Kernel/LibC: Add initial pseudo terminal support

This patch implements posix_openpt() and ptsname()

grantpt() and unlockpt() are left in LibC as stubs, as posix_openpt
currently does all of the needed work.

kernel/include/kernel/Device/DeviceNumbers.h

@@ -9,7 +9,7 @@ namespace Kernel
 	{
 		Framebuffer = 1,
 		TTY,
-		Serial,
+		PTSMaster,
 		Null,
 		Zero,
 		Debug,

kernel/include/kernel/Process.h

@@ -174,6 +174,8 @@ namespace Kernel
 
 		BAN::ErrorOr<long> sys_ttyname(int fildes, char* storage);
 		BAN::ErrorOr<long> sys_isatty(int fildes);
+		BAN::ErrorOr<long> sys_posix_openpt(int flags);
+		BAN::ErrorOr<long> sys_ptsname(int fildes, char* buffer, size_t buffer_len);
 
 		BAN::ErrorOr<long> sys_tty_ctrl(int fildes, int command, int flags);
 

kernel/include/kernel/Terminal/PseudoTerminal.h

@@ -0,0 +1,84 @@
+#pragma once
+
+#include <BAN/WeakPtr.h>
+#include <kernel/Terminal/TTY.h>
+
+namespace Kernel
+{
+
+	class PseudoTerminalSlave;
+
+	class PseudoTerminalMaster final : public CharacterDevice, public BAN::Weakable<PseudoTerminalMaster>
+	{
+	public:
+		static BAN::ErrorOr<BAN::RefPtr<PseudoTerminalMaster>> create(mode_t, uid_t, gid_t);
+
+		dev_t rdev() const override { return m_rdev; }
+		BAN::StringView name() const override { return "<ptmx>"_sv; }
+
+		BAN::ErrorOr<BAN::RefPtr<PseudoTerminalSlave>> slave();
+
+		BAN::ErrorOr<BAN::String> ptsname();
+
+		void putchar(uint8_t ch);
+
+	protected:
+		BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
+		BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan) override;
+
+		bool can_read_impl() const override { SpinLockGuard _(m_buffer_lock); return m_buffer_size > 0; }
+		bool can_write_impl() const override { SpinLockGuard _(m_buffer_lock); return m_buffer_size < m_buffer->size(); }
+		bool has_error_impl() const override { return false; }
+
+	private:
+		PseudoTerminalMaster(BAN::UniqPtr<VirtualRange>, mode_t, uid_t, gid_t);
+		~PseudoTerminalMaster();
+
+	private:
+		BAN::WeakPtr<PseudoTerminalSlave> m_slave;
+
+		mutable SpinLock m_buffer_lock;
+		ThreadBlocker m_buffer_blocker;
+		BAN::UniqPtr<VirtualRange> m_buffer;
+		size_t m_buffer_tail { 0 };
+		size_t m_buffer_size { 0 };
+
+		const dev_t m_rdev;
+
+		friend class BAN::RefPtr<PseudoTerminalMaster>;
+	};
+
+	class PseudoTerminalSlave final : public TTY, public BAN::Weakable<PseudoTerminalSlave>
+	{
+	public:
+		static BAN::ErrorOr<BAN::RefPtr<PseudoTerminalSlave>> create(BAN::String&& name, mode_t, uid_t, gid_t);
+
+		BAN::StringView name() const override { return m_name; }
+
+		uint32_t height() const override { return m_height; }
+		uint32_t width() const override { return m_width; }
+
+		void clear() override;
+
+	protected:
+		void putchar_impl(uint8_t ch) override;
+
+	private:
+		PseudoTerminalSlave(BAN::UniqPtr<VirtualRange>, BAN::String&& name, mode_t, uid_t, gid_t);
+
+	private:
+		BAN::String m_name;
+
+		BAN::WeakPtr<PseudoTerminalMaster> m_master;
+		BAN::UniqPtr<VirtualRange> m_buffer;
+		size_t m_buffer_tail { 0 };
+		size_t m_buffer_size { 0 };
+
+		uint32_t m_width { 0 };
+		uint32_t m_height { 0 };
+
+		friend class PseudoTerminalMaster;
+		friend class BAN::RefPtr<PseudoTerminalSlave>;
+	};
+
+}

kernel/include/kernel/Terminal/Serial.h

@@ -63,11 +63,6 @@ namespace Kernel
 		Serial m_serial;
 		BAN::CircularQueue<uint8_t, 128> m_input;
 		SpinLock m_input_lock;
-
-	public:
-		virtual dev_t rdev() const override { return m_rdev; }
-	private:
-		const dev_t m_rdev;
 	};
 
 }

kernel/include/kernel/Terminal/TTY.h

@@ -42,6 +42,8 @@ namespace Kernel
 		virtual uint32_t width() const = 0;
 		void putchar(uint8_t ch);
 
+		virtual dev_t rdev() const final override { return m_rdev; }
+
 		virtual void clear() = 0;
 
 		virtual BAN::ErrorOr<void> chmod_impl(mode_t) override;
@@ -54,17 +56,7 @@ namespace Kernel
 		virtual bool has_error_impl() const override { return false; }
 
 	protected:
-		TTY(mode_t mode, uid_t uid, gid_t gid)
-			: CharacterDevice(mode, uid, gid)
-		{
-			// FIXME: add correct baud and flags
-			m_termios.c_iflag = 0;
-			m_termios.c_oflag = 0;
-			m_termios.c_cflag = CS8;
-			m_termios.c_lflag = ECHO | ICANON;
-			m_termios.c_ospeed = B38400;
-			m_termios.c_ispeed = B38400;
-		}
+		TTY(mode_t mode, uid_t uid, gid_t gid);
 
 		virtual void putchar_impl(uint8_t ch) = 0;
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
@@ -79,6 +71,8 @@ namespace Kernel
 		termios m_termios;
 
 	private:
+		const dev_t m_rdev;
+
 		pid_t m_foreground_pgrp { 0 };
 
 		struct tty_ctrl_t

kernel/include/kernel/Terminal/VirtualTTY.h

@@ -83,11 +83,6 @@ namespace Kernel
 		bool m_show_cursor { true };
 
 		TerminalDriver* m_terminal_driver { nullptr };
-
-	public:
-		virtual dev_t rdev() const override { return m_rdev; }
-	private:
-		const dev_t m_rdev;
 	};
 
 }