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Source file src/os/dir_unix.go

Documentation: os

     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  // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
     6  
     7  package os
     8  
     9  import (
    10  	"io"
    11  	"runtime"
    12  	"syscall"
    13  )
    14  
    15  const (
    16  	blockSize = 4096
    17  )
    18  
    19  func (f *File) readdir(n int) (fi []FileInfo, err error) {
    20  	dirname := f.name
    21  	if dirname == "" {
    22  		dirname = "."
    23  	}
    24  	names, err := f.Readdirnames(n)
    25  	fi = make([]FileInfo, 0, len(names))
    26  	for _, filename := range names {
    27  		fip, lerr := lstat(dirname + "/" + filename)
    28  		if IsNotExist(lerr) {
    29  			// File disappeared between readdir + stat.
    30  			// Just treat it as if it didn't exist.
    31  			continue
    32  		}
    33  		if lerr != nil {
    34  			return fi, lerr
    35  		}
    36  		fi = append(fi, fip)
    37  	}
    38  	if len(fi) == 0 && err == nil && n > 0 {
    39  		// Per File.Readdir, the slice must be non-empty or err
    40  		// must be non-nil if n > 0.
    41  		err = io.EOF
    42  	}
    43  	return fi, err
    44  }
    45  
    46  func (f *File) readdirnames(n int) (names []string, err error) {
    47  	// If this file has no dirinfo, create one.
    48  	if f.dirinfo == nil {
    49  		f.dirinfo = new(dirInfo)
    50  		// The buffer must be at least a block long.
    51  		f.dirinfo.buf = make([]byte, blockSize)
    52  	}
    53  	d := f.dirinfo
    54  
    55  	size := n
    56  	if size <= 0 {
    57  		size = 100
    58  		n = -1
    59  	}
    60  
    61  	names = make([]string, 0, size) // Empty with room to grow.
    62  	for n != 0 {
    63  		// Refill the buffer if necessary
    64  		if d.bufp >= d.nbuf {
    65  			d.bufp = 0
    66  			var errno error
    67  			d.nbuf, errno = f.pfd.ReadDirent(d.buf)
    68  			runtime.KeepAlive(f)
    69  			if errno != nil {
    70  				return names, wrapSyscallError("readdirent", errno)
    71  			}
    72  			if d.nbuf <= 0 {
    73  				break // EOF
    74  			}
    75  		}
    76  
    77  		// Drain the buffer
    78  		var nb, nc int
    79  		nb, nc, names = syscall.ParseDirent(d.buf[d.bufp:d.nbuf], n, names)
    80  		d.bufp += nb
    81  		n -= nc
    82  	}
    83  	if n >= 0 && len(names) == 0 {
    84  		return names, io.EOF
    85  	}
    86  	return names, nil
    87  }
    88  

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