 ;
                return $buf_len ;
            }
        }

    }
    

    # return the number of uncompressed bytes read
    return $buf_len ;
}

sub reset
{
    my $self = shift ;

    return *$self->{Uncomp}->reset();
}

sub filterUncompressed
{
}

#sub isEndStream
#{
#    my $self = shift ;
#    return *$self->{NewStream} ||
#           *$self->{EndStream} ;
#}

sub nextStream
{
    my $self = shift ;

    my $status = $self->gotoNextStream();
    $status == 1
        or return $status ;

    *$self->{TotalInflatedBytesRead} = 0 ;
    *$self->{LineNo} = $. = 0;

    return 1;
}

sub gotoNextStream
{
    my $self = shift ;

    if (! *$self->{NewStream}) {
        my $status = 1;
        my $buffer ;

        # TODO - make this more efficient if know the offset for the end of
        # the stream and seekable
        $status = $self->read($buffer) 
            while $status > 0 ;

        return $status
            if $status < 0;
    }

    *$self->{NewStream} = 0 ;
    *$self->{EndStream} = 0 ;
    $self->reset();
    *$self->{UnCompSize}->reset();
    *$self->{CompSize}->reset();

    my $magic = $self->ckMagic();
    #*$self->{EndStream} = 0 ;

    if ( ! $magic) {
        if (! *$self->{Transparent} )
        {
            *$self->{EndStream} = 1 ;
            return 0;
        }

        $self->clearError();
        *$self->{Type} = 'plain';
        *$self->{Plain} = 1;
        $self->pushBack(*$self->{HeaderPending})  ;
    }
    else
    {
        *$self->{Info} = $self->readHeader($magic);

        if ( ! defined *$self->{Info} ) {
            *$self->{EndStream} = 1 ;
            return -1;
        }
    }

    push @{ *$self->{InfoList} }, *$self->{Info} ;

    return 1; 
}

sub streamCount
{
    my $self = shift ;
    return 1 if ! defined *$self->{InfoList};
    return scalar @{ *$self->{InfoList} }  ;
}

sub read
{
    # return codes
    # >0 - ok, number of bytes read
    # =0 - ok, eof
    # <0 - not ok
    
    my $self = shift ;

    return G_EOF if *$self->{Closed} ;
    return G_EOF if !length *$self->{Pending} && *$self->{EndStream} ;

    my $buffer ;

    #$self->croakError(*$self->{ClassName} . 
    #            "::read: buffer parameter is read-only")
    #    if Compress::Raw::Zlib::_readonly_ref($_[0]);

    if (ref $_[0] ) {
        $self->croakError(*$self->{ClassName} . "::read: buffer parameter is read-only")
            if readonly(${ $_[0] });

        $self->croakError(*$self->{ClassName} . "::read: not a scalar reference $_[0]" )
            unless ref $_[0] eq 'SCALAR' ;
        $buffer = $_[0] ;
    }
    else {
        $self->croakError(*$self->{ClassName} . "::read: buffer parameter is read-only")
            if readonly($_[0]);

        $buffer = \$_[0] ;
    }

    my $length = $_[1] ;
    my $offset = $_[2] || 0;

    # the core read will return 0 if asked for 0 bytes
    return 0 if defined $length && $length == 0 ;

    $length = $length || 0;

    $self->croakError(*$self->{ClassName} . "::read: length parameter is negative")
        if $length < 0 ;

    $$buffer = '' unless *$self->{AppendOutput}  || $offset ;

    # Short-circuit if this is a simple read, with no length
    # or offset specified.
    unless ( $length || $offset) {
        if (length *$self->{Pending}) {
            $$buffer .= *$self->{Pending} ;
            my $len = length *$self->{Pending};
            *$self->{Pending} = '' ;
            return $len ;
        }
        else {
            my $len = 0;
            $len = $self->_raw_read($buffer) 
                while ! *$self->{EndStream} && $len == 0 ;
            return $len ;
        }
    }

    # Need to jump through more hoops - either length or offset 
    # or both are specified.
    my $out_buffer = *$self->{Pending} ;

    while (! *$self->{EndStream} && length($out_buffer) < $length)
    {
        my $buf_len = $self->_raw_read(\$out_buffer);
        return $buf_len 
            if $buf_len < 0 ;
    }

    $length = length $out_buffer 
        if length($out_buffer) < $length ;

    return 0 
        if $length == 0 ;

    *$self->{Pending} = $out_buffer;
    $out_buffer = \*$self->{Pending} ;

    if ($offset) { 
        $$buffer .= "\x00" x ($offset - length($$buffer))
            if $offset > length($$buffer) ;
        #substr($$buffer, $offset) = substr($$out_buffer, 0, $length, '') ;
        substr($$buffer, $offset) = substr($$out_buffer, 0, $length) ;
        substr($$out_buffer, 0, $length) =  '' ;
    }
    else {
        #$$buffer .= substr($$out_buffer, 0, $length, '') ;
        $$buffer .= substr($$out_buffer, 0, $length) ;
        substr($$out_buffer, 0, $length) =  '' ;
    }

    return $length ;
}

sub _getline
{
    my $self = shift ;

    # Slurp Mode
    if ( ! defined $/ ) {
        my $data ;
        1 while $self->read($data) > 0 ;
        return \$data ;
    }

    # Record Mode
    if ( ref $/ eq 'SCALAR' && ${$/} =~ /^\d+$/ && ${$/} > 0) {
        my $reclen = ${$/} ;
        my $data ;
        $self->read($data, $reclen) ;
        return \$data ;
    }

    # Paragraph Mode
    if ( ! length $/ ) {
        my $paragraph ;    
        while ($self->read($paragraph) > 0 ) {
            if ($paragraph =~ s/^(.*?\n\n+)//s) {
                *$self->{Pending}  = $paragraph ;
                my $par = $1 ;
                return \$par ;
            }
        }
        return \$paragraph;
    }

    # $/ isn't empty, or a reference, so it's Line Mode.
    {
        my $line ;    
        my $offset;
        my $p = \*$self->{Pending}  ;

        if (length(*$self->{Pending}) && 
                    ($offset = index(*$self->{Pending}, $/)) >=0) {
            my $l = substr(*$self->{Pending}, 0, $offset + length $/ );
            substr(*$self->{Pending}, 0, $offset + length $/) = '';    
            return \$l;
        }

        while ($self->read($line) > 0 ) {
            my $offset = index($line, $/);
            if ($offset >= 0) {
                my $l = substr($line, 0, $offset + length $/ );
                substr($line, 0, $offset + length $/) = '';    
                $$p = $line;
                return \$l;
            }
        }

        return \$line;
    }
}

sub getline
{
    my $self = shift;
    my $current_append = *$self->{AppendOutput} ;
    *$self->{AppendOutput} = 1;
    my $lineref = $self->_getline();
    $. = ++ *$self->{LineNo} if defined $$lineref ;
    *$self->{AppendOutput} = $current_append;
    return $$lineref ;
}

sub getlines
{
    my $self = shift;
    $self->croakError(*$self->{ClassName} . 
            "::getlines: called in scalar context\n") unless wantarray;
    my($line, @lines);
    push(@lines, $line) 
        while defined($line = $self->getline);
    return @lines;
}

sub READLINE
{
    goto &getlines if wantarray;
    goto &getline;
}

sub getc
{
    my $self = shift;
    my $buf;
    return $buf if $self->read($buf, 1);
    return undef;
}

sub ungetc
{
    my $self = shift;
    *$self->{Pending} = ""  unless defined *$self->{Pending} ;    
    *$self->{Pending} = $_[0] . *$self->{Pending} ;    
}


sub trailingData
{
    my $self = shift ;

    if (defined *$self->{FH} || defined *$self->{InputEvent} ) {
        return *$self->{Prime} ;
    }
    else {
        my $buf = *$self->{Buffer} ;
        my $offset = *$self->{BufferOffset} ;
        return substr($$buf, $offset) ;
    }
}


sub eof
{
    my $self = shift ;

    return (*$self->{Closed} ||
              (!length *$self->{Pending} 
                && ( $self->smartEof() || *$self->{EndStream}))) ;
}

sub tell
{
    my $self = shift ;

    my $in ;
    if (*$self->{Plain}) {
        $in = *$self->{PlainBytesRead} ;
    }
    else {
        $in = *$self->{TotalInflatedBytesRead} ;
    }

    my $pending = length *$self->{Pending} ;

    return 0 if $pending > $in ;
    return $in - $pending ;
}

sub close
{
    # todo - what to do if close is called before the end of the gzip file
    #        do we remember any trailing data?
    my $self = shift ;

    return 1 if *$self->{Closed} ;

    untie *$self 
        if $] >= 5.008 ;

    my $status = 1 ;

    if (defined *$self->{FH}) {
        if ((! *$self->{Handle} || *$self->{AutoClose}) && ! *$self->{StdIO}) {
        #if ( *$self->{AutoClose}) {
            local $.; 
            $! = 0 ;
            $status = *$self->{FH}->close();
            return $self->saveErrorString(0, $!, $!)
                if !*$self->{InNew} && $self->saveStatus($!) != 0 ;
        }
        delete *$self->{FH} ;
        $! = 0 ;
    }
    *$self->{Closed} = 1 ;

    return 1;
}

sub DESTROY
{
    my $self = shift ;
    $self->close() ;
}

sub seek
{
    my $self     = shift ;
    my $position = shift;
    my $whence   = shift ;

    my $here = $self->tell() ;
    my $target = 0 ;


    if ($whence == SEEK_SET) {
        $target = $position ;
    }
    elsif ($whence == SEEK_CUR) {
        $target = $here + $position ;
    }
    elsif ($whence == SEEK_END) {
        $target = $position ;
        $self->croakError(*$self->{ClassName} . "::seek: SEEK_END not allowed") ;
    }
    else {
        $self->croakError(*$self->{ClassName} ."::seek: unknown value, $whence, for whence parameter");
    }

    # short circuit if seeking to current offset
    return 1 if $target == $here ;    

    # Outlaw any attempt to seek backwards
    $self->croakError( *$self->{ClassName} ."::seek: cannot seek backwards")
        if $target < $here ;

    # Walk the file to the new offset
    my $offset = $target - $here ;

    my $got;
    while (($got = $self->read(my $buffer, min($offset, *$self->{BlockSize})) ) > 0)
    {
        $offset -= $got;
        last if $offset == 0 ;
    }

    return $offset == 0 ? 1 : 0 ;
}

sub fileno
{
    my $self = shift ;
    return defined *$self->{FH} 
           ? fileno *$self->{FH} 
           : undef ;
}

sub binmode
{
    1;
#    my $self     = shift ;
#    return defined *$self->{FH} 
#            ? binmode *$self->{FH} 
#            : 1 ;
}

sub opened
{
    my $self     = shift ;
    return ! *$self->{Closed} ;
}

sub autoflush
{
    my $self     = shift ;
    return defined *$self->{FH} 
            ? *$self->{FH}->autoflush(@_) 
            : undef ;
}

sub input_line_number
{
    my $self = shift ;
    my $last = *$self->{LineNo};
    $. = *$self->{LineNo} = $_[1] if @_ ;
    return $last;
}


*BINMODE  = \&binmode;
*SEEK     = \&seek; 
*READ     = \&read;
*sysread  = \&read;
*TELL     = \&tell;
*EOF      = \&eof;

*FILENO   = \&fileno;
*CLOSE    = \&close;

sub _notAvailable
{
    my $name = shift ;
    #return sub { croak "$name Not Available" ; } ;
    return sub { croak "$name Not Available: File opened only for intput" ; } ;
}


*print    = _notAvailable('print');
*PRINT    = _notAvailable('print');
*printf   = _notAvailable('printf');
*PRINTF   = _notAvailable('printf');
*write    = _notAvailable('write');
*WRITE    = _notAvailable('write');

#*sysread  = \&read;
#*syswrite = \&_notAvailable;


package IO::Uncompress::Base ;


1 ;
__END__

=head1 NAME


IO::Uncompress::Base - Base Class for IO::Uncompress modules 


=head1 SYNOPSIS

    use IO::Uncompress::Base ;

=head1 DESCRIPTION


This module is not intended for direct use in application code. Its sole
purpose if to to be sub-classed by IO::Unompress modules.


=head1 SEE ALSO

L<Compress::Zlib>, L<IO::Compress::Gzip>, L<IO::Uncompress::Gunzip>, L<IO::Compress::Deflate>, L<IO::Uncompress::Inflate>, L<IO::Compress::RawDeflate>, L<IO::Uncompress::RawInflate>, L<IO::Compress::Bzip2>, L<IO::Uncompress::Bunzip2>, L<IO::Compress::Lzop>, L<IO::Uncompress::UnLzop>, L<IO::Compress::Lzf>, L<IO::Uncompress::UnLzf>, L<IO::Uncompress::AnyInflate>, L<IO::Uncompress::AnyUncompress>

L<Compress::Zlib::FAQ|Compress::Zlib::FAQ>

L<File::GlobMapper|File::GlobMapper>, L<Archive::Zip|Archive::Zip>,
L<Archive::Tar|Archive::Tar>,
L<IO::Zlib|IO::Zlib>


=head1 AUTHOR

This module was written by Paul Marquess, F<pmqs@cpan.org>. 


=head1 MODIFICATION HISTORY

See the Changes file.

=head1 COPYRIGHT AND LICENSE

Copyright (c) 2005-2007 Paul Marquess. All rights reserved.

This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.