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

<assertions>
  <assertion id="1" tag="ref:XSH6:33908:33911">
   The function

   int pthread_mutex_lock(pthread_mutex_t *mutex);

  locks the mutex object referenced by 'mutex'.  If the mutex is
  already locked, the calling thread shall block until the mutex becomes
  available.  This operation returns with the mutex object referenced
  by 'mutex' in the locked state with the calling thread as its owner.
  </assertion>

  <assertion id="2" tag="ref:XSH6:33945:33945">
  Upon success, it returns 0.
  </assertion>

  <assertion id="3" 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.
  It may fail if:
  -[EINVAL]  'mutex' does not refer to an initialized mutex object
  -[EDEADLK] The current thread already owns the mutex
  It shall not return [EINTR].
  </assertion>

  <assertion id="4" tag="ref:XSH6:33950:33965">
  If the mutex type is PTHREAD_MUTEX_RECURSIVE,
  the mutex shall maintain the concept of a lock count
  </assertion>

  <assertion id="5" tag="ref:XSH6:33950:33965">
  If a signal is delivered to a thread waiting for a mutex,
  when return from the signal handler the thread shall resume waiting.
  </assertion>
</assertions>