Initial downloader implementation

lib/vagrant/util/downloader.rb

@@ -0,0 +1,102 @@
+require "log4r"
+
+require "vagrant/util/subprocess"
+
+module Vagrant
+  module Util
+    # This class downloads files using various protocols by subprocessing
+    # to cURL. cURL is a much more capable and complete download tool than
+    # a hand-rolled Ruby library, so we defer to it's expertise.
+    class Downloader
+      def initialize(source, destination, options=nil)
+        @logger      = Log4r::Logger.new("vagrant::util::downloader")
+        @source      = source
+        @destination = destination
+
+        # Get the various optional values
+        @options     ||= {}
+        @ui          = @options[:ui]
+      end
+
+      # This executes the actual download, downloading the source file
+      # to the destination with the given opens used to initialize this
+      # class.
+      #
+      # If this method returns without an exception, the download
+      # succeeded. An exception will be raised if the download failed.
+      def download!
+        # Build the list of parameters to execute with cURL
+        options = [
+          "--fail",
+          "--output", @destination,
+          @source
+        ]
+
+        # This variable can contain the proc that'll be sent to
+        # the subprocess execute.
+        data_proc = nil
+
+        if @ui
+          # If we're outputting progress, then setup the subprocess to
+          # tell us output so we can parse it out.
+          options << { :notify => :stderr }
+
+          # Setup the proc that'll receive the real-time data from
+          # the downloader.
+          data_proc = Proc.new do |type, data|
+            # Type will always be "stderr" because that is the only
+            # type of data we're subscribed for notifications.
+
+            # If the data doesn't start with a \r then it isn't a progress
+            # notification, so ignore it.
+            next if data[0] != "\r"
+
+            # Ignore the first \r and split by whitespace to grab the columns
+            columns = data[1..-1].split(/\s+/)
+
+            # COLUMN DATA:
+            #
+            # 0 - blank
+            # 1 - % total
+            # 2 - Total size
+            # 3 - % received
+            # 4 - Received size
+            # 5 - % transferred
+            # 6 - Transferred size
+            # 7 - Average download speed
+            # 8 - Average upload speed
+            # 9 - Total time
+            # 10 - Time spent
+            # 11 - Time left
+            # 12 - Current speed
+
+            output = "Progress: #{columns[1]}% (Rate: #{columns[12]}/s, Estimated time remaining: #{columns[11]}"
+            @ui.clear_line
+            @ui.info(output, :new_line => false)
+          end
+        end
+
+        @logger.info("Downloader starting download: ")
+        @logger.info("  -- Source: #{@source}")
+        @logger.info("  -- Destination: #{@destination}")
+
+        # Execute!
+        result = Subprocess.execute("curl", *options, &data_proc)
+
+        # If it didn't exit successfully, we need to parse the data and
+        # show an error message.
+        if result.exit_code != 0
+          parts = result.stderr.split(/\ncurl:\s+\(\d+\)\s*/, 2)
+
+          # If the length is correct, we properly parsed an error message
+          if parts.length == 2
+            # TODO: Raise the error
+          end
+        end
+
+        # Everything succeeded
+        true
+      end
+    end
+  end
+end