signal/tst-minsigstksz-3a.c

   1 /* Tests of signal delivery on an alternate stack (_exit).
   2    Copyright (C) 2019-2020 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 <support/xsignal.h>
  20 #include <support/support.h>
  21 #include <support/check.h>
  22 #include <unistd.h>
  23
  24 /* C2011 7.4.1.1p5 specifies that only the following operations are
  25    guaranteed to be well-defined inside an asynchronous signal handler:
  26      * any operation on a lock-free atomic object
  27      * assigning a value to an object declared as volatile sig_atomic_t
  28      * calling abort, _Exit, quick_exit, or signal
  29        * signal may only be called with its first argument equal to the
  30          number of the signal that caused the handler to be called
  31
  32    We use this list as a guideline for the set of operations that ought
  33    also to be safe in a _synchronous_ signal delivered on an alternate
  34    signal stack with only MINSIGSTKSZ bytes of space.
  35
  36    This test program tests calls to _exit, which is the same function
  37    as _Exit, but specified by POSIX rather than ISO C.  For reasons
  38    unknown to the author of this program, the C committee did not
  39    think it could standardize _exit under that name; regardless, in a
  40    POSIX-conformant environment, they should be completely
  41    interchangeable.  */
  42
  43 #define EXPECTED_STATUS 3
  44
  45 static void
  46 handler (int unused)
  47 {
  48   _exit (EXPECTED_STATUS);
  49 }
  50
  51 int
  52 do_test (void)
  53 {
  54   void *sstk = xalloc_sigstack (0);
  55   struct sigaction sa;
  56
  57   sa.sa_handler = handler;
  58   sa.sa_flags   = SA_RESTART | SA_ONSTACK;
  59   sigfillset (&sa.sa_mask);
  60   if (sigaction (SIGUSR1, &sa, 0))
  61     FAIL_RET ("sigaction (SIGUSR1, handler): %m\n");
  62
  63   raise (SIGUSR1);
  64
  65   xfree_sigstack (sstk);
  66   FAIL_RET ("test process was not terminated by _exit in signal handler");
  67 }
  68
  69 #include <support/test-driver.c>