Instead of having a default set of terminals in terminal-overrides that

get XT added and using that as a marker for xterm(1)-like, assume that
if the terminfo(5) entry already has XT or the clear capability starts
with CSI then the terminal is VT100-like and it should be safe to send
DA requests. The DA responses trigger additional features being added.

5 files changed, 27 insertions, 19 deletions

diff --git a/usr.bin/tmux/options-table.c b/usr.bin/tmux/options-table.c
index 0472875ebdf..cd2238351e6 100644
--- a/usr.bin/tmux/options-table.c
+++ b/usr.bin/tmux/options-table.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: options-table.c,v 1.121 2020/05/16 14:39:40 nicm Exp $ */
+/* $OpenBSD: options-table.c,v 1.122 2020/05/16 14:46:14 nicm Exp $ */
 
 /*
  * Copyright (c) 2011 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -261,7 +261,7 @@ const struct options_table_entry options_table[] = {
 	  .type = OPTIONS_TABLE_STRING,
 	  .scope = OPTIONS_TABLE_SERVER,
 	  .flags = OPTIONS_TABLE_IS_ARRAY,
-	  .default_str = "tmux*:XT,rxvt*:XT,screen*:XT,xterm*:XT",
+	  .default_str = "",
 	  .separator = ","
 	},
 
diff --git a/usr.bin/tmux/tmux.h b/usr.bin/tmux/tmux.h
index 2f2a6477406..e5024ba8b56 100644
--- a/usr.bin/tmux/tmux.h
+++ b/usr.bin/tmux/tmux.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tmux.h,v 1.1021 2020/05/16 14:39:40 nicm Exp $ */
+/* $OpenBSD: tmux.h,v 1.1022 2020/05/16 14:46:14 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -1200,6 +1200,7 @@ struct tty_term {
 #define TERM_DECSLRM 0x4
 #define TERM_DECFRA 0x8
 #define TERM_RGBCOLOURS 0x10
+#define TERM_VT100LIKE 0x20
 	int		 flags;
 
 	LIST_ENTRY(tty_term) entry;
diff --git a/usr.bin/tmux/tty-features.c b/usr.bin/tmux/tty-features.c
index 9f4a9f46d40..ab4d640c03d 100644
--- a/usr.bin/tmux/tty-features.c
+++ b/usr.bin/tmux/tty-features.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tty-features.c,v 1.12 2020/05/16 14:39:40 nicm Exp $ */
+/* $OpenBSD: tty-features.c,v 1.13 2020/05/16 14:46:14 nicm Exp $ */
 
 /*
  * Copyright (c) 2020 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -28,10 +28,9 @@
  * - mouse (under kmous capability);
  * - default colours (under AX or op capabilities);
  * - AIX colours (under colors >= 16);
- * - alternate escape (under XT).
+ * - alternate escape (if terminal is VT100-like).
  *
  * Also:
- * - XT is used to decide whether to send DA and XDA;
  * - DECFRA uses a flag instead of capabilities;
  * - UTF-8 is a separate flag on the client; needed for unattached clients.
  */
diff --git a/usr.bin/tmux/tty-term.c b/usr.bin/tmux/tty-term.c
index 27ccf8f28da..2ca3c99123f 100644
--- a/usr.bin/tmux/tty-term.c
+++ b/usr.bin/tmux/tty-term.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tty-term.c,v 1.79 2020/05/16 14:39:40 nicm Exp $ */
+/* $OpenBSD: tty-term.c,v 1.80 2020/05/16 14:46:14 nicm Exp $ */
 
 /*
  * Copyright (c) 2008 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -549,10 +549,22 @@ tty_term_create(struct tty *tty, char *name, int *feat, int fd, char **cause)
 		goto error;
 	}
 
-	/* These can be emulated so one of the two is required. */
-	if (!tty_term_has(term, TTYC_CUD1) && !tty_term_has(term, TTYC_CUD)) {
-		xasprintf(cause, "terminal does not support cud1 or cud");
-		goto error;
+	/*
+	 * If TERM has XT or clear starts with CSI then it is safe to assume
+	 * the terminal is derived from the VT100. This controls whether device
+	 * attributes requests are sent to get more information.
+	 *
+	 * This is a bit of a hack but there aren't that many alternatives.
+	 * Worst case tmux will just fall back to using whatever terminfo(5)
+	 * says without trying to correct anything that is missing.
+	 *
+	 * Also add few features that VT100-like terminals should either
+	 * support or safely ignore.
+	 */
+	s = tty_term_string(term, TTYC_CLEAR);
+	if (tty_term_flag(term, TTYC_XT) || strncmp(s, "\033[", 2) == 0) {
+		term->flags |= TERM_VT100LIKE;
+		tty_add_features(feat, "bpaste,focus,title", ",");
 	}
 
 	/* Add RGB feature if terminal has RGB colours. */
@@ -561,10 +573,6 @@ tty_term_create(struct tty *tty, char *name, int *feat, int fd, char **cause)
 	    !tty_term_has(term, TTYC_SETRGBB)))
 		tty_add_features(feat, "RGB", ",");
 
-	/* Add some features if terminal has XT. */
-	if (tty_term_flag(term, TTYC_XT))
-		tty_add_features(feat, "bpaste,focus,title", ",");
-
 	/* Apply the features and overrides again. */
 	tty_apply_features(term, *feat);
 	tty_term_apply_overrides(term);
diff --git a/usr.bin/tmux/tty.c b/usr.bin/tmux/tty.c
index f565c700f1e..6ae908f4fb6 100644
--- a/usr.bin/tmux/tty.c
+++ b/usr.bin/tmux/tty.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tty.c,v 1.368 2020/05/16 14:42:06 nicm Exp $ */
+/* $OpenBSD: tty.c,v 1.369 2020/05/16 14:46:14 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -334,7 +334,7 @@ tty_start_tty(struct tty *tty)
 		tty->flags |= TTY_FOCUS;
 		tty_raw(tty, tty_term_string(tty->term, TTYC_ENFCS));
 	}
-	if (tty_term_flag(tty->term, TTYC_XT))
+	if (tty->term->flags & TERM_VT100LIKE)
 		tty_puts(tty, "\033[?7727h");
 
 	evtimer_set(&tty->start_timer, tty_start_timer_callback, tty);
@@ -357,7 +357,7 @@ tty_send_requests(struct tty *tty)
 	if (~tty->flags & TTY_STARTED)
 		return;
 
-	if (tty_term_flag(tty->term, TTYC_XT)) {
+	if (tty->term->flags & TERM_VT100LIKE) {
 		if (~tty->flags & TTY_HAVEDA)
 			tty_puts(tty, "\033[>c");
 		if (~tty->flags & TTY_HAVEXDA)
@@ -420,7 +420,7 @@ tty_stop_tty(struct tty *tty)
 		tty->flags &= ~TTY_FOCUS;
 		tty_raw(tty, tty_term_string(tty->term, TTYC_DSFCS));
 	}
-	if (tty_term_flag(tty->term, TTYC_XT))
+	if (tty->term->flags & TERM_VT100LIKE)
 		tty_raw(tty, "\033[?7727l");
 
 	if (tty_use_margin(tty))