6 files changed, 82 insertions, 11 deletions
diff --git a/src/pkg/archive/zip/reader.go b/src/pkg/archive/zip/reader.go
index 116737337..80ee03006 100644
--- a/src/pkg/archive/zip/reader.go
+++ b/src/pkg/archive/zip/reader.go
@@ -253,7 +253,7 @@ func readDirectoryHeader(f *File, r io.Reader) error {
 			}
 			if tag == zip64ExtraId {
 				// update directory values from the zip64 extra block
-				eb := readBuf(b)
+				eb := readBuf(b[:size])
 				if len(eb) >= 8 {
 					f.UncompressedSize64 = eb.uint64()
 				}
diff --git a/src/pkg/archive/zip/reader_test.go b/src/pkg/archive/zip/reader_test.go
index 78875ecbf..5652f3a50 100644
--- a/src/pkg/archive/zip/reader_test.go
+++ b/src/pkg/archive/zip/reader_test.go
@@ -235,6 +235,18 @@ var tests = []ZipTest{
 			},
 		},
 	},
+	// Another zip64 file with different Extras fields. (golang.org/issue/7069)
+	{
+		Name: "zip64-2.zip",
+		File: []ZipTestFile{
+			{
+				Name:    "README",
+				Content: []byte("This small file is in ZIP64 format.\n"),
+				Mtime:   "08-10-12 14:33:32",
+				Mode:    0644,
+			},
+		},
+	},
 }
 
 var crossPlatform = []ZipTestFile{
@@ -343,19 +355,13 @@ func readTestFile(t *testing.T, zt ZipTest, ft ZipTestFile, f *File) {
 
 	testFileMode(t, zt.Name, f, ft.Mode)
 
-	size0 := f.UncompressedSize
-
 	var b bytes.Buffer
 	r, err := f.Open()
 	if err != nil {
-		t.Error(err)
+		t.Errorf("%s: %v", zt.Name, err)
 		return
 	}
 
-	if size1 := f.UncompressedSize; size0 != size1 {
-		t.Errorf("file %q changed f.UncompressedSize from %d to %d", f.Name, size0, size1)
-	}
-
 	_, err = io.Copy(&b, r)
 	if err != ft.ContentErr {
 		t.Errorf("%s: copying contents: %v (want %v)", zt.Name, err, ft.ContentErr)
@@ -365,6 +371,14 @@ func readTestFile(t *testing.T, zt ZipTest, ft ZipTestFile, f *File) {
 	}
 	r.Close()
 
+	size := uint64(f.UncompressedSize)
+	if size == uint32max {
+		size = f.UncompressedSize64
+	}
+	if g := uint64(b.Len()); g != size {
+		t.Errorf("%v: read %v bytes but f.UncompressedSize == %v", f.Name, g, size)
+	}
+
 	var c []byte
 	if ft.Content != nil {
 		c = ft.Content
diff --git a/src/pkg/archive/zip/register.go b/src/pkg/archive/zip/register.go
index c046f081b..4211ec7af 100644
--- a/src/pkg/archive/zip/register.go
+++ b/src/pkg/archive/zip/register.go
@@ -6,6 +6,7 @@ package zip
 
 import (
 	"compress/flate"
+	"errors"
 	"io"
 	"io/ioutil"
 	"sync"
@@ -21,12 +22,50 @@ type Compressor func(io.Writer) (io.WriteCloser, error)
 // when they're finished reading.
 type Decompressor func(io.Reader) io.ReadCloser
 
+var flateWriterPool sync.Pool
+
+func newFlateWriter(w io.Writer) io.WriteCloser {
+	fw, ok := flateWriterPool.Get().(*flate.Writer)
+	if ok {
+		fw.Reset(w)
+	} else {
+		fw, _ = flate.NewWriter(w, 5)
+	}
+	return &pooledFlateWriter{fw: fw}
+}
+
+type pooledFlateWriter struct {
+	mu sync.Mutex // guards Close and Write
+	fw *flate.Writer
+}
+
+func (w *pooledFlateWriter) Write(p []byte) (n int, err error) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	if w.fw == nil {
+		return 0, errors.New("Write after Close")
+	}
+	return w.fw.Write(p)
+}
+
+func (w *pooledFlateWriter) Close() error {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	var err error
+	if w.fw != nil {
+		err = w.fw.Close()
+		flateWriterPool.Put(w.fw)
+		w.fw = nil
+	}
+	return err
+}
+
 var (
 	mu sync.RWMutex // guards compressor and decompressor maps
 
 	compressors = map[uint16]Compressor{
 		Store:   func(w io.Writer) (io.WriteCloser, error) { return &nopCloser{w}, nil },
-		Deflate: func(w io.Writer) (io.WriteCloser, error) { return flate.NewWriter(w, 5) },
+		Deflate: func(w io.Writer) (io.WriteCloser, error) { return newFlateWriter(w), nil },
 	}
 
 	decompressors = map[uint16]Decompressor{
diff --git a/src/pkg/archive/zip/struct.go b/src/pkg/archive/zip/struct.go
index 65e5238c3..cb28e8324 100644
--- a/src/pkg/archive/zip/struct.go
+++ b/src/pkg/archive/zip/struct.go
@@ -174,13 +174,13 @@ func timeToMsDosTime(t time.Time) (fDate uint16, fTime uint16) {
 	return
 }
 
-// ModTime returns the modification time.
+// ModTime returns the modification time in UTC.
 // The resolution is 2s.
 func (h *FileHeader) ModTime() time.Time {
 	return msDosTimeToTime(h.ModifiedDate, h.ModifiedTime)
 }
 
-// SetModTime sets the ModifiedTime and ModifiedDate fields to the given time.
+// SetModTime sets the ModifiedTime and ModifiedDate fields to the given time in UTC.
 // The resolution is 2s.
 func (h *FileHeader) SetModTime(t time.Time) {
 	h.ModifiedDate, h.ModifiedTime = timeToMsDosTime(t)
diff --git a/src/pkg/archive/zip/testdata/zip64-2.zip b/src/pkg/archive/zip/testdata/zip64-2.zip
new file mode 100644
index 000000000..f844e3537
--- /dev/null
+++ b/src/pkg/archive/zip/testdata/zip64-2.zip
diff --git a/src/pkg/archive/zip/writer_test.go b/src/pkg/archive/zip/writer_test.go
index 8b1c4dfd2..4bfa87080 100644
--- a/src/pkg/archive/zip/writer_test.go
+++ b/src/pkg/archive/zip/writer_test.go
@@ -125,3 +125,21 @@ func testReadFile(t *testing.T, f *File, wt *WriteTest) {
 		t.Errorf("File contents %q, want %q", b, wt.Data)
 	}
 }
+
+func BenchmarkCompressedZipGarbage(b *testing.B) {
+	b.ReportAllocs()
+	var buf bytes.Buffer
+	bigBuf := bytes.Repeat([]byte("a"), 1<<20)
+	for i := 0; i < b.N; i++ {
+		buf.Reset()
+		zw := NewWriter(&buf)
+		for j := 0; j < 3; j++ {
+			w, _ := zw.CreateHeader(&FileHeader{
+				Name:   "foo",
+				Method: Deflate,
+			})
+			w.Write(bigBuf)
+		}
+		zw.Close()
+	}
+}