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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 (
"runtime"
"syscall"
)
// Auxiliary information if the File describes a directory
type dirInfo struct {
stat syscall.Stat_t
usefirststat bool
}
const DevNull = "NUL"
func (file *File) isdir() bool { return file != nil && file.dirinfo != nil }
func openFile(name string, flag int, perm uint32) (file *File, err Error) {
r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, perm)
if e != 0 {
return nil, &PathError{"open", name, Errno(e)}
}
// There's a race here with fork/exec, which we are
// content to live with. See ../syscall/exec.go
if syscall.O_CLOEXEC == 0 { // O_CLOEXEC not supported
syscall.CloseOnExec(r)
}
return NewFile(r, name), nil
}
func openDir(name string) (file *File, err Error) {
d := new(dirInfo)
r, e := syscall.FindFirstFile(syscall.StringToUTF16Ptr(name+"\\*"), &d.stat.Windata)
if e != 0 {
return nil, &PathError{"open", name, Errno(e)}
}
f := NewFile(int(r), name)
d.usefirststat = true
f.dirinfo = d
return f, nil
}
// Open opens the named file with specified flag (O_RDONLY etc.) and perm, (0666 etc.)
// if applicable. If successful, methods on the returned File can be used for I/O.
// It returns the File and an Error, if any.
func Open(name string, flag int, perm uint32) (file *File, err Error) {
// TODO(brainman): not sure about my logic of assuming it is dir first, then fall back to file
r, e := openDir(name)
if e == nil {
if flag&O_WRONLY != 0 || flag&O_RDWR != 0 {
r.Close()
return nil, &PathError{"open", name, EISDIR}
}
return r, nil
}
r, e = openFile(name, flag, perm)
if e == nil {
return r, nil
}
// Imitating Unix behavior by replacing syscall.ERROR_PATH_NOT_FOUND with
// os.ENOTDIR. Not sure if we should go into that.
if e2, ok := e.(*PathError); ok {
if e3, ok := e2.Error.(Errno); ok {
if e3 == Errno(syscall.ERROR_PATH_NOT_FOUND) {
return nil, &PathError{"open", name, ENOTDIR}
}
}
}
return nil, e
}
// Close closes the File, rendering it unusable for I/O.
// It returns an Error, if any.
func (file *File) Close() Error {
if file == nil || file.fd < 0 {
return EINVAL
}
var e int
if file.isdir() {
_, e = syscall.FindClose(int32(file.fd))
} else {
_, e = syscall.CloseHandle(int32(file.fd))
}
var err Error
if e != 0 {
err = &PathError{"close", file.name, Errno(e)}
}
file.fd = -1 // so it can't be closed again
// no need for a finalizer anymore
runtime.SetFinalizer(file, nil)
return err
}
func (file *File) statFile(name string) (fi *FileInfo, err Error) {
var stat syscall.ByHandleFileInformation
if ok, e := syscall.GetFileInformationByHandle(int32(file.fd), &stat); !ok {
return nil, &PathError{"stat", file.name, Errno(e)}
}
return fileInfoFromByHandleInfo(new(FileInfo), file.name, &stat), nil
}
// Stat returns the FileInfo structure describing file.
// It returns the FileInfo and an error, if any.
func (file *File) Stat() (fi *FileInfo, err Error) {
if file == nil || file.fd < 0 {
return nil, EINVAL
}
if file.isdir() {
// I don't know any better way to do that for directory
return Stat(file.name)
}
return file.statFile(file.name)
}
// Readdir reads the contents of the directory associated with file and
// returns an array of up to count FileInfo structures, as would be returned
// by Lstat, in directory order. Subsequent calls on the same file will yield
// further FileInfos.
// A negative count means to read until EOF.
// Readdir returns the array and an Error, if any.
func (file *File) Readdir(count int) (fi []FileInfo, err Error) {
if file == nil || file.fd < 0 {
return nil, EINVAL
}
if !file.isdir() {
return nil, &PathError{"Readdir", file.name, ENOTDIR}
}
di := file.dirinfo
size := count
if size < 0 {
size = 100
}
fi = make([]FileInfo, 0, size) // Empty with room to grow.
for count != 0 {
if di.usefirststat {
di.usefirststat = false
} else {
_, e := syscall.FindNextFile(int32(file.fd), &di.stat.Windata)
if e != 0 {
if e == syscall.ERROR_NO_MORE_FILES {
break
} else {
return nil, &PathError{"FindNextFile", file.name, Errno(e)}
}
}
}
var f FileInfo
fileInfoFromWin32finddata(&f, &di.stat.Windata)
if f.Name == "." || f.Name == ".." { // Useless names
continue
}
count--
fi = append(fi, f)
}
return fi, nil
}
// Truncate changes the size of the named file.
// If the file is a symbolic link, it changes the size of the link's target.
func Truncate(name string, size int64) Error {
f, e := Open(name, O_WRONLY|O_CREAT, 0666)
if e != nil {
return e
}
defer f.Close()
e1 := f.Truncate(size)
if e1 != nil {
return e1
}
return nil
}
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