Kernel: Add basic ZeroDevice to /dev/zero

kernel/CMakeLists.txt

@@ -16,6 +16,7 @@ set(KERNEL_SOURCES
 	kernel/Debug.cpp
 	kernel/Device/Device.cpp
 	kernel/Device/NullDevice.cpp
+	kernel/Device/ZeroDevice.cpp
 	kernel/Errors.cpp
 	kernel/Font.cpp
 	kernel/FS/DevFS/FileSystem.cpp

kernel/include/kernel/Device/ZeroDevice.h

@@ -0,0 +1,26 @@
+#include <kernel/Device/Device.h>
+
+namespace Kernel
+{
+
+	class ZeroDevice : public CharacterDevice
+	{
+	public:
+		static BAN::ErrorOr<BAN::RefPtr<ZeroDevice>> create(mode_t, uid_t, gid_t);
+
+		virtual dev_t rdev() const override { return m_rdev; }
+
+	protected:
+		ZeroDevice(mode_t mode, uid_t uid, gid_t gid, dev_t rdev)
+			: CharacterDevice(mode, uid, gid)
+			, m_rdev(rdev)
+		{ }
+
+		virtual BAN::ErrorOr<size_t> read_impl(off_t, void*, size_t) override;
+		virtual BAN::ErrorOr<size_t> write_impl(off_t, const void*, size_t size) override { return size; };
+	
+	private:
+		const dev_t m_rdev;
+	};
+
+}

kernel/kernel/Device/ZeroDevice.cpp

@@ -0,0 +1,22 @@
+#include <kernel/Device/ZeroDevice.h>
+#include <kernel/FS/DevFS/FileSystem.h>
+
+namespace Kernel
+{
+
+	BAN::ErrorOr<BAN::RefPtr<ZeroDevice>> ZeroDevice::create(mode_t mode, uid_t uid, gid_t gid)
+	{
+		auto* result = new ZeroDevice(mode, uid, gid, DevFileSystem::get().get_next_dev());
+		if (result == nullptr)
+			return BAN::Error::from_errno(ENOMEM);
+		return BAN::RefPtr<ZeroDevice>::adopt(result);
+	}
+
+
+	BAN::ErrorOr<size_t> ZeroDevice::read_impl(off_t, void* buffer, size_t bytes)
+	{
+		memset(buffer, 0, bytes);
+		return bytes;
+	}
+
+}

kernel/kernel/FS/DevFS/FileSystem.cpp

@@ -1,5 +1,6 @@
 #include <BAN/ScopeGuard.h>
 #include <kernel/Device/NullDevice.h>
+#include <kernel/Device/ZeroDevice.h>
 #include <kernel/FS/DevFS/FileSystem.h>
 #include <kernel/FS/RamFS/Inode.h>
 #include <kernel/LockGuard.h>
@@ -21,6 +22,7 @@ namespace Kernel
 		MUST(s_instance->set_root_inode(root_inode));
 
 		s_instance->add_device("null", MUST(NullDevice::create(0666, 0, 0)));
+		s_instance->add_device("zero", MUST(ZeroDevice::create(0666, 0, 0)));
 	}
 
 	DevFileSystem& DevFileSystem::get()