odk: core serialization structs & functions

odk directory copied from wvgerrit.
branch oemcrypto-v16
commit 0c9a7dc

Bug: 140758896
Test: odk_test
Change-Id: I0c631f771b794468a63e4395f6b9c3b60a1dfd4f

libwvdrmengine/oemcrypto/odk/src/odk_overflow.c

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2019 Google LLC. All Rights Reserved. This file and proprietary
+ * source code may only be used and distributed under the Widevine Master
+ * License Agreement.
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+
+int odk_sub_overflow_u64(uint64_t a, uint64_t b, uint64_t* c) {
+  if (a >= b) {
+    if (c) {
+      *c = a - b;
+    }
+    return 0;
+  }
+  return 1;
+}
+
+int odk_add_overflow_u64(uint64_t a, uint64_t b, uint64_t* c) {
+  if (UINT64_MAX - a >= b) {
+    if (c) {
+      *c = a + b;
+    }
+    return 0;
+  }
+  return 1;
+}
+
+int odk_add_overflow_ux(size_t a, size_t b, size_t* c) {
+  if (SIZE_MAX - a >= b) {
+    if (c) {
+      *c = a + b;
+    }
+    return 0;
+  }
+  return 1;
+}