Merge pull request #357 from skids/rand

Workaround tommath issue #56, affects random bigint numbers > 32bits
MoarVM · Oct 16, 2016 · 3f1ef57 · 3f1ef57
2 parents 80aa6f7 + d60390f
commit 3f1ef57
Showing 1 changed file with 10 additions and 0 deletions.
diff --git a/src/math/bigintops.c b/src/math/bigintops.c
@@ -893,8 +893,18 @@ void MVM_bigint_rand(MVMThreadContext *tc, MVMObject *a, MVMObject *b) {
     mp_int *rnd = MVM_malloc(sizeof(mp_int));
     mp_int *max = force_bigint(bb, tmp);
 
+    /* Workaround tommath issue #56 */
+    mp_int workaround;
+    mp_init (&workaround);
+    mp_rand(&workaround, USED(max) + 1);
+    mp_mul_2d(&workaround, 29, &workaround);
+
     mp_init(rnd);
     mp_rand(rnd, USED(max) + 1);
+
+    mp_xor(rnd, &workaround, rnd);
+    mp_clear(&workaround);
+
     mp_mod(rnd, max, rnd);
     store_bigint_result(ba, rnd);
     clear_temp_bigints(tmp, 1);