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support for synchronized output #195

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support for synchronized output #195

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289 changes: 288 additions & 1 deletion src/unix_term.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,8 @@ use std::io;
use std::io::{BufRead, BufReader};
use std::mem;
use std::os::unix::io::AsRawFd;
use std::ptr;
use std::os::unix::io::FromRawFd;
use std::os::unix::io::IntoRawFd;
use std::str;

use crate::kb::Key;
Expand Down Expand Up @@ -360,3 +361,289 @@ pub fn wants_emoji() -> bool {
pub fn set_title<T: Display>(title: T) {
print!("\x1b]0;{}\x07", title);
}

fn with_raw_terminal<R>(f: impl FnOnce(&mut fs::File) -> R) -> io::Result<R> {
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If this is only used within sync_output, I would move it inside the module.

// We need a custom drop implementation for File,
// so that the fd for stdin does not get closed
enum CustomDropFile {
CloseFd(Option<fs::File>),
NotCloseFd(Option<fs::File>),
}

impl Drop for CustomDropFile {
fn drop(&mut self) {
match self {
CustomDropFile::CloseFd(_) => {}
CustomDropFile::NotCloseFd(inner) => {
if let Some(file) = inner.take() {
file.into_raw_fd();
}
}
}
}
}

let (mut tty_handle, tty_fd) = if unsafe { libc::isatty(libc::STDIN_FILENO) } == 1 {
(
CustomDropFile::NotCloseFd(Some(unsafe { fs::File::from_raw_fd(libc::STDIN_FILENO) })),
libc::STDIN_FILENO,
)
} else {
let handle = fs::OpenOptions::new()
.read(true)
.write(true)
.open("/dev/tty")?;
let fd = handle.as_raw_fd();
(CustomDropFile::CloseFd(Some(handle)), fd)
};

// Get current mode
let mut termios = mem::MaybeUninit::uninit();
c_result(|| unsafe { libc::tcgetattr(tty_fd, termios.as_mut_ptr()) })?;

let mut termios = unsafe { termios.assume_init() };
let old_iflag = termios.c_iflag;
let old_oflag = termios.c_oflag;
let old_cflag = termios.c_cflag;
let old_lflag = termios.c_lflag;

// Go into raw mode
unsafe { libc::cfmakeraw(&mut termios) };
if old_lflag & libc::ISIG != 0 {
// Re-enable INTR, QUIT, SUSP, DSUSP, if it was activated before
termios.c_lflag |= libc::ISIG;
}
c_result(|| unsafe { libc::tcsetattr(tty_fd, libc::TCSADRAIN, &termios) })?;

let result = match &mut tty_handle {
CustomDropFile::CloseFd(Some(handle)) => f(handle),
CustomDropFile::NotCloseFd(Some(handle)) => f(handle),
_ => unreachable!(),
};

// Reset to previous mode
termios.c_iflag = old_iflag;
termios.c_oflag = old_oflag;
termios.c_cflag = old_cflag;
termios.c_lflag = old_lflag;
c_result(|| unsafe { libc::tcsetattr(tty_fd, libc::TCSADRAIN, &termios) })?;

Ok(result)
}

pub fn supports_synchronized_output() -> bool {
*sync_output::SUPPORTS_SYNCHRONIZED_OUTPUT
}

/// Specification: https://gist.github.com/christianparpart/d8a62cc1ab659194337d73e399004036
mod sync_output {
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I think Rust style would suggest not abbreviating synchronized_ to sync_ for the module name.

use std::convert::TryInto as _;
use std::io::Read as _;
use std::io::Write as _;
use std::os::unix::io::AsRawFd as _;
use std::time;

use lazy_static::lazy_static;

use super::select_or_poll_term_fd;
use super::with_raw_terminal;

const RESPONSE_TIMEOUT: time::Duration = time::Duration::from_millis(10);

lazy_static! {
pub(crate) static ref SUPPORTS_SYNCHRONIZED_OUTPUT: bool =
supports_synchronized_output_uncached();
}

struct ResponseParser {
state: ResponseParserState,
response: u8,
}

#[derive(PartialEq)]
enum ResponseParserState {
None,
CsiOne,
CsiTwo,
QuestionMark,
ModeDigit1,
ModeDigit2,
ModeDigit3,
ModeDigit4,
Semicolon,
Response,
DollarSign,
Ypsilon,
}

impl ResponseParser {
const fn new() -> Self {
Self {
state: ResponseParserState::None,
response: u8::MAX,
}
}

fn process_byte(&mut self, byte: u8) {
match byte {
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Suggest writing this as such:

self.state = match (self.state, byte) {
    ..
};

b'\x1b' => {
self.state = ResponseParserState::CsiOne;
}
b'[' => {
self.state = if self.state == ResponseParserState::CsiOne {
ResponseParserState::CsiTwo
} else {
ResponseParserState::None
};
}
b'?' => {
self.state = if self.state == ResponseParserState::CsiTwo {
ResponseParserState::QuestionMark
} else {
ResponseParserState::None
};
}
byte @ b'0' => {
self.state = if self.state == ResponseParserState::Semicolon {
self.response = byte;
ResponseParserState::Response
} else if self.state == ResponseParserState::ModeDigit1 {
ResponseParserState::ModeDigit2
} else {
ResponseParserState::None
};
}
byte @ b'2' => {
self.state = if self.state == ResponseParserState::Semicolon {
self.response = byte;
ResponseParserState::Response
} else if self.state == ResponseParserState::QuestionMark {
ResponseParserState::ModeDigit1
} else if self.state == ResponseParserState::ModeDigit2 {
ResponseParserState::ModeDigit3
} else {
ResponseParserState::None
};
}
byte @ b'1' | byte @ b'3' | byte @ b'4' => {
self.state = if self.state == ResponseParserState::Semicolon {
self.response = byte;
ResponseParserState::Response
} else {
ResponseParserState::None
};
}
b'6' => {
self.state = if self.state == ResponseParserState::ModeDigit3 {
ResponseParserState::ModeDigit4
} else {
ResponseParserState::None
};
}
b';' => {
self.state = if self.state == ResponseParserState::ModeDigit4 {
ResponseParserState::Semicolon
} else {
ResponseParserState::None
};
}
b'$' => {
self.state = if self.state == ResponseParserState::Response {
ResponseParserState::DollarSign
} else {
ResponseParserState::None
};
}
b'y' => {
self.state = if self.state == ResponseParserState::DollarSign {
ResponseParserState::Ypsilon
} else {
ResponseParserState::None
};
}
_ => {
self.state = ResponseParserState::None;
}
}
}

fn get_response(&self) -> Option<u8> {
if self.state == ResponseParserState::Ypsilon {
Some(self.response - b'0')
} else {
None
}
}
}

fn supports_synchronized_output_uncached() -> bool {
with_raw_terminal(|term_handle| {
// Query the state of the (DEC) mode 2026 (Synchronized Output)
write!(term_handle, "\x1b[?2026$p").ok()?;
term_handle.flush().ok()?;

// Wait for response or timeout
let term_fd = term_handle.as_raw_fd();
let mut parser = ResponseParser::new();
let mut buf = [0u8; 256];
let deadline = time::Instant::now() + RESPONSE_TIMEOUT;

loop {
let remaining_time = deadline
.saturating_duration_since(time::Instant::now())
.as_millis()
.try_into()
.ok()?;

if remaining_time == 0 {
// Timeout
return Some(false);
}

match select_or_poll_term_fd(term_fd, remaining_time) {
Ok(false) => {
// Timeout
return Some(false);
}
Ok(true) => {
'read: loop {
match term_handle.read(&mut buf) {
Ok(0) => {
// Reached EOF
return Some(false);
}
Ok(size) => {
for byte in &buf[..size] {
parser.process_byte(*byte);

match parser.get_response() {
Some(1) | Some(2) => return Some(true),
Some(_) => return Some(false),
None => {}
}
}

break 'read;
}
Err(err) if err.kind() == std::io::ErrorKind::Interrupted => {
// Got interrupted, retry read
continue 'read;
}
Err(_) => {
return Some(false);
}
}
}
}
Err(_) => {
// Error
return Some(false);
}
}
}
})
.ok()
.flatten()
.unwrap_or(false)
}
}
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