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27d83441a2
The behavior of the signal mask on threads created by timer_create for SIGEV_THREAD timers are implementation-defined and glibc explicit unblocks all signals before calling the user-defined function. This behavior, although not incorrect standard-wise, opens a race if a program using a blocked rt-signal plus sigwaitinfo (and without an installed signal handler for the rt-signal) receives a signal while executing the used-defined function for SIGEV_THREAD. A better alternative discussed in bug report is to rather block all signals (besides the internal ones not available to application usage). This patch fixes this issue by only unblocking SIGSETXID (used on set*uid function) and SIGCANCEL (used for thread cancellation). Checked on x86_64-linux-gnu and i686-linux-gnu.
80 lines
2.1 KiB
C
80 lines
2.1 KiB
C
/* Check if the thread created by POSIX timer using SIGEV_THREAD is
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cancellable.
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Copyright (C) 2020 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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<https://www.gnu.org/licenses/>. */
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#include <stdio.h>
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#include <time.h>
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#include <signal.h>
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#include <unistd.h>
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#include <stdbool.h>
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#include <support/check.h>
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#include <support/test-driver.h>
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#include <support/xthread.h>
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static pthread_barrier_t barrier;
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static pthread_t timer_thread;
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static void
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cl (void *arg)
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{
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xpthread_barrier_wait (&barrier);
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}
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static void
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thread_handler (union sigval sv)
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{
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timer_thread = pthread_self ();
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xpthread_barrier_wait (&barrier);
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pthread_cleanup_push (cl, NULL);
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while (1)
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clock_nanosleep (CLOCK_REALTIME, 0, &(struct timespec) { 1, 0 }, NULL);
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pthread_cleanup_pop (0);
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}
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static int
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do_test (void)
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{
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struct sigevent sev = { 0 };
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sev.sigev_notify = SIGEV_THREAD;
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sev.sigev_notify_function = &thread_handler;
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timer_t timerid;
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TEST_COMPARE (timer_create (CLOCK_REALTIME, &sev, &timerid), 0);
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xpthread_barrier_init (&barrier, NULL, 2);
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struct itimerspec trigger = { 0 };
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trigger.it_value.tv_nsec = 1000000;
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TEST_COMPARE (timer_settime (timerid, 0, &trigger, NULL), 0);
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xpthread_barrier_wait (&barrier);
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xpthread_cancel (timer_thread);
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xpthread_barrier_init (&barrier, NULL, 2);
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xpthread_barrier_wait (&barrier);
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return 0;
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}
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/* A stall in cancellation is a regression. */
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#include <support/test-driver.c>
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