IO::Compress::Zip - perldoc.perl.org

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Perl 5 version 24.3 documentation

IO::Compress::Zip

NAME
SYNOPSIS
DESCRIPTION
Functional Interface

zip $input_filename_or_reference => $output_filename_or_reference [, OPTS]
Notes
Optional Parameters
Examples

OO Interface

Constructor
Constructor Options
Examples

Methods

print
printf
syswrite
write
flush
tell
eof
seek
binmode
opened
autoflush
input_line_number
fileno
close
newStream([OPTS])
deflateParams

Importing
EXAMPLES

Apache::GZip Revisited
Working with Net::FTP

SEE ALSO
AUTHOR
MODIFICATION HISTORY
COPYRIGHT AND LICENSE

NAME

IO::Compress::Zip - Write zip files/buffers

SYNOPSIS

    use IO::Compress::Zip qw(zip $ZipError) ;
    my $status = zip $input => $output [,OPTS] 
        or die "zip failed: $ZipError\n";
    my $z = new IO::Compress::Zip $output [,OPTS]
        or die "zip failed: $ZipError\n";
    $z->print($string);
    $z->printf($format, $string);
    $z->write($string);
    $z->syswrite($string [, $length, $offset]);
    $z->flush();
    $z->tell();
    $z->eof();
    $z->seek($position, $whence);
    $z->binmode();
    $z->fileno();
    $z->opened();
    $z->autoflush();
    $z->input_line_number();
    $z->newStream( [OPTS] );
    
    $z->deflateParams();
    
    $z->close() ;
    $ZipError ;
    # IO::File mode
    print $z $string;
    printf $z $format, $string;
    tell $z
    eof $z
    seek $z, $position, $whence
    binmode $z
    fileno $z
    close $z ;

DESCRIPTION

This module provides a Perl interface that allows writing zip compressed data to files or buffer.

The primary purpose of this module is to provide streaming write access to zip files and buffers. It is not a general-purpose file archiver. If that is what you want, check out Archive::Zip .

At present three compression methods are supported by IO::Compress::Zip, namely Store (no compression at all), Deflate, Bzip2 and LZMA.

Note that to create Bzip2 content, the module IO::Compress::Bzip2 must be installed.

Note that to create LZMA content, the module IO::Compress::Lzma must be installed.

For reading zip files/buffers, see the companion module IO::Uncompress::Unzip.

Functional Interface

A top-level function, zip , is provided to carry out "one-shot" compression between buffers and/or files. For finer control over the compression process, see the OO Interface section.

    use IO::Compress::Zip qw(zip $ZipError) ;
    zip $input_filename_or_reference => $output_filename_or_reference [,OPTS] 
        or die "zip failed: $ZipError\n";

The functional interface needs Perl5.005 or better.

zip $input_filename_or_reference => $output_filename_or_reference [, OPTS]

zip expects at least two parameters, $input_filename_or_reference and $output_filename_or_reference .

The `$input_filename_or_reference` parameter

The parameter, $input_filename_or_reference , is used to define the source of the uncompressed data.

It can take one of the following forms:

A filename
If the <$input_filename_or_reference> parameter is a simple scalar, it is assumed to be a filename. This file will be opened for reading and the input data will be read from it.
A filehandle
If the $input_filename_or_reference parameter is a filehandle, the input data will be read from it. The string '-' can be used as an alias for standard input.
A scalar reference
If $input_filename_or_reference is a scalar reference, the input data will be read from $$input_filename_or_reference .
An array reference
If $input_filename_or_reference is an array reference, each element in the array must be a filename.

The input data will be read from each file in turn.

The complete array will be walked to ensure that it only contains valid filenames before any data is compressed.
An Input FileGlob string
If $input_filename_or_reference is a string that is delimited by the characters "<" and ">" zip will assume that it is an input fileglob string. The input is the list of files that match the fileglob.

See File::GlobMapper for more details.

If the $input_filename_or_reference parameter is any other type, undef will be returned.

In addition, if $input_filename_or_reference is a simple filename, the default values for the Name , Time , TextFlag , ExtAttr , exUnixN and exTime options will be sourced from that file.

If you do not want to use these defaults they can be overridden by explicitly setting the Name , Time , TextFlag , ExtAttr , exUnixN and exTime options or by setting the Minimal parameter.

The `$output_filename_or_reference` parameter

The parameter $output_filename_or_reference is used to control the destination of the compressed data. This parameter can take one of these forms.

A filename
If the $output_filename_or_reference parameter is a simple scalar, it is assumed to be a filename. This file will be opened for writing and the compressed data will be written to it.
A filehandle
If the $output_filename_or_reference parameter is a filehandle, the compressed data will be written to it. The string '-' can be used as an alias for standard output.
A scalar reference
If $output_filename_or_reference is a scalar reference, the compressed data will be stored in $$output_filename_or_reference .
An Array Reference
If $output_filename_or_reference is an array reference, the compressed data will be pushed onto the array.
An Output FileGlob
If $output_filename_or_reference is a string that is delimited by the characters "<" and ">" zip will assume that it is an output fileglob string. The output is the list of files that match the fileglob.

When $output_filename_or_reference is an fileglob string, $input_filename_or_reference must also be a fileglob string. Anything else is an error.

See File::GlobMapper for more details.

If the $output_filename_or_reference parameter is any other type, undef will be returned.

Notes

When $input_filename_or_reference maps to multiple files/buffers and $output_filename_or_reference is a single file/buffer the input files/buffers will each be stored in $output_filename_or_reference as a distinct entry.

Optional Parameters

Unless specified below, the optional parameters for zip , OPTS , are the same as those used with the OO interface defined in the Constructor Options section below.

AutoClose => 0|1
This option applies to any input or output data streams to zip that are filehandles.

If AutoClose is specified, and the value is true, it will result in all input and/or output filehandles being closed once zip has completed.

This parameter defaults to 0.
BinModeIn => 0|1
When reading from a file or filehandle, set binmode before reading.

Defaults to 0.
Append => 0|1
The behaviour of this option is dependent on the type of output data stream.
- A Buffer
  If Append is enabled, all compressed data will be append to the end of the output buffer. Otherwise the output buffer will be cleared before any compressed data is written to it.
- A Filename
  If Append is enabled, the file will be opened in append mode. Otherwise the contents of the file, if any, will be truncated before any compressed data is written to it.
- A Filehandle
  If Append is enabled, the filehandle will be positioned to the end of the file via a call to seek before any compressed data is written to it. Otherwise the file pointer will not be moved.
When Append is specified, and set to true, it will append all compressed data to the output data stream.

So when the output is a filehandle it will carry out a seek to the eof before writing any compressed data. If the output is a filename, it will be opened for appending. If the output is a buffer, all compressed data will be appended to the existing buffer.

Conversely when Append is not specified, or it is present and is set to false, it will operate as follows.

When the output is a filename, it will truncate the contents of the file before writing any compressed data. If the output is a filehandle its position will not be changed. If the output is a buffer, it will be wiped before any compressed data is output.

Defaults to 0.

Examples

To read the contents of the file file1.txt and write the compressed data to the file file1.txt.zip .

    use strict ;
    use warnings ;
    use IO::Compress::Zip qw(zip $ZipError) ;
    my $input = "file1.txt";
    zip $input => "$input.zip"
        or die "zip failed: $ZipError\n";

To read from an existing Perl filehandle, $input , and write the compressed data to a buffer, $buffer .

    use strict ;
    use warnings ;
    use IO::Compress::Zip qw(zip $ZipError) ;
    use IO::File ;
    my $input = new IO::File "<file1.txt"
        or die "Cannot open 'file1.txt': $!\n" ;
    my $buffer ;
    zip $input => \$buffer 
        or die "zip failed: $ZipError\n";

To create a zip file, output.zip , that contains the compressed contents of the files alpha.txt and beta.txt

    use strict ;
    use warnings ;
    use IO::Compress::Zip qw(zip $ZipError) ;
    zip [ 'alpha.txt', 'beta.txt' ] => 'output.zip'
        or die "zip failed: $ZipError\n";

Alternatively, rather than having to explicitly name each of the files that you want to compress, you could use a fileglob to select all the txt files in the current directory, as follows

    use strict ;
    use warnings ;
    use IO::Compress::Zip qw(zip $ZipError) ;
    my @files = <*.txt>;
    zip \@files => 'output.zip'
        or die "zip failed: $ZipError\n";

or more succinctly

    zip [ <*.txt> ] => 'output.zip'
        or die "zip failed: $ZipError\n";

OO Interface

Constructor

The format of the constructor for IO::Compress::Zip is shown below

    my $z = new IO::Compress::Zip $output [,OPTS]
        or die "IO::Compress::Zip failed: $ZipError\n";

It returns an IO::Compress::Zip object on success and undef on failure. The variable $ZipError will contain an error message on failure.

If you are running Perl 5.005 or better the object, $z , returned from IO::Compress::Zip can be used exactly like an IO::File filehandle. This means that all normal output file operations can be carried out with $z . For example, to write to a compressed file/buffer you can use either of these forms

    $z->print("hello world\n");
    print $z "hello world\n";

The mandatory parameter $output is used to control the destination of the compressed data. This parameter can take one of these forms.

A filename
If the $output parameter is a simple scalar, it is assumed to be a filename. This file will be opened for writing and the compressed data will be written to it.
A filehandle
If the $output parameter is a filehandle, the compressed data will be written to it. The string '-' can be used as an alias for standard output.
A scalar reference
If $output is a scalar reference, the compressed data will be stored in $$output .

If the $output parameter is any other type, IO::Compress::Zip ::new will return undef.

Constructor Options

OPTS is any combination of the following options:

AutoClose => 0|1
This option is only valid when the $output parameter is a filehandle. If specified, and the value is true, it will result in the $output being closed once either the close method is called or the IO::Compress::Zip object is destroyed.

This parameter defaults to 0.
Append => 0|1
Opens $output in append mode.

The behaviour of this option is dependent on the type of $output .
- A Buffer
  If $output is a buffer and Append is enabled, all compressed data will be append to the end of $output . Otherwise $output will be cleared before any data is written to it.
- A Filename
  If $output is a filename and Append is enabled, the file will be opened in append mode. Otherwise the contents of the file, if any, will be truncated before any compressed data is written to it.
- A Filehandle
  If $output is a filehandle, the file pointer will be positioned to the end of the file via a call to seek before any compressed data is written to it. Otherwise the file pointer will not be moved.
This parameter defaults to 0.
Name => $string
Stores the contents of $string in the zip filename header field.

If Name is not specified and the $input parameter is a filename, the value of $input will be used for the zip filename header field.

If Name is not specified and the $input parameter is not a filename, no zip filename field will be created.

Note that both the CanonicalName and FilterName options can modify the value used for the zip filename header field.
CanonicalName => 0|1
This option controls whether the filename field in the zip header is normalized into Unix format before being written to the zip file.

It is recommended that you enable this option unless you really need to create a non-standard Zip file.

This is what APPNOTE.TXT has to say on what should be stored in the zip filename header field.
```
    The name of the file, with optional relative path.          
    The path stored should not contain a drive or
    device letter, or a leading slash.  All slashes
    should be forward slashes '/' as opposed to
    backwards slashes '\' for compatibility with Amiga
    and UNIX file systems etc.
```
This option defaults to false.
FilterName => sub { ... }
This option allow the filename field in the zip header to be modified before it is written to the zip file.

This option takes a parameter that must be a reference to a sub. On entry to the sub the $_ variable will contain the name to be filtered. If no filename is available $_ will contain an empty string.

The value of $_ when the sub returns will be stored in the filename header field.

Note that if CanonicalName is enabled, a normalized filename will be passed to the sub.

If you use FilterName to modify the filename, it is your responsibility to keep the filename in Unix format.

Although this option can be used with the OO interface, it is of most use with the one-shot interface. For example, the code below shows how FilterName can be used to remove the path component from a series of filenames before they are stored in $zipfile .
```
    sub compressTxtFiles
    {
        my $zipfile = shift ;
        my $dir     = shift ;
        zip [ <$dir/*.txt> ] => $zipfile,
            FilterName => sub { s[^$dir/][] } ;  
    }
```
Time => $number
Sets the last modified time field in the zip header to $number.

This field defaults to the time the IO::Compress::Zip object was created if this option is not specified and the $input parameter is not a filename.
ExtAttr => $attr
This option controls the "external file attributes" field in the central header of the zip file. This is a 4 byte field.

If you are running a Unix derivative this value defaults to
```
    0100644 << 16
```
This should allow read/write access to any files that are extracted from the zip file/buffer`.

For all other systems it defaults to 0.
exTime => [$atime, $mtime, $ctime]
This option expects an array reference with exactly three elements: $atime , mtime and $ctime . These correspond to the last access time, last modification time and creation time respectively.

It uses these values to set the extended timestamp field (ID is "UT") in the local zip header using the three values, $atime, $mtime, $ctime. In addition it sets the extended timestamp field in the central zip header using $mtime .

If any of the three values is undef that time value will not be used. So, for example, to set only the $mtime you would use this
```
    exTime => [undef, $mtime, undef]
```
If the Minimal option is set to true, this option will be ignored.

By default no extended time field is created.
exUnix2 => [$uid, $gid]
This option expects an array reference with exactly two elements: $uid and $gid . These values correspond to the numeric User ID (UID) and Group ID (GID) of the owner of the files respectively.

When the exUnix2 option is present it will trigger the creation of a Unix2 extra field (ID is "Ux") in the local zip header. This will be populated with $uid and $gid . An empty Unix2 extra field will also be created in the central zip header.

Note - The UID & GID are stored as 16-bit integers in the "Ux" field. Use exUnixN if your UID or GID are 32-bit.

If the Minimal option is set to true, this option will be ignored.

By default no Unix2 extra field is created.
exUnixN => [$uid, $gid]
This option expects an array reference with exactly two elements: $uid and $gid . These values correspond to the numeric User ID (UID) and Group ID (GID) of the owner of the files respectively.

When the exUnixN option is present it will trigger the creation of a UnixN extra field (ID is "ux") in both the local and central zip headers. This will be populated with $uid and $gid . The UID & GID are stored as 32-bit integers.

If the Minimal option is set to true, this option will be ignored.

By default no UnixN extra field is created.
Comment => $comment
Stores the contents of $comment in the Central File Header of the zip file.

By default, no comment field is written to the zip file.
ZipComment => $comment
Stores the contents of $comment in the End of Central Directory record of the zip file.

By default, no comment field is written to the zip file.
Method => $method
Controls which compression method is used. At present four compression methods are supported, namely Store (no compression at all), Deflate, Bzip2 and Lzma.

The symbols, ZIP_CM_STORE, ZIP_CM_DEFLATE, ZIP_CM_BZIP2 and ZIP_CM_LZMA are used to select the compression method.

These constants are not imported by IO::Compress::Zip by default.
```
    use IO::Compress::Zip qw(:zip_method);
    use IO::Compress::Zip qw(:constants);
    use IO::Compress::Zip qw(:all);
```
Note that to create Bzip2 content, the module IO::Compress::Bzip2 must be installed. A fatal error will be thrown if you attempt to create Bzip2 content when IO::Compress::Bzip2 is not available.

Note that to create Lzma content, the module IO::Compress::Lzma must be installed. A fatal error will be thrown if you attempt to create Lzma content when IO::Compress::Lzma is not available.

The default method is ZIP_CM_DEFLATE.
Stream => 0|1
This option controls whether the zip file/buffer output is created in streaming mode.

Note that when outputting to a file with streaming mode disabled (Stream is 0), the output file must be seekable.

The default is 1.
Zip64 => 0|1
Create a Zip64 zip file/buffer. This option is used if you want to store files larger than 4 Gig or store more than 64K files in a single zip archive..

Zip64 will be automatically set, as needed, if working with the one-shot interface when the input is either a filename or a scalar reference.

If you intend to manipulate the Zip64 zip files created with this module using an external zip/unzip, make sure that it supports Zip64.

In particular, if you are using Info-Zip you need to have zip version 3.x or better to update a Zip64 archive and unzip version 6.x to read a zip64 archive.

The default is 0.
TextFlag => 0|1
This parameter controls the setting of a bit in the zip central header. It is used to signal that the data stored in the zip file/buffer is probably text.

In one-shot mode this flag will be set to true if the Perl -T operator thinks the file contains text.

The default is 0.
ExtraFieldLocal => $data
ExtraFieldCentral => $data
The ExtraFieldLocal option is used to store additional metadata in the local header for the zip file/buffer. The ExtraFieldCentral does the same for the matching central header.

An extra field consists of zero or more subfields. Each subfield consists of a two byte header followed by the subfield data.

The list of subfields can be supplied in any of the following formats
```
    ExtraFieldLocal => [$id1, $data1,
                        $id2, $data2,
                         ...
                       ]
    ExtraFieldLocal => [ [$id1 => $data1],
                         [$id2 => $data2],
                         ...
                       ]
    ExtraFieldLocal => { $id1 => $data1,
                         $id2 => $data2,
                         ...
                       }
```
Where $id1 , $id2 are two byte subfield ID's.

If you use the hash syntax, you have no control over the order in which the ExtraSubFields are stored, plus you cannot have SubFields with duplicate ID.

Alternatively the list of subfields can by supplied as a scalar, thus
```
    ExtraField => $rawdata
```
In this case IO::Compress::Zip will check that $rawdata consists of zero or more conformant sub-fields.

The Extended Time field (ID "UT"), set using the exTime option, and the Unix2 extra field (ID "Ux), set using the exUnix2 option, are examples of extra fields.

If the Minimal option is set to true, this option will be ignored.

The maximum size of an extra field 65535 bytes.
Minimal => 1|0
If specified, this option will disable the creation of all extra fields in the zip local and central headers. So the exTime , exUnix2 , exUnixN , ExtraFieldLocal and ExtraFieldCentral options will be ignored.

This parameter defaults to 0.
BlockSize100K => number
Specify the number of 100K blocks bzip2 uses during compression.

Valid values are from 1 to 9, where 9 is best compression.

This option is only valid if the Method is ZIP_CM_BZIP2. It is ignored otherwise.

The default is 1.
WorkFactor => number
Specifies how much effort bzip2 should take before resorting to a slower fallback compression algorithm.

Valid values range from 0 to 250, where 0 means use the default value 30.

This option is only valid if the Method is ZIP_CM_BZIP2. It is ignored otherwise.

The default is 0.
Preset => number
Used to choose the LZMA compression preset.

Valid values are 0-9 and LZMA_PRESET_DEFAULT .

0 is the fastest compression with the lowest memory usage and the lowest compression.

9 is the slowest compression with the highest memory usage but with the best compression.

This option is only valid if the Method is ZIP_CM_LZMA. It is ignored otherwise.

Defaults to LZMA_PRESET_DEFAULT (6).
Extreme => 0|1
Makes LZMA compression a lot slower, but a small compression gain.

This option is only valid if the Method is ZIP_CM_LZMA. It is ignored otherwise.

Defaults to 0.
-Level
Defines the compression level used by zlib. The value should either be a number between 0 and 9 (0 means no compression and 9 is maximum compression), or one of the symbolic constants defined below.
```
   Z_NO_COMPRESSION
   Z_BEST_SPEED
   Z_BEST_COMPRESSION
   Z_DEFAULT_COMPRESSION
```
The default is Z_DEFAULT_COMPRESSION.

Note, these constants are not imported by IO::Compress::Zip by default.
```
    use IO::Compress::Zip qw(:strategy);
    use IO::Compress::Zip qw(:constants);
    use IO::Compress::Zip qw(:all);
```
-Strategy
Defines the strategy used to tune the compression. Use one of the symbolic constants defined below.
```
   Z_FILTERED
   Z_HUFFMAN_ONLY
   Z_RLE
   Z_FIXED
   Z_DEFAULT_STRATEGY
```
The default is Z_DEFAULT_STRATEGY.
Strict => 0|1
This is a placeholder option.

Examples

TODO

Methods

print

Usage is

    $z->print($data)
    print $z $data

Compresses and outputs the contents of the $data parameter. This has the same behaviour as the print built-in.

Returns true if successful.

printf

Usage is

    $z->printf($format, $data)
    printf $z $format, $data

Compresses and outputs the contents of the $data parameter.

Returns true if successful.

syswrite

Usage is

    $z->syswrite $data
    $z->syswrite $data, $length
    $z->syswrite $data, $length, $offset

Compresses and outputs the contents of the $data parameter.

Returns the number of uncompressed bytes written, or undef if unsuccessful.

write

Usage is

    $z->write $data
    $z->write $data, $length
    $z->write $data, $length, $offset

Compresses and outputs the contents of the $data parameter.

Returns the number of uncompressed bytes written, or undef if unsuccessful.

flush

Usage is

    $z->flush;
    $z->flush($flush_type);

Flushes any pending compressed data to the output file/buffer.

This method takes an optional parameter, $flush_type , that controls how the flushing will be carried out. By default the $flush_type used is Z_FINISH . Other valid values for $flush_type are Z_NO_FLUSH , Z_SYNC_FLUSH , Z_FULL_FLUSH and Z_BLOCK . It is strongly recommended that you only set the flush_type parameter if you fully understand the implications of what it does - overuse of flush can seriously degrade the level of compression achieved. See the zlib documentation for details.

Returns true on success.

tell

Usage is

    $z->tell()
    tell $z

Returns the uncompressed file offset.

eof

Usage is

    $z->eof();
    eof($z);

Returns true if the close method has been called.

seek

    $z->seek($position, $whence);
    seek($z, $position, $whence);

Provides a sub-set of the seek functionality, with the restriction that it is only legal to seek forward in the output file/buffer. It is a fatal error to attempt to seek backward.

Empty parts of the file/buffer will have NULL (0x00) bytes written to them.

The $whence parameter takes one the usual values, namely SEEK_SET, SEEK_CUR or SEEK_END.

Returns 1 on success, 0 on failure.

binmode

Usage is

    $z->binmode
    binmode $z ;

This is a noop provided for completeness.

opened

    $z->opened()

Returns true if the object currently refers to a opened file/buffer.

autoflush

    my $prev = $z->autoflush()
    my $prev = $z->autoflush(EXPR)

If the $z object is associated with a file or a filehandle, this method returns the current autoflush setting for the underlying filehandle. If EXPR is present, and is non-zero, it will enable flushing after every write/print operation.

If $z is associated with a buffer, this method has no effect and always returns undef.

Note that the special variable $| cannot be used to set or retrieve the autoflush setting.

input_line_number

    $z->input_line_number()
    $z->input_line_number(EXPR)

This method always returns undef when compressing.

fileno

    $z->fileno()
    fileno($z)

If the $z object is associated with a file or a filehandle, fileno will return the underlying file descriptor. Once the close method is called fileno will return undef.

If the $z object is associated with a buffer, this method will return undef.

close

    $z->close() ;
    close $z ;

Flushes any pending compressed data and then closes the output file/buffer.

For most versions of Perl this method will be automatically invoked if the IO::Compress::Zip object is destroyed (either explicitly or by the variable with the reference to the object going out of scope). The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In these cases, the close method will be called automatically, but not until global destruction of all live objects when the program is terminating.

Therefore, if you want your scripts to be able to run on all versions of Perl, you should call close explicitly and not rely on automatic closing.

Returns true on success, otherwise 0.

If the AutoClose option has been enabled when the IO::Compress::Zip object was created, and the object is associated with a file, the underlying file will also be closed.

newStream([OPTS])

Usage is

    $z->newStream( [OPTS] )

Closes the current compressed data stream and starts a new one.

OPTS consists of any of the options that are available when creating the $z object.

See the Constructor Options section for more details.

deflateParams

Usage is

    $z->deflateParams

TODO

Importing

A number of symbolic constants are required by some methods in IO::Compress::Zip . None are imported by default.

:all
Imports zip , $ZipError and all symbolic constants that can be used by IO::Compress::Zip . Same as doing this
```
    use IO::Compress::Zip qw(zip $ZipError :constants) ;
```

:constants

Import all symbolic constants. Same as doing this

    use IO::Compress::Zip qw(:flush :level :strategy :zip_method) ;

:flush

These symbolic constants are used by the flush method.

    Z_NO_FLUSH
    Z_PARTIAL_FLUSH
    Z_SYNC_FLUSH
    Z_FULL_FLUSH
    Z_FINISH
    Z_BLOCK

:level

These symbolic constants are used by the Level option in the constructor.

    Z_NO_COMPRESSION
    Z_BEST_SPEED
    Z_BEST_COMPRESSION
    Z_DEFAULT_COMPRESSION

:strategy

These symbolic constants are used by the Strategy option in the constructor.

    Z_FILTERED
    Z_HUFFMAN_ONLY
    Z_RLE
    Z_FIXED
    Z_DEFAULT_STRATEGY

:zip_method
These symbolic constants are used by the Method option in the constructor.
```
    ZIP_CM_STORE
    ZIP_CM_DEFLATE
    ZIP_CM_BZIP2
```