pkzip

Documentation

Overview

Package pkzip provides constants and functions for working with PKZip files to determine the compression methods used. Most modern zip files use the Deflated method, which is supported by the Go standard library's archive/zip package and the Stored method, which is uncompressed.

But many older zip files use other compression methods, such as Shrunk, Reduced, Imploded, and others. This package provides a way to determine the compression methods used in a zip file and whether the file should be handled by a third-party application installed on the host system.

Index

• func Zip(name string) (bool, error)
• type Compression
  • func Methods(name string) ([]Compression, error)
  • func (c Compression) String() string
  • func (c Compression) Zip() bool
• type Diagnostic
  • func ExitStatus(err error) Diagnostic
  • func (d Diagnostic) String() string

Functions

func Zip

func Zip(name string) (bool, error)

Zip returns true if the named file is a PKZip file that exclusively uses the Deflated or Stored compression methods. These are the methods supported by the Go standard library's archive/zip package.

Types

type Compression

type Compression uint16

Compression is the PKZip compression method used by a ZIP archive file.

const (
	Stored Compression = iota
	Shrunk
	ReducedFactor1
	ReducedFactor2
	ReducedFactor3
	ReducedFactor4
	Imploded
	Reserved
	Deflated
	EnhancedDeflated
	PKWareDataCompressionLibraryImplode
	BZIP2
	Reserved2
	LZMA
	Reserved3
	Reserved4
	IBMTERSE
	IBMLZ77z
)

const (
	PPMd1 Compression = iota + 98
)

func Methods

func Methods(name string) ([]Compression, error)

Methods returns the PKZip compression methods used in the named file.

func (Compression) String

func (c Compression) String() string

func (Compression) Zip

func (c Compression) Zip() bool

Zip returns true if the compression method is Deflated or Stored.

type Diagnostic

type Diagnostic uint16

Diagnostic is a diagnostic code returned by the PKZip command-line utilities.

const (
	Normal Diagnostic = iota
	Warning
	GenericError
	SevereError
	BufferError
	TTYError
	DiskError
	MemoryError
	Unused
	ZipNotFound
	OptionsError
	FilesNoFound
	ZipBomb
)

const (
	DiskFull          Diagnostic = 50
	PrematureExit     Diagnostic = 51
	UserAbort         Diagnostic = 80
	CompressionMethod Diagnostic = 81
	BadDecryption     Diagnostic = 82
)

func ExitStatus

func ExitStatus(err error) Diagnostic

ExitStatus is intended to be used with the exec.Command.Run method to determine the exit status of the PKZip command-line utilities.

err := exec.Command("unzip", "-T", "archive.zip").Run()
if err != nil {
	diag := pkzip.ExitStatus(err)
	switch diag {
	case pkzip.Normal, pkzip.Warning:
		// normal or warnings are fine
		return nil
	}
	return fmt.Errorf("unzip test failed: %s", diag)
}

func (Diagnostic) String

func (d Diagnostic) String() string