tests/efault2.c

   1 /* Test that libsigsegv does not interfere with fault handling inside
   2    system calls.
   3    Copyright (C) 2009-2010  Eric Blake <ebb9@byu.net>
   4    Copyright (C) 2021  Bruno Haible <bruno@clisp.org>
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _MSC_VER
  20 # include <config.h>
  21 #endif
  22
  23 #include "sigsegv.h"
  24
  25 #if HAVE_STACK_OVERFLOW_RECOVERY && HAVE_EFAULT_SUPPORT
  26
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <unistd.h>
  32
  33 #include "altstack-util.h"
  34
  35 /* A NULL pointer.
  36    If we were to use a literal NULL, gcc would give a warning on glibc systems:
  37    "warning: null argument where non-null required".  */
  38 const char *null_pointer = NULL;
  39
  40 static void
  41 handler (int emergency, stackoverflow_context_t scp)
  42 {
  43   /* This test is only enabled when ENABLE_EFAULT is true.  If we get here,
  44      the ENABLE_EFAULT handling in libsigsegv is incomplete.  */
  45   abort ();
  46 }
  47
  48 int
  49 main ()
  50 {
  51   /* Test whether the OS handles some faults by itself.  */
  52   if (open (null_pointer, O_RDONLY) != -1 || errno != EFAULT)
  53     {
  54       fprintf (stderr, "EFAULT not detected alone.\n");
  55       exit (1);
  56     }
  57
  58   /* Prepare the storage for the alternate stack.  */
  59   prepare_alternate_stack ();
  60
  61   /* Install the stack overflow handler.  */
  62   if (stackoverflow_install_handler (&handler, mystack, SIGSTKSZ) < 0)
  63     exit (2);
  64
  65   /* Test that the library does not interfere with OS faults.  */
  66   if (open (null_pointer, O_RDONLY) != -1 || errno != EFAULT)
  67     {
  68       fprintf (stderr, "EFAULT not detected with handler.\n");
  69       exit (1);
  70     }
  71
  72   /* Validate that the alternate stack did not overflow.  */
  73   check_alternate_stack_no_overflow ();
  74
  75   /* Test passed!  */
  76   printf ("Test passed.\n");
  77   return 0;
  78 }
  79
  80 #else
  81
  82 int
  83 main ()
  84 {
  85   return 77;
  86 }
  87
  88 #endif