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/* Tests of signal delivery on an alternate stack (_exit).
Copyright (C) 2019-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <support/xsignal.h>
#include <support/support.h>
#include <support/check.h>
#include <unistd.h>
/* C2011 7.4.1.1p5 specifies that only the following operations are
guaranteed to be well-defined inside an asynchronous signal handler:
* any operation on a lock-free atomic object
* assigning a value to an object declared as volatile sig_atomic_t
* calling abort, _Exit, quick_exit, or signal
* signal may only be called with its first argument equal to the
number of the signal that caused the handler to be called
We use this list as a guideline for the set of operations that ought
also to be safe in a _synchronous_ signal delivered on an alternate
signal stack with only MINSIGSTKSZ bytes of space.
This test program tests calls to _exit, which is the same function
as _Exit, but specified by POSIX rather than ISO C. For reasons
unknown to the author of this program, the C committee did not
think it could standardize _exit under that name; regardless, in a
POSIX-conformant environment, they should be completely
interchangeable. */
#define EXPECTED_STATUS 3
static void
handler (int unused)
{
_exit (EXPECTED_STATUS);
}
int
do_test (void)
{
void *sstk = xalloc_sigstack (0);
struct sigaction sa;
sa.sa_handler = handler;
sa.sa_flags = SA_RESTART | SA_ONSTACK;
sigfillset (&sa.sa_mask);
if (sigaction (SIGUSR1, &sa, 0))
FAIL_RET ("sigaction (SIGUSR1, handler): %m\n");
raise (SIGUSR1);
xfree_sigstack (sstk);
FAIL_RET ("test process was not terminated by _exit in signal handler");
}
#include <support/test-driver.c>
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