signal/tst-minsigstksz-5.c

   1 /* Test of signal delivery on an alternate stack with MINSIGSTKSZ size.
   2    Copyright (C) 2020-2023 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 <signal.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <support/check.h>
  24 #include <support/support.h>
  25
  26 static volatile sig_atomic_t handler_run;
  27
  28 static void
  29 handler (int signo)
  30 {
  31   /* Clear a bit of on-stack memory.  */
  32   volatile char buffer[256];
  33   for (size_t i = 0; i < sizeof (buffer); ++i)
  34     buffer[i] = 0;
  35   handler_run = 1;
  36 }
  37
  38 int
  39 do_test (void)
  40 {
  41   size_t stack_buffer_size = 64 * 1024 * 1024;
  42   void *stack_buffer = xmalloc (stack_buffer_size);
  43   void *stack_end = stack_buffer + stack_buffer_size;
  44   memset (stack_buffer, 0xCC, stack_buffer_size);
  45
  46   void *stack_bottom = stack_buffer + (stack_buffer_size + MINSIGSTKSZ) / 2;
  47   void *stack_top = stack_bottom + MINSIGSTKSZ;
  48   stack_t stack =
  49     {
  50       .ss_sp = stack_bottom,
  51       .ss_size = MINSIGSTKSZ,
  52     };
  53   if (sigaltstack (&stack, NULL) < 0)
  54     FAIL_RET ("sigaltstack: %m\n");
  55
  56   struct sigaction act =
  57     {
  58       .sa_handler = handler,
  59       .sa_flags = SA_ONSTACK,
  60     };
  61   if (sigaction (SIGUSR1, &act, NULL) < 0)
  62     FAIL_RET ("sigaction: %m\n");
  63
  64   if (kill (getpid (), SIGUSR1) < 0)
  65     FAIL_RET ("kill: %m\n");
  66
  67   if (handler_run != 1)
  68     FAIL_RET ("handler did not run\n");
  69
  70   for (void *p = stack_buffer; p < stack_bottom; ++p)
  71     if (*(unsigned char *) p != 0xCC)
  72       FAIL_RET ("changed byte %ld bytes below configured stack\n",
  73                 (long) (stack_bottom - p));
  74   for (void *p = stack_top; p < stack_end; ++p)
  75     if (*(unsigned char *) p != 0xCC)
  76       FAIL_RET ("changed byte %ld bytes above configured stack\n",
  77                 (long) (p - stack_top));
  78
  79   free (stack_buffer);
  80
  81   return 0;
  82 }
  83
  84 #include <support/test-driver.c>