Kernel: Implement static Process::kill()

This allows killing processes even when there does not exist a current
thread.

kernel/include/kernel/Process.h

@@ -171,6 +171,7 @@ namespace Kernel
 
 		BAN::ErrorOr<long> sys_tty_ctrl(int fildes, int command, int flags);
 
+		static BAN::ErrorOr<void> kill(pid_t pid, int signal);
 		BAN::ErrorOr<long> sys_kill(pid_t pid, int signal);
 		BAN::ErrorOr<long> sys_sigaction(int signal, const struct sigaction* act, struct sigaction* oact);
 		BAN::ErrorOr<long> sys_sigpending(sigset_t* set);

kernel/kernel/Process.cpp

@@ -1847,20 +1847,13 @@ namespace Kernel
 		return 0;
 	}
 
-	BAN::ErrorOr<long> Process::sys_kill(pid_t pid, int signal)
+	BAN::ErrorOr<void> Process::kill(pid_t pid, int signal)
 	{
 		if (pid == 0 || pid == -1)
 			return BAN::Error::from_errno(ENOTSUP);
 		if (signal != 0 && (signal < _SIGMIN || signal > _SIGMAX))
 			return BAN::Error::from_errno(EINVAL);
 
-		if (pid == m_pid)
-		{
-			if (signal)
-				add_pending_signal(signal);
-			return 0;
-		}
-
 		bool found = false;
 		for_each_process(
 			[&](Process& process)
@@ -1880,10 +1873,28 @@ namespace Kernel
 		);
 
 		if (found)
-			return 0;
+			return {};
 		return BAN::Error::from_errno(ESRCH);
 	}
 
+	BAN::ErrorOr<long> Process::sys_kill(pid_t pid, int signal)
+	{
+		if (pid == 0 || pid == -1)
+			return BAN::Error::from_errno(ENOTSUP);
+		if (signal != 0 && (signal < _SIGMIN || signal > _SIGMAX))
+			return BAN::Error::from_errno(EINVAL);
+
+		if (pid == m_pid)
+		{
+			if (signal)
+				add_pending_signal(signal);
+			return 0;
+		}
+
+		TRY(kill(pid, signal));
+		return 0;
+	}
+
 	BAN::ErrorOr<long> Process::sys_sigaction(int signal, const struct sigaction* act, struct sigaction* oact)
 	{
 		if (signal < _SIGMIN || signal > _SIGMAX)

kernel/kernel/Terminal/TTY.cpp

@@ -273,7 +273,7 @@ namespace Kernel
 		// ^C
 		if (ch == '\x03')
 		{
-			if (auto ret = Process::current().sys_kill(-m_foreground_pgrp, SIGINT); ret.is_error())
+			if (auto ret = Process::kill(-m_foreground_pgrp, SIGINT); ret.is_error())
 				dwarnln("TTY: {}", ret.error());
 			return;
 		}