libuv/docs/src/tty.rst
Anna Henningsen 843b64faf5
win: add ENABLE_VIRTUAL_TERMINAL_INPUT raw tty mode (#4688)
Windows provides the `ENABLE_VIRTUAL_TERMINAL_INPUT` flag for TTY input
streams as a companion flag to `ENABLE_VIRTUAL_TERMINAL_PROCESSING`,
which libuv is already setting for TTY output streams.

Setting this flag lets the terminal emulator perform some of the
processing that libuv already currently does for input events,
but most notably enables receiving control sequences that are
otherwise entirely unavailable, e.g. for bracketed paste
(which the Node.js readline implementation added basic support for
in https://github.com/nodejs/node/commit/87af913b66eab78088acfd).

libuv currently already provides translations for key events to
control sequences, i.e. what this mode is intended to provide,
but libuv does not and cannot translate all such events.
Since the control sequences differ from the ones that Windows
has chosen to standardize on, and applications may not be expecting
this change, this is opt-in for now (but ideally will be the default
behavior starting in libuv v2.x, should that ever happen).

Another downside of this change is that not all shells reset
this mode when an application exits. For example, when running a
Node.js program with this flag enabled inside of PowerShell in
Windows terminal, if the application exits while in raw TTY input mode,
neither the shell nor the terminal emulator reset this flag, rendering
the input stream unusable.

While there's general awareness of the problem that console state is
global state rather than per-process (same as on UNIX platforms),
it seems that applications like PowerShell aren't expecting to need to
unset this flag on the input stream, only its output counterpart
(e.g. 4e7942135f/src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHost.cs (L1156)).

Hence, `uv_tty_reset_mode()` is extended to reset the terminal
to its original state if the new mode is being used.

Refs: 87af913b66
Refs: https://github.com/microsoft/terminal/issues/4954
2025-02-21 23:34:53 +01:00

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.. _tty:
:c:type:`uv_tty_t` --- TTY handle
=================================
TTY handles represent a stream for the console.
:c:type:`uv_tty_t` is a 'subclass' of :c:type:`uv_stream_t`.
Data types
----------
.. c:type:: uv_tty_t
TTY handle type.
.. c:enum:: uv_tty_mode_t
.. versionadded:: 1.2.0
TTY mode type:
::
typedef enum {
/* Initial/normal terminal mode */
UV_TTY_MODE_NORMAL,
/*
* Raw input mode (On Windows, ENABLE_WINDOW_INPUT is also enabled).
* May become equivalent to UV_TTY_MODE_RAW_VT in future libuv versions.
*/
UV_TTY_MODE_RAW,
/* Binary-safe I/O mode for IPC (Unix-only) */
UV_TTY_MODE_IO,
/* Raw input mode. On Windows ENABLE_VIRTUAL_TERMINAL_INPUT is also set. */
UV_TTY_MODE_RAW_VT
} uv_tty_mode_t;
.. c:enum:: uv_tty_vtermstate_t
Console virtual terminal mode type:
::
typedef enum {
/*
* The console supports handling of virtual terminal sequences
* (Windows10 new console, ConEmu)
*/
UV_TTY_SUPPORTED,
/* The console cannot process virtual terminal sequences. (Legacy
* console)
*/
UV_TTY_UNSUPPORTED
} uv_tty_vtermstate_t
Public members
^^^^^^^^^^^^^^
N/A
.. seealso:: The :c:type:`uv_stream_t` members also apply.
API
---
.. c:function:: int uv_tty_init(uv_loop_t* loop, uv_tty_t* handle, uv_file fd, int unused)
Initialize a new TTY stream with the given file descriptor. Usually the
file descriptor will be:
* 0 = stdin
* 1 = stdout
* 2 = stderr
On Unix this function will determine the path of the fd of the terminal
using :man:`ttyname_r(3)`, open it, and use it if the passed file descriptor
refers to a TTY. This lets libuv put the tty in non-blocking mode without
affecting other processes that share the tty.
This function is not thread safe on systems that don't support
ioctl TIOCGPTN or TIOCPTYGNAME, for instance OpenBSD and Solaris.
.. note::
If reopening the TTY fails, libuv falls back to blocking writes.
.. versionchanged:: 1.23.1: the `readable` parameter is now unused and ignored.
The correct value will now be auto-detected from the kernel.
.. versionchanged:: 1.9.0: the path of the TTY is determined by
:man:`ttyname_r(3)`. In earlier versions libuv opened
`/dev/tty` instead.
.. versionchanged:: 1.5.0: trying to initialize a TTY stream with a file
descriptor that refers to a file returns `UV_EINVAL`
on UNIX.
.. c:function:: int uv_tty_set_mode(uv_tty_t* handle, uv_tty_mode_t mode)
.. versionchanged:: 1.2.0: the mode is specified as a
:c:enum:`uv_tty_mode_t` value.
Set the TTY using the specified terminal mode.
.. c:function:: int uv_tty_reset_mode(void)
To be called when the program exits. Resets TTY settings to default
values for the next process to take over.
This function is async signal-safe on Unix platforms but can fail with error
code ``UV_EBUSY`` if you call it when execution is inside
:c:func:`uv_tty_set_mode`.
.. c:function:: int uv_tty_get_winsize(uv_tty_t* handle, int* width, int* height)
Gets the current Window size. On success it returns 0.
.. seealso:: The :c:type:`uv_stream_t` API functions also apply.
.. c:function:: void uv_tty_set_vterm_state(uv_tty_vtermstate_t state)
Controls whether console virtual terminal sequences are processed by libuv
or console.
Useful in particular for enabling ConEmu support of ANSI X3.64 and Xterm
256 colors. Otherwise Windows10 consoles are usually detected automatically.
This function is only meaningful on Windows systems. On Unix it is silently
ignored.
.. versionadded:: 1.33.0
.. c:function:: int uv_tty_get_vterm_state(uv_tty_vtermstate_t* state)
Get the current state of whether console virtual terminal sequences are
handled by libuv or the console.
This function is not implemented on Unix, where it returns ``UV_ENOTSUP``.
.. versionadded:: 1.33.0