1 files changed, 38 insertions, 0 deletions
diff --git a/libgo/go/compress/gzip/gzip_test.go b/libgo/go/compress/gzip/gzip_test.go
index 865c529f55c..e16aba1572d 100644
--- a/libgo/go/compress/gzip/gzip_test.go
+++ b/libgo/go/compress/gzip/gzip_test.go
@@ -7,6 +7,7 @@ package gzip
 import (
 	"bufio"
 	"bytes"
+	"io"
 	"io/ioutil"
 	"reflect"
 	"testing"
@@ -233,3 +234,40 @@ func TestWriterReset(t *testing.T) {
 		t.Errorf("buf2 %q != original buf of %q", buf2.String(), buf.String())
 	}
 }
+
+type limitedWriter struct {
+	N int
+}
+
+func (l *limitedWriter) Write(p []byte) (n int, err error) {
+	if n := l.N; n < len(p) {
+		l.N = 0
+		return n, io.ErrShortWrite
+	}
+	l.N -= len(p)
+	return len(p), nil
+}
+
+// Write should never return more bytes than the input slice.
+func TestLimitedWrite(t *testing.T) {
+	msg := []byte("a")
+
+	for lim := 2; lim < 20; lim++ {
+		z := NewWriter(&limitedWriter{lim})
+		if n, _ := z.Write(msg); n > len(msg) {
+			t.Errorf("Write() = %d, want %d or less", n, len(msg))
+		}
+
+		z.Reset(&limitedWriter{lim})
+		z.Header = Header{
+			Comment: "comment",
+			Extra:   []byte("extra"),
+			ModTime: time.Now(),
+			Name:    "name",
+			OS:      1,
+		}
+		if n, _ := z.Write(msg); n > len(msg) {
+			t.Errorf("Write() = %d, want %d or less", n, len(msg))
+		}
+	}
+}