#!/usr/bin/perl

# zipdetails
#
# Display info on the contents of a Zip file
#

BEGIN { pop @INC if $INC[-1] eq '.' }
use strict;
use warnings ;

use IO::File;
use Encode;

# Compression types 
use constant ZIP_CM_STORE                      => 0 ;
use constant ZIP_CM_IMPLODE                    => 6 ;
use constant ZIP_CM_DEFLATE                    => 8 ;
use constant ZIP_CM_BZIP2                      => 12 ;
use constant ZIP_CM_LZMA                       => 14 ;
use constant ZIP_CM_PPMD                       => 98 ; 

# General Purpose Flag
use constant ZIP_GP_FLAG_ENCRYPTED_MASK        => (1 << 0) ;
use constant ZIP_GP_FLAG_STREAMING_MASK        => (1 << 3) ;
use constant ZIP_GP_FLAG_PATCHED_MASK          => (1 << 5) ;
use constant ZIP_GP_FLAG_STRONG_ENCRYPTED_MASK => (1 << 6) ;
use constant ZIP_GP_FLAG_LZMA_EOS_PRESENT      => (1 << 1) ;
use constant ZIP_GP_FLAG_LANGUAGE_ENCODING     => (1 << 11) ;

# Internal File Attributes
use constant ZIP_IFA_TEXT_MASK                 => 1;

# Signatures for each of the headers
use constant ZIP_LOCAL_HDR_SIG                 => 0x04034b50;
use constant ZIP_DATA_HDR_SIG                  => 0x08074b50;
use constant ZIP_CENTRAL_HDR_SIG               => 0x02014b50;
use constant ZIP_END_CENTRAL_HDR_SIG           => 0x06054b50;
use constant ZIP64_END_CENTRAL_REC_HDR_SIG     => 0x06064b50;
use constant ZIP64_END_CENTRAL_LOC_HDR_SIG     => 0x07064b50;
use constant ZIP64_ARCHIVE_EXTRA_SIG           => 0x08064b50;
use constant ZIP64_DIGITAL_SIGNATURE_SIG       => 0x05054b50;

use constant ZIP_ARCHIVE_EXTRA_DATA_RECORD_SIG => 0x08064b50;

# Extra sizes
use constant ZIP_EXTRA_HEADER_SIZE          => 2 ;
use constant ZIP_EXTRA_MAX_SIZE             => 0xFFFF ;
use constant ZIP_EXTRA_SUBFIELD_ID_SIZE     => 2 ;
use constant ZIP_EXTRA_SUBFIELD_LEN_SIZE    => 2 ;
use constant ZIP_EXTRA_SUBFIELD_HEADER_SIZE => ZIP_EXTRA_SUBFIELD_ID_SIZE +
                                               ZIP_EXTRA_SUBFIELD_LEN_SIZE;
use constant ZIP_EXTRA_SUBFIELD_MAX_SIZE    => ZIP_EXTRA_MAX_SIZE - 
                                               ZIP_EXTRA_SUBFIELD_HEADER_SIZE;

my %ZIP_CompressionMethods =
    (
          0 => 'Stored',
          1 => 'Shrunk',
          2 => 'Reduced compression factor 1',
          3 => 'Reduced compression factor 2',
          4 => 'Reduced compression factor 3',
          5 => 'Reduced compression factor 4',
          6 => 'Imploded',
          7 => 'Reserved for Tokenizing compression algorithm',
          8 => 'Deflated',
          9 => 'Enhanced Deflating using Deflate64(tm)',
         10 => 'PKWARE Data Compression Library Imploding',
         11 => 'Reserved by PKWARE',
         12 => 'BZIP2 ',
         13 => 'Reserved by PKWARE',
         14 => 'LZMA',
         15 => 'Reserved by PKWARE',
         16 => 'Reserved by PKWARE',
         17 => 'Reserved by PKWARE',
         18 => 'File is compressed using IBM TERSE (new)',
         19 => 'IBM LZ77 z Architecture (PFS)',
         95 => 'XZ',         
         96 => 'WinZip JPEG Compression',
         97 => 'WavPack compressed data',
         98 => 'PPMd version I, Rev 1',
         99 => 'AES Encryption',
     );

my %OS_Lookup = (
    0   => "MS-DOS",
    1   => "Amiga",
    2   => "OpenVMS",
    3   => "Unix",
    4   => "VM/CMS",
    5   => "Atari ST",
    6   => "HPFS (OS/2, NT 3.x)",
    7   => "Macintosh",
    8   => "Z-System",
    9   => "CP/M",
    10  => "Windoxs NTFS or TOPS-20",
    11  => "MVS or NTFS",
    12  => "VSE or SMS/QDOS",
    13  => "Acorn RISC OS",
    14  => "VFAT",
    15  => "alternate MVS",
    16  => "BeOS",
    17  => "Tandem",
    18  => "OS/400",
    19  => "OS/X (Darwin)",
    30  => "AtheOS/Syllable",
    );


my %Lookup = (
    ZIP_LOCAL_HDR_SIG,             \&LocalHeader,
    ZIP_DATA_HDR_SIG,              \&DataHeader,
    ZIP_CENTRAL_HDR_SIG,           \&CentralHeader,
    ZIP_END_CENTRAL_HDR_SIG,       \&EndCentralHeader,
    ZIP64_END_CENTRAL_REC_HDR_SIG, \&Zip64EndCentralHeader,
    ZIP64_END_CENTRAL_LOC_HDR_SIG, \&Zip64EndCentralLocator,
    
    # TODO - Archive Encryption Headers
    #ZIP_ARCHIVE_EXTRA_DATA_RECORD_SIG
);

my %Extras = (
      0x0001,  ['ZIP64', \&decode_Zip64],
      0x0007,  ['AV Info', undef],
      0x0008,  ['Extended Language Encoding', undef],
      0x0009,  ['OS/2 extended attributes', undef],
      0x000a,  ['NTFS FileTimes', \&decode_NTFS_Filetimes],
      0x000c,  ['OpenVMS', undef],
      0x000d,  ['Unix', undef],
      0x000e,  ['Stream & Fork Descriptors', undef],
      0x000f,  ['Patch Descriptor', undef],
      0x0014,  ['PKCS#7 Store for X.509 Certificates', undef],
      0x0015,  ['X.509 Certificate ID and Signature for individual file', undef],
      0x0016,  ['X.509 Certificate ID for Central Directory', undef],
      0x0017,  ['Strong Encryption Header', undef],
      0x0018,  ['Record Management Controls', undef],
      0x0019,  ['PKCS#7 Encryption Recipient Certificate List', undef],
      

      # The Header ID mappings defined by Info-ZIP and third parties are:

      0x0065,  ['IBM S/390 attributes - uncompressed', undef],
      0x0066,  ['IBM S/390 attributes - compressed', undef],
      0x07c8,  ['Info-ZIP Macintosh (old, J. Lee)', undef],
      0x2605,  ['ZipIt Macintosh (first version)', undef],
      0x2705,  ['ZipIt Macintosh v 1.3.5 and newer (w/o full filename)', undef],
      0x2805,  ['ZipIt Macintosh v 1.3.5 and newer ', undef],
      0x334d,  ["Info-ZIP Macintosh (new, D. Haase's 'Mac3' field)", undef],
      0x4154,  ['Tandem NSK', undef],
      0x4341,  ['Acorn/SparkFS (David Pilling)', undef],
      0x4453,  ['Windows NT security descriptor', \&decode_NT_security],
      0x4690,  ['POSZIP 4690', undef],
      0x4704,  ['VM/CMS', undef],
      0x470f,  ['MVS', undef],
      0x4854,  ['Theos, old inofficial port', undef],
      0x4b46,  ['FWKCS MD5 (see below)', undef],
      0x4c41,  ['OS/2 access control list (text ACL)', undef],
      0x4d49,  ['Info-ZIP OpenVMS (obsolete)', undef],
      0x4d63,  ['Macintosh SmartZIP, by Macro Bambini', undef],
      0x4f4c,  ['Xceed original location extra field', undef],
      0x5356,  ['AOS/VS (binary ACL)', undef],
      0x5455,  ['Extended Timestamp', \&decode_UT],
      0x554e,  ['Xceed unicode extra field', \&decode_Xceed_unicode],
      0x5855,  ['Info-ZIP Unix (original; also OS/2, NT, etc.)', \&decode_UX],
      0x5a4c,  ['ZipArchive Unicode Filename', undef],
      0x5a4d,  ['ZipArchive Offsets Array', undef],
      0x6375,  ['Info-ZIP Unicode Comment', \&decode_up ],
      0x6542,  ['BeOS (BeBox, PowerMac, etc.)', undef],
      0x6854,  ['Theos', undef],
      0x7075,  ['Info-ZIP Unicode Path', \&decode_up ],
      0x756e,  ['ASi Unix', undef],
      0x7441,  ['AtheOS (AtheOS/Syllable attributes)', undef],
      0x7855,  ['Unix Extra type 2', \&decode_Ux],
      0x7875,  ['Unix Extra Type 3', \&decode_ux],
      0x9901,  ['AES Encryption', \&decode_AES],
      0xa11e,  ['Data Stream Alignment', undef],
      0xA220,  ['Open Packaging Growth Hint', undef ],
      0xCAFE,  ['Java Executable', \&decode_Java_exe],
      0xfb4a,  ['SMS/QDOS', undef],

       );

my $VERSION = "1.09" ;

my $FH;

my $ZIP64 = 0 ;
my $NIBBLES = 8;
my $LocalHeaderCount = 0;
my $CentralHeaderCount = 0;

my $START;
my $OFFSET = new U64 0;
my $TRAILING = 0 ;
my $PAYLOADLIMIT = 256; #new U64 256;
my $ZERO = new U64 0 ;

sub prOff
{
    my $offset = shift;
    my $s = offset($OFFSET);
    $OFFSET->add($offset);
    return $s;
}

sub offset
{
    my $v = shift ;

    if (ref $v eq 'U64') {
        my $hi = $v->getHigh();
        my $lo = $v->getLow();

        if ($hi)
        {
            my $hiNib = $NIBBLES - 8 ;
            sprintf("%0${hiNib}X", $hi) .
            sprintf("%08X", $lo);
        }
        else
        {
            sprintf("%0${NIBBLES}X", $lo);
        }
    }
    else {
        sprintf("%0${NIBBLES}X", $v);
    }

}

my ($OFF,  $LENGTH,  $CONTENT, $TEXT, $VALUE) ;

my $FMT1 ;
my $FMT2 ;

sub setupFormat
{
    my $wantVerbose = shift ;
    my $nibbles = shift;
    
    my $width = '@' . ('>' x ($nibbles -1));
    my $space = " " x length($width);

    my $fmt ;
    
    if ($wantVerbose) {
        
        $FMT1 = "
        format STDOUT =
$width $width ^<<<<<<<<<<<^<<<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
\$OFF,     \$LENGTH,  \$CONTENT, \$TEXT,               \$VALUE
$space $space ^<<<<<<<<<<<^<<<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<~~
                    \$CONTENT, \$TEXT,               \$VALUE
.                    
";
                    
        $FMT2 = "
        format STDOUT =
$width $width ^<<<<<<<<<<<  ^<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
\$OFF,     \$LENGTH,  \$CONTENT, \$TEXT,               \$VALUE
$space $space ^<<<<<<<<<<<  ^<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<~~
              \$CONTENT, \$TEXT,               \$VALUE
.  " ;

    }
    else {

        $FMT1 = "
        format STDOUT =
$width ^<<<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
\$OFF,      \$TEXT,               \$VALUE
$space ^<<<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<~~
                    \$TEXT,               \$VALUE
.
";

        $FMT2 = "
    format STDOUT =
$width   ^<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
\$OFF,     \$TEXT,               \$VALUE
$space   ^<<<<<<<<<<<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<~~
                    \$TEXT,               \$VALUE
.
" ;
    }

    eval "$FMT1";
    
    $| = 1;

}

sub mySpr
{    
    my $format = shift ;
    
    return "" if ! defined $format;
    return $format unless @_ ;
    return sprintf $format, @_ ;
}

sub out0
{
    my $size = shift;
    my $text = shift;
    my $format = shift;
    
    $OFF     = prOff($size);
    $LENGTH  = offset($size) ;
    $CONTENT = '...';
    $TEXT    = $text;
    $VALUE   = mySpr $format,  @_;
       
    write;

    skip($FH, $size);
}

sub xDump
{
    my $input = shift;

    $input =~ tr/\0-\37\177-\377/./;
    return $input;
}

sub hexDump
{
    my $input = shift;

    my $out = unpack('H*', $input) ;   
    $out =~ s#(..)# $1#g ;
    $out =~ s/^ //;
    $out = uc $out;  

    return $out;
}

sub out
{
    my $data = shift;
    my $text = shift;
    my $format = shift;
    
    my $size = length($data) ;

    $OFF     = prOff($size);
    $LENGTH  = offset($size) ;
    $CONTENT = hexDump($data);
    $TEXT    = $text;
    $VALUE   = mySpr $format,  @_;
       
    no warnings;

    write;
}

sub out1
{
    my $text = shift;
    my $format = shift;
      
    $OFF     = '';
    $LENGTH  = '' ;
    $CONTENT = '';
    $TEXT    = $text;    
    $VALUE   = mySpr $format,  @_; 

    write;
}

sub out2
{
    my $data = shift ;
    my $text = shift ;
    my $format = shift;
      
    my $size = length($data) ;
    $OFF     = prOff($size);
    $LENGTH  = offset($size);
    $CONTENT = hexDump($data);
    $TEXT    = $text;    
    $VALUE   = mySpr $format,  @_; 

    no warnings;
    eval "$FMT2";
    write ;
    eval "$FMT1";
}

sub Value
{
    my $letter = shift;
    my @value = @_;

    if ($letter eq 'C')
      { return Value_C(@value) }
    elsif ($letter eq 'v')
      { return Value_v(@value) }
    elsif ($letter eq 'V')
      { return Value_V(@value) }
    elsif ($letter eq 'VV')
      { return Value_VV(@value) }
}

sub outer
{
    my $name = shift ;
    my $unpack = shift ;
    my $size = shift ;
    my $cb1  = shift ;
    my $cb2  = shift ;


    myRead(my $buff, $size);    
    my (@value) = unpack $unpack, $buff;
    my $hex = Value($unpack,  @value);

    if (defined $cb1) {
        my $v ;
        if (ref $cb1 eq 'CODE') {
            $v = $cb1->(@value) ;
        }
        else {
            $v = $cb1 ;
        }

        $v = "'" . $v unless $v =~ /^'/;
        $v .= "'"  unless $v =~ /'$/;
        $hex .= " $v" ;
    }

    out $buff, $name, $hex ;

    $cb2->(@value)
        if defined $cb2 ;
    
    return $value[0];
}

sub out_C
{
    my $name = shift ;
    my $cb1  = shift ;
    my $cb2  = shift ;

    outer($name, 'C', 1, $cb1, $cb2);
}

sub out_v
{
    my $name = shift ;
    my $cb1  = shift ;
    my $cb2  = shift ;

    outer($name, 'v', 2, $cb1, $cb2);
}

sub out_V
{
    my $name = shift ;
    my $cb1  = shift ;
    my $cb2  = shift ;

    outer($name, 'V', 4, $cb1, $cb2);
}

sub out_VV
{
    my $name = shift ;
    my $cb1  = shift ;
    my $cb2  = shift ;

    outer($name, 'VV', 8, $cb1, $cb2);
}

# sub outSomeData
# {
#     my $size = shift;
#     my $message = shift;

#     my $size64 = U64::mkU64($size);

#     if ($size64->gt($ZERO)) {
#         my $size32 = $size64->getLow();
#         if ($size64->gt($PAYLOADLIMIT) ) {
#             out0 $size32, $message;
#         } else {
#             myRead(my $buffer, $size32 );
#             out $buffer, $message, xDump $buffer ;
#         }
#     }
# }

sub outSomeData
{
    my $size = shift;
    my $message = shift;

    if ($size > 0) {
        if ($size > $PAYLOADLIMIT) {
            my $before = $FH->tell();
            out0 $size, $message;
            # printf "outSomeData %X %X $size %X\n", $before, $FH->tell(), $size;
        } else {
            myRead(my $buffer, $size );
            out $buffer, $message, xDump $buffer ;
        }
    }
}

sub unpackValue_C
{
    Value_v(unpack "C", $_[0]);
}

sub Value_C
{
    sprintf "%02X", $_[0];
}


sub unpackValue_v
{
    Value_v(unpack "v", $_[0]);
}

sub Value_v
{
    sprintf "%04X", $_[0];
}

sub unpackValue_V
{
    Value_V(unpack "V", $_[0]);
}

sub Value_V
{
    my $v = defined $_[0] ? $_[0] : 0;
    sprintf "%08X", $v;
}

sub unpackValue_VV
{
    my ($lo, $hi) = unpack ("V V", $_[0]);
    Value_VV($lo, $hi);
}

sub Value_U64
{
    my $u64 = shift ;
    Value_VV($u64->getLow(), $u64->getHigh());
}

sub Value_VV
{
    my $lo = defined $_[0] ? $_[0] : 0;
    my $hi = defined $_[1] ? $_[1] : 0;

    if ($hi == 0)
    {
        sprintf "%016X", $lo;
    }
    else
    {
        sprintf("%08X", $hi) .
        sprintf "%08X", $lo;
    }
}

sub Value_VV64
{
    my $buffer = shift;

    # This needs perl 5.10
    # return unpack "Q<", $buffer;

    my ($lo, $hi) = unpack ("V V" , $buffer);
    no warnings 'uninitialized';
    return $hi * (0xFFFFFFFF+1) + $lo;
}

sub read_U64
{
    my $b ;
    myRead($b, 8);    
    my ($lo, $hi) = unpack ("V V" , $b);
    no warnings 'uninitialized';
    return ($b, new U64 $hi, $lo);
}

sub read_VV
{
    my $b ;
    myRead($b, 8);    
    my ($lo, $hi) = unpack ("V V" , $b);
    no warnings 'uninitialized';
    return ($b, $hi * (0xFFFFFFFF+1) + $lo);
}

sub read_V
{
    my $b ;
    myRead($b, 4);
    return ($b, unpack ("V", $b));
}

sub read_v
{
    my $b ;
    myRead($b, 2);
    return ($b, unpack "v", $b);
}


sub read_C
{
    my $b ;
    myRead($b, 1);
    return ($b, unpack "C", $b);
}


my $opt_verbose = 0;
while (@ARGV && $ARGV[0] =~ /^-/)
{
    my $opt = shift;
    
    if ($opt =~ /^-h/i)
    {
        Usage();
        exit;
    }
    elsif ($opt =~ /^-v/i)
    {
        $opt_verbose = 1;
    }
    else {
        Usage();
    }
}

Usage() unless @ARGV == 1;

my $filename = shift @ARGV;

die "$filename does not exist\n"
    unless -e $filename ;

die "$filename not a standard file\n"
    unless -f $filename ;

$FH = new IO::File "<$filename"
    or die "Cannot open $filename: $!\n";


my $FILELEN = -s $filename ;    
$TRAILING = -s $filename ;    
$NIBBLES = U64::nibbles(-s $filename) ; 
#$NIBBLES = int ($NIBBLES / 4) + ( ($NIBBLES % 4) ? 1 : 0 );
#$NIBBLES = 4 * $NIBBLES;
# Minimum of 4 nibbles
$NIBBLES = 4 if $NIBBLES < 4 ;

die "$filename too short to be a zip file\n"
    if $FILELEN <  22 ;

setupFormat($opt_verbose, $NIBBLES);

if(0)
{
    # Sanity check that this is a Zip file
    my ($buffer, $signature) = read_V();

    warn "$filename doesn't look like a zip file\n"
        if $signature != ZIP_LOCAL_HDR_SIG ;
    $FH->seek(0, SEEK_SET) ;
}


our ($CdExists, @CentralDirectory) = scanCentralDirectory($FH);

die "No Central Directory records found\n"
    if ! $CdExists ;

$OFFSET->reset();
$FH->seek(0, SEEK_SET) ;

outSomeData($START, "PREFIX DATA")
    if defined $START && $START > 0 ;

while (1)
{
    last if $FH->eof();

    my $here = $FH->tell();
    if ($here >= $TRAILING) {
        print "\n" ;
        outSomeData($FILELEN - $TRAILING, "TRAILING DATA");
        last;

    }

    my ($buffer, $signature) = read_V();

    my $handler = $Lookup{$signature};

    if (!defined $handler)
    {
        if (@CentralDirectory) {
            # Should be at offset that central directory says
            my $locOffset = $CentralDirectory[0][0];
            my $delta = $locOffset - $here ;
            
            if ($here  < $locOffset ) {
                for (0 .. 3) {
                    $FH->ungetc(ord(substr($buffer, $_, 1)))
                }
                outSomeData($delta, "UNEXPECTED PADDING");
                next;
            }
        }

        printf "\n\nUnexpecded END at offset %08X, value %s\n", $here, Value_V($signature);
        last;    
    }

    $ZIP64 = 0 if $signature != ZIP_DATA_HDR_SIG ;
    $handler->($signature, $buffer);
}

print "Done\n";

exit ;

sub compressionMethod
{
    my $id = shift ;
    Value_v($id) . " '" . ($ZIP_CompressionMethods{$id} || "Unknown Method") . "'" ;
}

sub LocalHeader
{
    my $signature = shift ;  
    my $data = shift ;  
        
    print "\n";
    ++ $LocalHeaderCount;
    out $data, "LOCAL HEADER #" . sprintf("%X", $LocalHeaderCount) , Value_V($signature);

    my $buffer;

    my ($loc, $CDcompressedLength) = @{ shift @CentralDirectory };
    # print "LocalHeader loc $loc CDL $CDcompressedLength\n";
    # TODO - add test to check that the loc from central header matches

    out_C  "Extract Zip Spec", \&decodeZipVer;
    out_C  "Extract OS", \&decodeOS;

    my ($bgp, $gpFlag) = read_v();
    my ($bcm, $compressedMethod) = read_v();

    out $bgp, "General Purpose Flag", Value_v($gpFlag) ;
    GeneralPurposeBits($compressedMethod, $gpFlag);    

    out $bcm, "Compression Method",   compressionMethod($compressedMethod) ;

    out_V "Last Mod Time", sub { scalar getTime(_dosToUnixTime($_[0])) };

    my $crc                = out_V "CRC";
    my $compressedLength   = out_V "Compressed Length";
    my $uncompressedLength = out_V "Uncompressed Length";
    my $filenameLength     = out_v "Filename Length";
    my $extraLength        = out_v "Extra Length";

    my $filename ;
    myRead($filename, $filenameLength);
    out $filename, "Filename",  "'". $filename . "'";

    my $cl64 = new U64 $compressedLength ;
    my %ExtraContext = ();
    if ($extraLength)
    {
        my @z64 = ($uncompressedLength, $compressedLength, 1, 1);
        $ExtraContext{Zip64} = \@z64 ;
        $ExtraContext{InCentralDir} = 0;
        walkExtra($extraLength, \%ExtraContext);
    }

    my $size = 0;
    $size = printAes(\%ExtraContext)
        if $compressedMethod == 99 ;

    $size += printLzmaProperties()
        if $compressedMethod == ZIP_CM_LZMA ;

    # $CDcompressedLength->subtract($size)
        # if $size ;
    $CDcompressedLength -= $size;
        
    # if ($CDcompressedLength->getHigh() || $CDcompressedLength->getLow()) {
    if ($CDcompressedLength) {
        outSomeData($CDcompressedLength, "PAYLOAD") ;
    }

    if ($compressedMethod == 99) {
        my $auth ;
        myRead($auth, 10);
        out $auth, "AES Auth",  hexDump($auth);
    }
}


sub CentralHeader
{
    my $signature = shift ;
    my $data = shift ;  
        
    ++ $CentralHeaderCount;
    print "\n";
    out $data, "CENTRAL HEADER #" . sprintf("%X", $CentralHeaderCount) . "", Value_V($signature);
    my $buffer;

    out_C "Created Zip Spec", \&decodeZipVer;
    out_C "Created OS", \&decodeOS;
    out_C  "Extract Zip Spec", \&decodeZipVer;
    out_C  "Extract OS", \&decodeOS;

    my ($bgp, $gpFlag) = read_v();
    my ($bcm, $compressedMethod) = read_v();

    out $bgp, "General Purpose Flag", Value_v($gpFlag) ;
    GeneralPurposeBits($compressedMethod, $gpFlag);    

    out $bcm, "Compression Method", compressionMethod($compressedMethod) ;

    out_V "Last Mod Time", sub { scalar getTime(_dosToUnixTime($_[0])) };

    my $crc                = out_V "CRC";
    my $compressedLength   = out_V "Compressed Length";
    my $uncompressedLength = out_V "Uncompressed Length";
    my $filenameLength     = out_v "Filename Length";
    my $extraLength        = out_v "Extra Length";
    my $comment_length     = out_v "Comment Length";
    my $disk_start         = out_v "Disk Start";
    my $int_file_attrib    = out_v "Int File Attributes";

    out1 "[Bit 0]",  $int_file_attrib & 1 ? "1 Text Data" : "0 'Binary Data'";

    my $ext_file_attrib    = out_V "Ext File Attributes";
    out1 "[Bit 0]",  "Read-Only" 
        if $ext_file_attrib & 0x01 ;
    out1 "[Bit 1]",  "Hidden" 
        if $ext_file_attrib & 0x02 ;
    out1 "[Bit 2]",  "System" 
        if $ext_file_attrib & 0x04 ;
    out1 "[Bit 3]",  "Label" 
        if $ext_file_attrib & 0x08 ;
    out1 "[Bit 4]",  "Directory" 
        if $ext_file_attrib & 0x10 ;
    out1 "[Bit 5]",  "Archive" 
        if $ext_file_attrib & 0x20 ;

    my $lcl_hdr_offset     = out_V "Local Header Offset";

    my $filename ;
    myRead($filename, $filenameLength);
    out $filename, "Filename",  "'". $filename . "'";

    my %ExtraContext = ();
    if ($extraLength)
    {
        my @z64 = ($uncompressedLength, $compressedLength, $lcl_hdr_offset, $disk_start);
        $ExtraContext{Zip64} = \@z64 ;
        $ExtraContext{InCentralDir} = 1;
        walkExtra($extraLength, \%ExtraContext);        
    }

    if ($comment_length)
    {
        my $comment ;
        myRead($comment, $comment_length);
        out $comment, "Comment",  "'". $comment . "'";
    }
}

sub decodeZipVer
{
    my $ver = shift ;
    
    my $sHi = int($ver /10) ;
    my $sLo = $ver % 10 ;
    
    #out1 "Zip Spec", "$sHi.$sLo";       
    "$sHi.$sLo";       
}

sub decodeOS
{
    my $ver = shift ;
    
    $OS_Lookup{$ver} || "Unknown" ;
}

sub Zip64EndCentralHeader
{
    my $signature = shift ;    
    my $data = shift ;  

    print "\n";
    out $data, "ZIP64 END CENTRAL DIR RECORD", Value_V($signature);

    my $buff;
    myRead($buff, 8);

    out $buff, "Size of record",       unpackValue_VV($buff);    

    my $size  = Value_VV64($buff);

    out_C  "Created Zip Spec", \&decodeZipVer;
    out_C  "Created OS", \&decodeOS;
    out_C  "Extract Zip Spec", \&decodeZipVer;
    out_C  "Extract OS", \&decodeOS;
    out_V  "Number of this disk";
    out_V  "Central Dir Disk no";
    out_VV "Entries in this disk";
    out_VV "Total Entries";
    out_VV "Size of Central Dir";
    out_VV "Offset to Central dir";

    # TODO - 
    die "Unsupported Size ($size) in Zip64EndCentralHeader\n" 
        if $size !=  44;
}


sub Zip64EndCentralLocator
{
    my $signature = shift ;
    my $data = shift ;  
        
    print "\n";
    out $data, "ZIP64 END CENTRAL DIR LOCATOR", Value_V($signature);
    
    out_V  "Central Dir Disk no";
    out_VV "Offset to Central dir";
    out_V  "Total no of Disks";    
}

sub EndCentralHeader
{
    my $signature = shift ;  
    my $data = shift ;  
        
    print "\n";
    out $data, "END CENTRAL HEADER", Value_V($signature);

    out_v "Number of this disk";
    out_v "Central Dir Disk no";
    out_v "Entries in this disk";
    out_v "Total Entries";
    out_V "Size of Central Dir";
    out_V "Offset to Central Dir";
    my $comment_length = out_v "Comment Length";

    if ($comment_length)
    {
        my $comment ;        
        myRead($comment, $comment_length);
        out $comment, "Comment", "'$comment'";
    }    
}

sub DataHeader
{
    my $signature = shift ;  
    my $data = shift ;  
        
    print "\n";
    out $data, "STREAMING DATA HEADER", Value_V($signature);
    
    out_V "CRC";
    
    if ($ZIP64)
    {
        out_VV "Compressed Length" ;
        out_VV "Uncompressed Length" ;        
    }
    else
    {
        out_V "Compressed Length" ;
        out_V "Uncompressed Length" ;  
    }
}


sub GeneralPurposeBits
{
    my $method = shift;
    my $gp = shift;

    out1 "[Bit  0]", "1 'Encryption'" if $gp & ZIP_GP_FLAG_ENCRYPTED_MASK;   
    
    my %lookup = (
        0 =>    "Normal Compression",
        1 =>    "Maximum Compression",
        2 =>    "Fast Compression",
        3 =>    "Super Fast Compression");


    if ($method == ZIP_CM_DEFLATE)
    {
        my $mid = $gp & 0x03;
        
        out1 "[Bits 1-2]", "$mid '$lookup{$mid}'";        
    }

    if ($method == ZIP_CM_LZMA)
    {
        if ($gp & ZIP_GP_FLAG_LZMA_EOS_PRESENT) {
            out1 "[Bit 1]", "1 'LZMA EOS Marker Present'" ;
        }
        else {
            out1 "[Bit 1]", "0 'LZMA EOS Marker Not Present'" ;
        }
    }
    
    if ($method == ZIP_CM_IMPLODE) # Imploding
    {
        out1 "[Bit 1]", ($gp & 1 ? "1 '8k" : "0 '4k") . " Sliding Dictionary'" ;
        out1 "[Bit 2]", ($gp & 2 ? "1 '3" : "0 '2"  ) . " Shannon-Fano
        Trees'" ;
    }    
    
    out1 "[Bit  3]", "1 'Streamed'"           if $gp & ZIP_GP_FLAG_STREAMING_MASK;
    out1 "[Bit  4]", "1 'Enhanced Deflating'" if $gp & 1 << 4;
    out1 "[Bit  5]", "1 'Compressed Patched'" if $gp & 1 << 5 ;
    out1 "[Bit  6]", "1 'Strong Encryption'"  if $gp & ZIP_GP_FLAG_STRONG_ENCRYPTED_MASK;
    out1 "[Bit 11]", "1 'Language Encoding'"  if $gp & ZIP_GP_FLAG_LANGUAGE_ENCODING;  
    out1 "[Bit 12]", "1 'Pkware Enhanced Compression'"  if $gp & 1 <<12 ; 
    out1 "[Bit 13]", "1 'Encrypted Central Dir'"  if $gp & 1 <<13 ; 
    
    return ();    
}


sub seekSet
{
    my $fh = $_[0] ;
    my $size = $_[1];

    use Fcntl qw(SEEK_SET);
    if (ref $size eq 'U64') {
        seek($fh, $size->get64bit(), SEEK_SET);
    }
    else {
        seek($fh, $size, SEEK_SET);
    }
    
}

sub skip
{
    my $fh = $_[0] ;
    my $size = $_[1];

    use Fcntl qw(SEEK_CUR);
    if (ref $size eq 'U64') {
        seek($fh, $size->get64bit(), SEEK_CUR);
    }
    else {
        seek($fh, $size, SEEK_CUR);
    }
    
}


sub myRead
{
    my $got = \$_[0] ;
    my $size = $_[1];

    my $wantSize = $size;
    $$got = '';

    if ($size == 0)
    {
        return ;
    }

    if ($size > 0)
    {
        my $buff ;
        my $status = $FH->read($buff, $size);
        return $status
            if $status < 0;
        $$got .= $buff ;
    }

    my $len = length $$got;
    die "Truncated file (got $len, wanted $wantSize): $!\n"
        if length $$got != $wantSize;
}




sub walkExtra
{
    my $XLEN = shift;
    my $context = shift; 

    my $buff ;
    my $offset = 0 ;
    
    my $id;
    my $subLen;
    my $payload ;
    
    my $count = 0 ;
    
    if ($XLEN < ZIP_EXTRA_SUBFIELD_ID_SIZE + ZIP_EXTRA_SUBFIELD_LEN_SIZE)
    {
        # Android zipalign is prime candidate for this non-standard extra field.
        myRead($payload, $XLEN); 
        my $data = hexDump($payload);
        
        out $payload, "Malformed Extra Data", $data;

        return undef;
    }

    while ($offset < $XLEN) {

        ++ $count;
        
        return undef
            if $offset + ZIP_EXTRA_SUBFIELD_HEADER_SIZE  > $XLEN ;

        myRead($id, ZIP_EXTRA_SUBFIELD_ID_SIZE); 
        $offset += ZIP_EXTRA_SUBFIELD_ID_SIZE;
        my $lookID = unpack "v", $id ;
        my ($who, $decoder) =  @{ defined $Extras{$lookID} ? $Extras{$lookID} : ['', undef] };
        #my ($who, $decoder) =  @{ $Extras{unpack "v", $id} || ['', undef] };
        
        $who = "$id: $who"
            if $id =~ /\w\w/ ;

        $who = "'$who'";    
        out $id, "Extra ID #" . Value_v($count), unpackValue_v($id) . " $who" ;
        
        myRead($buff, ZIP_EXTRA_SUBFIELD_LEN_SIZE); 
        $offset += ZIP_EXTRA_SUBFIELD_LEN_SIZE;        
        
        $subLen =  unpack("v", $buff);
        out2 $buff, "Length", Value_v($subLen) ;

        return undef
            if $offset + $subLen > $XLEN ;

        if (! defined $decoder)
        {
            myRead($payload, $subLen);
            my $data = hexDump($payload);
        
            out2 $payload, "Extra Payload", $data;
        }
        else
        {
            $decoder->($subLen, $context) ;
        }
               
        $offset += $subLen ;
    }
        
    return undef ;
}


sub full32 
{
    return $_[0] == 0xFFFFFFFF ;
}

sub decode_Zip64
{
    my $len = shift;
    my $context = shift;
    
    my $z64Data = $context->{Zip64};    

    $ZIP64 = 1;

    if (full32 $z64Data->[0] ) {
        out_VV "  Uncompressed Size";
    }

    if (full32 $z64Data->[1] ) {
        out_VV "  Compressed Size";
    }

    if (full32 $z64Data->[2] ) {
        out_VV "  Offset to Central Dir";        
    }

    if ($z64Data->[3] == 0xFFFF ) {
        out_V "  Disk Number";        
    }
}

sub Ntfs2Unix
{
    my $v = shift;
    my $u64 = shift;

    # NTFS offset is 19DB1DED53E8000

    my $hex = Value_U64($u64) ;
    my $NTFS_OFFSET = new U64 0x19DB1DE, 0xD53E8000 ;
    $u64->subtract($NTFS_OFFSET);
    my $elapse = $u64->get64bit();
    my $ns = ($elapse % 10000000) * 100;
    $elapse = int ($elapse/10000000);
    return "$hex '" . localtime($elapse) . 
           " " . sprintf("%0dns'", $ns);
}

sub decode_NTFS_Filetimes
{
    my $len = shift;
    my $context = shift;

    out_V "  Reserved";
    out_v "  Tag1";
    out_v "  Size1" ;
    
    my ($m, $s1) = read_U64;
    out $m, "  Mtime", Ntfs2Unix($m, $s1);

    my ($c, $s2) = read_U64;
    out $c, "  Ctime", Ntfs2Unix($m, $s2);

    my ($a, $s3) = read_U64;
    out $m, "  Atime", Ntfs2Unix($m, $s3);
}

sub getTime
{
    my $time = shift ;

    return "'" . localtime($time) . "'" ;
}

sub decode_UT
{
    my $len = shift;
    my $context = shift;
        
    my ($data, $flags) = read_C();

    my $f = Value_C $flags;
    $f .= " mod"    if $flags & 1;
    $f .= " access" if $flags & 2;
    $f .= " change" if $flags & 4;
    
    out $data, "  Flags", "'$f'";
    
    -- $len;
    
    if ($flags & 1)
    {
        my ($data, $time) = read_V();

        out2 $data, "Mod Time",    Value_V($time) . " " . getTime($time) ;
        
        $len -= 4 ;
    }


      if ($flags & 2 && $len > 0 )
      {
          my ($data, $time) = read_V();
  
          out2 $data, "Access Time",    Value_V($time) . " " . getTime($time) ;
          $len -= 4 ;
      }
  
      if ($flags & 4 && $len > 0)
      {
          my ($data, $time) = read_V();
  
          out2 $data, "Change Time",    Value_V($time) . " " . getTime($time) ;
      }
}



sub decode_AES
{
    my $len = shift;
    my $context = shift;

    return if $len == 0 ;
    
    my %lookup = ( 1 => "AE-1", 2 => "AE-2");
    out_v "  Vendor Version", sub {  $lookup{$_[0]} || "Unknown"  } ;
    
    my $id ; 
    myRead($id, 2);
    out $id, "  Vendor ID", unpackValue_v($id) . " '$id'";
    
    my %strengths = (1 => "128-bit encryption key",
                     2 => "192-bit encryption key",
                     3 => "256-bit encryption key",
                    );
    
    my $strength = out_C "  Encryption Strength", sub {$strengths{$_[0]} || "Unknown" } ; 

    my ($bmethod, $method) = read_v();
    out $bmethod, "  Compression Method", compressionMethod($method) ;

    $context->{AesStrength} = $strength ;     
}

sub decode_UX
{
    my $len = shift;
    my $context = shift;
    my $inCentralHdr = $context->{InCentralDir} ;

    return if $len == 0 ;    

    my ($data, $time) = read_V();
    out2 $data, "Access Time",    Value_V($time) . " " . getTime($time) ;

    ($data, $time) = read_V();
    out2 $data, "Mod Time",    Value_V($time) . " " . getTime($time) ;

    if (! $inCentralHdr ) {
        out_v "  UID" ;
        out_v "  GID";    
    }
}

sub decode_Ux
{
    my $len = shift;
    my $context = shift;

    return if $len == 0 ;    
    out_v "  UID" ;
    out_v "  GID";    
}

sub decodeLitteEndian
{
    my $value = shift ;

    if (length $value == 4)
    {
        return Value_V unpack ("V", $value)
    }
    else {
        # TODO - fix this
        die "unsupported\n";
    }

    my $got = 0 ;
    my $shift = 0;

    #hexDump 
    #reverse
    #my @a =unpack "C*", $value;
    #@a = reverse @a;
    #hexDump(@a);

    for (reverse unpack "C*", $value)
    {
        $got = ($got << 8) + $_ ;
    }
    
    return $got ;
}

sub decode_ux
{
    my $len = shift;
    my $context = shift;

    return if $len == 0 ;    
    out_C "  Version" ;
    my $uidSize = out_C "  UID Size";    
    myRead(my $data, $uidSize);
    out2 $data, "UID", decodeLitteEndian($data);

    my $gidSize = out_C "  GID Size";    
    myRead($data, $gidSize);
    out2 $data, "GID", decodeLitteEndian($data);
    
}

sub decode_Java_exe
{
    my $len = shift;
    my $context = shift;

}

sub decode_up
{
    my $len = shift;
    my $context = shift;

    
    out_C "  Version";
    out_V "  NameCRC32";
    
    myRead(my $data, $len - 5);
    
    out $data, "  UnicodeName", $data;     
}

sub decode_Xceed_unicode
{
    my $len = shift;
    my $context = shift;

    my $data ;
    
    # guess the fields used for this one
    myRead($data, 4);
    out $data, "  ID", $data;     

    out_v "  Length";
    out_v "  Null";
    
    myRead($data, $len - 8);
    
    out $data, "  UTF16LE Name", decode("UTF16LE", $data);     
}


sub decode_NT_security
{
    my $len = shift;
    my $context = shift;
    my $inCentralHdr = $context->{InCentralDir} ;
    
    out_V "  Uncompressed Size" ;
    
    if (! $inCentralHdr) {
  
        out_C "  Version" ;
     
        out_v "  Type";  
        
        out_V "  NameCRC32" ;
        
        my $plen = $len - 4 - 1 - 2 - 4;        
        myRead(my $payload, $plen);
        out $plen, "  Extra Payload", hexDump($payload);
    }
}

sub printAes
{
    my $context = shift ;

    my %saltSize = (
                        1 => 8,
                        2 => 12,
                        3 => 16,
                    );

    myRead(my $salt, $saltSize{$context->{AesStrength} });
    out $salt, "AES Salt", hexDump($salt);
    myRead(my $pwv, 2);
    out $pwv, "AES Pwd Ver", hexDump($pwv);  

    return  $saltSize{$context->{AesStrength}} + 2 + 10;
}

sub printLzmaProperties
{
    my $len = 0;

    my $b1;
    my $b2;
    my $buffer;

    myRead($b1, 2);
    my ($verHi, $verLow) = unpack ("CC", $b1);

    out $b1, "LZMA Version", sprintf("%02X%02X", $verHi, $verLow) . " '$verHi.$verLow'";
    my $LzmaPropertiesSize = out_v "LZMA Properties Size";
    $len += 4;

    my $LzmaInfo = out_C "LZMA Info",  sub { $_[0] == 93 ? "(Default)" : ""};

    my $PosStateBits = 0;
    my $LiteralPosStateBits = 0;
    my $LiteralContextBits = 0;
    $PosStateBits = int($LzmaInfo / (9 * 5));
	$LzmaInfo -= $PosStateBits * 9 * 5;
	$LiteralPosStateBits = int($LzmaInfo / 9);
	$LiteralContextBits = $LzmaInfo - $LiteralPosStateBits * 9;

    out1 "  PosStateBits",        $PosStateBits;
    out1 "  LiteralPosStateBits", $LiteralPosStateBits;
    out1 "  LiteralContextBits",  $LiteralContextBits;
    
    out_V "LZMA Dictionary Size";

    # TODO - assumption that this is 5
    $len += $LzmaPropertiesSize;

    skip($FH, $LzmaPropertiesSize - 5)
        if  $LzmaPropertiesSize != 5 ;

    return $len;
}

sub scanCentralDirectory
{
    my $fh = shift;

    my $here = $fh->tell();

    # Use cases
    # 1 32-bit CD
    # 2 64-bit CD

    my @CD = ();
    my $offset = findCentralDirectoryOffset($fh);

    return ()
        if ! defined $offset;

    $fh->seek($offset, SEEK_SET) ;

    # Now walk the Central Directory Records
    my $buffer ;
    while ($fh->read($buffer, 46) == 46  && 
           unpack("V", $buffer) == ZIP_CENTRAL_HDR_SIG) {

        my $compressedLength   = unpack("V", substr($buffer, 20, 4));
        my $uncompressedLength = unpack("V", substr($buffer, 24, 4));
        my $filename_length    = unpack("v", substr($buffer, 28, 2));
        my $extra_length       = unpack("v", substr($buffer, 30, 2));
        my $comment_length     = unpack("v", substr($buffer, 32, 2));
        my $locHeaderOffset    = unpack("V", substr($buffer, 42, 4));

        $START = $locHeaderOffset
            if ! defined $START;

        skip($fh, $filename_length ) ;

        if ($extra_length)
        {
            $fh->read(my $extraField, $extra_length) ;
            # $self->smartReadExact(\$extraField, $extra_length);               

            # Check for Zip64
            # my $zip64Extended = findID("\x01\x00", $extraField);
            my $zip64Extended = findID(0x0001, $extraField);
            
            if ($zip64Extended)
            {
                if ($uncompressedLength == 0xFFFFFFFF)
                {
                    $uncompressedLength = Value_VV64  substr($zip64Extended, 0, 8, "");
                    # $uncompressedLength = unpack "Q<", substr($zip64Extended, 0, 8, "");
                }
                if ($compressedLength == 0xFFFFFFFF)
                {
                    $compressedLength = Value_VV64  substr($zip64Extended, 0, 8, "");
                    # $compressedLength = unpack "Q<", substr($zip64Extended, 0, 8, "");
                } 
                if ($locHeaderOffset == 0xFFFFFFFF)
                {
                    $locHeaderOffset = Value_VV64  substr($zip64Extended, 0, 8, "");
                    # $locHeaderOffset = unpack "Q<", substr($zip64Extended, 0, 8, "");
                }                         
            }                
        }        

        my $got = [$locHeaderOffset, $compressedLength] ;

        # my $v64 = new U64 $compressedLength ;
        # my $loc64 = new U64 $locHeaderOffset ;
        # my $got = [$loc64, $v64] ;

        # if (full32 $compressedLength || full32  $locHeaderOffset) {
        #     $fh->read($buffer, $extra_length) ;
        #     # TODO - fix this
        #     die "xxx $offset $comment_length $filename_length $extra_length" . length($buffer) 
        #         if length($buffer) != $extra_length;
        #     $got = get64Extra($buffer, full32($uncompressedLength),
        #                          $v64,
        #                          $loc64);

        #     # If not Zip64 extra field, assume size is 0xFFFFFFFF
        #     #$v64 = $got if defined $got;
        # }
        # else {
        #     skip($fh, $extra_length) ;
        # }

        skip($fh, $comment_length ) ;
            
        push @CD, $got ;
    }

    $fh->seek($here, SEEK_SET) ;

    # @CD = sort { $a->[0]->cmp($b->[0]) } @CD ;
    @CD = sort { $a->[0] <=> $b->[0] } @CD ;
    return (1, @CD);
}


sub offsetFromZip64
{
    my $fh = shift ;
    my $here = shift;

    $fh->seek($here - 20, SEEK_SET) 
    # TODO - fix this
        or die "xx $!" ;

    my $buffer;
    my $got = 0;
    ($got = $fh->read($buffer, 20)) == 20 
    # TODO - fix this
        or die "xxx $here $got $!" ;

    if ( unpack("V", $buffer) == ZIP64_END_CENTRAL_LOC_HDR_SIG ) {
        my $cd64 = Value_VV64 substr($buffer,  8, 8);
       
        $fh->seek($cd64, SEEK_SET) ;

        $fh->read($buffer, 4) == 4
        # TODO - fix this
            or die "xxx" ;

        if ( unpack("V", $buffer) == ZIP64_END_CENTRAL_REC_HDR_SIG ) {

            $fh->read($buffer, 8) ==  8
            # TODO - fix this
                or die "xxx" ;
            my $size  = Value_VV64($buffer);
            $fh->read($buffer, $size) ==  $size
            # TODO - fix this
                or die "xxx" ;

            my $cd64 =  Value_VV64 substr($buffer,  36, 8);

            return $cd64 ;
        }
        
        # TODO - fix this
        die "zzz";
    }

    # TODO - fix this
    die "zzz";
}

use constant Pack_ZIP_END_CENTRAL_HDR_SIG => pack("V", ZIP_END_CENTRAL_HDR_SIG);

sub findCentralDirectoryOffset
{
    my $fh = shift ;

    # Most common use-case is where there is no comment, so
    # know exactly where the end of central directory record
    # should be.

    $fh->seek(-22, SEEK_END) ;
    my $here = $fh->tell();

    my $buffer;
    $fh->read($buffer, 22) == 22 
    # TODO - fix this
        or die "xxx" ;

    my $zip64 = 0;                             
    my $centralDirOffset ;
    if ( unpack("V", $buffer) == ZIP_END_CENTRAL_HDR_SIG ) {
        $centralDirOffset = unpack("V", substr($buffer, 16,  4));
    }
    else {
        $fh->seek(0, SEEK_END) ;

        my $fileLen = $fh->tell();
        my $want = 0 ;

        while(1) {
            $want += 1024 * 32;
            my $seekTo = $fileLen - $want;
            if ($seekTo < 0 ) {
                $seekTo = 0;
                $want = $fileLen ;
            }
            $fh->seek( $seekTo, SEEK_SET) 
            # TODO - fix this
                or die "xxx $!" ;
            my $got;
            ($got = $fh->read($buffer, $want)) == $want
            # TODO - fix this
                or die "xxx $got  $!" ;
            my $pos = rindex( $buffer, Pack_ZIP_END_CENTRAL_HDR_SIG);

            if ($pos >= 0 && $want - $pos > 22) {
                $here = $seekTo + $pos ;
                $centralDirOffset = unpack("V", substr($buffer, $pos + 16,  4));
                my $commentLength = unpack("V", substr($buffer, $pos + 20,  2));
                $commentLength = 0 if ! defined $commentLength ;

                my $expectedEof = $fileLen - $want + $pos + 22 + $commentLength  ;
                # check for trailing data after end of zip
                if ($expectedEof < $fileLen ) {
                    $TRAILING = $expectedEof ;
                }
                last ;
            }

            return undef
                if $want == $fileLen;
        }
    }

    $centralDirOffset = offsetFromZip64($fh, $here)
        if full32 $centralDirOffset ;

    return $centralDirOffset ;
}

sub findID
{
    my $id_want = shift ;
    my $data    = shift;

    my $XLEN = length $data ;

    my $offset = 0 ;
    while ($offset < $XLEN) {

        return undef
            if $offset + ZIP_EXTRA_SUBFIELD_HEADER_SIZE  > $XLEN ;

        my $id = substr($data, $offset, ZIP_EXTRA_SUBFIELD_ID_SIZE);    
        $id = unpack("v", $id);
        $offset += ZIP_EXTRA_SUBFIELD_ID_SIZE;

        my $subLen =  unpack("v", substr($data, $offset,
                                            ZIP_EXTRA_SUBFIELD_LEN_SIZE));
        $offset += ZIP_EXTRA_SUBFIELD_LEN_SIZE ;

        return undef
            if $offset + $subLen > $XLEN ;

        return substr($data, $offset, $subLen)
            if $id eq $id_want ;

        $offset += $subLen ;
    }
        
    return undef ;
}


sub _dosToUnixTime
{
    my $dt = shift;

    my $year = ( ( $dt >> 25 ) & 0x7f ) + 80;
    my $mon  = ( ( $dt >> 21 ) & 0x0f ) - 1;
    my $mday = ( ( $dt >> 16 ) & 0x1f );

    my $hour = ( ( $dt >> 11 ) & 0x1f );
    my $min  = ( ( $dt >> 5  ) & 0x3f );
    my $sec  = ( ( $dt << 1  ) & 0x3e );


    use POSIX 'mktime';

    my $time_t = mktime( $sec, $min, $hour, $mday, $mon, $year, 0, 0, -1 );
    return 0 if ! defined $time_t;
    return $time_t;
}


{
    package U64;

    use constant MAX32 => 0xFFFFFFFF ;
    use constant HI_1 => MAX32 + 1 ;
    use constant LOW   => 0 ;
    use constant HIGH  => 1;

    sub new
    {
        my $class = shift ;

        my $high = 0 ;
        my $low  = 0 ;

        if (@_ == 2) {
            $high = shift ;
            $low  = shift ;
        }
        elsif (@_ == 1) {
            $low  = shift ;
        }

        bless [$low, $high], $class;
    }

    sub newUnpack_V64
    {
        my $string = shift;

        my ($low, $hi) = unpack "V V", $string ;
        bless [ $low, $hi ], "U64";
    }

    sub newUnpack_V32
    {
        my $string = shift;

        my $low = unpack "V", $string ;
        bless [ $low, 0 ], "U64";
    }

    sub reset
    {
        my $self = shift;
        $self->[HIGH] = $self->[LOW] = 0;
    }

    sub clone
    {
        my $self = shift;
        bless [ @$self ], ref $self ;
    }

    sub mkU64
    {
        my $value = shift;

        return $value
            if ref $value eq 'U64';

        bless [  $value, 0 ], "U64" ;
    }

    sub getHigh
    {
        my $self = shift;
        return $self->[HIGH];
    }

    sub getLow
    {
        my $self = shift;
        return $self->[LOW];
    }

    sub get32bit
    {
        my $self = shift;
        return $self->[LOW];
    }

    sub get64bit
    {
        my $self = shift;
        # Not using << here because the result will still be
        # a 32-bit value on systems where int size is 32-bits
        return $self->[HIGH] * HI_1 + $self->[LOW];
    }

    sub add
    {
        my $self = shift;
        my $value = shift;

        if (ref $value eq 'U64') {
            $self->[HIGH] += $value->[HIGH] ;
            $value = $value->[LOW];
        }
         
        my $available = MAX32 - $self->[LOW] ;

        if ($value > $available) {
           ++ $self->[HIGH] ;
           $self->[LOW] = $value - $available - 1;
        }
        else {
           $self->[LOW] += $value ;
        }

    }

    sub subtract
    {
        my $self = shift;
        my $value = shift;

        if (ref $value eq 'U64') {

            if ($value->[HIGH]) {
                die "unsupport subtract option"
                    if $self->[HIGH] == 0 ||
                       $value->[HIGH] > $self->[HIGH] ;

               $self->[HIGH] -= $value->[HIGH] ;
            }

            $value = $value->[LOW] ;
        }

        if ($value > $self->[LOW]) {
           -- $self->[HIGH] ;
           $self->[LOW] = MAX32 - $value + $self->[LOW] + 1;
        }
        else {
           $self->[LOW] -= $value;
        }
    }

    sub rshift
    {
        my $self = shift;
        my $count = shift;

        for (1 .. $count)
        {
            $self->[LOW] >>= 1;
            $self->[LOW] |= 0x80000000
                if $self->[HIGH] & 1 ; 
            $self->[HIGH] >>= 1;
        }
    }

    sub is64bit
    {
        my $self = shift;
        return $self->[HIGH] > 0 ;
    }

    sub getPacked_V64
    {
        my $self = shift;

        return pack "V V", @$self ;
    }

    sub getPacked_V32
    {
        my $self = shift;

        return pack "V", $self->[LOW] ;
    }

    sub pack_V64
    {
        my $low  = shift;

        return pack "V V", $low, 0;
    }

    sub max32
    {
        my $self = shift;
        return $self->[HIGH] == 0 && $self->[LOW] == MAX32;
    }

    sub stringify
    {
        my $self = shift;

        return "High [$self->[HIGH]], Low [$self->[LOW]]";
    }
    
    sub equal
    {
        my $self = shift;
        my $other = shift;

        return $self->[LOW]  == $other->[LOW] &&
               $self->[HIGH] == $other->[HIGH] ;
    }

    sub gt
    {
        my $self = shift;
        my $other = shift;

        return $self->cmp($other) > 0 ;
    }

    sub cmp
    {
        my $self = shift;
        my $other = shift ;

        if ($self->[LOW] == $other->[LOW]) {
            return $self->[HIGH] - $other->[HIGH] ;
        }
        else {
            return $self->[LOW] - $other->[LOW] ;
        }
    }
    
    sub nibbles
    {
        my @nibbles = (
            [ 16 => HI_1 * 0x10000000 ],
            [ 15 => HI_1 * 0x1000000 ],
            [ 14 => HI_1 * 0x100000 ],
            [ 13 => HI_1 * 0x10000 ],
            [ 12 => HI_1 * 0x1000 ],
            [ 11 => HI_1 * 0x100 ],
            [ 10 => HI_1 * 0x10 ],
            [  9 => HI_1 * 0x1 ],

            [  8 => 0x10000000 ],
            [  7 => 0x1000000 ],
            [  6 => 0x100000 ],
            [  5 => 0x10000 ],
            [  4 => 0x1000 ],
            [  3 => 0x100 ],
            [  2 => 0x10 ],
            [  1 => 0x1 ],
        );
        my $value = shift ;

        for my $pair (@nibbles)
        {
            my ($count, $limit) = @{ $pair };

            return $count
                if $value >= $limit ;
        }

    }
}

sub Usage
{
    die <<EOM;
zipdetails [OPTIONS] file

Display details about the internal structure of a Zip file.

This is zipdetails version $VERSION

OPTIONS
     -h     display help
     -v     Verbose - output more stuff
    
Copyright (c) 2011-2018 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.
EOM

        
}

__END__

=head1 NAME

zipdetails - display the internal structure of zip files

=head1 SYNOPSIS

    zipdetails [-v] zipfile.zip
	zipdetails -h

=head1 DESCRIPTION

Zipdetails displays information about the internal record structure of the
zip file. It is not concerned with displaying any details of the compressed
data stored in the zip file.

The program assumes prior understanding of the internal structure of a Zip
file. You should have a copy of the Zip APPNOTE file at hand to help
understand the output from this program (L<SEE ALSO> for details).

=head2 OPTIONS

=over 5

=item -v

Enable Verbose mode

=item -h

Display help

=back


By default zipdetails will output the details of the zip file in three
columns.

=over 5

=item Column 1

This contains the offset from the start of the file in hex.

=item Column 2

This contains a textual description of the field.

=item Column 3

If the field contains a numeric value it will be displayed in hex. Zip
stored most numbers in little-endian format - the value displayed will have
the little-endian encoding removed.

Next, is an optional description of what the value means.


=back

If the C<-v> option is present, column 1 is expanded to include

=over 5

=item *

The offset from the start of the file in hex.

=item *

The length of the filed in hex.

=item *

A hex dump of the bytes in field in the order they are stored in the zip
file.

=back


=head1 TODO 

Error handling is still a work in progress.  If the program encounters a
problem reading a zip file it is likely to terminate with an unhelpful
error message. 


=head1 SEE ALSO


The primary reference for Zip files is the "appnote" document available at
L<http://www.pkware.com/documents/casestudies/APPNOTE.TXT>.

An alternative reference is the Info-Zip appnote. This is available from
L<ftp://ftp.info-zip.org/pub/infozip/doc/>


The C<zipinfo> program that comes with the info-zip distribution
(L<http://www.info-zip.org/>) can also display details of the structure of
a zip file.

See also L<Archive::Zip::SimpleZip>, L<IO::Compress::Zip>,
L<IO::Uncompress::Unzip>.


=head1 AUTHOR

Paul Marquess F<pmqs@cpan.org>.

=head1 COPYRIGHT 

Copyright (c) 2011-2018 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.