dir.go

     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  	"internal/safefilepath"
     9  	"io"
    10  	"io/fs"
    11  	"sort"
    12  )
    13  
    14  type readdirMode int
    15  
    16  const (
    17  	readdirName readdirMode = iota
    18  	readdirDirEntry
    19  	readdirFileInfo
    20  )
    21  
    22  // Readdir reads the contents of the directory associated with file and
    23  // returns a slice of up to n [FileInfo] values, as would be returned
    24  // by [Lstat], in directory order. Subsequent calls on the same file will yield
    25  // further FileInfos.
    26  //
    27  // If n > 0, Readdir returns at most n FileInfo structures. In this case, if
    28  // Readdir returns an empty slice, it will return a non-nil error
    29  // explaining why. At the end of a directory, the error is [io.EOF].
    30  //
    31  // If n <= 0, Readdir returns all the FileInfo from the directory in
    32  // a single slice. In this case, if Readdir succeeds (reads all
    33  // the way to the end of the directory), it returns the slice and a
    34  // nil error. If it encounters an error before the end of the
    35  // directory, Readdir returns the FileInfo read until that point
    36  // and a non-nil error.
    37  //
    38  // Most clients are better served by the more efficient ReadDir method.
    39  func (f *File) Readdir(n int) ([]FileInfo, error) {
    40  	if f == nil {
    41  		return nil, ErrInvalid
    42  	}
    43  	_, _, infos, err := f.readdir(n, readdirFileInfo)
    44  	if infos == nil {
    45  		// Readdir has historically always returned a non-nil empty slice, never nil,
    46  		// even on error (except misuse with nil receiver above).
    47  		// Keep it that way to avoid breaking overly sensitive callers.
    48  		infos = []FileInfo{}
    49  	}
    50  	return infos, err
    51  }
    52  
    53  // Readdirnames reads the contents of the directory associated with file
    54  // and returns a slice of up to n names of files in the directory,
    55  // in directory order. Subsequent calls on the same file will yield
    56  // further names.
    57  //
    58  // If n > 0, Readdirnames returns at most n names. In this case, if
    59  // Readdirnames returns an empty slice, it will return a non-nil error
    60  // explaining why. At the end of a directory, the error is [io.EOF].
    61  //
    62  // If n <= 0, Readdirnames returns all the names from the directory in
    63  // a single slice. In this case, if Readdirnames succeeds (reads all
    64  // the way to the end of the directory), it returns the slice and a
    65  // nil error. If it encounters an error before the end of the
    66  // directory, Readdirnames returns the names read until that point and
    67  // a non-nil error.
    68  func (f *File) Readdirnames(n int) (names []string, err error) {
    69  	if f == nil {
    70  		return nil, ErrInvalid
    71  	}
    72  	names, _, _, err = f.readdir(n, readdirName)
    73  	if names == nil {
    74  		// Readdirnames has historically always returned a non-nil empty slice, never nil,
    75  		// even on error (except misuse with nil receiver above).
    76  		// Keep it that way to avoid breaking overly sensitive callers.
    77  		names = []string{}
    78  	}
    79  	return names, err
    80  }
    81  
    82  // A DirEntry is an entry read from a directory
    83  // (using the [ReadDir] function or a [File.ReadDir] method).
    84  type DirEntry = fs.DirEntry
    85  
    86  // ReadDir reads the contents of the directory associated with the file f
    87  // and returns a slice of [DirEntry] values in directory order.
    88  // Subsequent calls on the same file will yield later DirEntry records in the directory.
    89  //
    90  // If n > 0, ReadDir returns at most n DirEntry records.
    91  // In this case, if ReadDir returns an empty slice, it will return an error explaining why.
    92  // At the end of a directory, the error is [io.EOF].
    93  //
    94  // If n <= 0, ReadDir returns all the DirEntry records remaining in the directory.
    95  // When it succeeds, it returns a nil error (not io.EOF).
    96  func (f *File) ReadDir(n int) ([]DirEntry, error) {
    97  	if f == nil {
    98  		return nil, ErrInvalid
    99  	}
   100  	_, dirents, _, err := f.readdir(n, readdirDirEntry)
   101  	if dirents == nil {
   102  		// Match Readdir and Readdirnames: don't return nil slices.
   103  		dirents = []DirEntry{}
   104  	}
   105  	return dirents, err
   106  }
   107  
   108  // testingForceReadDirLstat forces ReadDir to call Lstat, for testing that code path.
   109  // This can be difficult to provoke on some Unix systems otherwise.
   110  var testingForceReadDirLstat bool
   111  
   112  // ReadDir reads the named directory,
   113  // returning all its directory entries sorted by filename.
   114  // If an error occurs reading the directory,
   115  // ReadDir returns the entries it was able to read before the error,
   116  // along with the error.
   117  func ReadDir(name string) ([]DirEntry, error) {
   118  	f, err := openDir(name)
   119  	if err != nil {
   120  		return nil, err
   121  	}
   122  	defer f.Close()
   123  
   124  	dirs, err := f.ReadDir(-1)
   125  	sort.Slice(dirs, func(i, j int) bool { return dirs[i].Name() < dirs[j].Name() })
   126  	return dirs, err
   127  }
   128  
   129  // CopyFS copies the file system fsys into the directory dir,
   130  // creating dir if necessary.
   131  //
   132  // Newly created directories and files have their default modes
   133  // where any bits from the file in fsys that are not part of the
   134  // standard read, write, and execute permissions will be zeroed
   135  // out, and standard read and write permissions are set for owner,
   136  // group, and others while retaining any existing execute bits from
   137  // the file in fsys.
   138  //
   139  // Symbolic links in fsys are not supported, a *PathError with Err set
   140  // to ErrInvalid is returned on symlink.
   141  //
   142  // Copying stops at and returns the first error encountered.
   143  func CopyFS(dir string, fsys fs.FS) error {
   144  	return fs.WalkDir(fsys, ".", func(path string, d fs.DirEntry, err error) error {
   145  		if err != nil {
   146  			return err
   147  		}
   148  
   149  		fpath, err := safefilepath.Localize(path)
   150  		if err != nil {
   151  			return err
   152  		}
   153  		newPath := joinPath(dir, fpath)
   154  		if d.IsDir() {
   155  			return MkdirAll(newPath, 0777)
   156  		}
   157  
   158  		// TODO(panjf2000): handle symlinks with the help of fs.ReadLinkFS
   159  		// 		once https://go.dev/issue/49580 is done.
   160  		//		we also need safefilepath.IsLocal from https://go.dev/cl/564295.
   161  		if !d.Type().IsRegular() {
   162  			return &PathError{Op: "CopyFS", Path: path, Err: ErrInvalid}
   163  		}
   164  
   165  		r, err := fsys.Open(path)
   166  		if err != nil {
   167  			return err
   168  		}
   169  		defer r.Close()
   170  		info, err := r.Stat()
   171  		if err != nil {
   172  			return err
   173  		}
   174  		w, err := OpenFile(newPath, O_CREATE|O_TRUNC|O_WRONLY, 0666|info.Mode()&0777)
   175  		if err != nil {
   176  			return err
   177  		}
   178  
   179  		if _, err := io.Copy(w, r); err != nil {
   180  			w.Close()
   181  			return &PathError{Op: "Copy", Path: newPath, Err: err}
   182  		}
   183  		return w.Close()
   184  	})
   185  }
   186
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