forked from moby/moby
/
fileutils.go
72 lines (68 loc) · 1.9 KB
/
fileutils.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
package fileutils // import "github.com/docker/docker/pkg/fileutils"
import (
"fmt"
"io"
"os"
"path/filepath"
)
// CopyFile copies from src to dst until either EOF is reached
// on src or an error occurs. It verifies src exists and removes
// the dst if it exists.
func CopyFile(src, dst string) (int64, error) {
cleanSrc := filepath.Clean(src)
cleanDst := filepath.Clean(dst)
if cleanSrc == cleanDst {
return 0, nil
}
sf, err := os.Open(cleanSrc)
if err != nil {
return 0, err
}
defer sf.Close()
if err := os.Remove(cleanDst); err != nil && !os.IsNotExist(err) {
return 0, err
}
df, err := os.Create(cleanDst)
if err != nil {
return 0, err
}
defer df.Close()
return io.Copy(df, sf)
}
// ReadSymlinkedDirectory returns the target directory of a symlink.
// The target of the symbolic link may not be a file.
func ReadSymlinkedDirectory(path string) (realPath string, err error) {
if realPath, err = filepath.Abs(path); err != nil {
return "", fmt.Errorf("unable to get absolute path for %s: %w", path, err)
}
if realPath, err = filepath.EvalSymlinks(realPath); err != nil {
return "", fmt.Errorf("failed to canonicalise path for %s: %w", path, err)
}
realPathInfo, err := os.Stat(realPath)
if err != nil {
return "", fmt.Errorf("failed to stat target '%s' of '%s': %w", realPath, path, err)
}
if !realPathInfo.Mode().IsDir() {
return "", fmt.Errorf("canonical path points to a file '%s'", realPath)
}
return realPath, nil
}
// CreateIfNotExists creates a file or a directory only if it does not already exist.
func CreateIfNotExists(path string, isDir bool) error {
if _, err := os.Stat(path); err != nil {
if os.IsNotExist(err) {
if isDir {
return os.MkdirAll(path, 0755)
}
if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
return err
}
f, err := os.OpenFile(path, os.O_CREATE, 0755)
if err != nil {
return err
}
f.Close()
}
}
return nil
}