1  /* Bug 18125: Verify setcontext calls exit() and not _exit().
       2     Copyright (C) 2015-2023 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 <errno.h>
      20  #include <signal.h>
      21  #include <stdio.h>
      22  #include <stdlib.h>
      23  #include <string.h>
      24  #include <ucontext.h>
      25  #include <unistd.h>
      26  #include <limits.h>
      27  #include <sys/types.h>
      28  #include <sys/stat.h>
      29  #include <fcntl.h>
      30  
      31  /* Please note that depending on the outcome of Bug 18135 this test
      32     may become invalid, and instead of testing for calling exit it
      33     should be reworked to test for the last context calling
      34     pthread_exit().  */
      35  
      36  static ucontext_t ctx;
      37  static char *filename;
      38  
      39  /* It is intended that this function does nothing.  */
      40  static void
      41  cf (void)
      42  {
      43    printf ("called context function\n");
      44  }
      45  
      46  static void
      47  exit_called (void)
      48  {
      49    int fd;
      50    ssize_t res;
      51    const char buf[] = "Called exit function\n";
      52  
      53    fd = open (filename, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
      54    if (fd == -1)
      55      {
      56        printf ("FAIL: Unable to create test file %s\n", filename);
      57        exit (1);
      58      }
      59    res = write (fd, buf, sizeof (buf));
      60    if (res != sizeof (buf))
      61      {
      62        printf ("FAIL: Expected to write test file in one write call.\n");
      63        exit (1);
      64      }
      65    res = close (fd);
      66    if (res == -1)
      67      {
      68        printf ("FAIL: Failed to close test file.\n");
      69        exit (1);
      70      }
      71    printf ("PASS: %s", buf);
      72  }
      73  
      74  /* The test expects a filename given by the wrapper calling script.
      75     The test then registers an atexit handler that will create the
      76     file to indicate that the atexit handler ran. Then the test
      77     creates a context, modifies it with makecontext, and sets it.
      78     The context has only a single context which then must exit.
      79     If it incorrectly exits via _exit then the atexit handler is
      80     not run, the file is not created, and the wrapper detects this
      81     and fails the test.  This test cannot be done using an _exit
      82     interposer since setcontext avoids the PLT and calls _exit
      83     directly.  */
      84  static int
      85  do_test (int argc, char **argv)
      86  {
      87    int ret;
      88    char st1[32768];
      89    ucontext_t tempctx = ctx;
      90  
      91    if (argc < 2)
      92      {
      93        printf ("FAIL: Test missing filename argument.\n");
      94        exit (1);
      95      }
      96  
      97    filename = argv[1];
      98  
      99    atexit (exit_called);
     100  
     101    puts ("making contexts");
     102    if (getcontext (&ctx) != 0)
     103      {
     104        if (errno == ENOSYS)
     105  	{
     106  	  /* Exit with 77 to mark the test as UNSUPPORTED.  */
     107  	  printf ("UNSUPPORTED: getcontext not implemented.\n");
     108  	  exit (77);
     109  	}
     110  
     111        printf ("FAIL: getcontext failed.\n");
     112        exit (1);
     113      }
     114  
     115    ctx.uc_stack.ss_sp = st1;
     116    ctx.uc_stack.ss_size = sizeof (st1);
     117    ctx.uc_link = 0;
     118    makecontext (&ctx, cf, 0);
     119  
     120    /* Without this check, a stub makecontext can make us spin forever.  */
     121    if (memcmp (&tempctx, &ctx, sizeof ctx) == 0)
     122      {
     123        puts ("UNSUPPORTED: makecontext was a no-op, presuming not implemented");
     124        exit (77);
     125      }
     126  
     127    ret = setcontext (&ctx);
     128    if (ret != 0)
     129      {
     130        printf ("FAIL: setcontext returned with %d and errno of %d.\n", ret, errno);
     131        exit (1);
     132      }
     133  
     134    printf ("FAIL: Impossibly returned to main.\n");
     135    exit (1);
     136  }
     137  
     138  #include "../test-skeleton.c"