stdlib/test-dlclose-exit-race-helper.c

   1 /* Helper for exit/dlclose race test (Bug 22180).
   2    Copyright (C) 2017 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <stdbool.h>
  21 #include <stdlib.h>
  22 #include <semaphore.h>
  23 #include <unistd.h>
  24 #include <support/check.h>
  25 #include <support/xthread.h>
  26
  27 /* Semaphore defined in executable to ensure we have a happens-before
  28    between the first function starting and exit being called.  */
  29 extern sem_t order1;
  30
  31 /* Semaphore defined in executable to ensure we have a happens-before
  32    between the second function starting and the first function returning.  */
  33 extern sem_t order2;
  34
  35 /* glibc function for registering DSO-specific exit functions.  */
  36 extern int __cxa_atexit (void (*func) (void *), void *arg, void *dso_handle);
  37
  38 /* Hidden compiler handle to this shared object.  */
  39 extern void *__dso_handle __attribute__ ((__weak__));
  40
  41 static void
  42 first (void *start)
  43 {
  44   /* Let the exiting thread run.  */
  45   sem_post (&order1);
  46
  47   /* Wait for exiting thread to finish.  */
  48   sem_wait (&order2);
  49
  50   printf ("first\n");
  51 }
  52
  53 static void
  54 second (void *start)
  55 {
  56   /* We may be called from different threads.
  57      This lock protects called.  */
  58   static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
  59   static bool called = false;
  60
  61   xpthread_mutex_lock (&mtx);
  62   if (called)
  63     FAIL_EXIT1 ("second called twice!");
  64
  65   called = true;
  66   xpthread_mutex_unlock (&mtx);
  67
  68   printf ("second\n");
  69 }
  70
  71
  72 __attribute__ ((constructor)) static void
  73 constructor (void)
  74 {
  75   sem_init (&order1, 0, 0);
  76   sem_init (&order2, 0, 0);
  77   __cxa_atexit (second, NULL, __dso_handle);
  78   __cxa_atexit (first, NULL, __dso_handle);
  79 }