1 files changed, 64 insertions, 0 deletions
diff --git a/lib/rubygems/package/digest_io.rb b/lib/rubygems/package/digest_io.rb
new file mode 100644
index 0000000000..f8bde0f557
--- /dev/null
+++ b/lib/rubygems/package/digest_io.rb
@@ -0,0 +1,64 @@
+##
+# IO wrapper that creates digests of contents written to the IO it wraps.
+
+class Gem::Package::DigestIO
+
+  ##
+  # Collected digests for wrapped writes.
+  #
+  #   {
+  #     'SHA1'   => #<OpenSSL::Digest: [...]>,
+  #     'SHA512' => #<OpenSSL::Digest: [...]>,
+  #   }
+
+  attr_reader :digests
+
+  ##
+  # Wraps +io+ and updates digest for each of the digest algorithms in
+  # the +digests+ Hash.  Returns the digests hash.  Example:
+  #
+  #   io = StringIO.new
+  #   digests = {
+  #     'SHA1'   => OpenSSL::Digest.new('SHA1'),
+  #     'SHA512' => OpenSSL::Digest.new('SHA512'),
+  #   }
+  #
+  #   Gem::Package::DigestIO.wrap io, digests do |digest_io|
+  #     digest_io.write "hello"
+  #   end
+  #
+  #   digests['SHA1'].hexdigest   #=> "aaf4c61d[...]"
+  #   digests['SHA512'].hexdigest #=> "9b71d224[...]"
+
+  def self.wrap io, digests
+    digest_io = new io, digests
+
+    yield digest_io
+
+    return digests
+  end
+
+  ##
+  # Creates a new DigestIO instance.  Using ::wrap is recommended, see the
+  # ::wrap documentation for documentation of +io+ and +digests+.
+
+  def initialize io, digests
+    @io = io
+    @digests = digests
+  end
+
+  ##
+  # Writes +data+ to the underlying IO and updates the digests
+
+  def write data
+    result = @io.write data
+
+    @digests.each do |_, digest|
+      digest << data
+    end
+
+    result
+  end
+
+end
+