RUBY-210 GridIO#seek with GridIO#read_all

lib/mongo/gridfs/grid_io.rb

@@ -32,7 +32,7 @@ module Mongo
     PROTECTED_ATTRS      = [:files_id, :file_length, :client_md5, :server_md5]
 
     attr_reader :content_type, :chunk_size, :upload_date, :files_id, :filename,
-      :metadata, :server_md5, :client_md5, :file_length
+      :metadata, :server_md5, :client_md5, :file_length, :file_position
 
     # Create a new GridIO object. Note that most users will not need to use this class directly;
     # the Grid and GridFileSystem classes will instantiate this class
@@ -242,11 +242,14 @@ module Mongo
     # Read a file in its entirety.
     def read_all
       buf = ''
-      while true
+      if @current_chunk
         buf << @current_chunk['data'].to_s
-        @current_chunk = get_chunk(@current_chunk['n'] + 1)
-        break unless @current_chunk
+        while chunk = get_chunk(@current_chunk['n'] + 1)
+          buf << chunk['data'].to_s
+          @current_chunk = chunk
+        end
       end
+      @file_position = @file_length
       buf
     end
 
@@ -254,7 +257,11 @@ module Mongo
     def read_length(length)
       cache_chunk_data
       remaining  = (@file_length - @file_position)
-      to_read    = length > remaining ? remaining : length
+      if length.nil?
+        to_read = remaining
+      else
+        to_read    = length > remaining ? remaining : length
+      end
       return nil unless remaining > 0
 
       buf        =  ''

test/grid_file_system_test.rb

@@ -9,8 +9,8 @@ class GridFileSystemTest < Test::Unit::TestCase
     end
 
     teardown do
-      @db['fs.files'].remove
-      @db['fs.chunks'].remove
+      @db.drop_collection('fs.files')
+      @db.drop_collection('fs.chunks')
     end
 
     context "When reading:" do

test/grid_io_test.rb

@@ -33,6 +33,39 @@ class GridIOTest < Test::Unit::TestCase
       end
     end
 
+    context "Seeking" do
+      setup do
+        @filename = 'test'
+        @mode     = 'w'
+        @data     = "1" * 1024 * 1024
+        @file = GridIO.new(@files, @chunks, @filename, @mode)
+        @file.write(@data)
+        @file.close
+      end
+
+      should "read all data using read_length and then be able to seek" do
+        file = GridIO.new(@files, @chunks, nil, "r", :query => {:_id => @file.files_id})
+        assert_equal @data, file.read(1024 * 1024)
+        file.seek(0)
+        assert_equal @data, file.read
+      end
+
+      should "read all data using read_all and then be able to seek" do
+        file = GridIO.new(@files, @chunks, nil, "r", :query => {:_id => @file.files_id})
+        assert_equal @data, file.read
+        file.seek(0)
+        assert_equal @data, file.read
+        file.seek(1024 * 512)
+        assert_equal 524288, file.file_position
+        assert_equal @data.length / 2, file.read.length
+        assert_equal 1048576, file.file_position
+        assert_nil file.read
+        file.seek(1024 * 512)
+        assert_equal 524288, file.file_position
+      end
+
+    end
+
     context "Grid MD5 check" do
       should "run in safe mode" do
         file = GridIO.new(@files, @chunks, 'smallfile', 'w', :safe => true)