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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build darwin freebsd linux netbsd openbsd
package os
import (
"io"
"syscall"
)
const (
blockSize = 4096
)
// Readdirnames reads and returns a slice of names from the directory f.
//
// If n > 0, Readdirnames returns at most n names. In this case, if
// Readdirnames returns an empty slice, it will return a non-nil error
// explaining why. At the end of a directory, the error is io.EOF.
//
// If n <= 0, Readdirnames returns all the names from the directory in
// a single slice. In this case, if Readdirnames succeeds (reads all
// the way to the end of the directory), it returns the slice and a
// nil error. If it encounters an error before the end of the
// directory, Readdirnames returns the names read until that point and
// a non-nil error.
func (f *File) Readdirnames(n int) (names []string, err error) {
// If this file has no dirinfo, create one.
if f.dirinfo == nil {
f.dirinfo = new(dirInfo)
// The buffer must be at least a block long.
f.dirinfo.buf = make([]byte, blockSize)
}
d := f.dirinfo
size := n
if size <= 0 {
size = 100
n = -1
}
names = make([]string, 0, size) // Empty with room to grow.
for n != 0 {
// Refill the buffer if necessary
if d.bufp >= d.nbuf {
d.bufp = 0
var errno error
d.nbuf, errno = syscall.ReadDirent(f.fd, d.buf)
if errno != nil {
return names, NewSyscallError("readdirent", errno)
}
if d.nbuf <= 0 {
break // EOF
}
}
// Drain the buffer
var nb, nc int
nb, nc, names = syscall.ParseDirent(d.buf[d.bufp:d.nbuf], n, names)
d.bufp += nb
n -= nc
}
if n >= 0 && len(names) == 0 {
return names, io.EOF
}
return names, nil
}
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