stdlib/test-dlclose-exit-race.c

   1 /* Test for exit/dlclose race (Bug 22180).
   2    Copyright (C) 2017-2022 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 /* This file must be run from within a directory called "stdlib".  */
  20
  21 /* This test verifies that when dlopen in one thread races against exit
  22    in another thread, we don't call registered destructor twice.
  23
  24    Expected result:
  25      second
  26      first
  27      ... clean termination
  28 */
  29
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <errno.h>
  33 #include <semaphore.h>
  34 #include <support/check.h>
  35 #include <support/xdlfcn.h>
  36 #include <support/xthread.h>
  37
  38 /* Semaphore to ensure we have a happens-before between the first function
  39    starting and exit being called.  */
  40 sem_t order1;
  41
  42 /* Semaphore to ensure we have a happens-before between the second function
  43    starting and the first function returning.  */
  44 sem_t order2;
  45
  46 void *
  47 exit_thread (void *arg)
  48 {
  49   /* Wait for the dlclose to start...  */
  50   sem_wait (&order1);
  51   /* Then try to run the exit sequence which should call all
  52      __cxa_atexit registered functions and in parallel with
  53      the executing dlclose().  */
  54   exit (0);
  55 }
  56
  57
  58 void
  59 last (void)
  60 {
  61   /* Let dlclose thread proceed.  */
  62   sem_post (&order2);
  63 }
  64
  65 int
  66 main (void)
  67 {
  68   int value;
  69   void *dso;
  70   pthread_t thread;
  71
  72   atexit (last);
  73
  74   dso = xdlopen ("$ORIGIN/test-dlclose-exit-race-helper.so",
  75                  RTLD_NOW|RTLD_GLOBAL);
  76   if ((value = pthread_create (&thread, NULL, exit_thread, NULL)) != 0)
  77     {
  78       /* If pthread_create fails, then exit() is called in the main
  79          thread instead of a second thread, so the semaphore post that
  80          would have happened in 'last' gets blocked behind the call to
  81          first() - which is waiting on the semaphore, and thus
  82          hangs.  */
  83       sem_post (&order2);
  84       errno = value;
  85       FAIL_EXIT1 ("pthread_create: %m");
  86     }
  87
  88   xdlclose (dso);
  89   xpthread_join (thread);
  90
  91   FAIL_EXIT1 ("Did not terminate via exit(0) in exit_thread() as expected.");
  92 }