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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"
"sync"
"syscall"
)
// File represents an open file descriptor.
type File struct {
fd syscall.Handle
name string
dirinfo *dirInfo // nil unless directory being read
nepipe int // number of consecutive EPIPE in Write
l sync.Mutex // used to implement windows pread/pwrite
}
// Fd returns the Windows handle referencing the open file.
func (file *File) Fd() syscall.Handle {
if file == nil {
return syscall.InvalidHandle
}
return file.fd
}
// NewFile returns a new File with the given file descriptor and name.
func NewFile(fd syscall.Handle, name string) *File {
if fd < 0 {
return nil
}
f := &File{fd: fd, name: name}
runtime.SetFinalizer(f, (*File).Close)
return f
}
// Auxiliary information if the File describes a directory
type dirInfo struct {
data syscall.Win32finddata
needdata 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.data)
if e != 0 {
return nil, &PathError{"open", name, Errno(e)}
}
f := NewFile(r, name)
f.dirinfo = d
return f, nil
}
// OpenFile is the generalized open call; most users will use Open
// or Create instead. It 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 OpenFile(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
}
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(syscall.Handle(file.fd))
} else {
e = syscall.CloseHandle(syscall.Handle(file.fd))
}
var err Error
if e != 0 {
err = &PathError{"close", file.name, Errno(e)}
}
file.fd = syscall.InvalidHandle // so it can't be closed again
// no need for a finalizer anymore
runtime.SetFinalizer(file, nil)
return err
}
// Readdir reads the contents of the directory associated with file and
// returns an array of up to n FileInfo structures, as would be returned
// by Lstat, in directory order. Subsequent calls on the same file will yield
// further FileInfos.
//
// If n > 0, Readdir returns at most n FileInfo structures. In this case, if
// Readdir returns an empty slice, it will return a non-nil error
// explaining why. At the end of a directory, the error is os.EOF.
//
// If n <= 0, Readdir returns all the FileInfo from the directory in
// a single slice. In this case, if Readdir succeeds (reads all
// the way to the end of the directory), it returns the slice and a
// nil os.Error. If it encounters an error before the end of the
// directory, Readdir returns the FileInfo read until that point
// and a non-nil error.
func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
if file == nil || file.fd < 0 {
return nil, EINVAL
}
if !file.isdir() {
return nil, &PathError{"Readdir", file.name, ENOTDIR}
}
wantAll := n <= 0
size := n
if wantAll {
n = -1
size = 100
}
fi = make([]FileInfo, 0, size) // Empty with room to grow.
d := &file.dirinfo.data
for n != 0 {
if file.dirinfo.needdata {
e := syscall.FindNextFile(syscall.Handle(file.fd), d)
if e != 0 {
if e == syscall.ERROR_NO_MORE_FILES {
break
} else {
err = &PathError{"FindNextFile", file.name, Errno(e)}
if !wantAll {
fi = nil
}
return
}
}
}
var f FileInfo
setFileInfo(&f, string(syscall.UTF16ToString(d.FileName[0:])), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime)
file.dirinfo.needdata = true
if f.Name == "." || f.Name == ".." { // Useless names
continue
}
n--
fi = append(fi, f)
}
if !wantAll && len(fi) == 0 {
return fi, EOF
}
return fi, nil
}
// read reads up to len(b) bytes from the File.
// It returns the number of bytes read and an error, if any.
func (f *File) read(b []byte) (n int, err int) {
f.l.Lock()
defer f.l.Unlock()
return syscall.Read(f.fd, b)
}
// pread reads len(b) bytes from the File starting at byte offset off.
// It returns the number of bytes read and the error, if any.
// EOF is signaled by a zero count with err set to 0.
func (f *File) pread(b []byte, off int64) (n int, err int) {
f.l.Lock()
defer f.l.Unlock()
curoffset, e := syscall.Seek(f.fd, 0, 1)
if e != 0 {
return 0, e
}
defer syscall.Seek(f.fd, curoffset, 0)
o := syscall.Overlapped{
OffsetHigh: uint32(off >> 32),
Offset: uint32(off),
}
var done uint32
e = syscall.ReadFile(syscall.Handle(f.fd), b, &done, &o)
if e != 0 {
return 0, e
}
return int(done), 0
}
// write writes len(b) bytes to the File.
// It returns the number of bytes written and an error, if any.
func (f *File) write(b []byte) (n int, err int) {
f.l.Lock()
defer f.l.Unlock()
return syscall.Write(f.fd, b)
}
// pwrite writes len(b) bytes to the File starting at byte offset off.
// It returns the number of bytes written and an error, if any.
func (f *File) pwrite(b []byte, off int64) (n int, err int) {
f.l.Lock()
defer f.l.Unlock()
curoffset, e := syscall.Seek(f.fd, 0, 1)
if e != 0 {
return 0, e
}
defer syscall.Seek(f.fd, curoffset, 0)
o := syscall.Overlapped{
OffsetHigh: uint32(off >> 32),
Offset: uint32(off),
}
var done uint32
e = syscall.WriteFile(syscall.Handle(f.fd), b, &done, &o)
if e != 0 {
return 0, e
}
return int(done), 0
}
// seek sets the offset for the next Read or Write on file to offset, interpreted
// according to whence: 0 means relative to the origin of the file, 1 means
// relative to the current offset, and 2 means relative to the end.
// It returns the new offset and an error, if any.
func (f *File) seek(offset int64, whence int) (ret int64, err int) {
f.l.Lock()
defer f.l.Unlock()
return syscall.Seek(f.fd, offset, whence)
}
// 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 := OpenFile(name, O_WRONLY|O_CREATE, 0666)
if e != nil {
return e
}
defer f.Close()
e1 := f.Truncate(size)
if e1 != nil {
return e1
}
return nil
}
// Pipe returns a connected pair of Files; reads from r return bytes written to w.
// It returns the files and an Error, if any.
func Pipe() (r *File, w *File, err Error) {
var p [2]syscall.Handle
// See ../syscall/exec.go for description of lock.
syscall.ForkLock.RLock()
e := syscall.Pipe(p[0:])
if iserror(e) {
syscall.ForkLock.RUnlock()
return nil, nil, NewSyscallError("pipe", e)
}
syscall.CloseOnExec(p[0])
syscall.CloseOnExec(p[1])
syscall.ForkLock.RUnlock()
return NewFile(p[0], "|0"), NewFile(p[1], "|1"), nil
}