From 34ad9f9e638163039405f2a6ac1e33a986084725 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Thu, 14 Dec 2017 17:51:59 +0700
Subject: [PATCH] when the stream write deadline expires, return the data
 length written

---
 stream.go      |  7 ++-----
 stream_test.go | 25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/stream.go b/stream.go
index 6dacfd3f..273e4efc 100644
--- a/stream.go
+++ b/stream.go
@@ -243,13 +243,10 @@ func (s *stream) Write(p []byte) (int, error) {
 		s.mutex.Lock()
 	}
 
-	if err != nil {
-		return 0, err
-	}
 	if s.err != nil {
-		return len(p) - len(s.dataForWriting), s.err
+		err = s.err
 	}
-	return len(p), nil
+	return len(p) - len(s.dataForWriting), err
 }
 
 func (s *stream) GetWriteOffset() protocol.ByteCount {
diff --git a/stream_test.go b/stream_test.go
index 5bc197cb..617de864 100644
--- a/stream_test.go
+++ b/stream_test.go
@@ -927,6 +927,31 @@ var _ = Describe("Stream", func() {
 				Expect(time.Now()).To(BeTemporally("~", deadline, scaleDuration(20*time.Millisecond)))
 			})
 
+			It("returns the number of bytes written, when the deadline expires", func() {
+				mockFC.EXPECT().SendWindowSize().Return(protocol.ByteCount(10000)).AnyTimes()
+				mockFC.EXPECT().AddBytesSent(gomock.Any())
+				deadline := time.Now().Add(scaleDuration(50 * time.Millisecond))
+				str.SetWriteDeadline(deadline)
+				var n int
+				writeReturned := make(chan struct{})
+				go func() {
+					defer GinkgoRecover()
+					var err error
+					n, err = strWithTimeout.Write(bytes.Repeat([]byte{0}, 100))
+					Expect(err).To(MatchError(errDeadline))
+					Expect(time.Now()).To(BeTemporally("~", deadline, scaleDuration(20*time.Millisecond)))
+					close(writeReturned)
+				}()
+				var frame *wire.StreamFrame
+				Eventually(func() *wire.StreamFrame {
+					defer GinkgoRecover()
+					frame = str.PopStreamFrame(50)
+					return frame
+				}).ShouldNot(BeNil())
+				Eventually(writeReturned, scaleDuration(80*time.Millisecond)).Should(BeClosed())
+				Expect(n).To(BeEquivalentTo(frame.DataLen()))
+			})
+
 			It("doesn't unblock if the deadline is changed before the first one expires", func() {
 				deadline1 := time.Now().Add(scaleDuration(50 * time.Millisecond))
 				deadline2 := time.Now().Add(scaleDuration(100 * time.Millisecond))