ladybird/Userland/sleep.cpp
Sergey Bugaev 039e529dbe Userland: Fix a signal race condition
It has been possible for a signal to arrive in between us checking
g_interrupted and exiting - sucessfully, even though we were interrupted.

This way, if a signal arrives before we reset the disposition, we
will reliably check for it later; if it arrives afterwards, it'll
kill us automatically.
2020-09-10 16:00:11 +02:00

67 lines
2.3 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <LibCore/ArgsParser.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
static volatile bool g_interrupted;
static void handle_sigint(int)
{
g_interrupted = true;
}
int main(int argc, char** argv)
{
int secs;
Core::ArgsParser args_parser;
args_parser.add_positional_argument(secs, "Number of seconds to sleep for", "num-seconds");
args_parser.parse(argc, argv);
struct sigaction sa;
memset(&sa, 0, sizeof(struct sigaction));
sa.sa_handler = handle_sigint;
sigaction(SIGINT, &sa, nullptr);
if (pledge("stdio sigaction", nullptr) < 0) {
perror("pledge");
return 1;
}
unsigned remaining = sleep(secs);
if (remaining) {
printf("Sleep interrupted with %u seconds remaining.\n", remaining);
}
signal(SIGINT, SIG_DFL);
if (g_interrupted)
raise(SIGINT);
return 0;
}