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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.
package os
import (
"syscall"
"unsafe"
)
const (
blockSize = 4096 // TODO(r): use statfs
)
// Readdirnames reads the contents of the directory associated with file and
// returns an array of up to count names, in directory order. Subsequent
// calls on the same file will yield further names.
// A negative count means to read until EOF.
// Readdirnames returns the array and an Error, if any.
func (file *File) Readdirnames(count int) (names []string, err Error) {
// If this file has no dirinfo, create one.
if file.dirinfo == nil {
file.dirinfo = new(dirInfo)
// The buffer must be at least a block long.
// TODO(r): use fstatfs to find fs block size.
file.dirinfo.buf = make([]byte, blockSize)
}
d := file.dirinfo
size := count
if size < 0 {
size = 100
}
names = make([]string, 0, size) // Empty with room to grow.
for count != 0 {
// Refill the buffer if necessary
if d.bufp >= d.nbuf {
var errno int
d.bufp = 0
// Final argument is (basep *uintptr) and the syscall doesn't take nil.
d.nbuf, errno = syscall.Getdirentries(file.fd, d.buf, new(uintptr))
if errno != 0 {
d.nbuf = 0
return names, NewSyscallError("getdirentries", errno)
}
if d.nbuf <= 0 {
break // EOF
}
}
// Drain the buffer
for count != 0 && d.bufp < d.nbuf {
dirent := (*syscall.Dirent)(unsafe.Pointer(&d.buf[d.bufp]))
if dirent.Reclen == 0 {
d.bufp = d.nbuf
break
}
d.bufp += int(dirent.Reclen)
if dirent.Ino == 0 { // File absent in directory.
continue
}
bytes := (*[10000]byte)(unsafe.Pointer(&dirent.Name[0]))
var name = string(bytes[0:dirent.Namlen])
if name == "." || name == ".." { // Useless names
continue
}
count--
names = append(names, name)
}
}
return names, nil
}
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