/
writer.go
74 lines (60 loc) · 1.14 KB
/
writer.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
package backend
import (
"errors"
"hash"
"io"
)
type HashAppendWriter struct {
w io.Writer
origWr io.Writer
h hash.Hash
sum []byte
closed bool
}
func NewHashAppendWriter(w io.Writer, h hash.Hash) *HashAppendWriter {
return &HashAppendWriter{
h: h,
w: io.MultiWriter(w, h),
origWr: w,
sum: make([]byte, 0, h.Size()),
}
}
func (h *HashAppendWriter) Close() error {
if h == nil {
return nil
}
if !h.closed {
h.closed = true
_, err := h.origWr.Write(h.h.Sum(nil))
return err
}
return nil
}
func (h *HashAppendWriter) Write(p []byte) (n int, err error) {
if !h.closed {
return h.w.Write(p)
}
return 0, errors.New("Write() called on closed HashAppendWriter")
}
type HashingWriter struct {
w io.Writer
h hash.Hash
size int
}
func NewHashingWriter(w io.Writer, h hash.Hash) *HashingWriter {
return &HashingWriter{
h: h,
w: io.MultiWriter(w, h),
}
}
func (h *HashingWriter) Write(p []byte) (int, error) {
n, err := h.w.Write(p)
h.size += n
return n, err
}
func (h *HashingWriter) Sum(d []byte) []byte {
return h.h.Sum(d)
}
func (h *HashingWriter) Size() int {
return h.size
}