132 lines
4.0 KiB
C
132 lines
4.0 KiB
C
/* Tests of signal delivery on an alternate stack (nonlethal).
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Copyright (C) 2019 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <support/xsignal.h>
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#include <support/support.h>
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#include <support/check.h>
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/* C2011 7.4.1.1p5 specifies that only the following operations are
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guaranteed to be well-defined inside an asynchronous signal handler:
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* any operation on a lock-free atomic object
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* assigning a value to an object declared as volatile sig_atomic_t
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* calling abort, _Exit, quick_exit, or signal
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* signal may only be called with its first argument equal to the
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number of the signal that caused the handler to be called
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We use this list as a guideline for the set of operations that ought
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also to be safe in a _synchronous_ signal delivered on an alternate
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signal stack with only MINSIGSTKSZ bytes of space.
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This test program tests all of the above operations that do not,
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one way or another, cause the program to be terminated. */
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/* We do not try to test atomic operations exhaustively, only a simple
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atomic counter increment. This is only safe if atomic_[u]int is
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unconditionally lock-free. */
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#ifdef __STDC_NO_ATOMICS__
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# define TEST_ATOMIC_OPS 0
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#else
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# include <stdatomic.h>
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# if ATOMIC_INT_LOCK_FREE != 2
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# define TEST_ATOMIC_OPS 0
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# else
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# define TEST_ATOMIC_OPS 1
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# endif
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#endif
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static volatile sig_atomic_t signal_flag = 0;
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static volatile sig_atomic_t signal_err = 0;
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static void
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handler_set_flag (int unused)
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{
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signal_flag = 1;
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}
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static void
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handler_set_flag_once (int sig)
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{
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signal_flag = 1;
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if (signal (sig, SIG_IGN) == SIG_ERR)
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/* It is not safe to call FAIL_EXIT1 here. Set another flag instead. */
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signal_err = 1;
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}
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#if TEST_ATOMIC_OPS
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static atomic_uint signal_count = 0;
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static void
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handler_count_up_1 (int unused)
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{
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atomic_fetch_add (&signal_count, 1);
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}
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#endif
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int
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do_test (void)
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{
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void *sstk = xalloc_sigstack (0);
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struct sigaction sa;
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/* Test 1: setting a volatile sig_atomic_t flag. */
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sa.sa_handler = handler_set_flag;
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sa.sa_flags = SA_RESTART | SA_ONSTACK;
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sigfillset (&sa.sa_mask);
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if (sigaction (SIGUSR1, &sa, 0))
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FAIL_EXIT1 ("sigaction (SIGUSR1, handler_set_flag): %m\n");
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TEST_VERIFY_EXIT (signal_flag == 0);
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raise (SIGUSR1);
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TEST_VERIFY_EXIT (signal_flag == 1);
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signal_flag = 0;
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raise (SIGUSR1);
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TEST_VERIFY_EXIT (signal_flag == 1);
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signal_flag = 0;
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/* Test 1: setting a volatile sig_atomic_t flag and then ignoring
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further delivery of the signal. */
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sa.sa_handler = handler_set_flag_once;
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if (sigaction (SIGUSR1, &sa, 0))
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FAIL_EXIT1 ("sigaction (SIGUSR1, handler_set_flag_once): %m\n");
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raise (SIGUSR1);
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TEST_VERIFY_EXIT (signal_flag == 1);
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/* Note: if signal_err is 1, a system call failed, but we can't
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report the error code because errno is indeterminate. */
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TEST_VERIFY_EXIT (signal_err == 0);
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signal_flag = 0;
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raise (SIGUSR1);
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TEST_VERIFY_EXIT (signal_flag == 0);
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TEST_VERIFY_EXIT (signal_err == 0);
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#if TEST_ATOMIC_OPS
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sa.sa_handler = handler_count_up_1;
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if (sigaction (SIGUSR1, &sa, 0))
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FAIL_EXIT1 ("sigaction (SIGUSR1, handler_count_up_1): %m\n");
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raise (SIGUSR1);
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TEST_VERIFY_EXIT (atomic_load (&signal_count) == 1);
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raise (SIGUSR1);
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TEST_VERIFY_EXIT (atomic_load (&signal_count) == 2);
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#endif
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xfree_sigstack (sstk);
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return 0;
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}
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#include <support/test-driver.c>
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