[newlib-cygwin] Cygwin: pty: Check response for CSI6n more strictly.

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=da8cebcdedb07ea1029009c19f6c2dc23216e4dd

commit da8cebcdedb07ea1029009c19f6c2dc23216e4dd
Author: Takashi Yano via Cygwin-patches <cygwin-patches@cygwin.com>
Date:   Wed Dec 16 18:10:15 2020 +0900

    Cygwin: pty: Check response for CSI6n more strictly.
    
    - Previous code to read response for CSI6n allows invalid response
      such as "CSI Pl; Pc H" other than correct response "CSI Pl; Pc R".
      With this patch, the response is checked more strictly.

Diff:
---
 winsup/cygwin/fhandler_tty.cc | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index 5f38ca8d3..77d9d9b47 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -2682,7 +2682,9 @@ fhandler_pty_slave::term_has_pcon_cap (const WCHAR *env)
 	  len -= n;
 	  *p = '\0';
 	  char *p1 = strrchr (buf, '\033');
-	  if (p1 == NULL || sscanf (p1, "\033[%d;%dR", &y1, &x1) != 2)
+	  char c;
+	  if (p1 == NULL || sscanf (p1, "\033[%d;%d%c", &y1, &x1, &c) != 3
+	      || c != 'R')
 	    continue;
 	  wait_cnt = 0;
 	  break;
@@ -2715,7 +2717,9 @@ fhandler_pty_slave::term_has_pcon_cap (const WCHAR *env)
       len -= n;
       *p = '\0';
       char *p2 = strrchr (buf, '\033');
-      if (p2 == NULL || sscanf (p2, "\033[%d;%dR", &y2, &x2) != 2)
+      char c;
+      if (p2 == NULL || sscanf (p2, "\033[%d;%d%c", &y2, &x2, &c) != 3
+	  || c != 'R')
 	continue;
       break;
     }