IO::Uncompress::Gunzip gives you a filehandle interface to a gzip file

my $fh = new IO::Uncompress::Gunzip "input file",
    or die "Cannot open file ..." ;

my $line = <$fh> ;
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It also has the ability to assume the input file is uncompressed if the input data isn't a gzipped at all. To enable that mode just give it the Transparent option like this

my $fh = new IO::Uncompress::Gunzip "input file",
                   Transparent => 1
    or die "Cannot open file ..." ;

my $line = <$fh> ;
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That will give you a filehandle that can read from either a gzip compressed file or uncompressed input file.

One limitation of IO::Uncompress::Gunzip is that it doesn't allow you to seek backwards in a file. If you have a requirement to be able to rewind the input file you will have to reopen the file again. Perhaps something like this (untested)

sub rewind
{
    $_[0]->close();
    $_[0] = new  new IO::Uncompress::Gunzip $_[1],
                   Transparent => 1
    or die "Cannot open file ..." ;
}

rewind($fh, "somefile");
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