Golang ReadWriteSeeker.Seek方法代码示例

// hashCopyN - Calculates Md5sum and SHA256sum for upto partSize amount of bytes.
func (c Client) hashCopyN(writer io.ReadWriteSeeker, reader io.Reader, partSize int64) (md5Sum, sha256Sum []byte, size int64, err error) {
	// MD5 and SHA256 hasher.
	var hashMD5, hashSHA256 hash.Hash
	// MD5 and SHA256 hasher.
	hashMD5 = md5.New()
	hashWriter := io.MultiWriter(writer, hashMD5)
	if c.signature.isV4() {
		hashSHA256 = sha256.New()
		hashWriter = io.MultiWriter(writer, hashMD5, hashSHA256)
	}

	// Copies to input at writer.
	size, err = io.CopyN(hashWriter, reader, partSize)
	if err != nil {
		// If not EOF return error right here.
		if err != io.EOF {
			return nil, nil, 0, err
		}
	}

	// Seek back to beginning of input, any error fail right here.
	if _, err := writer.Seek(0, 0); err != nil {
		return nil, nil, 0, err
	}

	// Finalize md5shum and sha256 sum.
	md5Sum = hashMD5.Sum(nil)
	if c.signature.isV4() {
		sha256Sum = hashSHA256.Sum(nil)
	}
	return md5Sum, sha256Sum, size, err
}

// ReadRawRecord reads a raw record from the provided file.
//
// On error, err will no non-nil.  Expected error values are io.EOF
// when the end of the file has been reached or io.ErrUnexpectedEOF if
// a complete record was unable to be read.
//
// In the case of io.ErrUnexpectedEOF the file offset will be reset
// back to where it was upon entering this function so it is ready to
// be read from again if it is expected more data will be written to
// the file.
func ReadRawRecord(file io.ReadWriteSeeker) (*RawRecord, error) {
	var header RawHeader

	/* Get the current offset so we can seek back to it. */
	offset, _ := file.Seek(0, 1)

	/* Now read in the header. */
	err := binary.Read(file, binary.BigEndian, &header)
	if err != nil {
		file.Seek(offset, 0)
		return nil, err
	}

	/* Create a buffer to hold the raw record data and read the
	/* record data into it */
	data := make([]byte, header.Len)
	n, err := file.Read(data)
	if err != nil {
		file.Seek(offset, 0)
		return nil, err
	}
	if uint32(n) != header.Len {
		file.Seek(offset, 0)
		return nil, io.ErrUnexpectedEOF
	}

	return &RawRecord{header.Type, data}, nil
}

func (geneMap GeneMap) Save(file io.ReadWriteSeeker) (err os.Error) {
	//go to the begging of the file
	file.Seek(0, 0)
	enc := gob.NewEncoder(file)
	err = enc.Encode(lens{len(geneMap)})
	for key, item := range geneMap {
		enc.Encode(keyVal{key, item})
		if err != nil {
			panic(err.String())
		}
	}
	return

}

func newIndex(rw io.ReadWriteSeeker) (*storeindex, error) {
	off, err := rw.Seek(0, os.SEEK_END)
	if err != nil {
		return nil, errwrap.Err(err, "cannot seek")
	}
	if off%8 != 0 {
		return nil, fmt.Errorf("corrupted index store: %d", off)
	}
	x := &storeindex{
		count: uint64(off / 8),
		rw:    rw,
	}
	return x, nil
}

func AppendAdder(genome io.ReadWriteSeeker, gene genome.Gene, geneMap genome.GeneMap) (pos int64, err os.Error) {
	//go to the end of the file
	pos, err = genome.Seek(0, 2)
	length, err := genome.Write(gene)
	if err != nil {
		panic(err.String())
	}

	genome.Seek(pos, 0)
	test := make([]byte, length)
	genome.Read(test)
	if !bytes.Equal(gene.GetData(), test) {
		panic("apperder broken")
	}
	return

}

func insertSample(cfg *BuildConfig, header *OctreeHeader, readWriter io.ReadWriteSeeker, sample Sample, bounds Box, voxelRes int) error {
	var node accNode
	for {
		if err := binary.Read(readWriter, binary.BigEndian, &node); err != nil {
			return err
		}

		if _, err := readWriter.Seek(int64(-mipR64G64B64A64S64UnpackUI32.NodeSize()), 1); err != nil {
			return err
		}

		color := sample.Color()
		node.Color[0] += uint64(color.R * 255)
		node.Color[1] += uint64(color.G * 255)
		node.Color[2] += uint64(color.B * 255)
		node.Color[3] += uint64(color.A * 255)
		node.Color[4]++

		if err := binary.Write(readWriter, binary.BigEndian, node.Color); err != nil {
			return err
		}

		if voxelRes == 1 {
			header.NumLeafs++
			return nil
		}

		var (
			childBounds Box
			newVoxelRes = voxelRes
		)

		for i, child := range node.Children {
			childBounds.Size = bounds.Size * 0.5
			childOffset := childPositions[i].scale(childBounds.Size)
			childBounds.Pos = bounds.Pos.add(&childOffset)

			if childBounds.Intersect(sample.Position()) == true {
				if child == 0 {
					currentPos, err := readWriter.Seek(0, 1)
					if err != nil {
						return err
					}

					newPos, err := readWriter.Seek(0, 2)
					if err != nil {
						return err
					}

					if _, err = readWriter.Seek(currentPos, 0); err != nil {
						return err
					}

					node.Children[i] = uint32((newPos - int64(header.Size())) / int64(mipR64G64B64A64S64UnpackUI32.NodeSize()))
					if err := binary.Write(readWriter, binary.BigEndian, node.Children); err != nil {
						return err
					}

					if _, err = readWriter.Seek(newPos, 0); err != nil {
						return err
					}

					header.NumNodes++
					var newNode accNode
					if err := binary.Write(readWriter, binary.BigEndian, newNode); err != nil {
						return err
					}

					if _, err := readWriter.Seek(int64(-mipR64G64B64A64S64UnpackUI32.NodeSize()), 1); err != nil {
						return err
					}
				} else {
					if _, err := readWriter.Seek(int64(int(child)*mipR64G64B64A64S64UnpackUI32.NodeSize()+header.Size()), 0); err != nil {
						return err
					}
				}

				newVoxelRes = voxelRes / 2
				break
			}
		}

		if newVoxelRes == voxelRes {
			return nil
		} else {
			bounds = childBounds
			voxelRes = newVoxelRes
		}
	}
}