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1/* Tests of signal delivery on an alternate stack (_exit).
2 Copyright (C) 2019 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 <http://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
45static void
46handler (int unused)
47{
48 _exit (EXPECTED_STATUS);
49}
50
51int
52do_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>
70

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