Golang File.Fd方法代码示例

func sendTTYToCommand(commandUsock *unixsocket.Usock, clientFile *os.File, err error) error {
	if err != nil {
		return err
	}

	return commandUsock.WriteFD(int(clientFile.Fd()))
}

func setFileLock(f *os.File, lock bool) error {
	how := syscall.LOCK_UN
	if lock {
		how = syscall.LOCK_EX
	}
	return syscall.Flock(int(f.Fd()), how|syscall.LOCK_NB)
}

// flock acquires an advisory lock on a file descriptor.
func flock(f *os.File, exclusive bool, timeout time.Duration) error {
	var t time.Time
	for {
		// If we're beyond our timeout then return an error.
		// This can only occur after we've attempted a flock once.
		if t.IsZero() {
			t = time.Now()
		} else if timeout > 0 && time.Since(t) > timeout {
			return ErrTimeout
		}
		flag := syscall.LOCK_SH
		if exclusive {
			flag = syscall.LOCK_EX
		}

		// Otherwise attempt to obtain an exclusive lock.
		err := syscall.Flock(int(f.Fd()), flag|syscall.LOCK_NB)
		if err == nil {
			return nil
		} else if err != syscall.EWOULDBLOCK {
			return err
		}

		// Wait for a bit and try again.
		time.Sleep(50 * time.Millisecond)
	}
}

// SetCapacity reloads the size for the loopback device.
func SetCapacity(file *os.File) error {
	if err := ioctlLoopSetCapacity(file.Fd(), 0); err != nil {
		logrus.Errorf("Error loopbackSetCapacity: %s", err)
		return ErrSetCapacity
	}
	return nil
}

func getFuseConn(local *os.File) (f *os.File, err os.Error) {
	var data [4]byte
	control := make([]byte, 4*256)

	// n, oobn, recvflags, from, errno  - todo: error checking.
	_, oobn, _, _,
		errno := syscall.Recvmsg(
		local.Fd(), data[:], control[:], 0)
	if errno != 0 {
		return
	}

	message := *(*syscall.Cmsghdr)(unsafe.Pointer(&control[0]))
	fd := *(*int32)(unsafe.Pointer(uintptr(unsafe.Pointer(&control[0])) + syscall.SizeofCmsghdr))

	if message.Type != 1 {
		err = os.NewError(fmt.Sprintf("getFuseConn: recvmsg returned wrong control type: %d", message.Type))
		return
	}
	if oobn <= syscall.SizeofCmsghdr {
		err = os.NewError(fmt.Sprintf("getFuseConn: too short control message. Length: %d", oobn))
		return
	}
	if fd < 0 {
		err = os.NewError(fmt.Sprintf("getFuseConn: fd < 0: %d", fd))
		return
	}
	f = os.NewFile(int(fd), "<fuseConnection>")
	return
}

func setupTerminal(file *os.File) (*sys.Termios, error) {
	fd := int(file.Fd())
	term, err := sys.NewTermiosFromFd(fd)
	if err != nil {
		return nil, fmt.Errorf("can't get terminal attribute: %s", err)
	}

	savedTermios := term.Copy()

	term.SetICanon(false)
	term.SetEcho(false)
	term.SetVMin(1)
	term.SetVTime(0)

	err = term.ApplyToFd(fd)
	if err != nil {
		return nil, fmt.Errorf("can't set up terminal attribute: %s", err)
	}

	/*
		err = sys.FlushInput(fd)
		if err != nil {
			return nil, fmt.Errorf("can't flush input: %s", err)
		}
	*/

	return savedTermios, nil
}

// ptsname retrieves the name of the first available pts for the given master.
func ptsname(f *os.File) (string, error) {
	var n int32
	if err := ioctl(f.Fd(), syscall.TIOCGPTN, uintptr(unsafe.Pointer(&n))); err != nil {
		return "", err
	}
	return fmt.Sprintf("/dev/pts/%d", n), nil
}

func (mon *SlaveMonitor) startInitialProcess(sock *os.File) {
	for {
		command := mon.tree.ExecCommand
		parts := strings.Split(command, " ")
		executable := parts[0]
		args := parts[1:]
		cmd := exec.Command(executable, args...)
		cmd.Env = append(os.Environ(), fmt.Sprintf("ZEUS_MASTER_FD=%d", sock.Fd()))
		cmd.ExtraFiles = []*os.File{sock}

		// We want to let this process run "forever", but it will eventually
		// die... either on program termination or when its dependencies change
		// and we kill it. when it's requested to restart, err is "signal 9",
		// and we do nothing.
		go func() {
			output, err := cmd.CombinedOutput()
			if err == nil {
				ErrorConfigCommandCrashed(string(output))
			}
			msg := err.Error()
			if len(msg) > 11 && err.Error()[:11] != "exit status" {
				ErrorConfigCommandCouldntStart(err.Error())
			}
		}()

		restartNow := make(chan bool)
		go func() {
			mon.tree.Root.WaitUntilRestartRequested()
			restartNow <- true
		}()

		<-restartNow
		mon.tree.Root.Kill()
	}
}

// TryExclusive is the non-blocking form of Exclusive and will return an
// error if the lock could not be obtained immediately.
func TryExclusive(file *os.File) error {
	lock := syscall.LOCK_EX | syscall.LOCK_NB
	if err := syscall.Flock(int(file.Fd()), lock); err != nil {
		return err
	}
	return nil
}

// Implement mmap for windows
func map_file(file *os.File, offset, size int) ([]byte, error) {

	// create the mapping handle
	h, err := syscall.CreateFileMapping(syscall.Handle(file.Fd()), nil, syscall.PAGE_READONLY, 0, uint32(size), nil)
	if err != nil {
		return nil, err
	}

	// perform the file map operation
	addr, err := syscall.MapViewOfFile(h, syscall.FILE_MAP_READ, uint32(offset>>32), uint32(offset), uintptr(size))
	if err != nil {
		return nil, err
	}

	// store the mapping handle
	win_mapper_mutex.Lock()
	win_mapper_handle[addr] = h
	win_mapper_mutex.Unlock()

	// Slice memory layout
	sl := reflect.SliceHeader{Data: addr, Len: size, Cap: size}

	// Use unsafe to turn sl into a []byte.
	bp := *(*[]byte)(unsafe.Pointer(&sl))

	return bp, err
}

func (g *GraphTool) tarCp(srcName string, tw *tar.Writer) (int64, error) {
	var (
		src *os.File
		err error
	)

	if src, err = os.Open(srcName); err != nil {
		return 0, err
	}
	defer src.Close()

	srcStat, err := src.Stat()
	if err != nil {
		g.logger.Error(err.Error())
	} else if err := unix.Fadvise(int(src.Fd()), 0, srcStat.Size(), unix.MADV_SEQUENTIAL); err != nil {
		g.logger.Error(err.Error())
	}

	if n, err := io.Copy(tw, src); err != nil {
		g.logger.Error(err.Error())
	} else {
		return n, nil
	}

	return 0, nil
}

// NewBufferFile maps a file to shared memory and returns a handle to the shared memory buffer
func NewBufferFile(file *os.File, size, prot int) (Buffer, error) {
	fi, err := file.Stat()
	if err != nil {
		return nil, err
	}
	sys := fi.Sys().(*syscall.Stat_t)
	if sys.Size != int64(size) {
		return nil, errWrongSize
	}

	// Dup to allow file parameter to be closed regardless
	fd, err := syscall.Dup(int(file.Fd()))
	if err != nil {
		return nil, err
	}
	const flags = syscall.MAP_SHARED
	b, err := syscall.Mmap(fd, 0, size, prot, flags)
	if err != nil {
		return nil, err
	}

	// localFile is nil because fd is from somewhere else
	buf := &sharedBuffer{os.NewFile(uintptr(fd), ""), nil, b, stackToKeep()}
	runtime.SetFinalizer(buf, (*sharedBuffer).finalize)

	return buf, nil
}

func main() {
	flag.Usage = usage
	flag.Parse()
	if flag.NArg() < 1 {
		usage()
	}

	vtnum, err := strconv.Atoi(flag.Arg(0))
	ck(err)

	consoles := []string{"/dev/console", "/dev/vc/0", "/dev/tty"}
	var f *os.File
	for _, cc := range consoles {
		f, err = os.OpenFile(cc, os.O_RDWR, 0644)
		if err == nil {
			break
		}
	}
	if f == nil {
		fmt.Fprintln(os.Stderr, "chvt: couldn't get file descriptor referring to console")
		os.Exit(1)
	}

	fd := f.Fd()
	_, _, err = syscall.Syscall(syscall.SYS_IOCTL, fd, 0x5606, uintptr(vtnum))
	if err != nil {
		_, _, err = syscall.Syscall(syscall.SYS_IOCTL, fd, 0x5607, uintptr(vtnum))
	}
	f.Close()

	if err != nil {
		fmt.Fprintln(os.Stderr, "chvt:", err)
		os.Exit(1)
	}
}

func handleSignals(processGroup *ProcessGroup, c <-chan os.Signal, startTime int, sockfile *os.File) {
	for {
		signal := <-c // os.Signal
		syscallSignal := signal.(syscall.Signal)

		switch syscallSignal {
		case syscall.SIGUSR1:
			socketMasterFdEnvVar := fmt.Sprintf("SOCKETMASTER_FD=%d", sockfile.Fd())
			syscall.Exec(os.Args[0], os.Args, append(os.Environ(), socketMasterFdEnvVar))
		case syscall.SIGHUP:
			process, err := processGroup.StartProcess()
			if err != nil {
				log.Printf("Could not start new process: %v\n", err)
			} else {
				if startTime > 0 {
					time.Sleep(time.Duration(startTime) * time.Millisecond)
				}

				// A possible improvement woud be to only swap the
				// process if the new child is still alive.
				processGroup.SignalAll(signal, process)
			}
		default:
			// Forward signal
			processGroup.SignalAll(signal, nil)
		}
	}
}

func fallocate(f *os.File, sz int64) error {
	err := syscall.Fallocate(int(f.Fd()), 0, 0, sz)
	if err == syscall.ENOTSUP {
		return f.Truncate(sz)
	}
	return err
}