1 files changed, 51 insertions, 13 deletions

diff --git a/lib/puppet/util/checksums.rb b/lib/puppet/util/checksums.rb
index 6f6ea59b5..598b3adfa 100644
--- a/lib/puppet/util/checksums.rb
+++ b/lib/puppet/util/checksums.rb
@@ -1,37 +1,75 @@
+# A stand-alone module for calculating checksums
+# in a generic way.
 module Puppet::Util::Checksums
+    # Calculate a checksum using Digest::MD5.
     def md5(content)
         require 'digest/md5'
         Digest::MD5.hexdigest(content)
     end
 
-    def md5_file(filename)
+    # Calculate a checksum of the first 500 chars of the content using Digest::MD5.
+    def md5lite(content)
+        md5(content[0..511])
+    end
+
+    # Calculate a checksum of a file's content using Digest::MD5.
+    def md5_file(filename, lite = false)
         require 'digest/md5'
 
-        incr_digest = Digest::MD5.new()
-        File.open(filename, 'r') do |file|
-            file.each_line do |line|
-                incr_digest << line
-            end
-        end
+        digest = Digest::MD5.new()
+        return checksum_file(digest, filename,  lite)
+    end
+
+    # Calculate a checksum of the first 500 chars of a file's content using Digest::MD5.
+    def md5lite_file(filename)
+        md5_file(filename, true)
+    end
 
-        return incr_digest.hexdigest
+    # Return the :mtime timestamp of a file.
+    def mtime_file(filename)
+        File.stat(filename).send(:mtime)
     end
 
+    # Calculate a checksum using Digest::SHA1.
     def sha1(content)
         require 'digest/sha1'
         Digest::SHA1.hexdigest(content)
     end
 
-    def sha1_file(filename)
+    # Calculate a checksum of the first 500 chars of the content using Digest::SHA1.
+    def sha1lite(content)
+        sha1(content[0..511])
+    end
+
+    # Calculate a checksum of a file's content using Digest::SHA1.
+    def sha1_file(filename, lite = false)
         require 'digest/sha1'
 
-        incr_digest = Digest::SHA1.new()
+        digest = Digest::SHA1.new()
+        return checksum_file(digest, filename, lite)
+    end
+
+    # Calculate a checksum of the first 500 chars of a file's content using Digest::SHA1.
+    def sha1lite_file(filename)
+        sha1_file(filename, true)
+    end
+
+    # Return the :ctime of a file.
+    def timestamp_file(filename)
+        File.stat(filename).send(:ctime)
+    end
+
+    private
+
+    # Perform an incremental checksum on a file.
+    def checksum_file(digest, filename, lite = false)
         File.open(filename, 'r') do |file|
-            file.each_line do |line|
-                incr_digest << line
+            while content = file.read(512)
+                digest << content
+                break if lite
             end
         end
 
-        return incr_digest.hexdigest
+        return digest.hexdigest
     end
 end