1  /* Verify the interaction of kill and thread groups.
       2     Copyright (C) 2019-2023 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  /* This test demonstrates that a signal which is sent to a specified
      20     thread ID using the kill function is delivered to the entire thread
      21     group (as if it had been sent to the process group).  */
      22  
      23  #include <errno.h>
      24  #include <signal.h>
      25  #include <support/check.h>
      26  #include <support/xsignal.h>
      27  #include <support/xthread.h>
      28  #include <support/xunistd.h>
      29  
      30  /* Signal set containing SIGUSR1.  */
      31  static sigset_t sigusr1_set;
      32  
      33  /* Used to synchronize the threads.  */
      34  static pthread_barrier_t barrier;
      35  
      36  /* TID of the thread to which the signal is sent.  */
      37  static pid_t target_tid;
      38  
      39  /* Thread which is expected to receive the SIGUSR1 signal.  */
      40  static pthread_t signal_thread;
      41  
      42  /* Pipe used to block and terminate the signal thread.  */
      43  static int pipe_signal[2];
      44  
      45  static volatile sig_atomic_t handler_tid;
      46  
      47  static void
      48  sigusr1_handler (int signo)
      49  {
      50    TEST_COMPARE (signo, SIGUSR1);
      51    TEST_VERIFY (pthread_self () == signal_thread);
      52    TEST_COMPARE (handler_tid, 0);
      53    handler_tid = gettid ();
      54    TEST_VERIFY (handler_tid > 0);
      55    /* Ensure that the read system call in thread_read exits if the
      56       signal is delivered before the system call is invoked.  */
      57    char ch = 'X';
      58    xwrite (pipe_signal[1], &ch, 1);
      59  }
      60  
      61  /* Thread which calls pause without expecting it to return.  The TID
      62     of this thread is used as the target in the kill function call.  */
      63  static void *
      64  thread_pause_noreturn (void *closure)
      65  {
      66    target_tid = gettid ();
      67    TEST_VERIFY (target_tid > 0);
      68    xpthread_barrier_wait (&barrier);
      69    pause ();
      70    FAIL_EXIT1 ("The pause function returned");
      71    return NULL;
      72  }
      73  
      74  /* Thread which is expected to receive the signal.  */
      75  static void *
      76  thread_read_signal (void *closure)
      77  {
      78    xpthread_sigmask (SIG_UNBLOCK, &sigusr1_set, NULL);
      79    xpthread_barrier_wait (&barrier);
      80    TEST_VERIFY (target_tid > 0);
      81    TEST_VERIFY (gettid () != target_tid);
      82    char ch;
      83    ssize_t ret = read (pipe_signal[0], &ch, 1);
      84    if (ret == 1)
      85      /* The signal was delivered before we entered the read system
      86         call.  */
      87      TEST_COMPARE (ch, 'X');
      88    else
      89      {
      90        /* The signal was delivered while blocked in the read system
      91           call.  */
      92        TEST_COMPARE (ret, -1);
      93        TEST_COMPARE (errno, EINTR);
      94      }
      95    TEST_COMPARE (handler_tid, gettid ());
      96    return NULL;
      97  }
      98  
      99  static int
     100  do_test (void)
     101  {
     102    /* Block the SIGUSR1 signal in all threads.  */
     103    sigemptyset (&sigusr1_set);
     104    sigaddset (&sigusr1_set, SIGUSR1);
     105    xpthread_sigmask (SIG_BLOCK, &sigusr1_set, NULL);
     106  
     107    xsignal (SIGUSR1, sigusr1_handler);
     108    xpipe (pipe_signal);
     109  
     110    xpthread_barrier_init (&barrier, NULL, 3);
     111  
     112    pthread_t target_thread
     113      = xpthread_create (NULL, thread_pause_noreturn, NULL);
     114    signal_thread = xpthread_create (NULL, thread_read_signal, NULL);
     115    xpthread_barrier_wait (&barrier);
     116  
     117    /* Send the SIGUSR1 signal to the thread which has it blocked, and
     118       expect it to be delivered to the other thread.  */
     119    TEST_COMPARE (kill (target_tid, SIGUSR1), 0);
     120  
     121    xpthread_join (signal_thread);
     122    xpthread_cancel (target_thread);
     123    xpthread_join (target_thread);
     124  
     125    xpthread_barrier_destroy (&barrier);
     126    return 0;
     127  }
     128  
     129  #include <support/test-driver.c>