LibC/Kernel: Implement ttyname

userspace/libraries/LibC/include/limits.h

@@ -62,6 +62,7 @@ __BEGIN_DECLS
 #define PATH_MAX 256
 #define LOGIN_NAME_MAX 256
 #define HOST_NAME_MAX 255
+#define TTY_NAME_MAX PATH_MAX
 
 __END_DECLS
 

userspace/libraries/LibC/include/sys/syscall.h

@@ -82,6 +82,7 @@ __BEGIN_DECLS
 	O(SYS_GETSOCKOPT,		getsockopt)		\
 	O(SYS_SETSOCKOPT,		setsockopt)		\
 	O(SYS_REALPATH,			realpath)		\
+	O(SYS_TTYNAME,			ttyname)		\
 
 enum Syscall
 {

userspace/libraries/LibC/unistd.cpp

@@ -488,3 +488,11 @@ char* getlogin(void)
 	endpwent();
 	return buffer;
 }
+
+char* ttyname(int fildes)
+{
+	static char storage[_POSIX_TTY_NAME_MAX];
+	if (syscall(SYS_TTYNAME, fildes, storage) == -1)
+		return nullptr;
+	return storage;
+}