package console

import "github.com/containerd/console"

Index ¶

• Variables
• func ClearONLCR(fd uintptr) error
• func SetONLCR(fd uintptr) error
• type Console
• func ConsoleFromFile(f File) (Console, error)
• func Current() (c Console)
• func NewPty() (Console, string, error)
• type EpollConsole
• func (ec *EpollConsole) Read(p []byte) (n int, err error)
• func (ec *EpollConsole) Shutdown(close func(int) error) error
• func (ec *EpollConsole) Write(p []byte) (n int, err error)
• type Epoller
• func NewEpoller() (*Epoller, error)
• func (e *Epoller) Add(console Console) (*EpollConsole, error)
• func (e *Epoller) Close() error
• func (e *Epoller) CloseConsole(fd int) error
• func (e *Epoller) Wait() error
• type File
• type WinSize

Variables ¶

var (
	ErrNotAConsole    = errors.New("provided file is not a console")
	ErrNotImplemented = errors.New("not implemented")
)

Functions ¶

func ClearONLCR ¶

func ClearONLCR(fd uintptr) error

ClearONLCR sets the necessary tty_ioctl(4)s to ensure that a pty pair created by us acts normally. In particular, a not-very-well-known default of Linux unix98 ptys is that they have +onlcr by default. While this isn't a problem for terminal emulators, because we relay data from the terminal we also relay that funky line discipline.

func SetONLCR ¶

func SetONLCR(fd uintptr) error

SetONLCR sets the necessary tty_ioctl(4)s to ensure that a pty pair created by us acts as intended for a terminal emulator.

Types ¶

type Console ¶

type Console interface {
	File

	// Resize resizes the console to the provided window size
	Resize(WinSize) error
	// ResizeFrom resizes the calling console to the size of the
	// provided console
	ResizeFrom(Console) error
	// SetRaw sets the console in raw mode
	SetRaw() error
	// DisableEcho disables echo on the console
	DisableEcho() error
	// Reset restores the console to its original state
	Reset() error
	// Size returns the window size of the console
	Size() (WinSize, error)
}

func ConsoleFromFile ¶

func ConsoleFromFile(f File) (Console, error)

ConsoleFromFile returns a console using the provided file nolint:revive

func Current ¶

func Current() (c Console)

Current returns the current process' console

func NewPty ¶

func NewPty() (Console, string, error)

NewPty creates a new pty pair The master is returned as the first console and a string with the path to the pty slave is returned as the second

type EpollConsole ¶

type EpollConsole struct {
	Console
	// contains filtered or unexported fields
}

EpollConsole acts like a console but registers its file descriptor with an epoll fd and uses epoll API to perform I/O.

func (*EpollConsole) Read ¶

func (ec *EpollConsole) Read(p []byte) (n int, err error)

Read reads up to len(p) bytes into p. It returns the number of bytes read (0 <= n <= len(p)) and any error encountered.

If the console's read returns EAGAIN or EIO, we assume that it's a temporary error because the other side went away and wait for the signal generated by epoll event to continue.

func (*EpollConsole) Shutdown ¶

func (ec *EpollConsole) Shutdown(close func(int) error) error

Shutdown closes the file descriptor and signals call waiters for this fd. It accepts a callback which will be called with the console's fd. The callback typically will be used to do further cleanup such as unregister the console's fd from the epoll interface. User should call Shutdown and wait for all I/O operation to be finished before closing the console.

func (*EpollConsole) Write ¶

func (ec *EpollConsole) Write(p []byte) (n int, err error)

Writes len(p) bytes from p to the console. It returns the number of bytes written from p (0 <= n <= len(p)) and any error encountered that caused the write to stop early.

If writes to the console returns EAGAIN or EIO, we assume that it's a temporary error because the other side went away and wait for the signal generated by epoll event to continue.

type Epoller ¶

type Epoller struct {
	// contains filtered or unexported fields
}

Epoller manages multiple epoll consoles using edge-triggered epoll api so we dont have to deal with repeated wake-up of EPOLLER or EPOLLHUP. For more details, see: - https://github.com/systemd/systemd/pull/4262 - https://github.com/moby/moby/issues/27202

Example usage of Epoller and EpollConsole can be as follow:

epoller, _ := NewEpoller()
epollConsole, _ := epoller.Add(console)
go epoller.Wait()
var (
	b  bytes.Buffer
	wg sync.WaitGroup
)
wg.Add(1)
go func() {
	io.Copy(&b, epollConsole)
	wg.Done()
}()
// perform I/O on the console
epollConsole.Shutdown(epoller.CloseConsole)
wg.Wait()
epollConsole.Close()

func NewEpoller ¶

func NewEpoller() (*Epoller, error)

NewEpoller returns an instance of epoller with a valid epoll fd.

func (*Epoller) Add ¶

func (e *Epoller) Add(console Console) (*EpollConsole, error)

Add creates an epoll console based on the provided console. The console will be registered with EPOLLET (i.e. using edge-triggered notification) and its file descriptor will be set to non-blocking mode. After this, user should use the return console to perform I/O.

func (*Epoller) Close ¶

func (e *Epoller) Close() error

Close closes the epoll fd

func (*Epoller) CloseConsole ¶

func (e *Epoller) CloseConsole(fd int) error

CloseConsole unregisters the console's file descriptor from epoll interface

func (*Epoller) Wait ¶

func (e *Epoller) Wait() error

Wait starts the loop to wait for its consoles' notifications and signal appropriate console that it can perform I/O.

type File ¶

type File interface {
	io.ReadWriteCloser

	// Fd returns its file descriptor
	Fd() uintptr
	// Name returns its file name
	Name() string
}

type WinSize ¶

type WinSize struct {
	// Height of the console
	Height uint16
	// Width of the console
	Width uint16
	// contains filtered or unexported fields
}

WinSize specifies the window size of the console

Source Files ¶

console.go console_linux.go console_unix.go pty_unix.go tc_linux.go tc_unix.go