tar

Documentation

Overview

Package tar implements access to tar archives. It aims to cover most of the variations, including those produced by GNU and BSD tars.

References:

http://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5
http://www.gnu.org/software/tar/manual/html_node/Standard.html

Index

• Constants
• Variables
• type Header
  • func FileInfoHeader(fi os.FileInfo, link string) (*Header, error)
• type Reader
  • func NewReader(r io.Reader) *Reader
  • func (tr *Reader) Next() (*Header, error)
  • func (tr *Reader) Read(b []byte) (n int, err error)
• type Writer
  • func NewWriter(w io.Writer) *Writer
  • func (tw *Writer) Close() error
  • func (tw *Writer) Flush() error
  • func (tw *Writer) Write(b []byte) (n int, err error)
  • func (tw *Writer) WriteHeader(hdr *Header) error

Constants

const (

	// Types
	TypeReg           = '0'    // regular file
	TypeRegA          = '\x00' // regular file
	TypeLink          = '1'    // hard link
	TypeSymlink       = '2'    // symbolic link
	TypeChar          = '3'    // character device node
	TypeBlock         = '4'    // block device node
	TypeDir           = '5'    // directory
	TypeFifo          = '6'    // fifo node
	TypeCont          = '7'    // reserved
	TypeXHeader       = 'x'    // extended header
	TypeXGlobalHeader = 'g'    // global extended header
)

Variables

var (
	ErrWriteTooLong    = errors.New("archive/tar: write too long")
	ErrFieldTooLong    = errors.New("archive/tar: header field too long")
	ErrWriteAfterClose = errors.New("archive/tar: write after close")
)

var (
	ErrHeader = errors.New("archive/tar: invalid tar header")
)

Types

type Header

type Header struct {
	Name       string    // name of header file entry
	Mode       int64     // permission and mode bits
	Uid        int       // user id of owner
	Gid        int       // group id of owner
	Size       int64     // length in bytes
	ModTime    time.Time // modified time
	Typeflag   byte      // type of header entry
	Linkname   string    // target name of link
	Uname      string    // user name of owner
	Gname      string    // group name of owner
	Devmajor   int64     // major number of character or block device
	Devminor   int64     // minor number of character or block device
	AccessTime time.Time // access time
	ChangeTime time.Time // status change time
}

A Header represents a single header in a tar archive. Some fields may not be populated.

func FileInfoHeader

func FileInfoHeader(fi os.FileInfo, link string) (*Header, error)

FileInfoHeader creates a partially-populated Header from fi. If fi describes a symlink, FileInfoHeader records link as the link target.

type Reader

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

A Reader provides sequential access to the contents of a tar archive. A tar archive consists of a sequence of files. The Next method advances to the next file in the archive (including the first), and then it can be treated as an io.Reader to access the file's data.

Example:

tr := tar.NewReader(r)
for {
	hdr, err := tr.Next()
	if err == io.EOF {
		// end of tar archive
		break
	}
	if err != nil {
		// handle error
	}
	io.Copy(data, tr)
}

func NewReader

func NewReader(r io.Reader) *Reader

NewReader creates a new Reader reading from r.

func (*Reader) Next

func (tr *Reader) Next() (*Header, error)

Next advances to the next entry in the tar archive.

func (*Reader) Read

func (tr *Reader) Read(b []byte) (n int, err error)

Read reads from the current entry in the tar archive. It returns 0, io.EOF when it reaches the end of that entry, until Next is called to advance to the next entry.

type Writer

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

A Writer provides sequential writing of a tar archive in POSIX.1 format. A tar archive consists of a sequence of files. Call WriteHeader to begin a new file, and then call Write to supply that file's data, writing at most hdr.Size bytes in total.

Example:

tw := tar.NewWriter(w)
hdr := new(tar.Header)
hdr.Size = length of data in bytes
// populate other hdr fields as desired
if err := tw.WriteHeader(hdr); err != nil {
	// handle error
}
io.Copy(tw, data)
tw.Close()

func NewWriter

func NewWriter(w io.Writer) *Writer

NewWriter creates a new Writer writing to w.

func (*Writer) Close

func (tw *Writer) Close() error

Close closes the tar archive, flushing any unwritten data to the underlying writer.

func (*Writer) Flush

func (tw *Writer) Flush() error

Flush finishes writing the current file (optional).

func (*Writer) Write

func (tw *Writer) Write(b []byte) (n int, err error)

Write writes to the current entry in the tar archive. Write returns the error ErrWriteTooLong if more than hdr.Size bytes are written after WriteHeader.

func (*Writer) WriteHeader

func (tw *Writer) WriteHeader(hdr *Header) error

WriteHeader writes hdr and prepares to accept the file's contents. WriteHeader calls Flush if it is not the first header. Calling after a Close will return ErrWriteAfterClose.