From abb0450de4cb6b57dc44206768e00e4a6b2816e9 Mon Sep 17 00:00:00 2001
From: Jason Hood <jadoxa@yahoo.com.au>
Date: Thu, 10 May 2018 21:57:52 +1000
Subject: [PATCH] Workaround a Windows 10 1803 bug

I create a secondary buffer to assist with wrap detection.  On Win10
1803 writing to this buffer outputs to the active buffer.  Disable
virtual terminal processing to prevent it.
---
 ANSI.c     | 10 ++++++++--
 ansicon.c  |  2 +-
 readme.txt |  7 ++++---
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/ANSI.c b/ANSI.c
index 37eb325..3192ef2 100644
--- a/ANSI.c
+++ b/ANSI.c
@@ -197,7 +197,7 @@
   v1.83, 16 February, 2018:
     create the flush thread on first use.
 
-  v1.84-wip, 17 February, 26 April to 9 May, 2018:
+  v1.84-wip, 17 February, 26 April to 10 May, 2018:
     close the flush handles on detach;
     dynamically load WINMM.DLL;
     use sprintf/_snprintf/_snwprintf instead of wsprintf, avoiding USER32.DLL;
@@ -208,7 +208,8 @@
     remove dependency on the CRT;
     increase heap to 256KiB to fix logging of really long command lines;
     default to 7 or -7 if ANSICON_DEF could not be parsed;
-    scrolling will use the default attribute for new lines.
+    scrolling will use the default attribute for new lines;
+    workaround Windows 10 1803 console bug.
 */
 
 #include "ansicon.h"
@@ -771,6 +772,11 @@ void FlushBuffer( void )
 	SetConsoleMode( hConWrap, (awm) ? ENABLE_WRAP_AT_EOL_OUTPUT : 0 );
       else if (!awm)
 	SetConsoleMode( hConWrap, ENABLE_PROCESSED_OUTPUT );
+      else if (cache[0].mode & 4) // ENABLE_VIRTUAL_TERMINAL_PROCESSING
+      {
+	// Windows 10 1803 writes to the active buffer if VT is enabled.
+	SetConsoleMode( hConWrap, cache[0].mode & ~4 );
+      }
       WriteConsole( hConWrap, ChBuffer, nCharInBuffer, &nWritten, NULL );
       GetConsoleScreenBufferInfo( hConWrap, &wi );
       if (pState->tb_margins && CUR.Y + wi.CURPOS.Y > TOP + pState->bot_margin)
diff --git a/ansicon.c b/ansicon.c
index 7d94d0a..35ed130 100644
--- a/ansicon.c
+++ b/ansicon.c
@@ -94,7 +94,7 @@
     import the DLL.
 */
 
-#define PDATE L"9 May, 2018"
+#define PDATE L"10 May, 2018"
 
 #include "ansicon.h"
 #include "version.h"
diff --git a/readme.txt b/readme.txt
index 85aae99..a39aee6 100644
--- a/readme.txt
+++ b/readme.txt
@@ -339,12 +339,13 @@ Version History
 
     Legend: + added, - bug-fixed, * changed.
 
-    1.84-wip - 9 May, 2018:
+    1.84-wip - 10 May, 2018:
     - close the flush handles on detach;
     - WriteFile wasn't properly testing if its handle was for a console;
     - use remote load on Win8+ if the process has no IAT;
     - fix logging really long command lines;
     - default to 7 or -7 if ANSICON_DEF could not be parsed;
+    - workaround for a Windows 10 1803 console bug (doubled CMD prompt);
     * remove dependency on CRT & USER32, dynamically load WINMM;
     * exit process if the primary thread is detached (for processes on Win10
       that return, rather than call ExitProcess);
@@ -624,5 +625,5 @@ Distribution
     in LICENSE.txt.
 
 
-========================
-Jason Hood, 9 May, 2018.
+=========================
+Jason Hood, 10 May, 2018.