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/bytealg"
     9  	"internal/filepathlite"
    10  	"io"
    11  	"io/fs"
    12  	"slices"
    13  )
    14  
    15  type readdirMode int
    16  
    17  const (
    18  	readdirName readdirMode = iota
    19  	readdirDirEntry
    20  	readdirFileInfo
    21  )
    22  
    23  // Readdir reads the contents of the directory associated with file and
    24  // returns a slice of up to n [FileInfo] values, as would be returned
    25  // by [Lstat], in directory order. Subsequent calls on the same file will yield
    26  // further FileInfos.
    27  //
    28  // If n > 0, Readdir returns at most n FileInfo structures. In this case, if
    29  // Readdir returns an empty slice, it will return a non-nil error
    30  // explaining why. At the end of a directory, the error is [io.EOF].
    31  //
    32  // If n <= 0, Readdir returns all the FileInfo from the directory in
    33  // a single slice. In this case, if Readdir succeeds (reads all
    34  // the way to the end of the directory), it returns the slice and a
    35  // nil error. If it encounters an error before the end of the
    36  // directory, Readdir returns the FileInfo read until that point
    37  // and a non-nil error.
    38  //
    39  // Most clients are better served by the more efficient ReadDir method.
    40  func (f *File) Readdir(n int) ([]FileInfo, error) {
    41  	if f == nil {
    42  		return nil, ErrInvalid
    43  	}
    44  	_, _, infos, err := f.readdir(n, readdirFileInfo)
    45  	if infos == nil {
    46  		// Readdir has historically always returned a non-nil empty slice, never nil,
    47  		// even on error (except misuse with nil receiver above).
    48  		// Keep it that way to avoid breaking overly sensitive callers.
    49  		infos = []FileInfo{}
    50  	}
    51  	return infos, err
    52  }
    53  
    54  // Readdirnames reads the contents of the directory associated with file
    55  // and returns a slice of up to n names of files in the directory,
    56  // in directory order. Subsequent calls on the same file will yield
    57  // further names.
    58  //
    59  // If n > 0, Readdirnames returns at most n names. In this case, if
    60  // Readdirnames returns an empty slice, it will return a non-nil error
    61  // explaining why. At the end of a directory, the error is [io.EOF].
    62  //
    63  // If n <= 0, Readdirnames returns all the names from the directory in
    64  // a single slice. In this case, if Readdirnames succeeds (reads all
    65  // the way to the end of the directory), it returns the slice and a
    66  // nil error. If it encounters an error before the end of the
    67  // directory, Readdirnames returns the names read until that point and
    68  // a non-nil error.
    69  func (f *File) Readdirnames(n int) (names []string, err error) {
    70  	if f == nil {
    71  		return nil, ErrInvalid
    72  	}
    73  	names, _, _, err = f.readdir(n, readdirName)
    74  	if names == nil {
    75  		// Readdirnames has historically always returned a non-nil empty slice, never nil,
    76  		// even on error (except misuse with nil receiver above).
    77  		// Keep it that way to avoid breaking overly sensitive callers.
    78  		names = []string{}
    79  	}
    80  	return names, err
    81  }
    82  
    83  // A DirEntry is an entry read from a directory
    84  // (using the [ReadDir] function or a [File.ReadDir] method).
    85  type DirEntry = fs.DirEntry
    86  
    87  // ReadDir reads the contents of the directory associated with the file f
    88  // and returns a slice of [DirEntry] values in directory order.
    89  // Subsequent calls on the same file will yield later DirEntry records in the directory.
    90  //
    91  // If n > 0, ReadDir returns at most n DirEntry records.
    92  // In this case, if ReadDir returns an empty slice, it will return an error explaining why.
    93  // At the end of a directory, the error is [io.EOF].
    94  //
    95  // If n <= 0, ReadDir returns all the DirEntry records remaining in the directory.
    96  // When it succeeds, it returns a nil error (not io.EOF).
    97  func (f *File) ReadDir(n int) ([]DirEntry, error) {
    98  	if f == nil {
    99  		return nil, ErrInvalid
   100  	}
   101  	_, dirents, _, err := f.readdir(n, readdirDirEntry)
   102  	if dirents == nil {
   103  		// Match Readdir and Readdirnames: don't return nil slices.
   104  		dirents = []DirEntry{}
   105  	}
   106  	return dirents, err
   107  }
   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 := openDir(name)
   116  	if err != nil {
   117  		return nil, err
   118  	}
   119  	defer f.Close()
   120  
   121  	dirs, err := f.ReadDir(-1)
   122  	slices.SortFunc(dirs, func(a, b DirEntry) int {
   123  		return bytealg.CompareString(a.Name(), b.Name())
   124  	})
   125  	return dirs, err
   126  }
   127  
   128  // CopyFS copies the file system fsys into the directory dir,
   129  // creating dir if necessary.
   130  //
   131  // Files are created with mode 0o666 plus any execute permissions
   132  // from the source, and directories are created with mode 0o777
   133  // (before umask).
   134  //
   135  // CopyFS will not overwrite existing files. If a file name in fsys
   136  // already exists in the destination, CopyFS will return an error
   137  // such that errors.Is(err, fs.ErrExist) will be true.
   138  //
   139  // Symbolic links in dir are followed.
   140  //
   141  // New files added to fsys (including if dir is a subdirectory of fsys)
   142  // while CopyFS is running are not guaranteed to be copied.
   143  //
   144  // Copying stops at and returns the first error encountered.
   145  func CopyFS(dir string, fsys fs.FS) error {
   146  	return fs.WalkDir(fsys, ".", func(path string, d fs.DirEntry, err error) error {
   147  		if err != nil {
   148  			return err
   149  		}
   150  
   151  		fpath, err := filepathlite.Localize(path)
   152  		if err != nil {
   153  			return err
   154  		}
   155  		newPath := joinPath(dir, fpath)
   156  
   157  		switch d.Type() {
   158  		case ModeDir:
   159  			return MkdirAll(newPath, 0777)
   160  		case ModeSymlink:
   161  			target, err := fs.ReadLink(fsys, path)
   162  			if err != nil {
   163  				return err
   164  			}
   165  			return Symlink(target, newPath)
   166  		case 0:
   167  			r, err := fsys.Open(path)
   168  			if err != nil {
   169  				return err
   170  			}
   171  			defer r.Close()
   172  			info, err := r.Stat()
   173  			if err != nil {
   174  				return err
   175  			}
   176  			w, err := OpenFile(newPath, O_CREATE|O_EXCL|O_WRONLY, 0666|info.Mode()&0777)
   177  			if err != nil {
   178  				return err
   179  			}
   180  
   181  			if _, err := io.Copy(w, r); err != nil {
   182  				w.Close()
   183  				return &PathError{Op: "Copy", Path: newPath, Err: err}
   184  			}
   185  			return w.Close()
   186  		default:
   187  			return &PathError{Op: "CopyFS", Path: path, Err: ErrInvalid}
   188  		}
   189  	})
   190  }
   191
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