[NaCl SDK] nacl_io: Add initial implementations of kill and signal

native_client_sdk/src/libraries/nacl_io/ioctl.h

 /* Copyright 2013 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 #ifndef LIBRARIES_NACL_IO_IOCTL_H_
 #define LIBRARIES_NACL_IO_IOCTL_H_
 
-/* ioctl to tell a tty mount to prefix every message with a particular
- * null-terminated string. Accepts a pointer to a C string which will
- * be the prefix.
- */
-#define TIOCNACLPREFIX 0xadcd01
+#include <sys/types.h>
 
-/* ioctl to feed input to a tty mount. Accepts a pointer to the following
+/*
+ * ioctl to feed input to a tty node. Accepts a pointer to the following
  * struct (tioc_nacl_input_string), which contains a pointer to an array
  * of characters.
  */
 #define TIOCNACLINPUT  0xadcd02
 
+/*
+ * ioctl to register an output handler with the tty node.  Will fail
+ * with EALREADY if a handler is already registered.  Expects an
+ * argument of type tioc_nacl_output.  The handler will be called during
+ * calls to write() on the thread that calls write(), or, for echoed input
+ * during the TIOCNACLINPUT ioctl() on the thread calling ioctl(). The
+ * handler should return the number of bytes written/handled, or -errno
+ * if an error occured.
+ */
+#define TIOCNACLOUTPUT 0xadcd03
+
 struct tioc_nacl_input_string {
   size_t length;
   const char* buffer;
 };
 
+
+typedef ssize_t (*tioc_nacl_output_handler_t)(const char* buf,
+                                              size_t count,
+                                              void* user_data);
+
+struct tioc_nacl_output {
+  tioc_nacl_output_handler_t handler;
+  void* user_data;
+};
+
+
 #endif  /* LIBRARIES_NACL_IO_NACL_IO_H_ */