Revert "termio/exec: fix SIGPIPE crash when reader exits early"

This reverts commit 3e24e96.

src/termio/Exec.zig

@@ -179,11 +179,8 @@ pub fn threadExit(self: *Exec, td: *termio.Termio.ThreadData) void {
     // Quit our read thread after exiting the subprocess so that
     // we don't get stuck waiting for data to stop flowing if it is
     // a particularly noisy process.
-    if (exec.read_thread_pipe) |pipe| {
-        posix.close(pipe);
-        // Tell deinit that we've already closed the pipe
-        exec.read_thread_pipe = null;
-    }
+    _ = posix.write(exec.read_thread_pipe, "x") catch |err|
+        log.warn("error writing to read thread quit pipe err={}", .{err});
 
     if (comptime builtin.os.tag == .windows) {
         // Interrupt the blocking read so the thread can see the quit message
@@ -642,7 +639,7 @@ pub const ThreadData = struct {
 
     /// Reader thread state
     read_thread: std.Thread,
-    read_thread_pipe: ?posix.fd_t,
+    read_thread_pipe: posix.fd_t,
     read_thread_fd: posix.fd_t,
 
     /// The timer to detect termios state changes.
@@ -655,8 +652,7 @@ pub const ThreadData = struct {
     termios_mode: ptypkg.Mode = .{},
 
     pub fn deinit(self: *ThreadData, alloc: Allocator) void {
-        // If the pipe isn't closed, close it.
-        if (self.read_thread_pipe) |pipe| posix.close(pipe);
+        posix.close(self.read_thread_pipe);
 
         // Clear our write pools. We know we aren't ever going to do
         // any more IO since we stop our data stream below so we can just
@@ -1437,12 +1433,9 @@ pub const ReadThread = struct {
                 };
 
                 // This happens on macOS instead of WouldBlock when the
-                // child process dies. It's equivalent to NotOpenForReading
-                // so we can just exit.
-                if (n == 0) {
-                    log.info("io reader exiting", .{});
-                    return;
-                }
+                // child process dies. To be safe, we just break the loop
+                // and let our poll happen.
+                if (n == 0) break;
 
                 // log.info("DATA: {d}", .{n});
                 @call(.always_inline, termio.Termio.processOutput, .{ io, buf[0..n] });
@@ -1454,8 +1447,8 @@ pub const ReadThread = struct {
                 return;
             };
 
-            // If our quit fd is closed, we're done.
-            if (pollfds[1].revents & posix.POLL.HUP != 0) {
+            // If our quit fd is set, we're done.
+            if (pollfds[1].revents & posix.POLL.IN != 0) {
                 log.info("read thread got quit signal", .{});
                 return;
             }