+bool is_valid(struct game_t* valgame)
+{
+ /* Save files can be roughly grouped into three groups:
+ * With valid, reaceable state, with valid, but unreachable
+ * state and with invaild state. We check that state is
+ * valid: no states are outside minimal or maximal value
+ */
+
+ /* Prevent division by zero */
+ if (valgame->abbnum == 0) {
+ return false;
+ }
+
+ /* Check for RNG overflow. Truncate */
+ if (valgame->lcg_x >= LCG_M) {
+ valgame->lcg_x %= LCG_M;
+ }
+
+ /* Check for RNG underflow. Transpose */
+ if (valgame->lcg_x < LCG_M) {
+ valgame->lcg_x = LCG_M + (valgame->lcg_x % LCG_M);
+ }
+
+ /* Bounds check for locations */
+ if ( valgame->chloc < -1 || valgame->chloc > NLOCATIONS ||
+ valgame->chloc2 < -1 || valgame->chloc2 > NLOCATIONS ||
+ valgame->loc < 0 || valgame->loc > NLOCATIONS ||
+ valgame->newloc < 0 || valgame->newloc > NLOCATIONS ||
+ valgame->oldloc < 0 || valgame->oldloc > NLOCATIONS ||
+ valgame->oldlc2 < 0 || valgame->oldlc2 > NLOCATIONS) {
+ return false;
+ }
+ /* Bounds check for location arrays */
+ for (int i = 0; i <= NDWARVES; i++) {
+ if (valgame->dloc[i] < -1 || valgame->dloc[i] > NLOCATIONS ||
+ valgame->odloc[i] < -1 || valgame->odloc[i] > NLOCATIONS) {
+ return false;
+ }
+ }
+
+ for (int i = 0; i <= NOBJECTS; i++) {
+ if (valgame->place[i] < -1 || valgame->place[i] > NLOCATIONS ||
+ valgame->fixed[i] < -1 || valgame->fixed[i] > NLOCATIONS) {
+ return false;
+ }
+ }
+
+ /* Bounds check for dwarves */
+ if (valgame->dtotal < 0 || valgame->dtotal > NDWARVES ||
+ valgame->dkill < 0 || valgame->dkill > NDWARVES) {
+ return false;
+ }
+
+ /* Validate that we didn't die too many times in save */
+ if (valgame->numdie >= NDEATHS) {
+ return false;
+ }
+
+ /* Recalculate tally, throw the towel if in disagreement */
+ long temp_tally = 0;
+ for (int treasure = 1; treasure <= NOBJECTS; treasure++) {
+ if (objects[treasure].is_treasure) {
+ if (valgame->prop[treasure] == STATE_NOTFOUND) {
+ ++temp_tally;
+ }
+ }
+ }
+ if (temp_tally != valgame->tally) {
+ return false;
+ }
+
+ /* Check that properties of objects aren't beyond expected */
+ for (obj_t obj = 0; obj <= NOBJECTS; obj++) {
+ if (valgame->prop[obj] < STATE_NOTFOUND || valgame->prop[obj] > 1) {
+ switch (obj) {
+ case RUG:
+ case DRAGON:
+ case BIRD:
+ case BOTTLE:
+ case PLANT:
+ case PLANT2:
+ case TROLL:
+ case URN:
+ case EGGS:
+ case VASE:
+ case CHAIN:
+ if (valgame->prop[obj] == 2) // There are multiple different states, but it's convenient to clump them together
+ continue;
+ /* FALLTHRU */
+ case BEAR:
+ if (valgame->prop[BEAR] == CONTENTED_BEAR || valgame->prop[BEAR] == BEAR_DEAD)
+ continue;
+ /* FALLTHRU */
+ default:
+ return false;
+ }
+ }
+ }
+
+ /* Check that values in linked lists for objects in locations are inside bounds */
+ for (loc_t loc = LOC_NOWHERE; loc <= NLOCATIONS; loc++) {
+ if (valgame->atloc[loc] < NO_OBJECT || valgame->atloc[loc] > NOBJECTS * 2) {
+ return false;
+ }
+ }
+ for (obj_t obj = 0; obj <= NOBJECTS * 2; obj++ ) {
+ if (valgame->link[obj] < NO_OBJECT || valgame->link[obj] > NOBJECTS * 2) {
+ return false;
+ }
+ }
+
+ return true;
+}
+