IO::Uncompress::Inflate(3pm) Perl Programmers Reference Guide IO::Uncompress::Inflate(3pm)
NAME
IO::Uncompress::Inflate - Read RFC 1950 files/buffers
SYNOPSIS
use IO::Uncompress::Inflate qw(inflate $InflateError) ;
my $status = inflate $input => $output [,OPTS]
or die "inflate failed: $InflateError
";
my $z = new IO::Uncompress::Inflate $input [OPTS]
or die "inflate failed: $InflateError
";
$status = $z->read($buffer)
$status = $z->read($buffer, $length)
$status = $z->read($buffer, $length, $offset)
$line = $z->getline()
$char = $z->getc()
$char = $z->ungetc()
$char = $z->opened()
$status = $z->inflateSync()
$data = $z->trailingData()
$status = $z->nextStream()
$data = $z->getHeaderInfo()
$z->tell()
$z->seek($position, $whence)
$z->binmode()
$z->fileno()
$z->eof()
$z->close()
$InflateError ;
# IO::File mode
<$z>
read($z, $buffer);
read($z, $buffer, $length);
read($z, $buffer, $length, $offset);
tell($z)
seek($z, $position, $whence)
binmode($z)
fileno($z)
eof($z)
close($z)
DESCRIPTION
This module provides a Perl interface that allows the reading of files/buffers that conform to RFC 1950.
For writing RFC 1950 files/buffers, see the companion module IO::Compress::Deflate.
Functional Interface
A top-level function, "inflate", is provided to carry out "one-shot" uncompression between buffers and/or files. For finer control over the
uncompression process, see the "OO Interface" section.
use IO::Uncompress::Inflate qw(inflate $InflateError) ;
inflate $input => $output [,OPTS]
or die "inflate failed: $InflateError
";
The functional interface needs Perl5.005 or better.
inflate $input => $output [, OPTS]
"inflate" expects at least two parameters, $input and $output.
The $input parameter
The parameter, $input, is used to define the source of the compressed data.
It can take one of the following forms:
A filename
If the $input 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 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 is a scalar reference, the input data will be read from $$input.
An array reference
If $input is an array reference, each element in the array must be a filename.
The input data will be read from each file in turn.
The complete array will be walked to ensure that it only contains valid filenames before any data is uncompressed.
An Input FileGlob string
If $input is a string that is delimited by the characters "<" and ">" "inflate" will assume that it is an input fileglob string. The
input is the list of files that match the fileglob.
See File::GlobMapper for more details.
If the $input parameter is any other type, "undef" will be returned.
The $output parameter
The parameter $output is used to control the destination of the uncompressed data. This parameter can take one of these forms.
A filename
If the $output parameter is a simple scalar, it is assumed to be a filename. This file will be opened for writing and the
uncompressed data will be written to it.
A filehandle
If the $output parameter is a filehandle, the uncompressed data will be written to it. The string '-' can be used as an alias for
standard output.
A scalar reference
If $output is a scalar reference, the uncompressed data will be stored in $$output.
An Array Reference
If $output is an array reference, the uncompressed data will be pushed onto the array.
An Output FileGlob
If $output is a string that is delimited by the characters "<" and ">" "inflate" will assume that it is an output fileglob string. The
output is the list of files that match the fileglob.
When $output is an fileglob string, $input must also be a fileglob string. Anything else is an error.
See File::GlobMapper for more details.
If the $output parameter is any other type, "undef" will be returned.
Notes
When $input maps to multiple compressed files/buffers and $output is a single file/buffer, after uncompression $output will contain a
concatenation of all the uncompressed data from each of the input files/buffers.
Optional Parameters
Unless specified below, the optional parameters for "inflate", "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 "inflate" 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 "inflate"
has completed.
This parameter defaults to 0.
"BinModeOut => 0|1"
When writing to a file or filehandle, set "binmode" before writing to the file.
Defaults to 0.
"Append => 0|1"
The behaviour of this option is dependent on the type of output data stream.
o A Buffer
If "Append" is enabled, all uncompressed data will be append to the end of the output buffer. Otherwise the output buffer will be
cleared before any uncompressed data is written to it.
o 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 uncompressed data is written to it.
o A Filehandle
If "Append" is enabled, the filehandle will be positioned to the end of the file via a call to "seek" before any uncompressed
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 uncompressed 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 uncompressed data. If the output is a
filename, it will be opened for appending. If the output is a buffer, all uncompressed 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 uncompressed 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 uncompressed data is output.
Defaults to 0.
"MultiStream => 0|1"
If the input file/buffer contains multiple compressed data streams, this option will uncompress the whole lot as a single data stream.
Defaults to 0.
"TrailingData => $scalar"
Returns the data, if any, that is present immediately after the compressed data stream once uncompression is complete.
This option can be used when there is useful information immediately following the compressed data stream, and you don't know the
length of the compressed data stream.
If the input is a buffer, "trailingData" will return everything from the end of the compressed data stream to the end of the buffer.
If the input is a filehandle, "trailingData" will return the data that is left in the filehandle input buffer once the end of the
compressed data stream has been reached. You can then use the filehandle to read the rest of the input file.
Don't bother using "trailingData" if the input is a filename.
If you know the length of the compressed data stream before you start uncompressing, you can avoid having to use "trailingData" by
setting the "InputLength" option.
Examples
To read the contents of the file "file1.txt.1950" and write the uncompressed data to the file "file1.txt".
use strict ;
use warnings ;
use IO::Uncompress::Inflate qw(inflate $InflateError) ;
my $input = "file1.txt.1950";
my $output = "file1.txt";
inflate $input => $output
or die "inflate failed: $InflateError
";
To read from an existing Perl filehandle, $input, and write the uncompressed data to a buffer, $buffer.
use strict ;
use warnings ;
use IO::Uncompress::Inflate qw(inflate $InflateError) ;
use IO::File ;
my $input = new IO::File "<file1.txt.1950"
or die "Cannot open 'file1.txt.1950': $!
" ;
my $buffer ;
inflate $input => $buffer
or die "inflate failed: $InflateError
";
To uncompress all files in the directory "/my/home" that match "*.txt.1950" and store the compressed data in the same directory
use strict ;
use warnings ;
use IO::Uncompress::Inflate qw(inflate $InflateError) ;
inflate '</my/home/*.txt.1950>' => '</my/home/#1.txt>'
or die "inflate failed: $InflateError
";
and if you want to compress each file one at a time, this will do the trick
use strict ;
use warnings ;
use IO::Uncompress::Inflate qw(inflate $InflateError) ;
for my $input ( glob "/my/home/*.txt.1950" )
{
my $output = $input;
$output =~ s/.1950// ;
inflate $input => $output
or die "Error compressing '$input': $InflateError
";
}
OO Interface
Constructor
The format of the constructor for IO::Uncompress::Inflate is shown below
my $z = new IO::Uncompress::Inflate $input [OPTS]
or die "IO::Uncompress::Inflate failed: $InflateError
";
Returns an "IO::Uncompress::Inflate" object on success and undef on failure. The variable $InflateError will contain an error message on
failure.
If you are running Perl 5.005 or better the object, $z, returned from IO::Uncompress::Inflate can be used exactly like an IO::File
filehandle. This means that all normal input file operations can be carried out with $z. For example, to read a line from a compressed
file/buffer you can use either of these forms
$line = $z->getline();
$line = <$z>;
The mandatory parameter $input is used to determine the source of the compressed data. This parameter can take one of three forms.
A filename
If the $input parameter is a scalar, it is assumed to be a filename. This file will be opened for reading and the compressed data will
be read from it.
A filehandle
If the $input parameter is a filehandle, the compressed data will be read from it. The string '-' can be used as an alias for
standard input.
A scalar reference
If $input is a scalar reference, the compressed data will be read from $$output.
Constructor Options
The option names defined below are case insensitive and can be optionally prefixed by a '-'. So all of the following are valid
-AutoClose
-autoclose
AUTOCLOSE
autoclose
OPTS is a combination of the following options:
"AutoClose => 0|1"
This option is only valid when the $input parameter is a filehandle. If specified, and the value is true, it will result in the file
being closed once either the "close" method is called or the IO::Uncompress::Inflate object is destroyed.
This parameter defaults to 0.
"MultiStream => 0|1"
Allows multiple concatenated compressed streams to be treated as a single compressed stream. Decompression will stop once either the
end of the file/buffer is reached, an error is encountered (premature eof, corrupt compressed data) or the end of a stream is not
immediately followed by the start of another stream.
This parameter defaults to 0.
"Prime => $string"
This option will uncompress the contents of $string before processing the input file/buffer.
This option can be useful when the compressed data is embedded in another file/data structure and it is not possible to work out where
the compressed data begins without having to read the first few bytes. If this is the case, the uncompression can be primed with these
bytes using this option.
"Transparent => 0|1"
If this option is set and the input file/buffer is not compressed data, the module will allow reading of it anyway.
In addition, if the input file/buffer does contain compressed data and there is non-compressed data immediately following it, setting
this option will make this module treat the whole file/buffer as a single data stream.
This option defaults to 1.
"BlockSize => $num"
When reading the compressed input data, IO::Uncompress::Inflate will read it in blocks of $num bytes.
This option defaults to 4096.
"InputLength => $size"
When present this option will limit the number of compressed bytes read from the input file/buffer to $size. This option can be used
in the situation where there is useful data directly after the compressed data stream and you know beforehand the exact length of the
compressed data stream.
This option is mostly used when reading from a filehandle, in which case the file pointer will be left pointing to the first byte
directly after the compressed data stream.
This option defaults to off.
"Append => 0|1"
This option controls what the "read" method does with uncompressed data.
If set to 1, all uncompressed data will be appended to the output parameter of the "read" method.
If set to 0, the contents of the output parameter of the "read" method will be overwritten by the uncompressed data.
Defaults to 0.
"Strict => 0|1"
This option controls whether the extra checks defined below are used when carrying out the decompression. When Strict is on, the extra
tests are carried out, when Strict is off they are not.
The default for this option is off.
1. The ADLER32 checksum field must be present.
2. The value of the ADLER32 field read must match the adler32 value of the uncompressed data actually contained in the file.
Examples
TODO
Methods
read
Usage is
$status = $z->read($buffer)
Reads a block of compressed data (the size the the compressed block is determined by the "Buffer" option in the constructor), uncompresses
it and writes any uncompressed data into $buffer. If the "Append" parameter is set in the constructor, the uncompressed data will be
appended to the $buffer parameter. Otherwise $buffer will be overwritten.
Returns the number of uncompressed bytes written to $buffer, zero if eof or a negative number on error.
read
Usage is
$status = $z->read($buffer, $length)
$status = $z->read($buffer, $length, $offset)
$status = read($z, $buffer, $length)
$status = read($z, $buffer, $length, $offset)
Attempt to read $length bytes of uncompressed data into $buffer.
The main difference between this form of the "read" method and the previous one, is that this one will attempt to return exactly $length
bytes. The only circumstances that this function will not is if end-of-file or an IO error is encountered.
Returns the number of uncompressed bytes written to $buffer, zero if eof or a negative number on error.
getline
Usage is
$line = $z->getline()
$line = <$z>
Reads a single line.
This method fully supports the use of of the variable $/ (or $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine what
constitutes an end of line. Paragraph mode, record mode and file slurp mode are all supported.
getc
Usage is
$char = $z->getc()
Read a single character.
ungetc
Usage is
$char = $z->ungetc($string)
inflateSync
Usage is
$status = $z->inflateSync()
TODO
getHeaderInfo
Usage is
$hdr = $z->getHeaderInfo();
@hdrs = $z->getHeaderInfo();
This method returns either a hash reference (in scalar context) or a list or hash references (in array context) that contains information
about each of the header fields in the compressed data stream(s).
tell
Usage is
$z->tell()
tell $z
Returns the uncompressed file offset.
eof
Usage is
$z->eof();
eof($z);
Returns true if the end of the compressed input stream has been reached.
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 input file/buffer. It is
a fatal error to attempt to seek backward.
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)
Returns the current uncompressed line number. If "EXPR" is present it has the effect of setting the line number. Note that setting the line
number does not change the current position within the file/buffer being read.
The contents of $/ are used to to determine what constitutes a line terminator.
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 ;
Closes the output file/buffer.
For most versions of Perl this method will be automatically invoked if the IO::Uncompress::Inflate 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::Uncompress::Inflate object was created, and the object is associated with a file,
the underlying file will also be closed.
nextStream
Usage is
my $status = $z->nextStream();
Skips to the next compressed data stream in the input file/buffer. If a new compressed data stream is found, the eof marker will be cleared
and $. will be reset to 0.
Returns 1 if a new stream was found, 0 if none was found, and -1 if an error was encountered.
trailingData
Usage is
my $data = $z->trailingData();
Returns the data, if any, that is present immediately after the compressed data stream once uncompression is complete. It only makes sense
to call this method once the end of the compressed data stream has been encountered.
This option can be used when there is useful information immediately following the compressed data stream, and you don't know the length of
the compressed data stream.
If the input is a buffer, "trailingData" will return everything from the end of the compressed data stream to the end of the buffer.
If the input is a filehandle, "trailingData" will return the data that is left in the filehandle input buffer once the end of the
compressed data stream has been reached. You can then use the filehandle to read the rest of the input file.
Don't bother using "trailingData" if the input is a filename.
If you know the length of the compressed data stream before you start uncompressing, you can avoid having to use "trailingData" by setting
the "InputLength" option in the constructor.
Importing
No symbolic constants are required by this IO::Uncompress::Inflate at present.
:all Imports "inflate" and $InflateError. Same as doing this
use IO::Uncompress::Inflate qw(inflate $InflateError) ;
EXAMPLES
Working with Net::FTP
See IO::Uncompress::Inflate::FAQ
SEE ALSO
Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip, IO::Compress::Deflate, IO::Compress::RawDeflate, IO::Uncompress::RawInflate,
IO::Compress::Bzip2, IO::Uncompress::Bunzip2, IO::Compress::Lzma, IO::Uncompress::UnLzma, IO::Compress::Xz, IO::Uncompress::UnXz,
IO::Compress::Lzop, IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Uncompress::AnyInflate,
IO::Uncompress::AnyUncompress
IO::Compress::FAQ
File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib
For RFC 1950, 1951 and 1952 see http://www.faqs.org/rfcs/rfc1950.html, http://www.faqs.org/rfcs/rfc1951.html and
http://www.faqs.org/rfcs/rfc1952.html
The zlib compression library was written by Jean-loup Gailly gzip@prep.ai.mit.edu and Mark Adler madler@alumni.caltech.edu.
The primary site for the zlib compression library is http://www.zlib.org.
The primary site for gzip is http://www.gzip.org.
AUTHOR
This module was written by Paul Marquess, pmqs@cpan.org.
MODIFICATION HISTORY
See the Changes file.
COPYRIGHT AND LICENSE
Copyright (c) 2005-2012 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.
perl v5.16.2 2012-10-25 IO::Uncompress::Inflate(3pm)