From 4527541ec66af8d82bb9dba5d25afdf489d71271 Mon Sep 17 00:00:00 2001
From: Takashi Yano via Cygwin-patches <cygwin-patches@cygwin.com>
Date: Sun, 31 May 2020 14:53:18 +0900
Subject: [PATCH] Cygwin: console: Discard some unsupported escape sequences.

- If the cygwin vim is started from a non-cygwin process which is
  executed in pseudo console, shift key and ctrl key do not work.
  In this case, vim is executed under /dev/cons*. If vim outputs
  escape sequence which is not supported by pseudo console, the
  escape sequence is leaked into the parent pty. This causes
  unexpected results. This patch fixes the issue by discarding
  "CSI > Pm m". "OSC 10;? BEL/ST" and "OSC 11;? BEL/ST" are
  discarded as well.
---
 winsup/cygwin/fhandler_console.cc | 54 ++++++++++++++++++++++---------
 1 file changed, 38 insertions(+), 16 deletions(-)

diff --git a/winsup/cygwin/fhandler_console.cc b/winsup/cygwin/fhandler_console.cc
index 5cb4343ea..dd979fb8e 100644
--- a/winsup/cygwin/fhandler_console.cc
+++ b/winsup/cygwin/fhandler_console.cc
@@ -2186,6 +2186,14 @@ fhandler_console::char_command (char c)
 	  /* Just send the sequence */
 	  wpbuf.send (get_output_handle ());
 	  break;
+	case 'm':
+	  if (con.saw_greater_than_sign)
+	    break; /* Ignore unsupported CSI > Pm m */
+	  /* Text attribute settings */
+	  wpbuf.put (c);
+	  /* Just send the sequence */
+	  wpbuf.send (get_output_handle ());
+	  break;
 	default:
 	  /* Other escape sequences */
 	  wpbuf.put (c);
@@ -3077,6 +3085,13 @@ fhandler_console::write (const void *vsrc, size_t len)
 	      con.state = normal;
 	      wpbuf.empty();
 	    }
+	  else if (*src == ']')		/* OSC Operating System Command */
+	    {
+	      wpbuf.put (*src);
+	      con.rarg = 0;
+	      con.my_title_buf[0] = '\0';
+	      con.state = gotrsquare;
+	    }
 	  else if (wincap.has_con_24bit_colors () && !con_is_legacy)
 	    {
 	      if (*src == 'c') /* RIS Full reset */
@@ -3095,13 +3110,6 @@ fhandler_console::write (const void *vsrc, size_t len)
 	      con.state = normal;
 	      wpbuf.empty();
 	    }
-	  else if (*src == ']')		/* OSC Operating System Command */
-	    {
-	      wpbuf.put (*src);
-	      con.rarg = 0;
-	      con.my_title_buf[0] = '\0';
-	      con.state = gotrsquare;
-	    }
 	  else if (*src == '(')		/* Designate G0 character set */
 	    {
 	      wpbuf.put (*src);
@@ -3179,7 +3187,8 @@ fhandler_console::write (const void *vsrc, size_t len)
 	    con.rarg = con.rarg * 10 + (*src - '0');
 	  else if (*src == ';' && (con.rarg == 2 || con.rarg == 0))
 	    con.state = gettitle;
-	  else if (*src == ';' && (con.rarg == 4 || con.rarg == 104))
+	  else if (*src == ';' && (con.rarg == 4 || con.rarg == 104
+				   || (con.rarg >= 10 && con.rarg <= 19)))
 	    con.state = eatpalette;
 	  else
 	    con.state = eattitle;
@@ -3189,10 +3198,13 @@ fhandler_console::write (const void *vsrc, size_t len)
 	case eattitle:
 	case gettitle:
 	  {
+	    wpbuf.put (*src);
 	    int n = strlen (con.my_title_buf);
 	    if (*src < ' ')
 	      {
-		if (*src == '\007' && con.state == gettitle)
+		if (wincap.has_con_24bit_colors () && !con_is_legacy)
+		  wpbuf.send (get_output_handle ());
+		else if (*src == '\007' && con.state == gettitle)
 		  set_console_title (con.my_title_buf);
 		con.state = normal;
 		wpbuf.empty();
@@ -3201,27 +3213,37 @@ fhandler_console::write (const void *vsrc, size_t len)
 	      {
 		con.my_title_buf[n++] = *src;
 		con.my_title_buf[n] = '\0';
-		wpbuf.put (*src);
 	      }
 	    src++;
 	    break;
 	  }
 	case eatpalette:
-	  if (*src == '\033')
-	    {
-	      wpbuf.put (*src);
-	      con.state = endpalette;
-	    }
+	  wpbuf.put (*src);
+	  if (*src == '?')
+	    con.saw_question_mark = true;
+	  else if (*src == '\033')
+	    con.state = endpalette;
 	  else if (*src == '\a')
 	    {
+	      /* Send OSC Ps; Pt BEL other than OSC Ps; ? BEL */
+	      if (wincap.has_con_24bit_colors () && !con_is_legacy
+		  && !con.saw_question_mark)
+		wpbuf.send (get_output_handle ());
 	      con.state = normal;
 	      wpbuf.empty();
 	    }
 	  src++;
 	  break;
 	case endpalette:
+	  wpbuf.put (*src);
 	  if (*src == '\\')
-	    con.state = normal;
+	    {
+	      /* Send OSC Ps; Pt ST other than OSC Ps; ? ST */
+	      if (wincap.has_con_24bit_colors () && !con_is_legacy
+		  && !con.saw_question_mark)
+		wpbuf.send (get_output_handle ());
+	      con.state = normal;
+	    }
 	  else
 	    /* Sequence error (abort) */
 	    con.state = normal;