Implement pthread_rwlock functions for NaCl newlib

src/untrusted/pthread/pthread_types.h

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*
  * Native Client pthreads implementation layer
  */
 
@@ skipping 29 matching lines @@
 struct __nc_basic_thread_data;
 
 /* This struct defines the layout of the TDB */
 /*
  * NOTE: Based on a conversation with mcgrathr, unused_dtv was added to enable
  *       experiments with newlib as a shared library talking to glibc's ld.so.
  *       ld.so does not mind if we trample over most of its tdb structure
  *       ("tcbhead_t") as long as we keep the field "dtv" untouched and
  *       use tls_base in a compatible way (which we already do).
  */
-typedef struct {
+typedef struct nc_thread_descriptor {
   void *tls_base;  /* tls accesses are made relative to this base */
   void *unused_dtv;  /* increase compatibility with glibc's tcbhead_t */
   int joinable;
   int join_waiting;
+  unsigned int rdlock_count;  /* number of rdlocks this thread holds */
   nc_thread_memory_block_t *stack_node;
   nc_thread_memory_block_t *tls_node;
   nc_thread_function start_func;
   void *state;
   /*
    * irt_thread_data is used when libpthread is linked into the IRT.
    * It is used for free()ing the thread block.
    * TODO(mseaborn): This plays a similar role to tls_node; the two
    * could be unified in future.
    */
@@ skipping 28 matching lines @@
 
 static inline void *nc_memory_block_to_payload(nc_thread_memory_block_t *node) {
   return &node[1];
 }
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif  /* NATIVE_CLIENT_SRC_UNTRUSTED_PTHREAD_NC_PTHREAD_TYPES_H_ */