Donut structure refined

This commit is contained in:
Frederick F. Kautz IV 2015-02-18 17:18:33 -08:00
parent ab80c0ce12
commit f7f34d08e8

View File

@ -17,42 +17,39 @@
package donut package donut
import ( import (
"bytes"
"encoding/binary"
"encoding/gob"
"io" "io"
) )
/* /*
** DONUT v1 Spec ** ** DONUT v1 Spec **
BlockStart uint32 // Magic="MINI" BlockStart [4]byte // Magic="MINI"
VersionMajor uint16 VersionMajor uint16
VersionMinor uint16 VersionMinor uint16
VersionPatch uint16 VersionPatch uint16
VersionReserved uint16 VersionReserved uint16
Reserved uint64 Reserved uint64
GobHeaderLen uint32 GobHeaderLen uint32
GobHeader Sizeof(GobHeader) GobHeader io.Reader // matches length
BlockData uint32 // Magic="DATA" BlockData [4]byte // Magic="DATA"
Data []byte Data io.Reader // matches length
BlockLen uint64 BlockLen uint64 // length to block start
BlockEnd uint32 // Magic="INIM" BlockEnd [4]byte // Magic="INIM"
*/ */
type DonutHeader struct { type DonutStructure struct {
BlockStart uint32 // Magic="MINI" BlockStart [4]byte // Magic="MINI"
VersionMajor uint16 VersionMajor uint16
VersionMinor uint16 VersionMinor uint16
VersionPatch uint16 VersionPatch uint16
VersionReserved uint16 VersionReserved uint16
Reserved uint64 Reserved uint64
GobHeaderLen uint32 GobHeaderLen uint32
} GobHeader GobHeader
BlockData [4]byte
type DonutGobHeader struct { Data io.Reader
DataLen uint64 BlockLen uint64
BlockEnd [4]byte
} }
type DonutFooter struct { type DonutFooter struct {
@ -62,63 +59,32 @@ type DonutFooter struct {
type Donut struct { type Donut struct {
file io.Writer file io.Writer
// mutex
} }
func (donut Donut) Write(header Header, object io.Reader) error { type GobHeader struct{}
var newObjectBuffer bytes.Buffer
var headerBuffer bytes.Buffer
// create gob header func (donut *Donut) Write(gobHeader GobHeader, object io.Reader) error {
headerEncoder := gob.NewEncoder(&headerBuffer) // TODO mutex
err := headerEncoder.Encode(header) // Create bytes buffer representing the new object
if err != nil { donutStructure := DonutStructure{
return err BlockStart: [4]byte{'M', 'I', 'N', 'I'},
VersionMajor: 1,
VersionMinor: 0,
VersionPatch: 0,
VersionReserved: 0,
Reserved: 0,
GobHeaderLen: 0,
GobHeader: gobHeader,
BlockData: [4]byte{'D', 'A', 'T', 'A'},
Data: object,
BlockLen: 0,
BlockEnd: [4]byte{'I', 'N', 'I', 'M'},
} }
if err := WriteStructure(donut.file, donutStructure); err != nil {
// prefix consists of a version number and a length
var headerPrefixBuffer bytes.Buffer
// write version
var version int
version = 1
err = binary.Write(&headerPrefixBuffer, binary.LittleEndian, version)
if err != nil {
return err
}
// write length
var headerLength int
headerLength = headerBuffer.Len()
err = binary.Write(&headerPrefixBuffer, binary.LittleEndian, headerLength)
if err != nil {
return err
}
// write header prefix
io.Copy(&newObjectBuffer, &headerPrefixBuffer)
// write header
io.Copy(&newObjectBuffer, &headerBuffer)
// write header marker
// TODO
// write data
_, err = io.Copy(&newObjectBuffer, object)
if err != nil {
return err
}
// write footer
// TODO
// write footer marker
// TODO
// write new object
_, err = io.Copy(donut.file, &newObjectBuffer)
if err != nil {
return err return err
} }
return nil return nil
} }
func WriteStructure(target io.Writer, donutStructure DonutStructure) error { return nil }