From 1adaafb706b4493550229fb0e410729ca936ce41 Mon Sep 17 00:00:00 2001
From: nicm <nicm@openbsd.org>
Date: Tue, 14 May 2024 07:52:19 +0000
Subject: [PATCH] Add a command-error hook when a command fails, from Hugh
 Davenport in GitHub issue 3973.

---
 usr.bin/tmux/cmd-queue.c     | 15 ++++++++++++---
 usr.bin/tmux/options-table.c |  3 ++-
 usr.bin/tmux/tmux.1          | 12 +++++++++++-
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/usr.bin/tmux/cmd-queue.c b/usr.bin/tmux/cmd-queue.c
index 623535a1208..81ed3de30a8 100644
--- a/usr.bin/tmux/cmd-queue.c
+++ b/usr.bin/tmux/cmd-queue.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-queue.c,v 1.116 2024/04/23 13:34:51 jsg Exp $ */
+/* $OpenBSD: cmd-queue.c,v 1.117 2024/05/14 07:52:19 nicm Exp $ */
 
 /*
  * Copyright (c) 2013 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -665,9 +665,18 @@ cmdq_fire_command(struct cmdq_item *item)
 
 out:
 	item->client = saved;
-	if (retval == CMD_RETURN_ERROR)
+	if (retval == CMD_RETURN_ERROR) {
+		fsp = NULL;
+		if (cmd_find_valid_state(&item->target))
+			fsp = &item->target;
+		else if (cmd_find_valid_state(&item->state->current))
+			fsp = &item->state->current;
+		else if (cmd_find_from_client(&fs, item->client, 0) == 0)
+			fsp = &fs;
+		cmdq_insert_hook(fsp != NULL ? fsp->s : NULL, item, fsp,
+		    "command-error");
 		cmdq_guard(item, "error", flags);
-	else
+	} else
 		cmdq_guard(item, "end", flags);
 	return (retval);
 }
diff --git a/usr.bin/tmux/options-table.c b/usr.bin/tmux/options-table.c
index 998e2764ff8..98c226d26af 100644
--- a/usr.bin/tmux/options-table.c
+++ b/usr.bin/tmux/options-table.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: options-table.c,v 1.172 2024/05/14 07:40:39 nicm Exp $ */
+/* $OpenBSD: options-table.c,v 1.173 2024/05/14 07:52:19 nicm Exp $ */
 
 /*
  * Copyright (c) 2011 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -1334,6 +1334,7 @@ const struct options_table_entry options_table[] = {
 	OPTIONS_TABLE_HOOK("client-focus-out", ""),
 	OPTIONS_TABLE_HOOK("client-resized", ""),
 	OPTIONS_TABLE_HOOK("client-session-changed", ""),
+	OPTIONS_TABLE_HOOK("command-error", ""),
 	OPTIONS_TABLE_PANE_HOOK("pane-died", ""),
 	OPTIONS_TABLE_PANE_HOOK("pane-exited", ""),
 	OPTIONS_TABLE_PANE_HOOK("pane-focus-in", ""),
diff --git a/usr.bin/tmux/tmux.1 b/usr.bin/tmux/tmux.1
index d29565f39e6..3bd92c46852 100644
--- a/usr.bin/tmux/tmux.1
+++ b/usr.bin/tmux/tmux.1
@@ -1,4 +1,4 @@
-.\" $OpenBSD: tmux.1,v 1.942 2024/05/14 07:40:39 nicm Exp $
+.\" $OpenBSD: tmux.1,v 1.943 2024/05/14 07:52:19 nicm Exp $
 .\"
 .\" Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
 .\"
@@ -4889,6 +4889,14 @@ layout after every
 set-hook -g after-split-window "selectl even-vertical"
 .Ed
 .Pp
+If a command fails, the
+.Ql command-error
+hook will be fired.
+For example, this could be used to write to a log file:
+.Bd -literal -offset indent
+set-hook -g command-error "run-shell \\"echo 'a tmux command failed' >>/tmp/log\\""
+.Ed
+.Pp
 All the notifications listed in the
 .Sx CONTROL MODE
 section are hooks (without any arguments), except
@@ -4921,6 +4929,8 @@ Run when focus exits a client
 Run when a client is resized.
 .It client-session-changed
 Run when a client's attached session is changed.
+.It command-error
+Run when a command fails.
 .It pane-died
 Run when the program running in a pane exits, but
 .Ic remain-on-exit
-- 
2.20.1