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IO::Uncompress::Gunzip - Read RFC 1952 files/buffers
use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
my $status = gunzip $input => $output [,OPTS]
or die "gunzip failed: $GunzipError\n";
my $z = new IO::Uncompress::Gunzip $input [OPTS]
or die "gunzip failed: $GunzipError\n";
$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()
$GunzipError ;
# IO::File mode
<$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)
For writing RFC 1952 files/buffers, see the companion module IO::Compress::Gzip.
use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
gunzip $input => $output [,OPTS]
or die "gunzip failed: $GunzipError\n";
The functional interface needs Perl5.005 or better.
The parameter, $input, is used to define the source of the compressed data.
It can take one of the following forms:
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.
If the fileglob does not match any files ...
See File::GlobMapper for more details.
If the $input parameter is any other type, "undef" will be returned.
The parameter $output is used to control the destination of the uncompressed data. This parameter can take one of these forms.
When $output is an fileglob string, $input must also be a fileglob string. Anything else is an error.
If the $output parameter is any other type, "undef" will be returned.
If "AutoClose" is specified, and the value is true, it will result in all input and/or output filehandles being closed once "gunzip" has completed.
This parameter defaults to 0.
Defaults to 0.
Defaults to 0.
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.
use strict ;
use warnings ;
use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
my $input = "file1.txt.gz";
my $output = "file1.txt";
gunzip $input => $output
or die "gunzip failed: $GunzipError\n";
To read from an existing Perl filehandle, $input, and write the uncompressed data to a buffer, $buffer.
use strict ;
use warnings ;
use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
use IO::File ;
my $input = new IO::File "<file1.txt.gz"
or die "Cannot open 'file1.txt.gz': $!\n" ;
my $buffer ;
gunzip $input => \$buffer
or die "gunzip failed: $GunzipError\n";
To uncompress all files in the directory ``/my/home'' that match ``*.txt.gz'' and store the compressed data in the same directory
use strict ;
use warnings ;
use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
gunzip '</my/home/*.txt.gz>' => '</my/home/#1.txt>'
or die "gunzip failed: $GunzipError\n";
and if you want to compress each file one at a time, this will do the trick
use strict ;
use warnings ;
use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
for my $input ( glob "/my/home/*.txt.gz" )
{
my $output = $input;
$output =~ s/.gz// ;
gunzip $input => $output
or die "Error compressing '$input': $GunzipError\n";
}
my $z = new IO::Uncompress::Gunzip $input [OPTS]
or die "IO::Uncompress::Gunzip failed: $GunzipError\n";
Returns an "IO::Uncompress::Gunzip" object on success and undef on failure. The variable $GunzipError will contain an error message on failure.
If you are running Perl 5.005 or better the object, $z, returned from IO::Uncompress::Gunzip 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.
-AutoClose
-autoclose
AUTOCLOSE
autoclose
OPTS is a combination of the following options:
This parameter defaults to 0.
This parameter defaults to 0.
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.
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/bufffer as a single data stream.
This option defaults to 1.
This option defaults to 4096.
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.
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.
The default for this option is off.
Defaults to 0.
$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.
$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.
$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.
$char = $z->getc()
$char = $z->ungetc($string)
$status = $z->inflateSync()
$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).
$z->tell()
tell $z
Returns the uncompressed file offset.
$z->eof();
eof($z);
Returns true if the end of the compressed input stream has been reached.
$z->seek($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.
$z->binmode
binmode $z ;
This is a noop provided for completeness.
$z->opened()
Returns true if the object currently refers to a opened file/buffer.
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.
$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.
$z->fileno()
fileno($z)
If the $z object is associated with a file or a filehandle, this method will return the underlying file descriptor.
If the $z object is is associated with a buffer, this method will return undef.
$z->close() ;
close $z ;
Closes the output file/buffer.
For most versions of Perl this method will be automatically invoked if the IO::Uncompress::Gunzip 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::Gunzip object was created, and the object is associated with a file, the underlying file will also be closed.
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.
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.
use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
Compress::Zlib::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.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
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