archive

README

This code provides helper functions for dealing with archive files.

Documentation

Index

• Constants
• Variables
• func ApplyLayer(dest string, layer ArchiveReader) error
• func ChangesSize(newDir string, changes []Change) int64
• func CmdStream(cmd *exec.Cmd, input io.Reader) (io.ReadCloser, error)
• func CompressStream(dest io.WriteCloser, compression Compression) (io.WriteCloser, error)
• func CopyFileWithTar(src, dst string) (err error)
• func CopyWithTar(src, dst string) error
• func DecompressStream(archive io.Reader) (io.ReadCloser, error)
• func IsArchive(header []byte) bool
• func Tar(path string, compression Compression) (io.ReadCloser, error)
• func TarUntar(src string, dst string) error
• func TarWithOptions(srcPath string, options *TarOptions) (io.ReadCloser, error)
• func Untar(archive io.Reader, dest string, options *TarOptions) error
• func UntarPath(src, dst string) error
• type Archive
  • func ExportChanges(dir string, changes []Change) (Archive, error)
  • func Generate(input ...string) (Archive, error)
• type ArchiveReader
• type Change
  • func Changes(layers []string, rw string) ([]Change, error)
  • func ChangesDirs(newDir, oldDir string) ([]Change, error)
  • func (change *Change) String() string
• type ChangeType
• type Compression
  • func DetectCompression(source []byte) Compression
  • func (compression *Compression) Extension() string
• type FileInfo
  • func (info *FileInfo) Changes(oldInfo *FileInfo) []Change
  • func (root *FileInfo) LookUp(path string) *FileInfo
• type TarOptions
• type TempArchive
  • func NewTempArchive(src Archive, dir string) (*TempArchive, error)
  • func (archive *TempArchive) Read(data []byte) (int, error)

Constants

const (
	ChangeModify = iota
	ChangeAdd
	ChangeDelete
)

Variables

var (
	ErrNotImplemented = errors.New("Function not implemented")
)

Functions

func ApplyLayer

func ApplyLayer(dest string, layer ArchiveReader) error

ApplyLayer parses a diff in the standard layer format from `layer`, and applies it to the directory `dest`.

func ChangesSize

func ChangesSize(newDir string, changes []Change) int64

ChangesSize calculates the size in bytes of the provided changes, based on newDir.

func CmdStream

func CmdStream(cmd *exec.Cmd, input io.Reader) (io.ReadCloser, error)

CmdStream executes a command, and returns its stdout as a stream. If the command fails to run or doesn't complete successfully, an error will be returned, including anything written on stderr.

func CompressStream

func CompressStream(dest io.WriteCloser, compression Compression) (io.WriteCloser, error)

func CopyFileWithTar

func CopyFileWithTar(src, dst string) (err error)

CopyFileWithTar emulates the behavior of the 'cp' command-line for a single file. It copies a regular file from path `src` to path `dst`, and preserves all its metadata.

If `dst` ends with a trailing slash '/', the final destination path will be `dst/base(src)`.

func CopyWithTar

func CopyWithTar(src, dst string) error

CopyWithTar creates a tar archive of filesystem path `src`, and unpacks it at filesystem path `dst`. The archive is streamed directly with fixed buffering and no intermediary disk IO.

func DecompressStream

func DecompressStream(archive io.Reader) (io.ReadCloser, error)

func IsArchive

func IsArchive(header []byte) bool

func Tar

func Tar(path string, compression Compression) (io.ReadCloser, error)

Tar creates an archive from the directory at `path`, and returns it as a stream of bytes.

func TarUntar

func TarUntar(src string, dst string) error

TarUntar is a convenience function which calls Tar and Untar, with the output of one piped into the other. If either Tar or Untar fails, TarUntar aborts and returns the error.

func TarWithOptions

func TarWithOptions(srcPath string, options *TarOptions) (io.ReadCloser, error)

TarWithOptions creates an archive from the directory at `path`, only including files whose relative paths are included in `options.Includes` (if non-nil) or not in `options.Excludes`.

func Untar

func Untar(archive io.Reader, dest string, options *TarOptions) error

Untar reads a stream of bytes from `archive`, parses it as a tar archive, and unpacks it into the directory at `path`. The archive may be compressed with one of the following algorithms:

identity (uncompressed), gzip, bzip2, xz.

FIXME: specify behavior when target path exists vs. doesn't exist.

func UntarPath

func UntarPath(src, dst string) error

UntarPath is a convenience function which looks for an archive at filesystem path `src`, and unpacks it at `dst`.

Types

type Archive

type Archive io.ReadCloser

func ExportChanges

func ExportChanges(dir string, changes []Change) (Archive, error)

ExportChanges produces an Archive from the provided changes, relative to dir.

func Generate

func Generate(input ...string) (Archive, error)

Generate generates a new archive from the content provided as input.

`files` is a sequence of path/content pairs. A new file is added to the archive for each pair. If the last pair is incomplete, the file is created with an empty content. For example:

Generate("foo.txt", "hello world", "emptyfile")

The above call will return an archive with 2 files:

• ./foo.txt with content "hello world"
• ./empty with empty content

FIXME: stream content instead of buffering FIXME: specify permissions and other archive metadata

type ArchiveReader

type ArchiveReader io.Reader

type Change

type Change struct {
	Path string
	Kind ChangeType
}

func Changes

func Changes(layers []string, rw string) ([]Change, error)

Changes walks the path rw and determines changes for the files in the path, with respect to the parent layers

func ChangesDirs

func ChangesDirs(newDir, oldDir string) ([]Change, error)

ChangesDirs compares two directories and generates an array of Change objects describing the changes. If oldDir is "", then all files in newDir will be Add-Changes.

func (*Change) String

func (change *Change) String() string

type ChangeType

type ChangeType int

type Compression

type Compression int

const (
	Uncompressed Compression = iota
	Bzip2
	Gzip
	Xz
)

func DetectCompression

func DetectCompression(source []byte) Compression

func (*Compression) Extension

func (compression *Compression) Extension() string

type FileInfo

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

func (*FileInfo) Changes

func (info *FileInfo) Changes(oldInfo *FileInfo) []Change

func (*FileInfo) LookUp

func (root *FileInfo) LookUp(path string) *FileInfo

type TarOptions

type TarOptions struct {
	Includes    []string
	Excludes    []string
	Compression Compression
	NoLchown    bool
}

type TempArchive

type TempArchive struct {
	*os.File
	Size int64 // Pre-computed from Stat().Size() as a convenience
}

func NewTempArchive

func NewTempArchive(src Archive, dir string) (*TempArchive, error)

NewTempArchive reads the content of src into a temporary file, and returns the contents of that file as an archive. The archive can only be read once - as soon as reading completes, the file will be deleted.

func (*TempArchive) Read

func (archive *TempArchive) Read(data []byte) (int, error)