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zip.go
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zip.go
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package archiver
import (
"bytes"
"compress/flate"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"path"
"path/filepath"
"strings"
"github.com/dsnet/compress/bzip2"
"github.com/klauspost/compress/zip"
"github.com/klauspost/compress/zstd"
"github.com/ulikunitz/xz"
)
// ZipCompressionMethod Compression type
type ZipCompressionMethod uint16
// Compression methods.
// see https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT.
// Note LZMA: Disabled - because 7z isn't able to unpack ZIP+LZMA ZIP+LZMA2 archives made this way - and vice versa.
const (
Store ZipCompressionMethod = 0
Deflate ZipCompressionMethod = 8
BZIP2 ZipCompressionMethod = 12
LZMA ZipCompressionMethod = 14
ZSTD ZipCompressionMethod = 93
XZ ZipCompressionMethod = 95
)
// Zip provides facilities for operating ZIP archives.
// See https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT.
type Zip struct {
// The compression level to use, as described
// in the compress/flate package.
CompressionLevel int
// Whether to overwrite existing files; if false,
// an error is returned if the file exists.
OverwriteExisting bool
// Whether to make all the directories necessary
// to create a zip archive in the desired path.
MkdirAll bool
// If enabled, selective compression will only
// compress files which are not already in a
// compressed format; this is decided based
// simply on file extension.
SelectiveCompression bool
// A single top-level folder can be implicitly
// created by the Archive or Unarchive methods
// if the files to be added to the archive
// or the files to be extracted from the archive
// do not all have a common root. This roughly
// mimics the behavior of archival tools integrated
// into OS file browsers which create a subfolder
// to avoid unexpectedly littering the destination
// folder with potentially many files, causing a
// problematic cleanup/organization situation.
// This feature is available for both creation
// and extraction of archives, but may be slightly
// inefficient with lots and lots of files,
// especially on extraction.
ImplicitTopLevelFolder bool
// Strip number of leading paths. This feature is available
// only during unpacking of the entire archive.
StripComponents int
// If true, errors encountered during reading
// or writing a single file will be logged and
// the operation will continue on remaining files.
ContinueOnError bool
// Compression algorithm
FileMethod ZipCompressionMethod
zw *zip.Writer
zr *zip.Reader
ridx int
//decinitialized bool
}
// CheckExt ensures the file extension matches the format.
func (*Zip) CheckExt(filename string) error {
if !strings.HasSuffix(filename, ".zip") {
return fmt.Errorf("filename must have a .zip extension")
}
return nil
}
// Registering a global decompressor is not reentrant and may panic
func registerDecompressor(zr *zip.Reader) {
// register zstd decompressor
zr.RegisterDecompressor(uint16(ZSTD), func(r io.Reader) io.ReadCloser {
zr, err := zstd.NewReader(r)
if err != nil {
return nil
}
return zr.IOReadCloser()
})
zr.RegisterDecompressor(uint16(BZIP2), func(r io.Reader) io.ReadCloser {
bz2r, err := bzip2.NewReader(r, nil)
if err != nil {
return nil
}
return bz2r
})
zr.RegisterDecompressor(uint16(XZ), func(r io.Reader) io.ReadCloser {
xr, err := xz.NewReader(r)
if err != nil {
return nil
}
return ioutil.NopCloser(xr)
})
}
// CheckPath ensures the file extension matches the format.
func (*Zip) CheckPath(to, filename string) error {
to, _ = filepath.Abs(to) //explicit the destination folder to prevent that 'string.HasPrefix' check can be 'bypassed' when no destination folder is supplied in input
dest := filepath.Join(to, filename)
//prevent path traversal attacks
if !strings.HasPrefix(dest, to) {
return &IllegalPathError{AbsolutePath: dest, Filename: filename}
}
return nil
}
// Archive creates a .zip file at destination containing
// the files listed in sources. The destination must end
// with ".zip". File paths can be those of regular files
// or directories. Regular files are stored at the 'root'
// of the archive, and directories are recursively added.
func (z *Zip) Archive(sources []string, destination string) error {
err := z.CheckExt(destination)
if err != nil {
return fmt.Errorf("checking extension: %v", err)
}
if !z.OverwriteExisting && fileExists(destination) {
return fmt.Errorf("file already exists: %s", destination)
}
// make the folder to contain the resulting archive
// if it does not already exist
destDir := filepath.Dir(destination)
if z.MkdirAll && !fileExists(destDir) {
err := mkdir(destDir, 0755)
if err != nil {
return fmt.Errorf("making folder for destination: %v", err)
}
}
out, err := os.Create(destination)
if err != nil {
return fmt.Errorf("creating %s: %v", destination, err)
}
defer out.Close()
err = z.Create(out)
if err != nil {
return fmt.Errorf("creating zip: %v", err)
}
defer z.Close()
var topLevelFolder string
if z.ImplicitTopLevelFolder && multipleTopLevels(sources) {
topLevelFolder = folderNameFromFileName(destination)
}
for _, source := range sources {
err := z.writeWalk(source, topLevelFolder, destination)
if err != nil {
return fmt.Errorf("walking %s: %v", source, err)
}
}
return nil
}
// Unarchive unpacks the .zip file at source to destination.
// Destination will be treated as a folder name.
func (z *Zip) Unarchive(source, destination string) error {
if !fileExists(destination) && z.MkdirAll {
err := mkdir(destination, 0755)
if err != nil {
return fmt.Errorf("preparing destination: %v", err)
}
}
file, err := os.Open(source)
if err != nil {
return fmt.Errorf("opening source file: %v", err)
}
defer file.Close()
fileInfo, err := file.Stat()
if err != nil {
return fmt.Errorf("statting source file: %v", err)
}
err = z.Open(file, fileInfo.Size())
if err != nil {
return fmt.Errorf("opening zip archive for reading: %v", err)
}
defer z.Close()
// if the files in the archive do not all share a common
// root, then make sure we extract to a single subfolder
// rather than potentially littering the destination...
if z.ImplicitTopLevelFolder {
files := make([]string, len(z.zr.File))
for i := range z.zr.File {
files[i] = z.zr.File[i].Name
}
if multipleTopLevels(files) {
destination = filepath.Join(destination, folderNameFromFileName(source))
}
}
for {
err := z.extractNext(destination)
if err == io.EOF {
break
}
if err != nil {
if z.ContinueOnError || IsIllegalPathError(err) {
log.Printf("[ERROR] Reading file in zip archive: %v", err)
continue
}
return fmt.Errorf("reading file in zip archive: %v", err)
}
}
return nil
}
func (z *Zip) extractNext(to string) error {
f, err := z.Read()
if err != nil {
return err // don't wrap error; calling loop must break on io.EOF
}
defer f.Close()
header, ok := f.Header.(zip.FileHeader)
if !ok {
return fmt.Errorf("expected header to be zip.FileHeader but was %T", f.Header)
}
errPath := z.CheckPath(to, header.Name)
if errPath != nil {
return fmt.Errorf("checking path traversal attempt: %v", errPath)
}
if z.StripComponents > 0 {
if strings.Count(header.Name, "/") < z.StripComponents {
return nil // skip path with fewer components
}
for i := 0; i < z.StripComponents; i++ {
slash := strings.Index(header.Name, "/")
header.Name = header.Name[slash+1:]
}
}
return z.extractFile(f, to, &header)
}
func (z *Zip) extractFile(f File, to string, header *zip.FileHeader) error {
to = filepath.Join(to, header.Name)
// if a directory, no content; simply make the directory and return
if f.IsDir() {
return mkdir(to, f.Mode())
}
// do not overwrite existing files, if configured
if !z.OverwriteExisting && fileExists(to) {
return fmt.Errorf("file already exists: %s", to)
}
// extract symbolic links as symbolic links
if isSymlink(header.FileInfo()) {
// symlink target is the contents of the file
buf := new(bytes.Buffer)
_, err := io.Copy(buf, f)
if err != nil {
return fmt.Errorf("%s: reading symlink target: %v", header.Name, err)
}
return writeNewSymbolicLink(to, strings.TrimSpace(buf.String()))
}
return writeNewFile(to, f, f.Mode())
}
func (z *Zip) writeWalk(source, topLevelFolder, destination string) error {
sourceInfo, err := os.Stat(source)
if err != nil {
return fmt.Errorf("%s: stat: %v", source, err)
}
destAbs, err := filepath.Abs(destination)
if err != nil {
return fmt.Errorf("%s: getting absolute path of destination %s: %v", source, destination, err)
}
return filepath.Walk(source, func(fpath string, info os.FileInfo, err error) error {
handleErr := func(err error) error {
if z.ContinueOnError {
log.Printf("[ERROR] Walking %s: %v", fpath, err)
return nil
}
return err
}
if err != nil {
return handleErr(fmt.Errorf("traversing %s: %v", fpath, err))
}
if info == nil {
return handleErr(fmt.Errorf("%s: no file info", fpath))
}
// make sure we do not copy the output file into the output
// file; that results in an infinite loop and disk exhaustion!
fpathAbs, err := filepath.Abs(fpath)
if err != nil {
return handleErr(fmt.Errorf("%s: getting absolute path: %v", fpath, err))
}
if within(fpathAbs, destAbs) {
return nil
}
// build the name to be used within the archive
nameInArchive, err := makeNameInArchive(sourceInfo, source, topLevelFolder, fpath)
if err != nil {
return handleErr(err)
}
var file io.ReadCloser
if info.Mode().IsRegular() {
file, err = os.Open(fpath)
if err != nil {
return handleErr(fmt.Errorf("%s: opening: %v", fpath, err))
}
defer file.Close()
}
err = z.Write(File{
FileInfo: FileInfo{
FileInfo: info,
CustomName: nameInArchive,
},
ReadCloser: file,
})
if err != nil {
return handleErr(fmt.Errorf("%s: writing: %s", fpath, err))
}
return nil
})
}
// Create opens z for writing a ZIP archive to out.
func (z *Zip) Create(out io.Writer) error {
if z.zw != nil {
return fmt.Errorf("zip archive is already created for writing")
}
z.zw = zip.NewWriter(out)
if z.CompressionLevel != flate.DefaultCompression {
z.zw.RegisterCompressor(zip.Deflate, func(out io.Writer) (io.WriteCloser, error) {
return flate.NewWriter(out, z.CompressionLevel)
})
}
switch z.FileMethod {
case BZIP2:
z.zw.RegisterCompressor(uint16(BZIP2), func(out io.Writer) (io.WriteCloser, error) {
return bzip2.NewWriter(out, &bzip2.WriterConfig{Level: z.CompressionLevel})
})
case ZSTD:
z.zw.RegisterCompressor(uint16(ZSTD), func(out io.Writer) (io.WriteCloser, error) {
return zstd.NewWriter(out)
})
case XZ:
z.zw.RegisterCompressor(uint16(XZ), func(out io.Writer) (io.WriteCloser, error) {
return xz.NewWriter(out)
})
}
return nil
}
// Write writes f to z, which must have been opened for writing first.
func (z *Zip) Write(f File) error {
if z.zw == nil {
return fmt.Errorf("zip archive was not created for writing first")
}
if f.FileInfo == nil {
return fmt.Errorf("no file info")
}
if f.FileInfo.Name() == "" {
return fmt.Errorf("missing file name")
}
header, err := zip.FileInfoHeader(f)
if err != nil {
return fmt.Errorf("%s: getting header: %v", f.Name(), err)
}
if f.IsDir() {
header.Name += "/" // required - strangely no mention of this in zip spec? but is in godoc...
header.Method = zip.Store
} else {
ext := strings.ToLower(path.Ext(header.Name))
if _, ok := compressedFormats[ext]; ok && z.SelectiveCompression {
header.Method = zip.Store
} else {
header.Method = uint16(z.FileMethod)
}
}
writer, err := z.zw.CreateHeader(header)
if err != nil {
return fmt.Errorf("%s: making header: %w", f.Name(), err)
}
return z.writeFile(f, writer)
}
func (z *Zip) writeFile(f File, writer io.Writer) error {
if f.IsDir() {
return nil // directories have no contents
}
if isSymlink(f) {
// file body for symlinks is the symlink target
linkTarget, err := os.Readlink(f.Name())
if err != nil {
return fmt.Errorf("%s: readlink: %v", f.Name(), err)
}
_, err = writer.Write([]byte(filepath.ToSlash(linkTarget)))
if err != nil {
return fmt.Errorf("%s: writing symlink target: %v", f.Name(), err)
}
return nil
}
if f.ReadCloser == nil {
return fmt.Errorf("%s: no way to read file contents", f.Name())
}
_, err := io.Copy(writer, f)
if err != nil {
return fmt.Errorf("%s: copying contents: %w", f.Name(), err)
}
return nil
}
// Open opens z for reading an archive from in,
// which is expected to have the given size and
// which must be an io.ReaderAt.
func (z *Zip) Open(in io.Reader, size int64) error {
inRdrAt, ok := in.(io.ReaderAt)
if !ok {
return fmt.Errorf("reader must be io.ReaderAt")
}
if z.zr != nil {
return fmt.Errorf("zip archive is already open for reading")
}
var err error
z.zr, err = zip.NewReader(inRdrAt, size)
if err != nil {
return fmt.Errorf("creating reader: %v", err)
}
registerDecompressor(z.zr)
z.ridx = 0
return nil
}
// Read reads the next file from z, which must have
// already been opened for reading. If there are no
// more files, the error is io.EOF. The File must
// be closed when finished reading from it.
func (z *Zip) Read() (File, error) {
if z.zr == nil {
return File{}, fmt.Errorf("zip archive is not open")
}
if z.ridx >= len(z.zr.File) {
return File{}, io.EOF
}
// access the file and increment counter so that
// if there is an error processing this file, the
// caller can still iterate to the next file
zf := z.zr.File[z.ridx]
z.ridx++
file := File{
FileInfo: zf.FileInfo(),
Header: zf.FileHeader,
}
rc, err := zf.Open()
if err != nil {
return file, fmt.Errorf("%s: open compressed file: %v", zf.Name, err)
}
file.ReadCloser = rc
return file, nil
}
// Close closes the zip archive(s) opened by Create and Open.
func (z *Zip) Close() error {
if z.zr != nil {
z.zr = nil
}
if z.zw != nil {
zw := z.zw
z.zw = nil
return zw.Close()
}
return nil
}
// Walk calls walkFn for each visited item in archive.
func (z *Zip) Walk(archive string, walkFn WalkFunc) error {
zr, err := zip.OpenReader(archive)
if err != nil {
return fmt.Errorf("opening zip reader: %v", err)
}
defer zr.Close()
registerDecompressor(&zr.Reader)
for _, zf := range zr.File {
zfrc, err := zf.Open()
if err != nil {
if zfrc != nil {
zfrc.Close()
}
if z.ContinueOnError {
log.Printf("[ERROR] Opening %s: %v", zf.Name, err)
continue
}
return fmt.Errorf("opening %s: %v", zf.Name, err)
}
err = walkFn(File{
FileInfo: zf.FileInfo(),
Header: zf.FileHeader,
ReadCloser: zfrc,
})
zfrc.Close()
if err != nil {
if err == ErrStopWalk {
break
}
if z.ContinueOnError {
log.Printf("[ERROR] Walking %s: %v", zf.Name, err)
continue
}
return fmt.Errorf("walking %s: %v", zf.Name, err)
}
}
return nil
}
// Extract extracts a single file from the zip archive.
// If the target is a directory, the entire folder will
// be extracted into destination.
func (z *Zip) Extract(source, target, destination string) error {
// target refers to a path inside the archive, which should be clean also
target = path.Clean(target)
// if the target ends up being a directory, then
// we will continue walking and extracting files
// until we are no longer within that directory
var targetDirPath string
return z.Walk(source, func(f File) error {
zfh, ok := f.Header.(zip.FileHeader)
if !ok {
return fmt.Errorf("expected header to be zip.FileHeader but was %T", f.Header)
}
// importantly, cleaning the path strips tailing slash,
// which must be appended to folders within the archive
name := path.Clean(zfh.Name)
if f.IsDir() && target == name {
targetDirPath = path.Dir(name)
}
if within(target, zfh.Name) {
// either this is the exact file we want, or is
// in the directory we want to extract
// build the filename we will extract to
end, err := filepath.Rel(targetDirPath, zfh.Name)
if err != nil {
return fmt.Errorf("relativizing paths: %v", err)
}
joined := filepath.Join(destination, end)
err = z.extractFile(f, joined, &zfh)
if err != nil {
return fmt.Errorf("extracting file %s: %v", zfh.Name, err)
}
// if our target was not a directory, stop walk
if targetDirPath == "" {
return ErrStopWalk
}
} else if targetDirPath != "" {
// finished walking the entire directory
return ErrStopWalk
}
return nil
})
}
// Match returns true if the format of file matches this
// type's format. It should not affect reader position.
func (*Zip) Match(file io.ReadSeeker) (bool, error) {
currentPos, err := file.Seek(0, io.SeekCurrent)
if err != nil {
return false, err
}
_, err = file.Seek(0, 0)
if err != nil {
return false, err
}
defer func() {
_, _ = file.Seek(currentPos, io.SeekStart)
}()
buf := make([]byte, 4)
if n, err := file.Read(buf); err != nil || n < 4 {
return false, nil
}
return bytes.Equal(buf, []byte("PK\x03\x04")), nil
}
func (z *Zip) String() string { return "zip" }
// NewZip returns a new, default instance ready to be customized and used.
func NewZip() *Zip {
return &Zip{
CompressionLevel: flate.DefaultCompression,
MkdirAll: true,
SelectiveCompression: true,
FileMethod: Deflate,
}
}
// Compile-time checks to ensure type implements desired interfaces.
var (
_ = Reader(new(Zip))
_ = Writer(new(Zip))
_ = Archiver(new(Zip))
_ = Unarchiver(new(Zip))
_ = Walker(new(Zip))
_ = Extractor(new(Zip))
_ = Matcher(new(Zip))
_ = ExtensionChecker(new(Zip))
_ = FilenameChecker(new(Zip))
)
// 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 extension 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": {},
}
// DefaultZip is a default instance that is conveniently ready to use.
var DefaultZip = NewZip()