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Package zip

import "archive/zip"
Overview
Index
Examples

Overview ▾

Package zip provides support for reading and writing 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.

Constants

const (
        Store   uint16 = 0
        Deflate uint16 = 8
)

Compression methods.

Variables

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

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

func RegisterDecompressor(method uint16, d Decompressor)

RegisterDecompressor allows custom decompressors for a specified method ID.

type Compressor

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

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

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

func (*File) DataOffset

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

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

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
        UncompressedSize   uint32 // deprecated; use UncompressedSize64
        CompressedSize64   uint64
        UncompressedSize64 uint64
        Extra              []byte
        ExternalAttrs      uint32 // Meaning depends on CreatorVersion
        Comment            string
}

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

func FileInfoHeader

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

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

FileInfo returns an os.FileInfo for the FileHeader.

func (*FileHeader) ModTime

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

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

func (*FileHeader) Mode

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

Mode returns the permission and mode bits for the FileHeader.

func (*FileHeader) SetModTime

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

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

func (*FileHeader) SetMode

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

SetMode changes the permission and mode bits for the FileHeader.

type ReadCloser

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

func OpenReader

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

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

func (*ReadCloser) Close

func (rc *ReadCloser) Close() error

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

type Reader

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

Example

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

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

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

Writer implements a zip file writer.

Example

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

func NewWriter(w io.Writer) *Writer

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

func (*Writer) Close

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

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

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.