1  /* C11 threads trylock mutex tests.
       2     Copyright (C) 2018-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <threads.h>
      20  #include <stdio.h>
      21  #include <unistd.h>
      22  
      23  #include <support/check.h>
      24  
      25  /* Shared mutex between child and parent.  */
      26  static mtx_t mutex;
      27  
      28  /* Shared counter to check possible race conditions.  */
      29  static char shrd_counter;
      30  
      31  /* Function to choose an action to do, depending on mtx_trylock
      32     return value.  */
      33  static inline void
      34  choose_action (int action, char* thread_name)
      35  {
      36    switch (action)
      37      {
      38        case thrd_success:
      39          ++shrd_counter;
      40  
      41  	if (mtx_unlock (&mutex) != thrd_success)
      42  	  FAIL_EXIT1 ("mtx_unlock failed");
      43        break;
      44  
      45        case thrd_busy:
      46          break;
      47  
      48        case thrd_error:
      49  	FAIL_EXIT1 ("%s lock error", thread_name);
      50          break;
      51      }
      52  }
      53  
      54  static int
      55  child_add (void *arg)
      56  {
      57    char child_name[] = "child";
      58  
      59    /* Try to lock mutex.  */
      60    choose_action (mtx_trylock (&mutex), child_name);
      61  
      62    thrd_exit (thrd_success);
      63  }
      64  
      65  static int
      66  do_test (void)
      67  {
      68    thrd_t id;
      69    char parent_name[] = "parent";
      70  
      71    if (mtx_init (&mutex, mtx_timed) != thrd_success)
      72      FAIL_EXIT1 ("mtx_init failed");
      73  
      74    if (thrd_create (&id, child_add, NULL) != thrd_success)
      75      FAIL_EXIT1 ("thrd_create failed");
      76  
      77    choose_action (mtx_trylock (&mutex), parent_name);
      78  
      79    if (thrd_join (id, NULL) != thrd_success)
      80      FAIL_EXIT1 ("thrd_join failed");
      81  
      82    if (shrd_counter != 2 && shrd_counter != 1)
      83      FAIL_EXIT1 ("shrd_counter != {1,2} (%d)", shrd_counter);
      84  
      85    mtx_destroy (&mutex);
      86  
      87    return 0;
      88  }
      89  
      90  #include <support/test-driver.c>