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 "sort" 10 ) 11 12 type readdirMode int 13 14 const ( 15 readdirName readdirMode = iota 16 readdirDirEntry 17 readdirFileInfo 18 ) 19 20 // Readdir reads the contents of the directory associated with file and 21 // returns a slice of up to n FileInfo values, as would be returned 22 // by Lstat, in directory order. Subsequent calls on the same file will yield 23 // further FileInfos. 24 // 25 // If n > 0, Readdir returns at most n FileInfo structures. In this case, if 26 // Readdir returns an empty slice, it will return a non-nil error 27 // explaining why. At the end of a directory, the error is io.EOF. 28 // 29 // If n <= 0, Readdir returns all the FileInfo from the directory in 30 // a single slice. In this case, if Readdir succeeds (reads all 31 // the way to the end of the directory), it returns the slice and a 32 // nil error. If it encounters an error before the end of the 33 // directory, Readdir returns the FileInfo read until that point 34 // and a non-nil error. 35 // 36 // Most clients are better served by the more efficient ReadDir method. 37 func (f *File) Readdir(n int) ([]FileInfo, error) { 38 if f == nil { 39 return nil, ErrInvalid 40 } 41 _, _, infos, err := f.readdir(n, readdirFileInfo) 42 if infos == nil { 43 // Readdir has historically always returned a non-nil empty slice, never nil, 44 // even on error (except misuse with nil receiver above). 45 // Keep it that way to avoid breaking overly sensitive callers. 46 infos = []FileInfo{} 47 } 48 return infos, err 49 } 50 51 // Readdirnames reads the contents of the directory associated with file 52 // and returns a slice of up to n names of files in the directory, 53 // in directory order. Subsequent calls on the same file will yield 54 // further names. 55 // 56 // If n > 0, Readdirnames returns at most n names. In this case, if 57 // Readdirnames returns an empty slice, it will return a non-nil error 58 // explaining why. At the end of a directory, the error is io.EOF. 59 // 60 // If n <= 0, Readdirnames returns all the names from the directory in 61 // a single slice. In this case, if Readdirnames succeeds (reads all 62 // the way to the end of the directory), it returns the slice and a 63 // nil error. If it encounters an error before the end of the 64 // directory, Readdirnames returns the names read until that point and 65 // a non-nil error. 66 func (f *File) Readdirnames(n int) (names []string, err error) { 67 if f == nil { 68 return nil, ErrInvalid 69 } 70 names, _, _, err = f.readdir(n, readdirName) 71 if names == nil { 72 // Readdirnames has historically always returned a non-nil empty slice, never nil, 73 // even on error (except misuse with nil receiver above). 74 // Keep it that way to avoid breaking overly sensitive callers. 75 names = []string{} 76 } 77 return names, err 78 } 79 80 // A DirEntry is an entry read from a directory 81 // (using the ReadDir function or a File's ReadDir method). 82 type DirEntry = fs.DirEntry 83 84 // ReadDir reads the contents of the directory associated with the file f 85 // and returns a slice of DirEntry values in directory order. 86 // Subsequent calls on the same file will yield later DirEntry records in the directory. 87 // 88 // If n > 0, ReadDir returns at most n DirEntry records. 89 // In this case, if ReadDir returns an empty slice, it will return an error explaining why. 90 // At the end of a directory, the error is io.EOF. 91 // 92 // If n <= 0, ReadDir returns all the DirEntry records remaining in the directory. 93 // When it succeeds, it returns a nil error (not io.EOF). 94 func (f *File) ReadDir(n int) ([]DirEntry, error) { 95 if f == nil { 96 return nil, ErrInvalid 97 } 98 _, dirents, _, err := f.readdir(n, readdirDirEntry) 99 if dirents == nil { 100 // Match Readdir and Readdirnames: don't return nil slices. 101 dirents = []DirEntry{} 102 } 103 return dirents, err 104 } 105 106 // testingForceReadDirLstat forces ReadDir to call Lstat, for testing that code path. 107 // This can be difficult to provoke on some Unix systems otherwise. 108 var testingForceReadDirLstat bool 109 110 // ReadDir reads the named directory, 111 // returning all its directory entries sorted by filename. 112 // If an error occurs reading the directory, 113 // ReadDir returns the entries it was able to read before the error, 114 // along with the error. 115 func ReadDir(name string) ([]DirEntry, error) { 116 f, err := Open(name) 117 if err != nil { 118 return nil, err 119 } 120 defer f.Close() 121 122 dirs, err := f.ReadDir(-1) 123 sort.Slice(dirs, func(i, j int) bool { return dirs[i].Name() < dirs[j].Name() }) 124 return dirs, err 125 } 126