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Strip extended-timestap extra block in zip2zip.

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The extended-timestap extra block changes between Local File Header and
Central Directory. We have to strip it out to avoid mis-filling during
zip2zip.

Bug: b/65455145
Test: add unit-test.
Change-Id: I17e3f6c10fd6a068019620b4426f6042f6fac317
This commit is contained in:
Nan Zhang
2017-09-19 17:13:11 -07:00
parent 8eded0ac86
commit 10e8e93710
2 changed files with 21 additions and 11 deletions
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25
third_party/zip/android.go vendored
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@@ -20,6 +20,7 @@ import (
)
const DataDescriptorFlag = 0x8
const ExtendedTimeStampTag = 0x5455
func (w *Writer) CopyFrom(orig *File, newName string) error {
if w.last != nil && !w.last.closed {
@@ -33,11 +34,9 @@ func (w *Writer) CopyFrom(orig *File, newName string) error {
fileHeader.Name = newName
fh := &fileHeader
// The zip64 extras change between the Central Directory and Local File Header, while we use
// the same structure for both. The Local File Haeder is taken care of by us writing a data
// descriptor with the zip64 values. The Central Directory Entry is written by Close(), where
// the zip64 extra is automatically created and appended when necessary.
fh.Extra = stripZip64Extras(fh.Extra)
// In some cases, we need strip the extras if it change between Central Directory
// and Local File Header.
fh.Extra = stripExtras(fh.Extra)
h := &header{
FileHeader: fh,
@@ -48,8 +47,6 @@ func (w *Writer) CopyFrom(orig *File, newName string) error {
if err := writeHeader(w.cw, fh); err != nil {
return err
}
// Copy data
dataOffset, err := orig.DataOffset()
if err != nil {
return err
@@ -79,8 +76,16 @@ func (w *Writer) CopyFrom(orig *File, newName string) error {
return err
}
// Strip any Zip64 extra fields
func stripZip64Extras(input []byte) []byte {
// The zip64 extras change between the Central Directory and Local File Header, while we use
// the same structure for both. The Local File Haeder is taken care of by us writing a data
// descriptor with the zip64 values. The Central Directory Entry is written by Close(), where
// the zip64 extra is automatically created and appended when necessary.
//
// The extended-timestamp extra block changes between the Central Directory Header and Local
// File Header.
// Extended-Timestamp extra(LFH): <tag-size-flag-modtime-actime-changetime>
// Extended-Timestamp extra(CDH): <tag-size-flag-modtime>
func stripExtras(input []byte) []byte {
ret := []byte{}
for len(input) >= 4 {
@@ -90,7 +95,7 @@ func stripZip64Extras(input []byte) []byte {
if int(size) > len(r) {
break
}
if tag != zip64ExtraId {
if tag != zip64ExtraId && tag != ExtendedTimeStampTag {
ret = append(ret, input[:4+size]...)
}
input = input[4+size:]