1 // Copyright 2016 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4 5 package os
6 7 import (
8 "io/fs"
9 )
10 11 type readdirMode int
12 13 const (
14 readdirName readdirMode = iota
15 readdirDirEntry
16 readdirFileInfo
17 )
18 19 // Readdir reads the contents of the directory associated with file and
20 // returns a slice of up to n FileInfo values, as would be returned
21 // by Lstat, in directory order. Subsequent calls on the same file will yield
22 // further FileInfos.
23 //
24 // If n > 0, Readdir returns at most n FileInfo structures. In this case, if
25 // Readdir returns an empty slice, it will return a non-nil error
26 // explaining why. At the end of a directory, the error is io.EOF.
27 //
28 // If n <= 0, Readdir returns all the FileInfo from the directory in
29 // a single slice. In this case, if Readdir succeeds (reads all
30 // the way to the end of the directory), it returns the slice and a
31 // nil error. If it encounters an error before the end of the
32 // directory, Readdir returns the FileInfo read until that point
33 // and a non-nil error.
34 //
35 // Most clients are better served by the more efficient ReadDir method.
36 func (f *File) Readdir(n int) ([]FileInfo, error) {
37 if f == nil {
38 return nil, ErrInvalid
39 }
40 _, _, infos, err := f.readdir(n, readdirFileInfo)
41 if infos == nil {
42 // Readdir has historically always returned a non-nil empty slice, never nil,
43 // even on error (except misuse with nil receiver above).
44 // Keep it that way to avoid breaking overly sensitive callers.
45 infos = []FileInfo{}
46 }
47 return infos, err
48 }
49 50 // Readdirnames reads the contents of the directory associated with file
51 // and returns a slice of up to n names of files in the directory,
52 // in directory order. Subsequent calls on the same file will yield
53 // further names.
54 //
55 // If n > 0, Readdirnames returns at most n names. In this case, if
56 // Readdirnames returns an empty slice, it will return a non-nil error
57 // explaining why. At the end of a directory, the error is io.EOF.
58 //
59 // If n <= 0, Readdirnames returns all the names from the directory in
60 // a single slice. In this case, if Readdirnames succeeds (reads all
61 // the way to the end of the directory), it returns the slice and a
62 // nil error. If it encounters an error before the end of the
63 // directory, Readdirnames returns the names read until that point and
64 // a non-nil error.
65 func (f *File) Readdirnames(n int) (names []string, err error) {
66 if f == nil {
67 return nil, ErrInvalid
68 }
69 names, _, _, err = f.readdir(n, readdirName)
70 if names == nil {
71 // Readdirnames has historically always returned a non-nil empty slice, never nil,
72 // even on error (except misuse with nil receiver above).
73 // Keep it that way to avoid breaking overly sensitive callers.
74 names = []string{}
75 }
76 return names, err
77 }
78 79 // A DirEntry is an entry read from a directory
80 // (using the ReadDir function or a File's ReadDir method).
81 type DirEntry = fs.DirEntry
82 83 // ReadDir reads the contents of the directory associated with the file f
84 // and returns a slice of DirEntry values in directory order.
85 // Subsequent calls on the same file will yield later DirEntry records in the directory.
86 //
87 // If n > 0, ReadDir returns at most n DirEntry records.
88 // In this case, if ReadDir returns an empty slice, it will return an error explaining why.
89 // At the end of a directory, the error is io.EOF.
90 //
91 // If n <= 0, ReadDir returns all the DirEntry records remaining in the directory.
92 // When it succeeds, it returns a nil error (not io.EOF).
93 func (f *File) ReadDir(n int) ([]DirEntry, error) {
94 if f == nil {
95 return nil, ErrInvalid
96 }
97 _, dirents, _, err := f.readdir(n, readdirDirEntry)
98 if dirents == nil {
99 // Match Readdir and Readdirnames: don't return nil slices.
100 dirents = []DirEntry{}
101 }
102 return dirents, err
103 }
104 105 // testingForceReadDirLstat forces ReadDir to call Lstat, for testing that code path.
106 // This can be difficult to provoke on some Unix systems otherwise.
107 var testingForceReadDirLstat bool
108 109 // ReadDir reads the named directory,
110 // returning all its directory entries sorted by filename.
111 // If an error occurs reading the directory,
112 // ReadDir returns the entries it was able to read before the error,
113 // along with the error.
114 func ReadDir(name string) ([]DirEntry, error) {
115 f, err := Open(name)
116 if err != nil {
117 return nil, err
118 }
119 defer f.Close()
120 121 dirs, err := f.ReadDir(-1)
122 // Simple insertion sort — no reflect-based sort.Slice needed.
123 for i := 1; i < len(dirs); i++ {
124 for j := i; j > 0 && dirs[j].Name() < dirs[j-1].Name(); j-- {
125 dirs[j], dirs[j-1] = dirs[j-1], dirs[j]
126 }
127 }
128 return dirs, err
129 }
130