From d3f95be85571a643fe0fb8d9428a03fb70a540e1 Mon Sep 17 00:00:00 2001
From: Ondrej Kokes <ondrej.kokes@gmail.com>
Date: Wed, 14 Sep 2022 20:56:17 +0200
Subject: [PATCH] return write error when encoding header fields (#28)

---
 encoder.go      |  4 ++--
 encoder_test.go | 25 +++++++++++++++++++++++--
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/encoder.go b/encoder.go
index 13e0ad2..ad69535 100644
--- a/encoder.go
+++ b/encoder.go
@@ -51,9 +51,9 @@ func (e *Encoder) WriteField(f HeaderField) error {
 		e.writeLiteralFieldWithoutNameReference(f)
 	}
 
-	e.w.Write(e.buf)
+	_, err := e.w.Write(e.buf)
 	e.buf = e.buf[:0]
-	return nil
+	return err
 }
 
 // Close declares that the encoding is complete and resets the Encoder
diff --git a/encoder_test.go b/encoder_test.go
index 493f621..37165a6 100644
--- a/encoder_test.go
+++ b/encoder_test.go
@@ -2,6 +2,7 @@ package qpack
 
 import (
 	"bytes"
+	"io"
 
 	"golang.org/x/net/http2/hpack"
 
@@ -9,14 +10,28 @@ import (
 	. "github.com/onsi/gomega"
 )
 
+// errWriter wraps bytes.Buffer and optionally fails on every write
+// useful for testing misbehaving writers
+type errWriter struct {
+	bytes.Buffer
+	fail bool
+}
+
+func (ew *errWriter) Write(b []byte) (int, error) {
+	if ew.fail {
+		return 0, io.ErrClosedPipe
+	}
+	return ew.Buffer.Write(b)
+}
+
 var _ = Describe("Encoder", func() {
 	var (
 		encoder *Encoder
-		output  *bytes.Buffer
+		output  *errWriter
 	)
 
 	BeforeEach(func() {
-		output = &bytes.Buffer{}
+		output = &errWriter{}
 		encoder = NewEncoder(output)
 	})
 
@@ -82,6 +97,12 @@ var _ = Describe("Encoder", func() {
 		Expect(data).To(BeEmpty())
 	})
 
+	It("encodes fails to encode when writer errs", func() {
+		hf := HeaderField{Name: "foobar", Value: "lorem ipsum"}
+		output.fail = true
+		Expect(encoder.WriteField(hf)).To(MatchError("io: read/write on closed pipe"))
+	})
+
 	It("encodes multiple fields", func() {
 		hf1 := HeaderField{Name: "foobar", Value: "lorem ipsum"}
 		hf2 := HeaderField{Name: "raboof", Value: "dolor sit amet"}