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path: root/chksum/size.go
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package chksum

import (
	"bytes"
	"fmt"
	"hash"
	"strconv"
)

type digest struct {
	size int
}

func (d *digest) Write(p []byte) (n int, err error) {
	n = len(p)
	d.size += n
	return
}

func (d *digest) Sum(b []byte) []byte {
	buf := new(bytes.Buffer)
	fmt.Fprint(buf, d.size)
	return append(b, buf.Bytes()...)
}

func (d *digest) Reset() {
	d.size = 0
}

func (d *digest) Size() int {
	return 1
}

func (d *digest) BlockSize() int {
	return 1
}

func NewSize() hash.Hash {
	return &digest{}
}

func ParseSize(s string) ([]byte, error) {
	n, err := strconv.Atoi(s)
	if err != nil {
		return nil, err
	}
	buf := new(bytes.Buffer)
	fmt.Fprint(buf, n)
	return buf.Bytes(), nil
}