Strip zip64 extras after writing local header when copying

writeHeader generates zip64 extras that are correct for the local
header, but incorrect for the central directory header.  Strip the
extras again after writeHeader so that the central directory header
extras are recreated correctly.

Test: Zip2Zip64
Bug: 296314205
Change-Id: I1ca6a5745a9f97426df6c111db444facdfa25b2e

2 files changed, 55 insertions, 0 deletions

diff --git a/cmd/zip2zip/zip2zip_test.go b/cmd/zip2zip/zip2zip_test.go
index c238098ec..85a69efeb 100644
--- a/cmd/zip2zip/zip2zip_test.go
+++ b/cmd/zip2zip/zip2zip_test.go
@@ -471,6 +471,56 @@ func TestZip2Zip(t *testing.T) {
 	}
 }
 
+// TestZip2Zip64 tests that zip2zip on zip file larger than 4GB produces a valid zip file.
+func TestZip2Zip64(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping slow test in short mode")
+	}
+	inputBuf := &bytes.Buffer{}
+	outputBuf := &bytes.Buffer{}
+
+	inputWriter := zip.NewWriter(inputBuf)
+	w, err := inputWriter.CreateHeaderAndroid(&zip.FileHeader{
+		Name:   "a",
+		Method: zip.Store,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	buf := make([]byte, 4*1024*1024)
+	for i := 0; i < 1025; i++ {
+		w.Write(buf)
+	}
+	w, err = inputWriter.CreateHeaderAndroid(&zip.FileHeader{
+		Name:   "b",
+		Method: zip.Store,
+	})
+	for i := 0; i < 1025; i++ {
+		w.Write(buf)
+	}
+	inputWriter.Close()
+	inputBytes := inputBuf.Bytes()
+
+	inputReader, err := zip.NewReader(bytes.NewReader(inputBytes), int64(len(inputBytes)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	outputWriter := zip.NewWriter(outputBuf)
+	err = zip2zip(inputReader, outputWriter, false, false, false,
+		nil, nil, nil, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	outputWriter.Close()
+	outputBytes := outputBuf.Bytes()
+	_, err = zip.NewReader(bytes.NewReader(outputBytes), int64(len(outputBytes)))
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestConstantPartOfPattern(t *testing.T) {
 	testCases := []struct{ in, out string }{
 		{
diff --git a/third_party/zip/android.go b/third_party/zip/android.go
index 0f41f6200..b97215689 100644
--- a/third_party/zip/android.go
+++ b/third_party/zip/android.go
@@ -56,6 +56,11 @@ func (w *Writer) CopyFrom(orig *File, newName string) error {
 	if err := writeHeader(w.cw, fh); err != nil {
 		return err
 	}
+
+	// Strip the extras again in case writeHeader added the local file header extras that are incorrect for the
+	// central directory.
+	fh.Extra = stripExtras(fh.Extra)
+
 	dataOffset, err := orig.DataOffset()
 	if err != nil {
 		return err