Remove checksum from downloader and replace with FileChecksum

Remove checksum implementation within the Util::Downloader and
relocate it into the FileChecksum helper class. Update Downloader
to use FileChecksum.

lib/vagrant/util/downloader.rb

@@ -8,6 +8,7 @@ require "vagrant/util/busy"
 require "vagrant/util/platform"
 require "vagrant/util/subprocess"
 require "vagrant/util/curl_helper"
+require "vagrant/util/file_checksum"
 
 module Vagrant
   module Util
@@ -21,15 +22,6 @@ module Vagrant
       #     Vagrant/1.7.4 (+https://www.vagrantup.com; ruby2.1.0)
       USER_AGENT = "Vagrant/#{VERSION} (+https://www.vagrantup.com; #{RUBY_ENGINE}#{RUBY_VERSION}) #{ENV['VAGRANT_USER_AGENT_PROVISIONAL_STRING']}".freeze
 
-      # Supported file checksum
-      CHECKSUM_MAP = {
-        :md5 => Digest::MD5,
-        :sha1 => Digest::SHA1,
-        :sha256 => Digest::SHA256,
-        :sha384 => Digest::SHA384,
-        :sha512 => Digest::SHA512
-      }.freeze
-
       # Hosts that do not require notification on redirect
       SILENCED_HOSTS = [
         "vagrantcloud.com".freeze,
@@ -76,7 +68,7 @@ module Vagrant
           :sha256 => options[:sha256],
           :sha384 => options[:sha384],
           :sha512 => options[:sha512]
-        }
+        }.compact
       end
 
       # This executes the actual download, downloading the source file
@@ -172,36 +164,23 @@ module Vagrant
       # @option checksums [String] :sha1 Compare SHA1 checksum
       # @return [Boolean]
       def validate_download!(source, path, checksums)
-        CHECKSUM_MAP.each do |type, klass|
-          if checksums[type]
-            result = checksum_file(klass, path)
-            @logger.debug("Validating checksum (#{type}) for #{source}. " \
-              "expected: #{checksums[type]} actual: #{result}")
-            if checksums[type] != result
-              raise Errors::DownloaderChecksumError.new(
-                source: source,
-                path: path,
-                type: type,
-                expected_checksum: checksums[type],
-                actual_checksum: result
-              )
-            end
+        checksums.each do |type, expected|
+          actual = FileChecksum.new(path, type).checksum
+          @logger.debug("Validating checksum (#{type}) for #{source}. " \
+            "expected: #{expected} actual: #{actual}")
+          if actual.casecmp(expected) != 0
+            raise Errors::DownloaderChecksumError.new(
+              source: source,
+              path: path,
+              type: type,
+              expected_checksum: expected,
+              actual_checksum: actual
+            )
           end
         end
         true
       end
 
-      # Generate checksum on given file
-      #
-      # @param digest_class [Class] Digest class to use for generating checksum
-      # @param path [String, Pathname] Path to file
-      # @return [String] hexdigest result
-      def checksum_file(digest_class, path)
-        digester = digest_class.new
-        digester.file(path)
-        digester.hexdigest
-      end
-
       def execute_curl(options, subprocess_options, &data_proc)
         options = options.dup
         options << subprocess_options

lib/vagrant/util/file_checksum.rb

@@ -10,13 +10,27 @@ end
 class FileChecksum
   BUFFER_SIZE = 1024 * 8
 
+  # Supported file checksum
+  CHECKSUM_MAP = {
+    :md5 => Digest::MD5,
+    :sha1 => Digest::SHA1,
+    :sha256 => Digest::SHA256,
+    :sha384 => Digest::SHA384,
+    :sha512 => Digest::SHA512
+  }.freeze
+
   # Initializes an object to calculate the checksum of a file. The given
   # ``digest_klass`` should implement the ``DigestClass`` interface. Note
   # that the built-in Ruby digest classes duck type this properly:
   # Digest::MD5, Digest::SHA1, etc.
   def initialize(path, digest_klass)
-    @digest_klass = digest_klass
-    @path         = path
+    if digest_klass.is_a?(Class)
+      @digest_klass = digest_klass
+    else
+      @digest_klass = load_digest(digest_klass)
+    end
+
+    @path = path
   end
 
   # This calculates the checksum of the file and returns it as a
@@ -40,6 +54,17 @@ class FileChecksum
       end
     end
 
-    return digest.hexdigest
+    digest.hexdigest
+  end
+
+  private
+
+  def load_digest(type)
+    digest = CHECKSUM_MAP[type.to_s.to_sym]
+    if digest.nil?
+      raise Errors::BoxChecksumInvalidType,
+        type: type.to_s
+    end
+    digest
   end
 end