1  /* Test the stack guard.
       2     Copyright (C) 2000-2023 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  #define _GNU_SOURCE
      20  
      21  #include <pthread.h>
      22  #include <assert.h>
      23  #include <unistd.h>
      24  #include <errno.h>
      25  #include <string.h>
      26  #include <stdio.h>
      27  
      28  size_t stacksize;
      29  
      30  void *
      31  thr (void *arg)
      32  {
      33    int i;
      34    char *foo;
      35  
      36    foo = alloca (3 * stacksize / 4);
      37    for (i = 0; i < sizeof foo; i++)
      38      foo[i] = -1;
      39  
      40    return (void *) 1;
      41  }
      42  
      43  int
      44  main (int argc, char *argv[])
      45  {
      46    error_t err;
      47    pid_t child;
      48  
      49    child = fork ();
      50    switch (child)
      51      {
      52      case -1:
      53        error (1, errno, "fork");
      54        break;
      55  
      56      case 0:
      57        {
      58  	pthread_attr_t attr;
      59  	pthread_t tid;
      60  	void *ret;
      61  
      62  	err = pthread_attr_init (&attr);
      63  	assert_perror (err);
      64  
      65  	err = pthread_attr_getstacksize (&attr, &stacksize);
      66  	assert_perror (err);
      67  
      68  	err = pthread_attr_setguardsize (&attr, stacksize / 2);
      69  	if (err == ENOTSUP)
      70  	  {
      71  	    printf ("Stack guard attribute not supported.\n");
      72  	    return 1;
      73  	  }
      74  	assert_perror (err);
      75  
      76  	err = pthread_create (&tid, &attr, thr, 0);
      77  	assert_perror (err);
      78  
      79  	err = pthread_attr_destroy (&attr);
      80  	assert_perror (err);
      81  
      82  	err = pthread_join (tid, &ret);
      83  	/* Should never be successful.  */
      84  	printf ("Thread did not segfault!?!\n");
      85  	assert_perror (err);
      86  	return 0;
      87        }
      88  
      89      default:
      90        {
      91  	pid_t pid;
      92  	int status;
      93  
      94  	pid = waitpid (child, &status, 0);
      95  	printf ("pid = %d; child = %d; status = %d\n", pid, child, status);
      96  	assert (pid == child);
      97  	assert (status != 0);
      98        }
      99      }
     100  
     101    return 0;
     102  }