tictactoe

commit e87c3093770a76d8d3410bff487b6639c4ecfc1c
parent 6129d4dee09b1b24b41630d2068b56082010368c
Author: Wilson Gheen <wilson@wilsonrgheen.com>
Date:   Fri, 23 Dec 2022 15:51:03 -0600

Use /dev/urandom if available for better randomness. Temporarily omitted for unit testing because it is slow for some reason

Diffstat:
M
tictactoe.h
 | 
22
++++++++++++++++++----

1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/tictactoe.h b/tictactoe.h
@@ -22,12 +22,26 @@ static _Bool srand_seeded = 0;
 struct move { int move_ind; char winner; };
 
 static int get_rand(int max_excl) {
+#ifndef UNIT_TEST
+    FILE *urandom = fopen("/dev/urandom", "r");
+    if(urandom) {
+        int rnd = 0;
+        size_t z = fread(&rnd, sizeof(int), 1, urandom);
+        fclose(urandom);
+        if(z) {
+            if(rnd < 0) rnd *= -1;
+            return rnd % max_excl;
+        }
+    }
+#endif
+    /* fallback if somehow we can't open urandom or read 4 bytes from it */
     if (!srand_seeded) {
         time_t seed = time(NULL);
-        FILE *f = fopen("seed", "w");
-        if(f) {
-            fprintf(f, "%ld\n", seed);
-            fclose(f);
+        /* save seed for later in case of bugs, so they're reproducible */
+        FILE *seed_file = fopen("seed", "w");
+        if(seed_file) {
+            fprintf(seed_file, "%ld\n", seed);
+            fclose(seed_file);
         }
         srand(seed);
         srand_seeded = 1;