init

Telegram/lib_base/base/random.cpp

@@ -0,0 +1,54 @@
+// This file is part of Desktop App Toolkit,
+// a set of libraries for developing nice desktop applications.
+//
+// For license and copyright information please follow this link:
+// https://github.com/desktop-app/legal/blob/master/LEGAL
+//
+#include "base/random.h"
+
+extern "C" {
+#include <openssl/rand.h>
+} // extern "C"
+
+namespace base {
+namespace {
+
+template <typename Next>
+int RandomIndex(int count, Next &&next) {
+	Expects(count > 0);
+
+	if (count == 1) {
+		return 0;
+	}
+	const auto max = (std::numeric_limits<uint32>::max() / count) * count;
+	while (true) {
+		const auto random = next();
+		if (random < max) {
+			return int(random % count);
+		}
+	}
+}
+
+} // namespace
+
+void RandomFill(bytes::span bytes) {
+	const auto result = RAND_bytes(
+		reinterpret_cast<unsigned char*>(bytes.data()),
+		bytes.size());
+
+	Ensures(result);
+}
+
+int RandomIndex(int count) {
+	return RandomIndex(count, [] { return  RandomValue<uint32>(); });
+}
+
+int RandomIndex(int count, BufferedRandom<uint32> buffered) {
+	return RandomIndex(count, [&] { return buffered.next(); });
+}
+
+void RandomAddSeed(bytes::const_span bytes) {
+	RAND_seed(bytes.data(), bytes.size());
+}
+
+} // namespace base