NAME

PerlIO::gzip - Perl extension to provide a PerlIO layer to gzip/gunzip

SYNOPSIS

use PerlIO::gzip;
open FOO, "<:gzip", "file.gz" or die $!;
print while <FOO>; # And it will be uncompressed.

binmode FOO, ":gzip(none)" # Starts reading deflate stream from here on.

DESCRIPTION

PerlIO::gzip provides a PerlIO layer that manipulates files in the format used by the gzip program. Currently only decompression is implemented.

EXPORT

PerlIO::gzip exports no subroutines or symbols, just a perl layer gzip

LAYER ARGUMENTS

The gzip layer takes a comma separated list of arguments. 3 exclusive options choose the header checking mode:

gzip

The default. Expects a standard gzip file header

none

Expects no file header; assumes the file handle is immediately a deflate stream (eg as would be found inside a zip file)

auto

Potentially dangerous. If the first two bytes match the gzip header "\x1f\x8b" then a gzip header is assumed (and checked) else a deflate stream is assumed

Optionally you can add this flag:

lazy

Defer header checking until the first read. By default, gzip header checking is done before the open (or binmode) returns, so if an error is detected in the gzip header the open or binmode will fail. However, this will require reading some data. With lazy set the check is deferred until the first read, so the open should always succeed, but any problems with the header will cause an error on read.

open FOO, "<:gzip(lazy)", "file.gz" or die $!; # Dangerous.
while (<FOO>) {
  print;
} # Whoa. Bad. You're not distinguishing between errors and EOF.

If you're not careful you won't spot the errors - like the example above you'll think you got end of file.

AUTHOR

Nicholas Clark, <nick@talking.bollo.cx>

SEE ALSO

perl, gzip.