term: don't shutdown terminal when PTY is closed, unless --pty was used

Unless --pty has been used, we do *not* want to shutdown the terminal
when the PTY is closed by the client application; we want to wait for
the client application to actually terminate.

This was the behavior before the --pty patch.

This was changed in the --pty patch, since then, we don't *have* a
client application. That is, foot has not forked+exec:ed anything. The
only way to trigger a shutdown (from the client side) is to close the
PTY.

This patch restores the old behavior, when --pty is *not* used.

Closes #1666

CHANGELOG.md

@@ -58,6 +58,11 @@
 ### Fixed
 
 * Log-level not respected by syslog.
+* Regression: terminal shutting down when the PTY is closed by the
+  client application, which may be earlier than when the client
+  application exits ([#1666][1666]).
+
+[1666]: https://codeberg.org/dnkl/foot/issues/1666
 
 
 ### Security

terminal.c

@@ -364,8 +364,20 @@ fdm_ptmx(struct fdm *fdm, int fd, int events, void *data)
         del_utmp_record(term->conf, term->reaper, term->ptmx);
         fdm_del(fdm, fd);
         term->ptmx = -1;
-        if (!term->conf->hold_at_exit)
+
+        /*
+         * Normally, we do *not* want to shutdown when the PTY is
+         * closed. Instead, we want to wait for the client application
+         * to exit.
+         *
+         * However, when we're using a pre-existing PTY (the --pty
+         * option), there _is_ no client application. That is, foot
+         * does *not* fork+exec anything, and thus the only way to
+         * shutdown is to wait for the PTY to be closed.
+         */
+        if (term->slave < 0 && !term->conf->hold_at_exit) {
             term_shutdown(term);
+        }
     }
 
     return true;