cli: Handle interrupts during an active spinner

radicle-signals/src/lib.rs

@@ -33,6 +33,9 @@ impl TryFrom<i32> for Signal {
 /// Signal notifications are sent via this channel.
 static NOTIFY: Mutex<Option<chan::Sender<Signal>>> = Mutex::new(None);
 
+/// A slice of signals to handle.
+const SIGNALS: &[i32] = &[libc::SIGINT, libc::SIGTERM, libc::SIGHUP, libc::SIGWINCH];
+
 /// Install global signal handlers.
 pub fn install(notify: chan::Sender<Signal>) -> io::Result<()> {
     if let Ok(mut channel) = NOTIFY.try_lock() {
@@ -54,23 +57,51 @@ pub fn install(notify: chan::Sender<Signal>) -> io::Result<()> {
     Ok(())
 }
 
+/// Uninstall global signal handlers.
+pub fn uninstall() -> io::Result<()> {
+    if let Ok(mut channel) = NOTIFY.try_lock() {
+        if channel.is_none() {
+            return Err(io::Error::new(
+                io::ErrorKind::NotFound,
+                "signal handler is already uninstalled",
+            ));
+        }
+        *channel = None;
+
+        unsafe { _uninstall() }?;
+    } else {
+        return Err(io::Error::new(
+            io::ErrorKind::WouldBlock,
+            "unable to uninstall signal handler",
+        ));
+    }
+    Ok(())
+}
+
 /// Install global signal handlers.
 ///
 /// # Safety
 ///
 /// Calls `libc` functions safely.
 unsafe fn _install() -> io::Result<()> {
-    if libc::signal(libc::SIGTERM, handler as libc::sighandler_t) == libc::SIG_ERR {
-        return Err(io::Error::last_os_error());
-    }
-    if libc::signal(libc::SIGINT, handler as libc::sighandler_t) == libc::SIG_ERR {
-        return Err(io::Error::last_os_error());
-    }
-    if libc::signal(libc::SIGHUP, handler as libc::sighandler_t) == libc::SIG_ERR {
-        return Err(io::Error::last_os_error());
+    for signal in SIGNALS {
+        if libc::signal(*signal, handler as libc::sighandler_t) == libc::SIG_ERR {
+            return Err(io::Error::last_os_error());
+        }
     }
-    if libc::signal(libc::SIGWINCH, handler as libc::sighandler_t) == libc::SIG_ERR {
-        return Err(io::Error::last_os_error());
+    Ok(())
+}
+
+/// Uninstall global signal handlers.
+///
+/// # Safety
+///
+/// Calls `libc` functions safely.
+unsafe fn _uninstall() -> io::Result<()> {
+    for signal in SIGNALS {
+        if libc::signal(*signal, libc::SIG_DFL) == libc::SIG_ERR {
+            return Err(io::Error::last_os_error());
+        }
     }
     Ok(())
 }

radicle-term/src/pager.rs

@@ -24,6 +24,12 @@ pub enum Error {
 /// A pager for the given element. Re-renders the element when the terminal is resized so that
 /// it doesn't wrap. If the output device is not a TTY, just prints the element via
 /// [`Element::print`].
+///
+/// # Signal Handling
+///
+/// This will install handlers for the pager until finished by the user, with there
+/// being only one element handling signals at a time. If the pager cannot install
+/// handlers, then it will return with an error.
 pub fn page<E: Element + Send + 'static>(element: E) -> Result<(), Error> {
     let (events_tx, events_rx) = chan::unbounded();
     let (signals_tx, signals_rx) = chan::unbounded();
@@ -35,9 +41,13 @@ pub fn page<E: Element + Send + 'static>(element: E) -> Result<(), Error> {
             events_tx.send(e).ok();
         }
     });
-    thread::spawn(move || main(element, signals_rx, events_rx))
+    let result = thread::spawn(move || main(element, signals_rx, events_rx))
         .join()
-        .unwrap()
+        .unwrap();
+
+    signals::uninstall()?;
+
+    result
 }
 
 fn main<E: Element>(

radicle-term/src/spinner.rs

@@ -3,6 +3,11 @@ use std::mem::ManuallyDrop;
 use std::sync::{Arc, Mutex};
 use std::{fmt, io, thread, time};
 
+use crossbeam_channel as chan;
+
+use radicle_signals as signals;
+use signals::Signal;
+
 use crate::io::{ERROR_PREFIX, WARNING_PREFIX};
 use crate::Paint;
 
@@ -103,10 +108,10 @@ impl Spinner {
 }
 
 /// Create a new spinner with the given message. Sends animation output to `stderr` and success or
-/// failure messages to `stdout`.
+/// failure messages to `stdout`. This function handles signals, with there being only one
+/// element handling signals at a time, and is a wrapper to [`spinner_to()`].
 pub fn spinner(message: impl ToString) -> Spinner {
     let (stdout, stderr) = (io::stdout(), io::stderr());
-
     if stderr.is_terminal() {
         spinner_to(message, stdout, stderr)
     } else {
@@ -115,13 +120,21 @@ pub fn spinner(message: impl ToString) -> Spinner {
 }
 
 /// Create a new spinner with the given message, and send output to the given writers.
+///
+/// # Signal Handling
+///
+/// This will install handlers for the spinner until cancelled or dropped, with there
+/// being only one element handling signals at a time. If the spinner cannot install
+/// handlers, then it will not attempt to install handlers again, and continue running.
 pub fn spinner_to(
     message: impl ToString,
     mut completion: impl io::Write + Send + 'static,
     animation: impl io::Write + Send + 'static,
 ) -> Spinner {
     let message = message.to_string();
     let progress = Arc::new(Mutex::new(Progress::new(Paint::new(message))));
+    let (sig_tx, sig_rx) = chan::unbounded();
+    let sig_result = signals::install(sig_tx);
     let handle = thread::Builder::new()
         .name(String::from("spinner"))
         .spawn({
@@ -134,6 +147,25 @@ pub fn spinner_to(
                     let Ok(mut progress) = progress.lock() else {
                         break;
                     };
+                    // If were unable to install handles, skip signal processing entirely.
+                    if sig_result.is_ok() {
+                        match sig_rx.try_recv() {
+                            Ok(sig) if sig == Signal::Interrupt || sig == Signal::Terminate => {
+                                write!(animation, "\r{}", termion::clear::UntilNewline).ok();
+                                writeln!(
+                                    completion,
+                                    "{ERROR_PREFIX} {} {}",
+                                    &progress.message,
+                                    Paint::red("<canceled>")
+                                )
+                                .ok();
+                                drop(animation);
+                                std::process::exit(-1);
+                            }
+                            Ok(_) => {}
+                            Err(_) => {}
+                        }
+                    }
                     match &mut *progress {
                         Progress {
                             state: State::Running { cursor },
@@ -192,6 +224,9 @@ pub fn spinner_to(
                     drop(progress);
                     thread::sleep(DEFAULT_TICK);
                 }
+                if sig_result.is_ok() {
+                    let _ = signals::uninstall();
+                }
             }
         })
         // SAFETY: Only panics if the thread name contains `null` bytes, which isn't the case here.