dir_plan9.go

     1  // Copyright 2009 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"
     9  	"io/fs"
    10  	"syscall"
    11  )
    12  
    13  func (file *File) readdir(n int, mode readdirMode) (names []string, dirents []DirEntry, infos []FileInfo, err error) {
    14  	var d *dirInfo
    15  	for {
    16  		d = file.dirinfo.Load()
    17  		if d != nil {
    18  			break
    19  		}
    20  		newD := new(dirInfo)
    21  		if file.dirinfo.CompareAndSwap(nil, newD) {
    22  			d = newD
    23  			break
    24  		}
    25  	}
    26  
    27  	d.mu.Lock()
    28  	defer d.mu.Unlock()
    29  
    30  	size := n
    31  	if size <= 0 {
    32  		size = 100
    33  		n = -1
    34  	}
    35  	for n != 0 {
    36  		// Refill the buffer if necessary.
    37  		if d.bufp >= d.nbuf {
    38  			nb, err := file.Read(d.buf[:])
    39  
    40  			// Update the buffer state before checking for errors.
    41  			d.bufp, d.nbuf = 0, nb
    42  
    43  			if err != nil {
    44  				if err == io.EOF {
    45  					break
    46  				}
    47  				return names, dirents, infos, &PathError{Op: "readdir", Path: file.name, Err: err}
    48  			}
    49  			if nb < syscall.STATFIXLEN {
    50  				return names, dirents, infos, &PathError{Op: "readdir", Path: file.name, Err: syscall.ErrShortStat}
    51  			}
    52  		}
    53  
    54  		// Get a record from the buffer.
    55  		b := d.buf[d.bufp:]
    56  		m := int(uint16(b[0])|uint16(b[1])<<8) + 2
    57  		if m < syscall.STATFIXLEN {
    58  			return names, dirents, infos, &PathError{Op: "readdir", Path: file.name, Err: syscall.ErrShortStat}
    59  		}
    60  
    61  		dir, err := syscall.UnmarshalDir(b[:m])
    62  		if err != nil {
    63  			return names, dirents, infos, &PathError{Op: "readdir", Path: file.name, Err: err}
    64  		}
    65  
    66  		if mode == readdirName {
    67  			names = append(names, dir.Name)
    68  		} else {
    69  			f := fileInfoFromStat(dir)
    70  			if mode == readdirDirEntry {
    71  				dirents = append(dirents, dirEntry{f})
    72  			} else {
    73  				infos = append(infos, f)
    74  			}
    75  		}
    76  		d.bufp += m
    77  		n--
    78  	}
    79  
    80  	if n > 0 && len(names)+len(dirents)+len(infos) == 0 {
    81  		return nil, nil, nil, io.EOF
    82  	}
    83  	return names, dirents, infos, nil
    84  }
    85  
    86  type dirEntry struct {
    87  	fs *fileStat
    88  }
    89  
    90  func (de dirEntry) Name() string            { return de.fs.Name() }
    91  func (de dirEntry) IsDir() bool             { return de.fs.IsDir() }
    92  func (de dirEntry) Type() FileMode          { return de.fs.Mode().Type() }
    93  func (de dirEntry) Info() (FileInfo, error) { return de.fs, nil }
    94  
    95  func (de dirEntry) String() string {
    96  	return fs.FormatDirEntry(de)
    97  }
    98
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