zseek

zseek

-- import "github.com/BenLubar/zseek"

Package zseek provides a seekable compressed file.

Usage

const (
	SeekStart = 0
	SeekCur   = 1
	SeekEnd   = 2
)

Constants for Seek

const (
	NoCompression      = zlib.NoCompression
	DefaultCompression = zlib.DefaultCompression
	BestSpeed          = zlib.BestSpeed
	BestCompression    = zlib.BestCompression
)

Constants for NewLevel and NewBuffer

const (
	DefaultBuffer = 32 * 1024
)

Constants for NewBuffer

var (
	ErrEarlyWrite  = errors.New("zseek: cannot write before EOF")
	ErrInvalidSeek = errors.New("zseek: cannot seek outside of file")
)

Errors specific to ZSeek

type ZSeek

type ZSeek struct {
}

ZSeek is a seekable compressed file. The file is written in chunks of zlib-compressed data prefixed with a 64-bit little endian integer representing the compressed size of the chunk. ZSeek can only be used as an io.Writer if it is at the end of the file. Attempting to write before reaching the end of the file will return ErrEarlyWrite.

func New

func New(f io.ReadWriteSeeker) (*ZSeek, error)

New is equivalent to calling NewBuffer(f, DefaultCompression, DefaultBuffer).

func NewBuffer

func NewBuffer(f io.ReadWriteSeeker, level, buf int) (*ZSeek, error)

NewBuffer creates a *ZSeek with a specified buffer size for writing. Whenever there are at least buf bytes of unwritten data during a Write call, Flush will automatically be called.

func NewLevel

func NewLevel(f io.ReadWriteSeeker, level int) (*ZSeek, error)

NewLevel is equivalent to calling NewBuffer(f, level, DefaultBuffer).

func (*ZSeek) Close

func (z *ZSeek) Close() error

Close implements io.Closer. Close does not close the underlying io.ReadWriteSeeker. After Close is called, any action on z will return io.ErrClosedPipe.

func (*ZSeek) Flush

func (z *ZSeek) Flush() error

Flush writes any buffered data to the underlying io.ReadWriteSeeker. Flush is a no-op if there is no data to be written.

func (*ZSeek) Read

func (z *ZSeek) Read(p []byte) (n int, err error)

Read implements io.Reader. If a read would cross a chunk boundary, a partial read is done instead. Use io.ReadFull to guarantee a full read.

func (*ZSeek) Seek

func (z *ZSeek) Seek(offset int64, whence int) (int64, error)

Seek implements io.Seeker. Flush will be called before an attempt is made to seek.

func (*ZSeek) Write

func (z *ZSeek) Write(p []byte) (n int, err error)

Write implements io.Writer. Write can only be called when z is at the end of the file.