Kernel: Move a bunch of generic devices code into new subdirectory

Kernel/Devices/Generic/RandomDevice.cpp

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Devices/DeviceManagement.h>
+#include <Kernel/Devices/Generic/RandomDevice.h>
+#include <Kernel/Random.h>
+#include <Kernel/Sections.h>
+
+namespace Kernel {
+
+UNMAP_AFTER_INIT NonnullLockRefPtr<RandomDevice> RandomDevice::must_create()
+{
+    auto random_device_or_error = DeviceManagement::try_create_device<RandomDevice>();
+    // FIXME: Find a way to propagate errors
+    VERIFY(!random_device_or_error.is_error());
+    return random_device_or_error.release_value();
+}
+
+UNMAP_AFTER_INIT RandomDevice::RandomDevice()
+    : CharacterDevice(1, 8)
+{
+}
+
+UNMAP_AFTER_INIT RandomDevice::~RandomDevice() = default;
+
+bool RandomDevice::can_read(OpenFileDescription const&, u64) const
+{
+    return true;
+}
+
+ErrorOr<size_t> RandomDevice::read(OpenFileDescription&, u64, UserOrKernelBuffer& buffer, size_t size)
+{
+    return buffer.write_buffered<256>(size, [&](Bytes bytes) {
+        get_good_random_bytes(bytes);
+        return bytes.size();
+    });
+}
+
+ErrorOr<size_t> RandomDevice::write(OpenFileDescription&, u64, UserOrKernelBuffer const&, size_t size)
+{
+    // FIXME: Use input for entropy? I guess that could be a neat feature?
+    return size;
+}
+
+}