LibC: add needed stubs to build executables with our compiler

libc/unistd.cpp

@@ -1,5 +1,40 @@
+#include <BAN/Assert.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <sys/syscall.h>
 #include <unistd.h>
 
+void _exit(int status)
+{
+	syscall(SYS_EXIT, status);
+	ASSERT_NOT_REACHED();
+}
+
+long syscall(long syscall, ...)
+{
+	va_list args;
+	va_start(args, syscall);
+
+	long ret = 0;
+
+	switch (syscall)
+	{
+	case SYS_EXIT:
+		ret = Kernel::syscall(SYS_EXIT, va_arg(args, int));
+		break;
+	case SYS_READ:
+		ret = Kernel::syscall(SYS_READ, va_arg(args, int), va_arg(args, void*), va_arg(args, size_t));
+		break;
+	case SYS_WRITE:
+		ret = Kernel::syscall(SYS_WRITE, va_arg(args, int), va_arg(args, const void*), va_arg(args, size_t));
+		break;
+	}
+
+	va_end(args);
+	
+	return ret;
+}
+
 pid_t fork(void)
 {
 	return -1;