Remove race condition in clock switching

[xboard.git] / backend.c

diff --git a/backend.c b/backend.c
index a54c6cc..8f77f6b 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -190,7 +190,7 @@ void ParseGameHistory P((char *game));
 void ParseBoard12 P((char *string));
 void KeepAlive P((void));
 void StartClocks P((void));
-void SwitchClocks P((void));
+void SwitchClocks P((int nr));
 void StopClocks P((void));
 void ResetClocks P((void));
 char *PGNDate P((void));
@@ -3318,10 +3318,10 @@ read_from_ics(isr, closure, data, count, error)
                    looking_at(buf, &i, "It is not your move")) {
                    /* Illegal move */
                    if (ics_user_moved && forwardMostMove > backwardMostMove) { // only backup if we already moved
-                       currentMove = --forwardMostMove;
+                       currentMove = forwardMostMove-1;
                        DisplayMove(currentMove - 1); /* before DMError */
                        DrawPosition(FALSE, boards[currentMove]);
-                       SwitchClocks();
+                       SwitchClocks(forwardMostMove-1); // [HGM] race
                        DisplayBothClocks();
                    }
                    DisplayMoveError(_("Illegal move (rejected by ICS)")); // [HGM] but always relay error msg
@@ -5338,6 +5338,8 @@ SendBoard(cps, moveNum)
     setboardSpoiledMachineBlack = 0; /* [HGM] assume WB 4.2.7 already solves this after sending setboard */
 }
 
+static int autoQueen; // [HGM] oneclick
+
 int
 HasPromotionChoice(int fromX, int fromY, int toX, int toY, char *promoChoice)
 {
@@ -5408,7 +5410,7 @@ HasPromotionChoice(int fromX, int fromY, int toX, int toY, char *promoChoice)
        *promoChoice = PieceToChar(BlackFerz);  // no choice
        return FALSE;
     }
-    if(appData.alwaysPromoteToQueen) { // predetermined
+    if(autoQueen) { // predetermined
        if(gameInfo.variant == VariantSuicide || gameInfo.variant == VariantLosers)
             *promoChoice = PieceToChar(BlackKing); // in Suicide Q is the last thing we want
        else *promoChoice = PieceToChar(BlackQueen);
@@ -5550,7 +5552,7 @@ OKToStartUserMove(x, y)
 }
 
 Boolean
-OnlyMove(int *x, int *y) {
+OnlyMove(int *x, int *y, Boolean captures) {
     DisambiguateClosure cl;
     if (appData.zippyPlay) return FALSE;
     switch(gameMode) {
@@ -5573,7 +5575,11 @@ OnlyMove(int *x, int *y) {
     cl.ftIn = -1;
     cl.promoCharIn = NULLCHAR;
     Disambiguate(boards[currentMove], PosFlags(currentMove), &cl);
-    if(cl.kind == NormalMove) {
+    if( cl.kind == NormalMove ||
+       cl.kind == AmbiguousMove && captures && cl.captures == 1 ||
+       cl.kind == WhitePromotionQueen || cl.kind == BlackPromotionQueen ||
+       cl.kind == WhitePromotionKnight || cl.kind == BlackPromotionKnight ||
+       cl.kind == WhiteCapturesEnPassant || cl.kind == BlackCapturesEnPassant) {
       fromX = cl.ff;
       fromY = cl.rf;
       *x = cl.ft;
@@ -5588,11 +5594,16 @@ OnlyMove(int *x, int *y) {
     cl.ftIn = *x;
     cl.promoCharIn = NULLCHAR;
     Disambiguate(boards[currentMove], PosFlags(currentMove), &cl);
-    if(cl.kind == NormalMove) {
+    if( cl.kind == NormalMove ||
+       cl.kind == AmbiguousMove && captures && cl.captures == 1 ||
+       cl.kind == WhitePromotionQueen || cl.kind == BlackPromotionQueen ||
+       cl.kind == WhitePromotionKnight || cl.kind == BlackPromotionKnight ||
+       cl.kind == WhiteCapturesEnPassant || cl.kind == BlackCapturesEnPassant) {
       fromX = cl.ff;
       fromY = cl.rf;
       *x = cl.ft;
       *y = cl.rt;
+      autoQueen = TRUE; // act as if autoQueen on when we click to-square
       return TRUE;
     }
     return FALSE;
@@ -6087,8 +6098,10 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
               || x == BOARD_RGHT+1 && y >= gameInfo.holdingsSize) )
        return;
 
+    autoQueen = appData.alwaysPromoteToQueen;
+
     if (fromX == -1) {
-      if(!appData.oneClick || !OnlyMove(&x, &y)) {
+      if(!appData.oneClick || !OnlyMove(&x, &y, FALSE)) {
        if (clickType == Press) {
            /* First square */
            if (OKToStartUserMove(x, y)) {
@@ -6129,6 +6142,7 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
             !(fromP == BlackKing && toP == BlackRook && frc))) {
            /* Clicked again on same color piece -- changed his mind */
            second = (x == fromX && y == fromY);
+          if(!second || !OnlyMove(&x, &y, TRUE)) {
            if (appData.highlightDragging) {
                SetHighlights(x, y, -1, -1);
            } else {
@@ -6141,6 +6155,7 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
                DragPieceBegin(xPix, yPix);
            }
            return;
+          }
        }
        // ignore clicks on holdings
        if(x < BOARD_LEFT || x >= BOARD_RGHT) return;
@@ -7272,9 +7287,9 @@ if(appData.debugMode) fprintf(debugFP, "nodes = %d, %lld\n", (int) programStats.
            gameMode = EditGame;
            ModeHighlight();
        }
-       currentMove = --forwardMostMove;
+       currentMove = forwardMostMove-1;
        DisplayMove(currentMove-1); /* before DisplayMoveError */
-       SwitchClocks();
+       SwitchClocks(forwardMostMove-1); // [HGM] race
        DisplayBothClocks();
        sprintf(buf1, _("Illegal move \"%s\" (rejected by %s chess program)"),
                parseList[currentMove], cps->which);
@@ -8347,8 +8362,8 @@ MakeMove(fromX, fromY, toX, toY, promoChar)
     }
     CopyBoard(boards[forwardMostMove+1], boards[forwardMostMove]);
     ApplyMove(fromX, fromY, toX, toY, promoChar, boards[forwardMostMove+1]);
-    forwardMostMove++; // [HGM] bare: moved to after ApplyMove, to make sure clock interrupt finds complete board
-    SwitchClocks(); // uses forwardMostMove, so must be done after incrementing it !
+    // forwardMostMove++; // [HGM] bare: moved to after ApplyMove, to make sure clock interrupt finds complete board
+    SwitchClocks(forwardMostMove+1); // [HGM] race: incrementing move nr inside
     timeRemaining[0][forwardMostMove] = whiteTimeRemaining;
     timeRemaining[1][forwardMostMove] = blackTimeRemaining;
     gameInfo.result = GameUnfinished;
@@ -8706,6 +8721,8 @@ GameEnds(result, resultDetails, whosays)
              result, resultDetails ? resultDetails : "(null)", whosays);
     }
 
+    fromX = fromY = -1; // [HGM] abort any move the user is entering.
+
     if (appData.icsActive && (whosays == GE_ENGINE || whosays >= GE_ENGINE1)) {
        /* If we are playing on ICS, the server decides when the
           game is over, but the engine can offer to draw, claim 
@@ -14015,7 +14032,7 @@ DecrementClocks()
    from the color that is *not* on move now.
 */
 void
-SwitchClocks()
+SwitchClocks(int newMoveNr)
 {
     long lastTickLength;
     TimeMark now;
@@ -14025,7 +14042,7 @@ SwitchClocks()
 
     if (StopClockTimer() && appData.clockMode) {
        lastTickLength = SubtractTimeMarks(&now, &tickStartTM);
-       if (WhiteOnMove(forwardMostMove)) {
+       if (!WhiteOnMove(forwardMostMove)) {
            if(blackNPS >= 0) lastTickLength = 0;
            blackTimeRemaining -= lastTickLength;
            /* [HGM] PGNtime: save time for PGN file if engine did not give it */
@@ -14042,6 +14059,7 @@ SwitchClocks()
        }
        flagged = CheckFlags();
     }
+    forwardMostMove = newMoveNr; // [HGM] race: change stm when no timer interrupt scheduled
     CheckTimeControl();
 
     if (flagged || !appData.clockMode) return;