jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * Copyright (c) 2022, Alex Major
4 *
5 * SPDX-License-Identifier: BSD-2-Clause
6 */
7
8#include <LibCore/ArgsParser.h>
9#include <LibCore/System.h>
10#include <LibMain/Main.h>
11#include <errno.h>
12#include <signal.h>
13#include <stdio.h>
14#include <string.h>
15#include <time.h>
16#include <unistd.h>
17
18static bool volatile g_interrupted;
19static void handle_sigint(int)
20{
21 g_interrupted = true;
22}
23
24ErrorOr<int> serenity_main(Main::Arguments arguments)
25{
26 double secs;
27
28 Core::ArgsParser args_parser;
29 args_parser.add_positional_argument(secs, "Number of seconds to sleep for", "num-seconds");
30 args_parser.parse(arguments);
31
32 struct sigaction sa;
33 memset(&sa, 0, sizeof(struct sigaction));
34 sa.sa_handler = handle_sigint;
35 sigaction(SIGINT, &sa, nullptr);
36
37 TRY(Core::System::pledge("stdio sigaction"));
38
39 double whole_seconds = static_cast<time_t>(secs);
40 double fraction = secs - whole_seconds;
41
42 timespec requested_sleep {
43 .tv_sec = static_cast<time_t>(whole_seconds),
44 .tv_nsec = static_cast<long>(fraction * (double)1000000000),
45 };
46
47 timespec remaining_sleep {};
48
49sleep_again:
50 if (clock_nanosleep(CLOCK_MONOTONIC, 0, &requested_sleep, &remaining_sleep) < 0) {
51 if (errno != EINTR) {
52 perror("clock_nanosleep");
53 return 1;
54 }
55 }
56
57 if (remaining_sleep.tv_sec || remaining_sleep.tv_nsec) {
58 if (!g_interrupted) {
59 // If not interrupted with SIGINT, just go back to sleep.
60 requested_sleep = remaining_sleep;
61 goto sleep_again;
62 }
63 outln("Sleep interrupted with {}.{} seconds remaining.", remaining_sleep.tv_sec, remaining_sleep.tv_nsec);
64 }
65
66 TRY(Core::System::signal(SIGINT, SIG_DFL));
67 if (g_interrupted)
68 raise(SIGINT);
69
70 return 0;
71}