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 ioutil implements some I/O utility functions.
package ioutil
import (
"bufio"
"errors"
"io"
)
type readPeeker interface {
io.Reader
Peek(int) ([]byte, error)
}
var (
ErrEmptyReader = errors.New("reader is empty")
)
// NonEmptyReader takes a reader and returns it if it is not empty, or
// `ErrEmptyReader` if it is empty. If there is an error when reading the first
// byte of the given reader, it will be propagated.
func NonEmptyReader(r io.Reader) (io.Reader, error) {
pr, ok := r.(readPeeker)
if !ok {
pr = bufio.NewReader(r)
}
_, err := pr.Peek(1)
if err == io.EOF {
return nil, ErrEmptyReader
}
if err != nil {
return nil, err
}
return pr, nil
}
type readCloser struct {
io.Reader
closer io.Closer
}
func (r *readCloser) Close() error {
return r.closer.Close()
}
// NewReadCloser creates an `io.ReadCloser` with the given `io.Reader` and
// `io.Closer`.
func NewReadCloser(r io.Reader, c io.Closer) io.ReadCloser {
return &readCloser{Reader: r, closer: c}
}
type writeNopCloser struct {
io.Writer
}
func (writeNopCloser) Close() error { return nil }
// WriteNopCloser returns a WriteCloser with a no-op Close method wrapping
// the provided Writer w.
func WriteNopCloser(w io.Writer) io.WriteCloser {
return writeNopCloser{w}
}
// CheckClose calls Close on the given io.Closer. If the given *error points to
// nil, it will be assigned the error returned by Close. Otherwise, any error
// returned by Close will be ignored. CheckClose is usually called with defer.
func CheckClose(c io.Closer, err *error) {
if cerr := c.Close(); cerr != nil && *err == nil {
*err = cerr
}
}
|
