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
|
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package fs
import "io"
// ReadFileFS is the interface implemented by a file system
// that provides an optimized implementation of ReadFile.
type ReadFileFS interface {
FS
// ReadFile reads the named file and returns its contents.
// A successful call returns a nil error, not io.EOF.
// (Because ReadFile reads the whole file, the expected EOF
// from the final Read is not treated as an error to be reported.)
//
// The caller is permitted to modify the returned byte slice.
// This method should return a copy of the underlying data.
ReadFile(name string) ([]byte, error)
}
// ReadFile reads the named file from the file system fs and returns its contents.
// A successful call returns a nil error, not io.EOF.
// (Because ReadFile reads the whole file, the expected EOF
// from the final Read is not treated as an error to be reported.)
//
// If fs implements ReadFileFS, ReadFile calls fs.ReadFile.
// Otherwise ReadFile calls fs.Open and uses Read and Close
// on the returned file.
func ReadFile(fsys FS, name string) ([]byte, error) {
if fsys, ok := fsys.(ReadFileFS); ok {
return fsys.ReadFile(name)
}
file, err := fsys.Open(name)
if err != nil {
return nil, err
}
defer file.Close()
var size int
if info, err := file.Stat(); err == nil {
size64 := info.Size()
if int64(int(size64)) == size64 {
size = int(size64)
}
}
data := make([]byte, 0, size+1)
for {
if len(data) >= cap(data) {
d := append(data[:cap(data)], 0)
data = d[:len(data)]
}
n, err := file.Read(data[len(data):cap(data)])
data = data[:len(data)+n]
if err != nil {
if err == io.EOF {
err = nil
}
return data, err
}
}
}
|
