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zip.go
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zip.go
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package archiver
import (
"archive/zip"
"bytes"
"context"
"errors"
"fmt"
"io"
"io/fs"
"log"
"path"
"strings"
"github.com/dsnet/compress/bzip2"
"github.com/klauspost/compress/zstd"
"github.com/ulikunitz/xz"
"golang.org/x/text/encoding"
"golang.org/x/text/encoding/charmap"
"golang.org/x/text/encoding/japanese"
"golang.org/x/text/encoding/korean"
"golang.org/x/text/encoding/simplifiedchinese"
"golang.org/x/text/encoding/traditionalchinese"
"golang.org/x/text/encoding/unicode"
)
func init() {
RegisterFormat(Zip{})
// TODO: What about custom flate levels too
zip.RegisterCompressor(ZipMethodBzip2, func(out io.Writer) (io.WriteCloser, error) {
return bzip2.NewWriter(out, &bzip2.WriterConfig{ /*TODO: Level: z.CompressionLevel*/ })
})
zip.RegisterCompressor(ZipMethodZstd, func(out io.Writer) (io.WriteCloser, error) {
return zstd.NewWriter(out)
})
zip.RegisterCompressor(ZipMethodXz, func(out io.Writer) (io.WriteCloser, error) {
return xz.NewWriter(out)
})
zip.RegisterDecompressor(ZipMethodBzip2, func(r io.Reader) io.ReadCloser {
bz2r, err := bzip2.NewReader(r, nil)
if err != nil {
return nil
}
return bz2r
})
zip.RegisterDecompressor(ZipMethodZstd, func(r io.Reader) io.ReadCloser {
zr, err := zstd.NewReader(r)
if err != nil {
return nil
}
return zr.IOReadCloser()
})
zip.RegisterDecompressor(ZipMethodXz, func(r io.Reader) io.ReadCloser {
xr, err := xz.NewReader(r)
if err != nil {
return nil
}
return io.NopCloser(xr)
})
}
type Zip struct {
// Only compress files which are not already in a
// compressed format (determined simply by examining
// file extension).
SelectiveCompression bool
// The method or algorithm for compressing stored files.
Compression uint16
// If true, errors encountered during reading or writing
// a file within an archive will be logged and the
// operation will continue on remaining files.
ContinueOnError bool
// For files in zip archives that do not have UTF-8
// encoded filenames and comments, specify the character
// encoding here.
TextEncoding string
}
func (z Zip) Name() string { return ".zip" }
func (z Zip) Match(filename string, stream io.Reader) (MatchResult, error) {
var mr MatchResult
// match filename
if strings.Contains(strings.ToLower(filename), z.Name()) {
mr.ByName = true
}
// match file header
buf, err := readAtMost(stream, len(zipHeader))
if err != nil {
return mr, err
}
mr.ByStream = bytes.Equal(buf, zipHeader)
return mr, nil
}
func (z Zip) Archive(ctx context.Context, output io.Writer, files []File) error {
zw := zip.NewWriter(output)
defer zw.Close()
for i, file := range files {
if err := z.archiveOneFile(ctx, zw, i, file); err != nil {
return err
}
}
return nil
}
func (z Zip) ArchiveAsync(ctx context.Context, output io.Writer, files <-chan File) error {
zw := zip.NewWriter(output)
defer zw.Close()
var i int
for file := range files {
if err := z.archiveOneFile(ctx, zw, i, file); err != nil {
if z.ContinueOnError && ctx.Err() == nil { // context errors should always abort
log.Printf("[ERROR] %v", err)
continue
}
return err
}
i++
}
return nil
}
func (z Zip) archiveOneFile(ctx context.Context, zw *zip.Writer, idx int, file File) error {
if err := ctx.Err(); err != nil {
return err // honor context cancellation
}
hdr, err := zip.FileInfoHeader(file)
if err != nil {
return fmt.Errorf("getting info for file %d: %s: %w", idx, file.Name(), err)
}
hdr.Name = file.NameInArchive // complete path, since FileInfoHeader() only has base name
// customize header based on file properties
if file.IsDir() {
if !strings.HasSuffix(hdr.Name, "/") {
hdr.Name += "/" // required
}
hdr.Method = zip.Store
} else if z.SelectiveCompression {
// only enable compression on compressable files
ext := strings.ToLower(path.Ext(hdr.Name))
if _, ok := compressedFormats[ext]; ok {
hdr.Method = zip.Store
} else {
hdr.Method = z.Compression
}
}
hdr.Modified = file.ModTime()
w, err := zw.CreateHeader(hdr)
if err != nil {
return fmt.Errorf("creating header for file %d: %s: %w", idx, file.Name(), err)
}
// directories have no file body
if file.IsDir() {
return nil
}
if err := openAndCopyFile(file, w); err != nil {
return fmt.Errorf("writing file %d: %s: %w", idx, file.Name(), err)
}
return nil
}
// Extract extracts files from z, implementing the Extractor interface. Uniquely, however,
// sourceArchive must be an io.ReaderAt and io.Seeker, which are oddly disjoint interfaces
// from io.Reader which is what the method signature requires. We chose this signature for
// the interface because we figure you can Read() from anything you can ReadAt() or Seek()
// with. Due to the nature of the zip archive format, if sourceArchive is not an io.Seeker
// and io.ReaderAt, an error is returned.
func (z Zip) Extract(ctx context.Context, sourceArchive io.Reader, pathsInArchive []string, handleFile FileHandler) error {
sra, ok := sourceArchive.(seekReaderAt)
if !ok {
return fmt.Errorf("input type must be an io.ReaderAt and io.Seeker because of zip format constraints")
}
size, err := streamSizeBySeeking(sra)
if err != nil {
return fmt.Errorf("determining stream size: %w", err)
}
zr, err := zip.NewReader(sra, size)
if err != nil {
return err
}
// important to initialize to non-nil, empty value due to how fileIsIncluded works
skipDirs := skipList{}
for i, f := range zr.File {
if err := ctx.Err(); err != nil {
return err // honor context cancellation
}
// ensure filename and comment are UTF-8 encoded (issue #147 and PR #305)
z.decodeText(&f.FileHeader)
if !fileIsIncluded(pathsInArchive, f.Name) {
continue
}
if fileIsIncluded(skipDirs, f.Name) {
continue
}
file := File{
FileInfo: f.FileInfo(),
Header: f.FileHeader,
NameInArchive: f.Name,
Open: func() (io.ReadCloser, error) { return f.Open() },
}
err := handleFile(ctx, file)
if errors.Is(err, fs.SkipDir) {
// if a directory, skip this path; if a file, skip the folder path
dirPath := f.Name
if !file.IsDir() {
dirPath = path.Dir(f.Name) + "/"
}
skipDirs.add(dirPath)
} else if err != nil {
return fmt.Errorf("handling file %d: %s: %w", i, f.Name, err)
}
}
return nil
}
// decodeText decodes the name and comment fields from hdr into UTF-8.
// It is a no-op if the text is already UTF-8 encoded or if z.TextEncoding
// is not specified.
func (z Zip) decodeText(hdr *zip.FileHeader) {
if hdr.NonUTF8 && z.TextEncoding != "" {
filename, err := decodeText(hdr.Name, z.TextEncoding)
if err == nil {
hdr.Name = filename
}
if hdr.Comment != "" {
comment, err := decodeText(hdr.Comment, z.TextEncoding)
if err == nil {
hdr.Comment = comment
}
}
}
}
type seekReaderAt interface {
io.ReaderAt
io.Seeker
}
func streamSizeBySeeking(s io.Seeker) (int64, error) {
currentPosition, err := s.Seek(0, io.SeekCurrent)
if err != nil {
return 0, fmt.Errorf("getting current offset: %w", err)
}
maxPosition, err := s.Seek(0, io.SeekEnd)
if err != nil {
return 0, fmt.Errorf("fast-forwarding to end: %w", err)
}
_, err = s.Seek(currentPosition, io.SeekStart)
if err != nil {
return 0, fmt.Errorf("returning to prior offset %d: %w", currentPosition, err)
}
return maxPosition, nil
}
// Additional compression methods not offered by archive/zip.
// See https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT section 4.4.5.
const (
ZipMethodBzip2 = 12
// TODO: LZMA: Disabled - because 7z isn't able to unpack ZIP+LZMA ZIP+LZMA2 archives made this way - and vice versa.
// ZipMethodLzma = 14
ZipMethodZstd = 93
ZipMethodXz = 95
)
// compressedFormats is a (non-exhaustive) set of lowercased
// file extensions for formats that are typically already
// compressed. Compressing files that are already compressed
// is inefficient, so use this set of extensions to avoid that.
var compressedFormats = map[string]struct{}{
".7z": {},
".avi": {},
".br": {},
".bz2": {},
".cab": {},
".docx": {},
".gif": {},
".gz": {},
".jar": {},
".jpeg": {},
".jpg": {},
".lz": {},
".lz4": {},
".lzma": {},
".m4v": {},
".mov": {},
".mp3": {},
".mp4": {},
".mpeg": {},
".mpg": {},
".png": {},
".pptx": {},
".rar": {},
".sz": {},
".tbz2": {},
".tgz": {},
".tsz": {},
".txz": {},
".xlsx": {},
".xz": {},
".zip": {},
".zipx": {},
}
var encodings = map[string]encoding.Encoding{
"ibm866": charmap.CodePage866,
"iso8859_2": charmap.ISO8859_2,
"iso8859_3": charmap.ISO8859_3,
"iso8859_4": charmap.ISO8859_4,
"iso8859_5": charmap.ISO8859_5,
"iso8859_6": charmap.ISO8859_6,
"iso8859_7": charmap.ISO8859_7,
"iso8859_8": charmap.ISO8859_8,
"iso8859_8I": charmap.ISO8859_8I,
"iso8859_10": charmap.ISO8859_10,
"iso8859_13": charmap.ISO8859_13,
"iso8859_14": charmap.ISO8859_14,
"iso8859_15": charmap.ISO8859_15,
"iso8859_16": charmap.ISO8859_16,
"koi8r": charmap.KOI8R,
"koi8u": charmap.KOI8U,
"macintosh": charmap.Macintosh,
"windows874": charmap.Windows874,
"windows1250": charmap.Windows1250,
"windows1251": charmap.Windows1251,
"windows1252": charmap.Windows1252,
"windows1253": charmap.Windows1253,
"windows1254": charmap.Windows1254,
"windows1255": charmap.Windows1255,
"windows1256": charmap.Windows1256,
"windows1257": charmap.Windows1257,
"windows1258": charmap.Windows1258,
"macintoshcyrillic": charmap.MacintoshCyrillic,
"gbk": simplifiedchinese.GBK,
"gb18030": simplifiedchinese.GB18030,
"big5": traditionalchinese.Big5,
"eucjp": japanese.EUCJP,
"iso2022jp": japanese.ISO2022JP,
"shiftjis": japanese.ShiftJIS,
"euckr": korean.EUCKR,
"utf16be": unicode.UTF16(unicode.BigEndian, unicode.IgnoreBOM),
"utf16le": unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM),
}
// decodeText returns UTF-8 encoded text from the given charset.
// Thanks to @zxdvd for contributing non-UTF-8 encoding logic in
// #149, and to @pashifika for helping in #305.
func decodeText(input, charset string) (string, error) {
if enc, ok := encodings[charset]; ok {
return enc.NewDecoder().String(input)
}
return "", fmt.Errorf("unrecognized charset %s", charset)
}
var zipHeader = []byte("PK\x03\x04") // NOTE: headers of empty zip files might end with 0x05,0x06 or 0x06,0x06 instead of 0x03,0x04