Revamp extended keys support to more closely match xterm and support

mode 2 as well as mode 1. From Stanislav Kljuhhin (GitHub issue 4038).

This changes tmux to always request mode 2 from parent terminal, change
to an unambiguous internal representation of keys, and adds an option
(extended-keys-format) to control the format similar to the xterm(1)
formatOtherKeys resource.

1 files changed, 41 insertions, 38 deletions

diff --git a/usr.bin/tmux/key-string.c b/usr.bin/tmux/key-string.c
index 9b22d2ea101..d9ba95afae6 100644
--- a/usr.bin/tmux/key-string.c
+++ b/usr.bin/tmux/key-string.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: key-string.c,v 1.71 2023/01/16 11:26:14 nicm Exp $ */
+/* $OpenBSD: key-string.c,v 1.72 2024/08/21 04:17:09 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -56,12 +56,47 @@ static const struct {
 	{ "PPage",	KEYC_PPAGE|KEYC_IMPLIED_META },
 	{ "PageUp",	KEYC_PPAGE|KEYC_IMPLIED_META },
 	{ "PgUp",	KEYC_PPAGE|KEYC_IMPLIED_META },
-	{ "Tab",	'\011' },
 	{ "BTab",	KEYC_BTAB },
 	{ "Space",	' ' },
 	{ "BSpace",	KEYC_BSPACE },
-	{ "Enter",	'\r' },
-	{ "Escape",	'\033' },
+
+	/*
+	 * C0 control characters, with the exception of Tab, Enter,
+	 * and Esc, should never appear as keys. We still render them,
+	 * so to be able to spot them in logs in case of an abnormality.
+	 */
+	{ "[NUL]",	C0_NUL },
+	{ "[SOH]",	C0_SOH },
+	{ "[STX]",	C0_STX },
+	{ "[ETX]",	C0_ETX },
+	{ "[EOT]",	C0_EOT },
+	{ "[ENQ]",	C0_ENQ },
+	{ "[ASC]",	C0_ASC },
+	{ "[BEL]",	C0_BEL },
+	{ "[BS]",	C0_BS },
+	{ "Tab",	C0_HT },
+	{ "[LF]",	C0_LF },
+	{ "[VT]",	C0_VT },
+	{ "[FF]",	C0_FF },
+	{ "Enter",	C0_CR },
+	{ "[SO]",	C0_SO },
+	{ "[SI]",	C0_SI },
+	{ "[DLE]",	C0_DLE },
+	{ "[DC1]",	C0_DC1 },
+	{ "[DC2]",	C0_DC2 },
+	{ "[DC3]",	C0_DC3 },
+	{ "[DC4]",	C0_DC4 },
+	{ "[NAK]",	C0_NAK },
+	{ "[SYN]",	C0_SYN },
+	{ "[ETB]",	C0_ETB },
+	{ "[CAN]",	C0_CAN },
+	{ "[EM]",	C0_EM },
+	{ "[SUB]",	C0_SUB },
+	{ "Escape",	C0_ESC },
+	{ "[FS]",	C0_FS },
+	{ "[GS]",	C0_GS },
+	{ "[RS]",	C0_RS },
+	{ "[US]",	C0_US },
 
 	/* Arrow keys. */
 	{ "Up",		KEYC_UP|KEYC_CURSOR|KEYC_IMPLIED_META },
@@ -206,7 +241,6 @@ key_string_get_modifiers(const char **string)
 key_code
 key_string_lookup_string(const char *string)
 {
-	static const char	*other = "!#()+,-.0123456789:;<=>'\r\t\177`/";
 	key_code		 key, modifiers;
 	u_int			 u, i;
 	struct utf8_data	 ud, *udp;
@@ -281,26 +315,6 @@ key_string_lookup_string(const char *string)
 			key &= ~KEYC_IMPLIED_META;
 	}
 
-	/* Convert the standard control keys. */
-	if (key <= 127 &&
-	    (modifiers & KEYC_CTRL) &&
-	    strchr(other, key) == NULL &&
-	    key != 9 &&
-	    key != 13 &&
-	    key != 27) {
-		if (key >= 97 && key <= 122)
-			key -= 96;
-		else if (key >= 64 && key <= 95)
-                       key -= 64;
-		else if (key == 32)
-			key = 0;
-		else if (key == 63)
-			key = 127;
-		else
-			return (KEYC_UNKNOWN);
-		modifiers &= ~KEYC_CTRL;
-	}
-
 	return (key|modifiers);
 }
 
@@ -324,10 +338,6 @@ key_string_lookup_key(key_code key, int with_flags)
 		goto out;
 	}
 
-	/* Display C-@ as C-Space. */
-	if ((key & (KEYC_MASK_KEY|KEYC_MASK_MODIFIERS)) == 0)
-		key = ' '|KEYC_CTRL;
-
 	/* Fill in the modifiers. */
 	if (key & KEYC_CTRL)
 		strlcat(out, "C-", sizeof out);
@@ -427,13 +437,8 @@ key_string_lookup_key(key_code key, int with_flags)
 		goto out;
 	}
 
-	/* Check for standard or control key. */
-	if (key <= 32) {
-		if (key == 0 || key > 26)
-			xsnprintf(tmp, sizeof tmp, "C-%c", (int)(64 + key));
-		else
-			xsnprintf(tmp, sizeof tmp, "C-%c", (int)(96 + key));
-	} else if (key >= 32 && key <= 126) {
+	/* Printable ASCII keys. */
+	if (key > 32 && key <= 126) {
 		tmp[0] = key;
 		tmp[1] = '\0';
 	} else if (key == 127)
@@ -460,8 +465,6 @@ out:
 			strlcat(out, "I", sizeof out);
 		if (saved & KEYC_BUILD_MODIFIERS)
 			strlcat(out, "B", sizeof out);
-		if (saved & KEYC_EXTENDED)
-			strlcat(out, "E", sizeof out);
 		if (saved & KEYC_SENT)
 			strlcat(out, "S", sizeof out);
 		strlcat(out, "]", sizeof out);