github.com/hikaru7719/go@v0.0.0-20181025140707-c8b2ac68906a/src/os/dir_unix.go (about)

     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 aix darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris
     6  
     7  package os
     8  
     9  import (
    10  	"io"
    11  	"runtime"
    12  	"syscall"
    13  )
    14  
    15  const (
    16  	// More than 5760 to work around https://golang.org/issue/24015.
    17  	blockSize = 8192
    18  )
    19  
    20  func (f *File) readdir(n int) (fi []FileInfo, err error) {
    21  	dirname := f.name
    22  	if dirname == "" {
    23  		dirname = "."
    24  	}
    25  	names, err := f.Readdirnames(n)
    26  	fi = make([]FileInfo, 0, len(names))
    27  	for _, filename := range names {
    28  		fip, lerr := lstat(dirname + "/" + filename)
    29  		if IsNotExist(lerr) {
    30  			// File disappeared between readdir + stat.
    31  			// Just treat it as if it didn't exist.
    32  			continue
    33  		}
    34  		if lerr != nil {
    35  			return fi, lerr
    36  		}
    37  		fi = append(fi, fip)
    38  	}
    39  	if len(fi) == 0 && err == nil && n > 0 {
    40  		// Per File.Readdir, the slice must be non-empty or err
    41  		// must be non-nil if n > 0.
    42  		err = io.EOF
    43  	}
    44  	return fi, err
    45  }
    46  
    47  func (f *File) readdirnames(n int) (names []string, err error) {
    48  	// If this file has no dirinfo, create one.
    49  	if f.dirinfo == nil {
    50  		f.dirinfo = new(dirInfo)
    51  		// The buffer must be at least a block long.
    52  		f.dirinfo.buf = make([]byte, blockSize)
    53  	}
    54  	d := f.dirinfo
    55  
    56  	size := n
    57  	if size <= 0 {
    58  		size = 100
    59  		n = -1
    60  	}
    61  
    62  	names = make([]string, 0, size) // Empty with room to grow.
    63  	for n != 0 {
    64  		// Refill the buffer if necessary
    65  		if d.bufp >= d.nbuf {
    66  			d.bufp = 0
    67  			var errno error
    68  			d.nbuf, errno = f.pfd.ReadDirent(d.buf)
    69  			runtime.KeepAlive(f)
    70  			if errno != nil {
    71  				return names, wrapSyscallError("readdirent", errno)
    72  			}
    73  			if d.nbuf <= 0 {
    74  				break // EOF
    75  			}
    76  		}
    77  
    78  		// Drain the buffer
    79  		var nb, nc int
    80  		nb, nc, names = syscall.ParseDirent(d.buf[d.bufp:d.nbuf], n, names)
    81  		d.bufp += nb
    82  		n -= nc
    83  	}
    84  	if n >= 0 && len(names) == 0 {
    85  		return names, io.EOF
    86  	}
    87  	return names, nil
    88  }