Kernel/Userspace/LibC: Implement basic dprintln for userspace

kernel/CMakeLists.txt

@@ -16,6 +16,7 @@ set(KERNEL_SOURCES
 	kernel/CPUID.cpp
 	kernel/Credentials.cpp
 	kernel/Debug.cpp
+	kernel/Device/DebugDevice.cpp
 	kernel/Device/Device.cpp
 	kernel/Device/FramebufferDevice.cpp
 	kernel/Device/NullDevice.cpp

kernel/include/kernel/Debug.h

@@ -5,7 +5,7 @@
 #define dprintln(...)										\
 	do {													\
 		Debug::DebugLock::lock();							\
-		Debug::print_prefix(__FILE__, __LINE__);				\
+		Debug::print_prefix(__FILE__, __LINE__);			\
 		BAN::Formatter::print(Debug::putchar, __VA_ARGS__);	\
 		BAN::Formatter::print(Debug::putchar, "\r\n");		\
 		Debug::DebugLock::unlock();							\

kernel/include/kernel/Device/DebugDevice.h

@@ -0,0 +1,28 @@
+#include <kernel/Device/Device.h>
+
+namespace Kernel
+{
+
+	class DebugDevice : public CharacterDevice
+	{
+	public:
+		static BAN::ErrorOr<BAN::RefPtr<DebugDevice>> create(mode_t, uid_t, gid_t);
+
+		virtual dev_t rdev() const override { return m_rdev; }
+
+		virtual BAN::StringView name() const override { return "debug"sv; }
+
+	protected:
+		DebugDevice(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, BAN::ByteSpan) override { return 0; }
+		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan buffer) override;
+
+	private:
+		const dev_t m_rdev;
+	};
+
+}

kernel/include/kernel/Process.h

@@ -62,6 +62,8 @@ namespace Kernel
 
 		bool is_session_leader() const { return pid() == sid(); }
 
+		const char* name() const { return m_cmdline.empty() ? "" : m_cmdline.front().data(); }
+
 		const Credentials& credentials() const { return m_credentials; }
 
 		BAN::ErrorOr<long> sys_exit(int status);

kernel/kernel/Device/DebugDevice.cpp

@@ -0,0 +1,32 @@
+#include <kernel/Device/DebugDevice.h>
+#include <kernel/FS/DevFS/FileSystem.h>
+#include <kernel/Process.h>
+#include <kernel/Timer/Timer.h>
+
+namespace Kernel
+{
+
+	BAN::ErrorOr<BAN::RefPtr<DebugDevice>> DebugDevice::create(mode_t mode, uid_t uid, gid_t gid)
+	{
+		auto* result = new DebugDevice(mode, uid, gid, DevFileSystem::get().get_next_dev());
+		if (result == nullptr)
+			return BAN::Error::from_errno(ENOMEM);
+		return BAN::RefPtr<DebugDevice>::adopt(result);
+	}
+
+	BAN::ErrorOr<size_t> DebugDevice::write_impl(off_t, BAN::ConstByteSpan buffer)
+	{
+		auto ms_since_boot = SystemTimer::get().ms_since_boot();
+		Debug::DebugLock::lock();
+		BAN::Formatter::print(Debug::putchar, "[{5}.{3}] {}: ",
+			ms_since_boot / 1000,
+			ms_since_boot % 1000,
+			Kernel::Process::current().name()
+		);
+		for (size_t i = 0; i < buffer.size(); i++)
+			Debug::putchar(buffer[i]);
+		Debug::DebugLock::unlock();
+		return buffer.size();
+	}
+
+}

kernel/kernel/FS/DevFS/FileSystem.cpp

@@ -1,4 +1,5 @@
 #include <BAN/ScopeGuard.h>
+#include <kernel/Device/DebugDevice.h>
 #include <kernel/Device/FramebufferDevice.h>
 #include <kernel/Device/NullDevice.h>
 #include <kernel/Device/ZeroDevice.h>
@@ -22,6 +23,7 @@ namespace Kernel
 		ASSERT(s_instance);
 
 		MUST(s_instance->TmpFileSystem::initialize(0755, 0, 0));
+		s_instance->add_device(MUST(DebugDevice::create(0666, 0, 0)));
 		s_instance->add_device(MUST(NullDevice::create(0666, 0, 0)));
 		s_instance->add_device(MUST(ZeroDevice::create(0666, 0, 0)));
 	}