Split platform specific code to its own file

PR #21368.

src/base/utils/randomlayer_other.cpp

@@ -0,0 +1,79 @@
+/*
+ * 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 <cerrno>
+#include <cstdio>
+#include <cstring>
+
+#include <QtLogging>
+
+namespace
+{
+    class RandomLayer
+    {
+    // need to satisfy UniformRandomBitGenerator requirements
+    public:
+        using result_type = uint32_t;
+
+        RandomLayer()
+            : m_randDev {fopen("/dev/urandom", "rb")}
+        {
+            if (!m_randDev)
+                qFatal("Failed to open /dev/urandom. Reason: %s. Error code: %d.", std::strerror(errno), errno);
+        }
+
+        ~RandomLayer()
+        {
+            fclose(m_randDev);
+        }
+
+        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()() const
+        {
+            result_type buf = 0;
+            if (fread(&buf, sizeof(buf), 1, m_randDev) != 1)
+                qFatal("Read /dev/urandom error. Reason: %s. Error code: %d.", std::strerror(errno), errno);
+
+            return buf;
+        }
+
+    private:
+        FILE *m_randDev = nullptr;
+    };
+}