Split platform specific code to its own file

PR #21368.

src/base/utils/randomlayer_win.cpp

@@ -0,0 +1,77 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2024  Mike Tzou (Chocobo1)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * In addition, as a special exception, the copyright holders give permission to
+ * link this program with the OpenSSL project's "OpenSSL" library (or with
+ * modified versions of it that use the same license as the "OpenSSL" library),
+ * and distribute the linked executables. You must obey the GNU General Public
+ * License in all respects for all of the code used other than "OpenSSL".  If you
+ * modify file(s), you may extend this exception to your version of the file(s),
+ * but you are not obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ */
+
+#include <limits>
+
+#include <windows.h>
+
+#include <QtLogging>
+
+#include "base/global.h"
+#include "base/utils/os.h"
+
+namespace
+{
+    class RandomLayer
+    {
+    // need to satisfy UniformRandomBitGenerator requirements
+    public:
+        using result_type = uint32_t;
+
+        RandomLayer()
+            : m_processPrng {Utils::OS::loadWinAPI<PPROCESSPRNG>(u"BCryptPrimitives.dll"_s, "ProcessPrng")}
+        {
+            if (!m_processPrng)
+                qFatal("Failed to load ProcessPrng().");
+        }
+
+        static constexpr result_type min()
+        {
+            return std::numeric_limits<result_type>::min();
+        }
+
+        static constexpr result_type max()
+        {
+            return std::numeric_limits<result_type>::max();
+        }
+
+        result_type operator()()
+        {
+            result_type buf = 0;
+            const bool result = m_processPrng(reinterpret_cast<PBYTE>(&buf), sizeof(buf));
+            if (!result)
+                qFatal("ProcessPrng() failed.");
+
+            return buf;
+        }
+
+    private:
+        using PPROCESSPRNG = BOOL (WINAPI *)(PBYTE, SIZE_T);
+        const PPROCESSPRNG m_processPrng = nullptr;
+    };
+}