330 lines
9.0 KiB
Go
330 lines
9.0 KiB
Go
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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/*
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Package zip provides support for reading and writing password protected ZIP archives.
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See: http://www.pkware.com/documents/casestudies/APPNOTE.TXT
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This package does not support disk spanning.
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A note about ZIP64:
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To be backwards compatible the FileHeader has both 32 and 64 bit Size
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fields. The 64 bit fields will always contain the correct value and
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for normal archives both fields will be the same. For files requiring
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the ZIP64 format the 32 bit fields will be 0xffffffff and the 64 bit
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fields must be used instead.
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Can read/write password protected files that use Winzip's AES encryption method.
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See: http://www.winzip.com/aes_info.htm
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*/
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package zip
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import (
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"os"
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"path"
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"time"
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)
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// Compression methods.
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const (
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Store uint16 = 0
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Deflate uint16 = 8
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)
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const (
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fileHeaderSignature = 0x04034b50
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directoryHeaderSignature = 0x02014b50
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directoryEndSignature = 0x06054b50
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directory64LocSignature = 0x07064b50
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directory64EndSignature = 0x06064b50
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dataDescriptorSignature = 0x08074b50 // de-facto standard; required by OS X Finder
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fileHeaderLen = 30 // + filename + extra
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directoryHeaderLen = 46 // + filename + extra + comment
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directoryEndLen = 22 // + comment
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dataDescriptorLen = 16 // four uint32: descriptor signature, crc32, compressed size, size
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dataDescriptor64Len = 24 // descriptor with 8 byte sizes
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directory64LocLen = 20 //
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directory64EndLen = 56 // + extra
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// Constants for the first byte in CreatorVersion
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creatorFAT = 0
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creatorUnix = 3
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creatorNTFS = 11
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creatorVFAT = 14
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creatorMacOSX = 19
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// version numbers
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zipVersion20 = 20 // 2.0
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zipVersion45 = 45 // 4.5 (reads and writes zip64 archives)
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// limits for non zip64 files
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uint16max = (1 << 16) - 1
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uint32max = (1 << 32) - 1
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// extra header id's
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zip64ExtraId = 0x0001 // zip64 Extended Information Extra Field
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winzipAesExtraId = 0x9901 // winzip AES Extra Field
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)
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// FileHeader describes a file within a zip file.
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// See the zip spec for details.
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type FileHeader struct {
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// Name is the name of the file.
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// It must be a relative path: it must not start with a drive
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// letter (e.g. C:) or leading slash, and only forward slashes
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// are allowed.
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Name string
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CreatorVersion uint16
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ReaderVersion uint16
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Flags uint16
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Method uint16
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ModifiedTime uint16 // MS-DOS time
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ModifiedDate uint16 // MS-DOS date
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CRC32 uint32
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CompressedSize uint32 // Deprecated: Use CompressedSize64 instead.
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UncompressedSize uint32 // Deprecated: Use UncompressedSize64 instead.
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CompressedSize64 uint64
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UncompressedSize64 uint64
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Extra []byte
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ExternalAttrs uint32 // Meaning depends on CreatorVersion
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Comment string
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// DeferAuth being set to true will delay hmac auth/integrity
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// checks when decrypting a file meaning the reader will be
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// getting unauthenticated plaintext. It is recommended to leave
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// this set to false. For more detail:
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// https://www.imperialviolet.org/2014/06/27/streamingencryption.html
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// https://www.imperialviolet.org/2015/05/16/aeads.html
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DeferAuth bool
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password passwordFn // Returns the password to use when reading/writing
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ae uint16
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aesStrength byte
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}
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// FileInfo returns an os.FileInfo for the FileHeader.
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func (h *FileHeader) FileInfo() os.FileInfo {
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return headerFileInfo{h}
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}
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// headerFileInfo implements os.FileInfo.
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type headerFileInfo struct {
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fh *FileHeader
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}
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func (fi headerFileInfo) Name() string { return path.Base(fi.fh.Name) }
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func (fi headerFileInfo) Size() int64 {
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if fi.fh.UncompressedSize64 > 0 {
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return int64(fi.fh.UncompressedSize64)
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}
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return int64(fi.fh.UncompressedSize)
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}
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func (fi headerFileInfo) IsDir() bool { return fi.Mode().IsDir() }
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func (fi headerFileInfo) ModTime() time.Time { return fi.fh.ModTime() }
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func (fi headerFileInfo) Mode() os.FileMode { return fi.fh.Mode() }
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func (fi headerFileInfo) Sys() interface{} { return fi.fh }
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// FileInfoHeader creates a partially-populated FileHeader from an
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// os.FileInfo.
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// Because os.FileInfo's Name method returns only the base name of
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// the file it describes, it may be necessary to modify the Name field
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// of the returned header to provide the full path name of the file.
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func FileInfoHeader(fi os.FileInfo) (*FileHeader, error) {
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size := fi.Size()
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fh := &FileHeader{
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Name: fi.Name(),
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UncompressedSize64: uint64(size),
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}
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fh.SetModTime(fi.ModTime())
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fh.SetMode(fi.Mode())
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if fh.UncompressedSize64 > uint32max {
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fh.UncompressedSize = uint32max
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} else {
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fh.UncompressedSize = uint32(fh.UncompressedSize64)
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}
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return fh, nil
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}
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type directoryEnd struct {
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diskNbr uint32 // unused
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dirDiskNbr uint32 // unused
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dirRecordsThisDisk uint64 // unused
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directoryRecords uint64
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directorySize uint64
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directoryOffset uint64 // relative to file
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commentLen uint16
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comment string
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}
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// msDosTimeToTime converts an MS-DOS date and time into a time.Time.
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// The resolution is 2s.
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// See: http://msdn.microsoft.com/en-us/library/ms724247(v=VS.85).aspx
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func msDosTimeToTime(dosDate, dosTime uint16) time.Time {
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return time.Date(
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// date bits 0-4: day of month; 5-8: month; 9-15: years since 1980
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int(dosDate>>9+1980),
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time.Month(dosDate>>5&0xf),
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int(dosDate&0x1f),
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// time bits 0-4: second/2; 5-10: minute; 11-15: hour
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int(dosTime>>11),
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int(dosTime>>5&0x3f),
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int(dosTime&0x1f*2),
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0, // nanoseconds
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time.UTC,
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)
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}
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// timeToMsDosTime converts a time.Time to an MS-DOS date and time.
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// The resolution is 2s.
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// See: http://msdn.microsoft.com/en-us/library/ms724274(v=VS.85).aspx
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func timeToMsDosTime(t time.Time) (fDate uint16, fTime uint16) {
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t = t.In(time.UTC)
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fDate = uint16(t.Day() + int(t.Month())<<5 + (t.Year()-1980)<<9)
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fTime = uint16(t.Second()/2 + t.Minute()<<5 + t.Hour()<<11)
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return
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}
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// ModTime returns the modification time in UTC.
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// The resolution is 2s.
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func (h *FileHeader) ModTime() time.Time {
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return msDosTimeToTime(h.ModifiedDate, h.ModifiedTime)
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}
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// SetModTime sets the ModifiedTime and ModifiedDate fields to the given time in UTC.
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// The resolution is 2s.
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func (h *FileHeader) SetModTime(t time.Time) {
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h.ModifiedDate, h.ModifiedTime = timeToMsDosTime(t)
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}
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const (
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// Unix constants. The specification doesn't mention them,
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// but these seem to be the values agreed on by tools.
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s_IFMT = 0xf000
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s_IFSOCK = 0xc000
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s_IFLNK = 0xa000
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s_IFREG = 0x8000
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s_IFBLK = 0x6000
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s_IFDIR = 0x4000
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s_IFCHR = 0x2000
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s_IFIFO = 0x1000
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s_ISUID = 0x800
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s_ISGID = 0x400
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s_ISVTX = 0x200
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msdosDir = 0x10
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msdosReadOnly = 0x01
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)
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// Mode returns the permission and mode bits for the FileHeader.
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func (h *FileHeader) Mode() (mode os.FileMode) {
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switch h.CreatorVersion >> 8 {
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case creatorUnix, creatorMacOSX:
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mode = unixModeToFileMode(h.ExternalAttrs >> 16)
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case creatorNTFS, creatorVFAT, creatorFAT:
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mode = msdosModeToFileMode(h.ExternalAttrs)
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}
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if len(h.Name) > 0 && h.Name[len(h.Name)-1] == '/' {
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mode |= os.ModeDir
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}
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return mode
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}
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// SetMode changes the permission and mode bits for the FileHeader.
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func (h *FileHeader) SetMode(mode os.FileMode) {
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h.CreatorVersion = h.CreatorVersion&0xff | creatorUnix<<8
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h.ExternalAttrs = fileModeToUnixMode(mode) << 16
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// set MSDOS attributes too, as the original zip does.
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if mode&os.ModeDir != 0 {
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h.ExternalAttrs |= msdosDir
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}
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if mode&0200 == 0 {
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h.ExternalAttrs |= msdosReadOnly
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}
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}
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// isZip64 reports whether the file size exceeds the 32 bit limit
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func (fh *FileHeader) isZip64() bool {
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return fh.CompressedSize64 > uint32max || fh.UncompressedSize64 > uint32max
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}
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func msdosModeToFileMode(m uint32) (mode os.FileMode) {
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if m&msdosDir != 0 {
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mode = os.ModeDir | 0777
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} else {
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mode = 0666
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}
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if m&msdosReadOnly != 0 {
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mode &^= 0222
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}
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return mode
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}
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func fileModeToUnixMode(mode os.FileMode) uint32 {
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var m uint32
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switch mode & os.ModeType {
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default:
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m = s_IFREG
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case os.ModeDir:
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m = s_IFDIR
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case os.ModeSymlink:
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m = s_IFLNK
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case os.ModeNamedPipe:
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m = s_IFIFO
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case os.ModeSocket:
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m = s_IFSOCK
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case os.ModeDevice:
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if mode&os.ModeCharDevice != 0 {
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m = s_IFCHR
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} else {
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m = s_IFBLK
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}
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}
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if mode&os.ModeSetuid != 0 {
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m |= s_ISUID
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}
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if mode&os.ModeSetgid != 0 {
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m |= s_ISGID
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}
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if mode&os.ModeSticky != 0 {
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m |= s_ISVTX
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}
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return m | uint32(mode&0777)
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}
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func unixModeToFileMode(m uint32) os.FileMode {
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mode := os.FileMode(m & 0777)
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switch m & s_IFMT {
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case s_IFBLK:
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mode |= os.ModeDevice
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case s_IFCHR:
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mode |= os.ModeDevice | os.ModeCharDevice
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case s_IFDIR:
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mode |= os.ModeDir
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case s_IFIFO:
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mode |= os.ModeNamedPipe
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case s_IFLNK:
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mode |= os.ModeSymlink
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case s_IFREG:
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// nothing to do
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case s_IFSOCK:
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mode |= os.ModeSocket
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}
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if m&s_ISGID != 0 {
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mode |= os.ModeSetgid
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}
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if m&s_ISUID != 0 {
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mode |= os.ModeSetuid
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}
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if m&s_ISVTX != 0 {
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mode |= os.ModeSticky
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}
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return mode
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}
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