1package moxio

2

3import (

4 "encoding/base64"

5 "io"

6)

7

8// implement io.Closer

9type closerFunc func() error

10

11func (f closerFunc) Close() error {

12 return f()

13}

14

15// Base64Writer turns a writer for data into one that writes base64 content on

16// \r\n separated lines of max 78+2 characters length.

17func Base64Writer(w io.Writer) io.WriteCloser {

18 lw := &lineWrapper{w: w}

19 bw := base64.NewEncoder(base64.StdEncoding, lw)

20 return struct {

21 io.Writer

22 io.Closer

23 }{

24 Writer: bw,

25 Closer: closerFunc(func() error {

26 if err := bw.Close(); err != nil {

27 return err

28 }

29 return lw.Close()

30 }),

31 }

32}

33

34type lineWrapper struct {

35 w io.Writer

36 n int // Written on current line.

37}

38

39func (lw *lineWrapper) Write(buf []byte) (int, error) {

40 wrote := 0

41 for len(buf) > 0 {

42 n := min(78-lw.n, len(buf))

43 nn, err := lw.w.Write(buf[:n])

44 if nn > 0 {

45 wrote += nn

46 buf = buf[nn:]

47 }

48 if err != nil {

49 return wrote, err

50 }

51 lw.n += nn

52 if lw.n == 78 {

53 _, err := lw.w.Write([]byte("\r\n"))

54 if err != nil {

55 return wrote, err

56 }

57 lw.n = 0

58 }

59 }

60 return wrote, nil

61}

62

63func (lw *lineWrapper) Close() error {

64 if lw.n > 0 {

65 lw.n = 0

66 _, err := lw.w.Write([]byte("\r\n"))

67 return err

68 }

69 return nil

70}

71