Satisfy IO#readpartial API

lib/http/connection.rb

@@ -34,7 +34,7 @@ def initialize(req, options)
       @pending_request      = false
       @pending_response     = false
       @failed_proxy_connect = false
-      @buffer               = "".b
+      @buffer               = String.new(capacity: BUFFER_SIZE, encoding: Encoding::BINARY)
 
       @parser = Response::Parser.new
 
@@ -89,18 +89,19 @@ def send_request(req)
     # Read a chunk of the body
     #
     # @return [String] data chunk
-    # @return [nil] when no more data left
-    def readpartial(size = BUFFER_SIZE)
-      return unless @pending_response
+    # @raise [EOFError] when there's no more data left
+    def readpartial(size = BUFFER_SIZE, outbuf = nil)
+      raise EOFError unless @pending_response
 
       chunk = @parser.read(size)
-      return chunk if chunk
 
-      finished = (read_more(size) == :eof) || @parser.finished?
-      chunk    = @parser.read(size)
-      finish_response if finished
+      unless chunk
+        finished = (read_more(size) == :eof) || @parser.finished?
+        chunk    = @parser.read(size) || String.new(encoding: Encoding::BINARY)
+        finish_response if finished
+      end
 
-      chunk || "".b
+      outbuf ? outbuf.replace(chunk) : chunk
     end
 
     # Reads data from socket up until headers are loaded

lib/http/response/body.rb

@@ -45,14 +45,16 @@ def to_s
 
         raise StateError, "body is being streamed" unless @streaming.nil?
 
-        begin
-          @streaming  = false
-          @contents   = String.new("", encoding: @encoding)
+        @streaming  = false
+        @contents   = String.new("", encoding: @encoding)
 
+        begin
           while (chunk = @stream.readpartial)
             @contents << String.new(chunk, encoding: @encoding)
             chunk = nil # deallocate string
           end
+        rescue EOFError
+          # do nothing
         rescue
           @contents = nil
           raise

spec/lib/http/connection_spec.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "stringio"
+
 RSpec.describe HTTP::Connection do
   let(:req) do
     HTTP::Request.new(
@@ -77,12 +79,38 @@
     it "reads data in parts" do
       connection.read_headers!
       buffer = String.new
-      while (s = connection.readpartial(3))
-        expect(connection.finished_request?).to be false if s != ""
-        buffer << s
+
+      begin
+        while (s = connection.readpartial(3))
+          expect(connection.finished_request?).to be false if s != ""
+          buffer << s
+        end
+      rescue EOFError
       end
+
       expect(buffer).to eq "1234567890"
       expect(connection.finished_request?).to be true
     end
+
+    it "fill outbuf when present" do
+      connection.read_headers!
+      outbuf = String.new
+      buffer = String.new
+
+      begin
+        buffer << outbuf while connection.readpartial(2, outbuf)
+      rescue EOFError
+      end
+
+      expect(buffer).to eq "1234567890"
+    end
+
+    it "can be used with IO.copy_stream" do
+      output = StringIO.new
+
+      IO.copy_stream(connection, output)
+
+      expect(output.string).to eq "1234567890"
+    end
   end
 end