testcases/open_posix_testsuite/conformance/interfaces/pthread_mutex_trylock/assertions.xml

<assertions>
  <assertion id="1" tag="ref:XSH6:33930:33932">
   The function

   int pthread_mutex_trylock(pthread_mutex_t *mutex);

  is equivalent to pthread_mutex_lock() except that if the mutex object 
  referenced by 'mutex' is currently locked (by any thread, including the
  current thread), the call returns immediately.
  </assertion>
  <assertion id="2" tag="ref:XSH6:33932:33934">
  If the mutex type is PTHREAD_MUTEX_RECURSIVE and the mutex is currently
  owned by the calling thread, the mutex lock count shall be incremented
  by one and the pthread_mutex_trylock() function immediately returns
  success.
  </assertion> 
  <assertion id="3" tag="ref:XSH6:33947:33948">
  It returns 0 if a lock on the mutex object referenced by 'mutex' is
  acquired.
  </assertion> 
  <assertion id="4" tag="ref:XSH6:33950:33965">
  Upon failure, it shall return:
  -[EINVAL]  The mutex was created with the protocol attribute
   	     PTHREAD_PRIO_PROTECT and the calling thread's priority is higher 
   	     than the mutex's current priority calling.
  -[EBUSY]   The mutex could not be acquired because it was already locked.

   It may fail if:
  -[EINVAL] 'mutex' does not refer to an initialized mutex object

  It shall not return [EINTR].
  </assertion> 
</assertions>