Class: Zlib::GzipReader

Zlib::GzipReader is the class for reading a gzipped file. GzipReader should be used an IO, or -IO-lie, object.

  Zlib::GzipReader.open('hoge.gz') {|gz|
    print gz.read
  }

  File.open('hoge.gz') do |f|
    gz = Zlib::GzipReader.new(f)
    print gz.read
    gz.close
  end

  # TODO: test these.  Are they equivalent?  Can GzipReader.new take a
  # block?

Method Catalogue

The following methods in Zlib::GzipReader are just like their counterparts in IO, but they raise Zlib::Error or Zlib::GzipFile::Error exception if an error was found in the gzip file.

Be careful of the footer of the gzip file. A gzip file has the checksum of pre-compressed data in its footer. GzipReader checks all uncompressed data against that checksum at the following cases, and if it fails, raises Zlib::GzipFile::NoFooter, Zlib::GzipFile::CRCError, or Zlib::GzipFile::LengthError exception.

When an reading request is received beyond the end of file (the end of compressed data). That is, when Zlib::GzipReader#read, Zlib::GzipReader#gets, or some other methods for reading returns nil.
When Zlib::GzipFile#close method is called after the object reaches the end of file.
When Zlib::GzipReader#unused method is called after the object reaches the end of file.

The rest of the methods are adequately described in their own documentation.

Methods

Public Class methods

Zlib::GzipReader.new(io)

Creates a GzipReader object associated with io. The GzipReader object reads gzipped data from io, and parses/decompresses them. At least, io must have a read method that behaves same as the read method in IO class.

If the gzip file header is incorrect, raises an Zlib::GzipFile::Error exception.

Zlib::GzipReader.open(filename) {|gz| ... }

Opens a file specified by filename as a gzipped file, and returns a GzipReader object associated with that file. Further details of this method are in Zlib::GzipReader.new and ZLib::GzipReader.wrap.