From 0f308bd18f8051ac7a725e02e18ad234b4f467fa Mon Sep 17 00:00:00 2001
From: Nicholas Marriott <nicholas.marriott@gmail.com>
Date: Fri, 22 Nov 2024 09:58:47 +0000
Subject: [PATCH] imsg no longer associates file descriptors with the imsg they
 were sent with, work around this for the moment (it is not clear if this is
 intentional).

---
 proc.c          | 27 ++++++++++++++++++++++-----
 server-client.c |  4 ++--
 tmux.h          |  1 +
 3 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/proc.c b/proc.c
index eb73ec31..587da26f 100644
--- a/proc.c
+++ b/proc.c
@@ -55,6 +55,7 @@ struct tmuxpeer {
 	struct tmuxproc	*parent;
 
 	struct imsgbuf	 ibuf;
+	int		 lastfd;
 	struct event	 event;
 	uid_t		 uid;
 
@@ -71,7 +72,7 @@ static int	peer_check_version(struct tmuxpeer *, struct imsg *);
 static void	proc_update_event(struct tmuxpeer *);
 
 static void
-proc_event_cb(__unused int fd, short events, void *arg)
+proc_event_cb(int fd, short events, void *arg)
 {
 	struct tmuxpeer	*peer = arg;
 	ssize_t		 n;
@@ -89,12 +90,16 @@ proc_event_cb(__unused int fd, short events, void *arg)
 			}
 			if (n == 0)
 				break;
-			log_debug("peer %p message %d", peer, imsg.hdr.type);
+			fd = imsg_get_fd(&imsg);
+			log_debug("peer %p message %d fd %d", peer,
+			    imsg.hdr.type, fd);
+			if (fd != -1) {
+				if (peer->lastfd != -1)
+					close(peer->lastfd);
+				peer->lastfd = fd;
+			}
 
 			if (peer_check_version(peer, &imsg) != 0) {
-				fd = imsg_get_fd(&imsg);
-				if (fd != -1)
-					close(fd);
 				imsg_free(&imsg);
 				break;
 			}
@@ -308,6 +313,7 @@ proc_add_peer(struct tmuxproc *tp, int fd,
 
 	peer = xcalloc(1, sizeof *peer);
 	peer->parent = tp;
+	peer->lastfd = -1;
 
 	peer->dispatchcb = dispatchcb;
 	peer->arg = arg;
@@ -336,6 +342,8 @@ proc_remove_peer(struct tmuxpeer *peer)
 	event_del(&peer->event);
 	imsgbuf_clear(&peer->ibuf);
 
+	if (peer->lastfd != -1)
+		close(peer->lastfd);
 	close(peer->ibuf.fd);
 	free(peer);
 }
@@ -387,3 +395,12 @@ proc_get_peer_uid(struct tmuxpeer *peer)
 {
 	return (peer->uid);
 }
+
+int
+proc_get_last_fd(struct tmuxpeer *peer)
+{
+	int	fd = peer->lastfd;
+
+	peer->lastfd = -1;
+	return (fd);
+}
diff --git a/server-client.c b/server-client.c
index a4b961a8..3053a51b 100644
--- a/server-client.c
+++ b/server-client.c
@@ -3559,13 +3559,13 @@ server_client_dispatch_identify(struct client *c, struct imsg *imsg)
 	case MSG_IDENTIFY_STDIN:
 		if (datalen != 0)
 			fatalx("bad MSG_IDENTIFY_STDIN size");
-		c->fd = imsg_get_fd(imsg);
+		c->fd = proc_get_last_fd(c->peer);
 		log_debug("client %p IDENTIFY_STDIN %d", c, c->fd);
 		break;
 	case MSG_IDENTIFY_STDOUT:
 		if (datalen != 0)
 			fatalx("bad MSG_IDENTIFY_STDOUT size");
-		c->out_fd = imsg_get_fd(imsg);
+		c->out_fd = proc_get_last_fd(c->peer);
 		log_debug("client %p IDENTIFY_STDOUT %d", c, c->out_fd);
 		break;
 	case MSG_IDENTIFY_ENVIRON:
diff --git a/tmux.h b/tmux.h
index c3d941c2..a4fc5a77 100644
--- a/tmux.h
+++ b/tmux.h
@@ -2225,6 +2225,7 @@ void	proc_flush_peer(struct tmuxpeer *);
 void	proc_toggle_log(struct tmuxproc *);
 pid_t	proc_fork_and_daemon(int *);
 uid_t	proc_get_peer_uid(struct tmuxpeer *);
+int	proc_get_last_fd(struct tmuxpeer *);
 
 /* cfg.c */
 extern int cfg_finished;