Remove nix and signal-hook dependencies

Cargo.toml

@@ -16,8 +16,6 @@ unicode-width = "0.1.7"
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2.69"
-nix = "0.17.0"
-signal-hook = "0.1.14"
 
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3.8", default-features = false, features = ["wincon"] }

README.md

@@ -232,13 +232,10 @@ This project is inspired by [`kilo`](https://github.com/antirez/kilo), a text ed
 This project must remain tiny, so using advanced dependencies such as [`ncurses`](https://crates.io/crates/ncurses),
 [`toml`](https://crates.io/crates/toml) or [`ansi-escapes`](https://crates.io/crates/ansi-escapes) would be cheating.
 
-The following dependencies provide wrappers around system calls. Safe wrappers are preferred to avoid using `unsafe`
-code as much as possible:
+The following dependencies provide wrappers around system calls.
 
 * On UNIX systems (Linux, macOS):
     * `libc`
-    * `nix`
-    * `signal-hook`
 * On Windows:
     * `winapi`
     * `winapi-util`

src/editor.rs

@@ -2,7 +2,6 @@
 
 use std::io::{self, BufRead, BufReader, ErrorKind::NotFound, Read, Seek, Write};
 use std::iter::{self, repeat, successors};
-use std::sync::mpsc::{Receiver, TryRecvError};
 use std::{fmt::Display, fs::File, path::Path, thread, time::Instant};
 
 use crate::row::{HLState, Row};
@@ -102,9 +101,6 @@ pub struct Editor {
     syntax: SyntaxConf,
     /// The number of bytes contained in `rows`. This excludes new lines.
     n_bytes: u64,
-    /// A channel receiver for the "window size changed" message. A message is received shortly
-    /// after a SIGWINCH signal is received.
-    ws_changed_receiver: Option<Receiver<()>>,
     /// The original terminal mode. It will be restored when the `Editor` instance is dropped.
     orig_term_mode: Option<sys::TermMode>,
 }
@@ -146,10 +142,10 @@ impl Editor {
     /// Will return `Err` if an error occurs when enabling termios raw mode, creating the signal hook
     /// or when obtaining the terminal window size.
     pub fn new(config: Config) -> Result<Self, Error> {
+        sys::register_winsize_change_signal_handler()?;
         let mut editor = Self::default();
         editor.quit_times = config.quit_times;
         editor.config = config;
-        editor.ws_changed_receiver = sys::get_window_size_update_receiver()?;
 
         // Enable raw mode and store the original (non-raw) terminal mode.
         editor.orig_term_mode = Some(sys::enable_raw_mode()?);
@@ -209,16 +205,9 @@ impl Editor {
     fn loop_until_keypress(&mut self) -> Result<Key, Error> {
         loop {
             // Handle window size if a signal has be received
-            match self.ws_changed_receiver.as_ref().map(Receiver::try_recv) {
-                // If there is no receiver or no "window size updated" signal has been received, do
-                // nothing.
-                None | Some(Err(TryRecvError::Empty)) => (),
-                // A "window size updated" signal has been received
-                Some(Ok(())) => {
-                    self.update_window_size()?;
-                    self.refresh_screen()?;
-                }
-                Some(Err(err)) => return Err(Error::MPSCTryRecv(err)),
+            if sys::has_window_size_changed() {
+                self.update_window_size()?;
+                self.refresh_screen()?;
             }
             let mut bytes = io::stdin().bytes();
             // Match on the next byte received or, if the first byte is <ESC> ('\x1b'), on the next

src/error.rs

@@ -5,11 +5,6 @@
 pub enum Error {
     /// Wrapper around `std::io::Error`
     IO(std::io::Error),
-    /// Wrapper around `nix::Error`
-    #[cfg(unix)]
-    Nix(nix::Error),
-    /// Wrapper around `std::sync::mpsc::TryRecvError`
-    MPSCTryRecv(std::sync::mpsc::TryRecvError),
     /// Error returned when the window size obtained through a system call is invalid.
     InvalidWindowSize,
     /// Error setting or retrieving the cursor position.
@@ -26,9 +21,3 @@ impl From<std::io::Error> for Error {
     /// Convert an IO Error into a Kibi Error.
     fn from(err: std::io::Error) -> Self { Self::IO(err) }
 }
-
-#[cfg(unix)]
-impl From<nix::Error> for Error {
-    /// Convert a nix Error into a Kibi Error.
-    fn from(err: nix::Error) -> Self { Self::Nix(err) }
-}

src/unix.rs

@@ -3,17 +3,23 @@
 //! UNIX-specific structs and functions. Will be imported as `sys` on UNIX systems.
 
 use std::env::var;
-use std::sync::mpsc::{self, Receiver};
+use std::sync::atomic::{AtomicBool, Ordering};
 
-use libc::{STDIN_FILENO, STDOUT_FILENO, TIOCGWINSZ, VMIN, VTIME};
-use nix::{pty::Winsize, sys::termios};
-use signal_hook::{iterator::Signals, SIGWINCH};
-
-// On UNIX systems, Termios represents the terminal mode.
-pub use nix::sys::termios::Termios as TermMode;
+// On UNIX systems, termios represents the terminal mode.
+pub use libc::termios as TermMode;
+use libc::{c_int, c_void, sigaction, sighandler_t, siginfo_t, winsize};
+use libc::{SA_SIGINFO, STDIN_FILENO, STDOUT_FILENO, TCSAFLUSH, TIOCGWINSZ, VMIN, VTIME};
 
 use crate::Error;
 
+fn cerr(err: c_int) -> Result<(), Error> {
+    if err < 0 {
+        Err(std::io::Error::last_os_error().into())
+    } else {
+        Ok(())
+    }
+}
+
 /// Return directories following the XDG Base Directory Specification
 ///
 /// See `conf_dirs()` and `data_dirs()` for usage example.
@@ -52,42 +58,55 @@ pub fn data_dirs() -> Vec<String> {
 /// populated.
 /// This ioctl is described here: <http://man7.org/linux/man-pages/man4/tty_ioctl.4.html>
 pub fn get_window_size() -> Result<(usize, usize), Error> {
-    nix::ioctl_read_bad!(get_ws, TIOCGWINSZ, Winsize);
-
-    let mut maybe_ws = std::mem::MaybeUninit::<Winsize>::uninit();
-
-    unsafe { get_ws(STDOUT_FILENO, maybe_ws.as_mut_ptr()).ok().map(|_| maybe_ws.assume_init()) }
+    let mut maybe_ws = std::mem::MaybeUninit::<winsize>::uninit();
+    cerr(unsafe { libc::ioctl(STDOUT_FILENO, TIOCGWINSZ, maybe_ws.as_mut_ptr()) })
+        .map_or(None, |_| unsafe { Some(maybe_ws.assume_init()) })
         .filter(|ws| ws.ws_col != 0 && ws.ws_row != 0)
         .map_or(Err(Error::InvalidWindowSize), |ws| Ok((ws.ws_row as usize, ws.ws_col as usize)))
 }
 
-/// Return a MPSC receiver that receives a message whenever the window size is updated.
-pub fn get_window_size_update_receiver() -> Result<Option<Receiver<()>>, Error> {
-    // Create a channel for receiving window size update requests
-    let (ws_changed_tx, ws_changed_rx) = mpsc::sync_channel(1);
-    // Spawn a new thread that will push to the aforementioned channel every time the SIGWINCH
-    // signal is received
-    let signals = Signals::new(&[SIGWINCH])?;
-    std::thread::spawn(move || signals.forever().for_each(|_| ws_changed_tx.send(()).unwrap()));
-    Ok(Some(ws_changed_rx))
+/// Register a signal handler that sets a global variable when the window size changes.
+/// After calling this function, use has_window_size_changed to query the global variable.
+pub fn register_winsize_change_signal_handler() -> Result<(), Error> {
+    #[no_mangle]
+    extern "C" fn handle_window_size_changed(_: c_int, _: *mut siginfo_t, _: *mut c_void) {
+        WIN_CHANGED.store(true, Ordering::Relaxed);
+    }
+    unsafe {
+        let mut maybe_sa = std::mem::MaybeUninit::<sigaction>::uninit();
+        cerr(libc::sigemptyset(&mut (*maybe_sa.as_mut_ptr()).sa_mask))?;
+        // We could use sa_handler here, however, sigaction defined in libc does not have
+        // sa_handler field, so we use sa_sigaction instead.
+        (*maybe_sa.as_mut_ptr()).sa_flags = SA_SIGINFO;
+        (*maybe_sa.as_mut_ptr()).sa_sigaction = handle_window_size_changed as sighandler_t;
+        cerr(libc::sigaction(libc::SIGWINCH, maybe_sa.as_ptr(), std::ptr::null_mut()))
+    }
 }
 
+static WIN_CHANGED: AtomicBool = AtomicBool::new(false);
+
+/// Check if the windows size has changed since the last call to this function.
+/// The register_winsize_change_signal_handler needs to be called before this function.
+pub fn has_window_size_changed() -> bool { WIN_CHANGED.swap(false, Ordering::Relaxed) }
+
 /// Set the terminal mode.
-pub fn set_term_mode(term: &TermMode) -> Result<(), nix::Error> {
-    termios::tcsetattr(STDIN_FILENO, termios::SetArg::TCSAFLUSH, term)
+pub fn set_term_mode(term: &TermMode) -> Result<(), Error> {
+    cerr(unsafe { libc::tcsetattr(STDIN_FILENO, TCSAFLUSH, term) })
 }
 
 /// Setup the termios to enable raw mode, and return the original termios.
 ///
 /// termios manual is available at: <http://man7.org/linux/man-pages/man3/termios.3.html>
 pub fn enable_raw_mode() -> Result<TermMode, Error> {
-    let orig_termios = termios::tcgetattr(STDIN_FILENO)?;
-    let mut term = orig_termios.clone();
-    termios::cfmakeraw(&mut term);
+    let mut maybe_term = std::mem::MaybeUninit::<TermMode>::uninit();
+    let orig_term = cerr(unsafe { libc::tcgetattr(STDIN_FILENO, maybe_term.as_mut_ptr()) })
+        .map(|_| unsafe { maybe_term.assume_init() })?;
+    let mut term = orig_term;
+    unsafe { libc::cfmakeraw(&mut term) };
     // Set the minimum number of characters for non-canonical reads
-    term.control_chars[VMIN] = 0;
+    term.c_cc[VMIN] = 0;
     // Set the timeout in deciseconds for non-canonical reads
-    term.control_chars[VTIME] = 1;
+    term.c_cc[VTIME] = 1;
     set_term_mode(&term)?;
-    Ok(orig_termios)
+    Ok(orig_term)
 }

src/windows.rs

@@ -4,7 +4,7 @@
 
 #![allow(clippy::wildcard_imports)]
 
-use std::{convert::TryInto, env::var, io, sync::mpsc::Receiver};
+use std::{convert::TryInto, env::var, io};
 
 use winapi::um::wincon::*;
 use winapi_util::{console as cons, HandleRef};
@@ -30,7 +30,9 @@ pub fn get_window_size() -> Result<(usize, usize), Error> {
     }
 }
 
-pub fn get_window_size_update_receiver() -> Result<Option<Receiver<()>>, Error> { Ok(None) }
+pub fn register_winsize_change_signal_handler() -> Result<(), Error> { Ok(()) }
+
+pub fn has_window_size_changed() -> bool { false }
 
 /// Set the terminal mode.
 #[allow(clippy::trivially_copy_pass_by_ref)]