From e3a14e1ad6844b8dd4d4e9bb179080d10d00e451 Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Mon, 17 Jun 2019 20:49:46 +0100
Subject: [PATCH] Withdraw support for the DECEDM escape sequence.

Having decided that the terminal's local echo setting shouldn't be
allowed to propagate through to termios, I think the local edit
setting shouldn't either. Also, no other terminal emulator I know
seems to implement this sequence, and if you enable it, things get
very confused in general. I think it's generally better off absent; if
somebody turns out to have been using it, then we'll at least be able
to find out what it's good for.
---
 ldisc.c            |  6 ++----
 putty.h            |  1 -
 terminal.c         | 15 ---------------
 terminal.h         |  1 -
 unix/uxplink.c     |  4 ----
 windows/winplink.c |  4 ----
 6 files changed, 2 insertions(+), 29 deletions(-)

diff --git a/ldisc.c b/ldisc.c
index 660e05d6..bd7ffb05 100644
--- a/ldisc.c
+++ b/ldisc.c
@@ -15,12 +15,10 @@
 
 #define ECHOING (ldisc->localecho == FORCE_ON || \
                  (ldisc->localecho == AUTO && \
-                      (backend_ldisc_option_state(ldisc->backend, LD_ECHO) || \
-			   term_ldisc(ldisc->term, LD_ECHO))))
+                      (backend_ldisc_option_state(ldisc->backend, LD_ECHO))))
 #define EDITING (ldisc->localedit == FORCE_ON || \
                  (ldisc->localedit == AUTO && \
-                      (backend_ldisc_option_state(ldisc->backend, LD_EDIT) || \
-			   term_ldisc(ldisc->term, LD_EDIT))))
+                      (backend_ldisc_option_state(ldisc->backend, LD_EDIT))))
 
 static void c_write(Ldisc *ldisc, const void *buf, int len)
 {
diff --git a/putty.h b/putty.h
index 89ead30f..c7fa53f2 100644
--- a/putty.h
+++ b/putty.h
@@ -1630,7 +1630,6 @@ void term_invalidate(Terminal *);
 void term_blink(Terminal *, bool set_cursor);
 void term_do_paste(Terminal *, const wchar_t *, int);
 void term_nopaste(Terminal *);
-bool term_ldisc(Terminal *, int option);
 void term_copyall(Terminal *, const int *, int);
 void term_reconfig(Terminal *, Conf *);
 void term_request_copy(Terminal *, const int *clipboards, int n_clipboards);
diff --git a/terminal.c b/terminal.c
index 86ed8f87..dd123d21 100644
--- a/terminal.c
+++ b/terminal.c
@@ -1341,7 +1341,6 @@ static void power_on(Terminal *term, bool clear)
 	term->alt_save_attr = term->curr_attr = ATTR_DEFAULT;
     term->curr_truecolour.fg = term->curr_truecolour.bg = optionalrgb_none;
     term->save_truecolour = term->alt_save_truecolour = term->curr_truecolour;
-    term->term_editing = false;
     term->app_cursor_keys = conf_get_bool(term->conf, CONF_app_cursor);
     term->app_keypad_keys = conf_get_bool(term->conf, CONF_app_keypad);
     term->use_bce = conf_get_bool(term->conf, CONF_bce);
@@ -2639,11 +2638,6 @@ static void toggle_mode(Terminal *term, int mode, int query, bool state)
 	  case 8:		       /* DECARM: auto key repeat */
 	    term->repeat_off = !state;
 	    break;
-	  case 10:		       /* DECEDM: set local edit mode */
-	    term->term_editing = state;
-	    if (term->ldisc)	       /* cause ldisc to notice changes */
-		ldisc_echoedit_update(term->ldisc);
-	    break;
 	  case 25:		       /* DECTCEM: enable/disable cursor */
 	    compatibility2(OTHER, VT220);
 	    term->cursor_on = state;
@@ -7025,15 +7019,6 @@ void term_lost_clipboard_ownership(Terminal *term, int clipboard)
         term_out(term);
 }
 
-bool term_ldisc(Terminal *term, int option)
-{
-    if (option == LD_ECHO)
-	return false;
-    if (option == LD_EDIT)
-	return term->term_editing;
-    return false;
-}
-
 static void term_added_data(Terminal *term)
 {
     if (!term->in_term_out) {
diff --git a/terminal.h b/terminal.h
index b8258630..23c91e1f 100644
--- a/terminal.h
+++ b/terminal.h
@@ -123,7 +123,6 @@ struct terminal_tag {
     bool cblinker;                     /* When blinking is the cursor on ? */
     bool tblinker;                     /* When the blinking text is on */
     bool blink_is_real;                /* Actually blink blinking text */
-    bool term_editing;                 /* Does terminal want local edit? */
     int sco_acs, save_sco_acs;	       /* CSI 10,11,12m -> OEM charset */
     bool vt52_bold;                    /* Force bold on non-bold colours */
     bool utf;                          /* Are we in toggleable UTF-8 mode? */
diff --git a/unix/uxplink.c b/unix/uxplink.c
index cb059893..13f4a898 100644
--- a/unix/uxplink.c
+++ b/unix/uxplink.c
@@ -79,10 +79,6 @@ char *x_get_default(const char *key)
 {
     return NULL;		       /* this is a stub */
 }
-bool term_ldisc(Terminal *term, int mode)
-{
-    return false;
-}
 static void plink_echoedit_update(Seat *seat, bool echo, bool edit)
 {
     /* Update stdin read mode to reflect changes in line discipline. */
diff --git a/windows/winplink.c b/windows/winplink.c
index 446de78d..46c19c69 100644
--- a/windows/winplink.c
+++ b/windows/winplink.c
@@ -43,10 +43,6 @@ WSAEVENT netevent;
 static Backend *backend;
 Conf *conf;
 
-bool term_ldisc(Terminal *term, int mode)
-{
-    return false;
-}
 static void plink_echoedit_update(Seat *seat, bool echo, bool edit)
 {
     /* Update stdin read mode to reflect changes in line discipline. */