Implement Zlib.gzip and Zlib.gunzip

lib/zlib.rb

@@ -68,6 +68,28 @@ def self.inflate(...)
     Inflate.inflate(...)
   end
 
+  def self.gunzip(input)
+    # windowBits can also be greater than 15 for optional gzip encoding. Add
+    # 16 to windowBits to write a simple gzip header and trailer around the
+    # compressed data instead of a zlib wrapper.
+    zstream = Zlib::Inflate.new(MAX_WBITS | 16)
+    zstream << input
+    zstream.finish.tap do
+      zstream.close
+    end
+  end
+
+  def self.gzip(src, level: nil, strategy: nil)
+    # windowBits can also be greater than 15 for optional gzip encoding. Add
+    # 16 to windowBits to write a simple gzip header and trailer around the
+    # compressed data instead of a zlib wrapper.
+    zstream = Zlib::Deflate.new(level || DEFAULT_COMPRESSION, MAX_WBITS | 16, DEF_MEM_LEVEL, strategy || DEFAULT_STRATEGY)
+    zstream << src
+    zstream.finish.tap do
+      zstream.close
+    end
+  end
+
   class ZStream
     __bind_method__ :adler, :Zlib_ZStream_adler, 0
     __bind_method__ :avail_in, :Zlib_ZStream_avail_in, 0

spec/library/zlib/gunzip_spec.rb

@@ -0,0 +1,14 @@
+require_relative '../../spec_helper'
+require 'zlib'
+
+describe "Zlib.gunzip" do
+  before :each do
+    @data = '12345abcde'
+    @zip = [31, 139, 8, 0, 44, 220, 209, 71, 0, 3, 51, 52, 50, 54, 49, 77,
+            76, 74, 78, 73, 5, 0, 157, 5, 0, 36, 10, 0, 0, 0].pack('C*')
+  end
+
+  it "decodes the given gzipped string" do
+    Zlib.gunzip(@zip).should == @data
+  end
+end

spec/library/zlib/gzip_spec.rb

@@ -0,0 +1,15 @@
+require_relative '../../spec_helper'
+require 'zlib'
+
+describe "Zlib.gzip" do
+  before :each do
+    @data = '12345abcde'
+    @zip = [31, 139, 8, 0, 44, 220, 209, 71, 0, 3, 51, 52, 50, 54, 49, 77,
+            76, 74, 78, 73, 5, 0, 157, 5, 0, 36, 10, 0, 0, 0].pack('C*')
+  end
+
+  it "gzips the given string" do
+    # skip gzip header for now
+    Zlib.gzip(@data)[10..-1].should == @zip[10..-1]
+  end
+end