1 files changed, 82 insertions, 0 deletions
diff --git a/lib/rubygems/format.rb b/lib/rubygems/format.rb
new file mode 100644
index 0000000..9644f6a
--- /dev/null
+++ b/lib/rubygems/format.rb
@@ -0,0 +1,82 @@
+#--
+# Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
+# All rights reserved.
+# See LICENSE.txt for permissions.
+#++
+
+require 'rubygems/package'
+
+##
+# Gem::Format knows the guts of the RubyGem .gem file format and provides the
+# capability to read gem files
+
+class Gem::Format
+
+  attr_accessor :spec
+  attr_accessor :file_entries
+  attr_accessor :gem_path
+
+  ##
+  # Constructs a Format representing the gem's data which came from +gem_path+
+
+  def initialize(gem_path)
+    @gem_path = gem_path
+  end
+
+  ##
+  # Reads the gem +file_path+ using +security_policy+ and returns a Format
+  # representing the data in the gem
+
+  def self.from_file_by_path(file_path, security_policy = nil)
+    unless File.file?(file_path)
+      raise Gem::Exception, "Cannot load gem at [#{file_path}] in #{Dir.pwd}"
+    end
+
+    start = File.read file_path, 20
+
+    if start.nil? or start.length < 20 then
+      nil
+    elsif start.include?("MD5SUM =") # old version gems
+      require 'rubygems/old_format'
+
+      Gem::OldFormat.from_file_by_path file_path
+    else
+      begin
+        open file_path, Gem.binary_mode do |io|
+          from_io io, file_path, security_policy
+        end
+      rescue Gem::Package::TarInvalidError => e
+        message = "corrupt gem (#{e.class}: #{e.message})"
+        raise Gem::Package::FormatError.new(message, file_path)
+      end
+    end
+  end
+
+  ##
+  # Reads a gem from +io+ at +gem_path+ using +security_policy+ and returns a
+  # Format representing the data from the gem
+
+  def self.from_io(io, gem_path="(io)", security_policy = nil)
+    format = new gem_path
+
+    Gem::Package.open io, 'r', security_policy do |pkg|
+      format.spec = pkg.metadata
+      format.file_entries = []
+
+      pkg.each do |entry|
+        size = entry.header.size
+        mode = entry.header.mode
+
+        format.file_entries << [{
+            "size" => size, "mode" => mode, "path" => entry.full_name,
+          },
+          entry.read
+        ]
+      end
+    end
+
+    format
+  end
+
+end
+