From: H.G. Muller <h.g.muller@hccnet.nl>
Date: Wed, 29 Jun 2011 11:53:00 +0000 (+0200)
Subject: Fix crash on making too-long FEN
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=55517059338842241bcc8d82b1dec21e92b138da;p=xboard.git

Fix crash on making too-long FEN

The buffer for in PositionToFEN was only 128 bytes, which was not enough
for large boards such as 19x19 Go. It is enlarged to MSG_SIZ(512) now.
There also is some approximate overflow checking added (but it is not
fool proof in case there are holdings...)
---

diff --git a/backend.c b/backend.c
index cc5fb3a..a1c3c86 100644
--- a/backend.c
+++ b/backend.c
@@ -15821,7 +15821,7 @@ PositionToFEN(move, overrideCastling)
 {
     int i, j, fromX, fromY, toX, toY;
     int whiteToPlay;
-    char buf[128];
+    char buf[MSG_SIZ];
     char *p, *q;
     int emptycount;
     ChessSquare piece;
@@ -15832,6 +15832,7 @@ PositionToFEN(move, overrideCastling)
 
     /* Piece placement data */
     for (i = BOARD_HEIGHT - 1; i >= 0; i--) {
+	if(MSG_SIZ - (p - buf) < BOARD_RGHT - BOARD_LEFT + 20) { *p = 0; return StrSave(buf); }
 	emptycount = 0;
         for (j = BOARD_LEFT; j < BOARD_RGHT; j++) {
 	    if (boards[move][i][j] == EmptySquare) {