1  /* Wait until all threads except the current thread has exited.
       2     Copyright (C) 2021-2023 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 <dirent.h>
      20  #include <errno.h>
      21  #include <string.h>
      22  #include <support/check.h>
      23  #include <support/support.h>
      24  #include <unistd.h>
      25  
      26  void
      27  support_wait_for_thread_exit (void)
      28  {
      29  #ifdef __linux__
      30    DIR *proc_self_task = opendir ("/proc/self/task");
      31    TEST_VERIFY_EXIT (proc_self_task != NULL);
      32  
      33    while (true)
      34      {
      35        errno = 0;
      36        struct dirent *e = readdir (proc_self_task);
      37        if (e == NULL && errno != 0)
      38          FAIL_EXIT1 ("readdir: %m");
      39        if (e == NULL)
      40          {
      41            /* Only the main thread remains.  Testing may continue.  */
      42            closedir (proc_self_task);
      43            return;
      44          }
      45  
      46        /* In some kernels, "0" entries denote a thread that has just
      47           exited.  */
      48        if (strcmp (e->d_name, ".") == 0 || strcmp (e->d_name, "..") == 0
      49            || strcmp (e->d_name, "0") == 0)
      50          continue;
      51  
      52        int task_tid = atoi (e->d_name);
      53        if (task_tid <= 0)
      54          FAIL_EXIT1 ("Invalid /proc/self/task entry: %s", e->d_name);
      55  
      56        if (task_tid == gettid ())
      57          /* The current thread.  Keep scanning for other
      58             threads.  */
      59          continue;
      60  
      61        /* task_tid does not refer to this thread here, i.e., there is
      62           another running thread.  */
      63  
      64        /* Small timeout to give the thread a chance to exit.  */
      65        usleep (50 * 1000);
      66  
      67        /* Start scanning the directory from the start.  */
      68        rewinddir (proc_self_task);
      69      }
      70  #else
      71    /* Use a large timeout because we cannot verify that the thread has
      72       exited.  */
      73    usleep (5 * 1000 * 1000);
      74  #endif
      75  }