github.com/peggyl/go@v0.0.0-20151008231540-ae315999c2d5/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 darwin dragonfly freebsd linux nacl netbsd openbsd solaris
     6  
     7  package os
     8  
     9  import (
    10  	"io"
    11  	"syscall"
    12  )
    13  
    14  const (
    15  	blockSize = 4096
    16  )
    17  
    18  func (f *File) readdirnames(n int) (names []string, err error) {
    19  	// If this file has no dirinfo, create one.
    20  	if f.dirinfo == nil {
    21  		f.dirinfo = new(dirInfo)
    22  		// The buffer must be at least a block long.
    23  		f.dirinfo.buf = make([]byte, blockSize)
    24  	}
    25  	d := f.dirinfo
    26  
    27  	size := n
    28  	if size <= 0 {
    29  		size = 100
    30  		n = -1
    31  	}
    32  
    33  	names = make([]string, 0, size) // Empty with room to grow.
    34  	for n != 0 {
    35  		// Refill the buffer if necessary
    36  		if d.bufp >= d.nbuf {
    37  			d.bufp = 0
    38  			var errno error
    39  			d.nbuf, errno = fixCount(syscall.ReadDirent(f.fd, d.buf))
    40  			if errno != nil {
    41  				return names, NewSyscallError("readdirent", errno)
    42  			}
    43  			if d.nbuf <= 0 {
    44  				break // EOF
    45  			}
    46  		}
    47  
    48  		// Drain the buffer
    49  		var nb, nc int
    50  		nb, nc, names = syscall.ParseDirent(d.buf[d.bufp:d.nbuf], n, names)
    51  		d.bufp += nb
    52  		n -= nc
    53  	}
    54  	if n >= 0 && len(names) == 0 {
    55  		return names, io.EOF
    56  	}
    57  	return names, nil
    58  }