Fix signal handling on Unix systems

This removes the the signal handling machinery in tty::unix, and
replaces it with functionality from signal-hook, which should be more
robust. Signals caught by signal-hook wake up the existing I/O event
loop, which then delegates back to the PTY to handle them.

In particular, this allows `SIGCHLD` (i.e. child process exits) to shut
down the terminal promptly, instead of sometimes leaving the window
lingering.

Fixes #915.
Fixes #1276.
Fixes #1313.

As a side effect, this fixes a very rare bug on Linux, where a `read`
from the PTY on the master side would sometimes "fail" with `EIO` if the
child closed the client side at a particular moment. This was subject to
a race condition, and was very difficult to trigger in practice.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/main.rs b/src/main.rs
index 0c7a6b49..4f569cf5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -236,7 +236,7 @@ fn run(
         }
 
         // Begin shutdown if the flag was raised
-        if terminal_lock.should_exit() {
+        if terminal_lock.should_exit() || tty::process_should_exit() {
             break;
         }