zip: github.com/alexmullins/zip Index | Examples | Files

package zip

import "github.com/alexmullins/zip"

Package zip provides support for reading and writing password protected ZIP archives.

See: http://www.pkware.com/documents/casestudies/APPNOTE.TXT

This package does not support disk spanning.

A note about ZIP64:

To be backwards compatible the FileHeader has both 32 and 64 bit Size fields. The 64 bit fields will always contain the correct value and for normal archives both fields will be the same. For files requiring the ZIP64 format the 32 bit fields will be 0xffffffff and the 64 bit fields must be used instead.

Can read/write password protected files that use Winzip's AES encryption method. See: http://www.winzip.com/aes_info.htm

Index

Examples

Package Files

crypto.go reader.go register.go struct.go writer.go

Constants

const (
    Store   uint16 = 0
    Deflate uint16 = 8
)

Compression methods.

Variables

var (
    ErrDecryption     = errors.New("zip: decryption error")
    ErrPassword       = errors.New("zip: invalid password")
    ErrAuthentication = errors.New("zip: authentication failed")
)

Encryption/Decryption Errors

var (
    ErrFormat    = errors.New("zip: not a valid zip file")
    ErrAlgorithm = errors.New("zip: unsupported compression algorithm")
    ErrChecksum  = errors.New("zip: checksum error")
)

func RegisterCompressor Uses

func RegisterCompressor(method uint16, comp Compressor)

RegisterCompressor registers custom compressors for a specified method ID. The common methods Store and Deflate are built in.

func RegisterDecompressor Uses

func RegisterDecompressor(method uint16, d Decompressor)

RegisterDecompressor allows custom decompressors for a specified method ID.

type Compressor Uses

type Compressor func(io.Writer) (io.WriteCloser, error)

A Compressor returns a compressing writer, writing to the provided writer. On Close, any pending data should be flushed.

type Decompressor Uses

type Decompressor func(io.Reader) io.ReadCloser

Decompressor is a function that wraps a Reader with a decompressing Reader. The decompressed ReadCloser is returned to callers who open files from within the archive. These callers are responsible for closing this reader when they're finished reading.

type File Uses

type File struct {
    FileHeader
    // contains filtered or unexported fields
}

func (*File) DataOffset Uses

func (f *File) DataOffset() (offset int64, err error)

DataOffset returns the offset of the file's possibly-compressed data, relative to the beginning of the zip file.

Most callers should instead use Open, which transparently decompresses data and verifies checksums.

func (*File) Open Uses

func (f *File) Open() (rc io.ReadCloser, err error)

Open returns a ReadCloser that provides access to the File's contents. Multiple files may be read concurrently.

type FileHeader Uses

type FileHeader struct {
    // Name is the name of the file.
    // It must be a relative path: it must not start with a drive
    // letter (e.g. C:) or leading slash, and only forward slashes
    // are allowed.
    Name string

    CreatorVersion     uint16
    ReaderVersion      uint16
    Flags              uint16
    Method             uint16
    ModifiedTime       uint16 // MS-DOS time
    ModifiedDate       uint16 // MS-DOS date
    CRC32              uint32
    CompressedSize     uint32 // Deprecated: Use CompressedSize64 instead.
    UncompressedSize   uint32 // Deprecated: Use UncompressedSize64 instead.
    CompressedSize64   uint64
    UncompressedSize64 uint64
    Extra              []byte
    ExternalAttrs      uint32 // Meaning depends on CreatorVersion
    Comment            string

    // DeferAuth being set to true will delay hmac auth/integrity
    // checks when decrypting a file meaning the reader will be
    // getting unauthenticated plaintext. It is recommended to leave
    // this set to false. For more detail:
    // https://www.imperialviolet.org/2014/06/27/streamingencryption.html
    // https://www.imperialviolet.org/2015/05/16/aeads.html
    DeferAuth bool
    // contains filtered or unexported fields
}

FileHeader describes a file within a zip file. See the zip spec for details.

func FileInfoHeader Uses

func FileInfoHeader(fi os.FileInfo) (*FileHeader, error)

FileInfoHeader creates a partially-populated FileHeader from an os.FileInfo. Because os.FileInfo's Name method returns only the base name of the file it describes, it may be necessary to modify the Name field of the returned header to provide the full path name of the file.

func (*FileHeader) FileInfo Uses

func (h *FileHeader) FileInfo() os.FileInfo

FileInfo returns an os.FileInfo for the FileHeader.

func (*FileHeader) IsEncrypted Uses

func (h *FileHeader) IsEncrypted() bool

IsEncrypted indicates whether this file's data is encrypted.

func (*FileHeader) ModTime Uses

func (h *FileHeader) ModTime() time.Time

ModTime returns the modification time in UTC. The resolution is 2s.

func (*FileHeader) Mode Uses

func (h *FileHeader) Mode() (mode os.FileMode)

Mode returns the permission and mode bits for the FileHeader.

func (*FileHeader) SetModTime Uses

func (h *FileHeader) SetModTime(t time.Time)

SetModTime sets the ModifiedTime and ModifiedDate fields to the given time in UTC. The resolution is 2s.

func (*FileHeader) SetMode Uses

func (h *FileHeader) SetMode(mode os.FileMode)

SetMode changes the permission and mode bits for the FileHeader.

func (*FileHeader) SetPassword Uses

func (h *FileHeader) SetPassword(password string)

SetPassword sets the password used for encryption/decryption.

type ReadCloser Uses

type ReadCloser struct {
    Reader
    // contains filtered or unexported fields
}

func OpenReader Uses

func OpenReader(name string) (*ReadCloser, error)

OpenReader will open the Zip file specified by name and return a ReadCloser.

func (*ReadCloser) Close Uses

func (rc *ReadCloser) Close() error

Close closes the Zip file, rendering it unusable for I/O.

type Reader Uses

type Reader struct {
    File    []*File
    Comment string
    // contains filtered or unexported fields
}

Code:

// Open a zip archive for reading.
r, err := zip.OpenReader("testdata/readme.zip")
if err != nil {
    log.Fatal(err)
}
defer r.Close()

// Iterate through the files in the archive,
// printing some of their contents.
for _, f := range r.File {
    fmt.Printf("Contents of %s:\n", f.Name)
    rc, err := f.Open()
    if err != nil {
        log.Fatal(err)
    }
    _, err = io.CopyN(os.Stdout, rc, 68)
    if err != nil {
        log.Fatal(err)
    }
    rc.Close()
    fmt.Println()
}

Output:

Contents of README:
This is the source code repository for the Go programming language.

func NewReader Uses

func NewReader(r io.ReaderAt, size int64) (*Reader, error)

NewReader returns a new Reader reading from r, which is assumed to have the given size in bytes.

type Writer Uses

type Writer struct {
    // contains filtered or unexported fields
}

Writer implements a zip file writer.

Code:

// Create a buffer to write our archive to.
buf := new(bytes.Buffer)

// Create a new zip archive.
w := zip.NewWriter(buf)

// Add some files to the archive.
var files = []struct {
    Name, Body string
}{
    {"readme.txt", "This archive contains some text files."},
    {"gopher.txt", "Gopher names:\nGeorge\nGeoffrey\nGonzo"},
    {"todo.txt", "Get animal handling licence.\nWrite more examples."},
}
for _, file := range files {
    f, err := w.Create(file.Name)
    if err != nil {
        log.Fatal(err)
    }
    _, err = f.Write([]byte(file.Body))
    if err != nil {
        log.Fatal(err)
    }
}

// Make sure to check the error on Close.
err := w.Close()
if err != nil {
    log.Fatal(err)
}

func NewWriter Uses

func NewWriter(w io.Writer) *Writer

NewWriter returns a new Writer writing a zip file to w.

func (*Writer) Close Uses

func (w *Writer) Close() error

Close finishes writing the zip file by writing the central directory. It does not (and can not) close the underlying writer.

func (*Writer) Create Uses

func (w *Writer) Create(name string) (io.Writer, error)

Create adds a file to the zip file using the provided name. It returns a Writer to which the file contents should be written. The name must be a relative path: it must not start with a drive letter (e.g. C:) or leading slash, and only forward slashes are allowed. The file's contents must be written to the io.Writer before the next call to Create, CreateHeader, or Close.

func (*Writer) CreateHeader Uses

func (w *Writer) CreateHeader(fh *FileHeader) (io.Writer, error)

CreateHeader adds a file to the zip file using the provided FileHeader for the file metadata. It returns a Writer to which the file contents should be written.

The file's contents must be written to the io.Writer before the next call to Create, CreateHeader, or Close. The provided FileHeader fh must not be modified after a call to CreateHeader.

func (*Writer) Encrypt Uses

func (w *Writer) Encrypt(name string, password string) (io.Writer, error)

Encrypt adds a file to the zip file using the provided name. It returns a Writer to which the file contents should be written. File contents will be encrypted with AES-256 using the given password. The file's contents must be written to the io.Writer before the next call to Create, CreateHeader, or Close.

Code:

contents := []byte("Hello World")

// write a password zip
raw := new(bytes.Buffer)
zipw := zip.NewWriter(raw)
w, err := zipw.Encrypt("hello.txt", "golang")
if err != nil {
    log.Fatal(err)
}
_, err = io.Copy(w, bytes.NewReader(contents))
if err != nil {
    log.Fatal(err)
}
zipw.Close()

// read the password zip
zipr, err := zip.NewReader(bytes.NewReader(raw.Bytes()), int64(raw.Len()))
if err != nil {
    log.Fatal(err)
}
for _, z := range zipr.File {
    z.SetPassword("golang")
    rr, err := z.Open()
    if err != nil {
        log.Fatal(err)
    }
    _, err = io.Copy(os.Stdout, rr)
    if err != nil {
        log.Fatal(err)
    }
    rr.Close()
}

Output:

Hello World

func (*Writer) Flush Uses

func (w *Writer) Flush() error

Flush flushes any buffered data to the underlying writer. Calling Flush is not normally necessary; calling Close is sufficient.

func (*Writer) SetOffset Uses

func (w *Writer) SetOffset(n int64)

SetOffset sets the offset of the beginning of the zip data within the underlying writer. It should be used when the zip data is appended to an existing file, such as a binary executable. It must be called before any data is written.

Package zip imports 21 packages (graph) and is imported by 8 packages. Updated 2020-07-24. Refresh now. Tools for package owners.