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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#include <Kernel/Process.h>
8#include <Kernel/Time/TimeManagement.h>
9#include <Kernel/TimerQueue.h>
10
11namespace Kernel {
12
13ErrorOr<FlatPtr> Process::sys$alarm(unsigned seconds)
14{
15 VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
16 TRY(require_promise(Pledge::stdio));
17 unsigned previous_alarm_remaining = 0;
18 if (m_alarm_timer) {
19 bool was_in_use = false;
20 if (TimerQueue::the().cancel_timer(*m_alarm_timer, &was_in_use)) {
21 // The timer hasn't fired. Round up the remaining time (if any)
22 Time remaining = m_alarm_timer->remaining() + Time::from_nanoseconds(999'999'999);
23 previous_alarm_remaining = remaining.to_truncated_seconds();
24 }
25 // We had an existing alarm, must return a non-zero value here!
26 if (was_in_use && previous_alarm_remaining == 0)
27 previous_alarm_remaining = 1;
28 }
29
30 if (seconds > 0) {
31 auto deadline = TimeManagement::the().current_time(CLOCK_REALTIME_COARSE);
32 deadline = deadline + Time::from_seconds(seconds);
33 if (!m_alarm_timer) {
34 m_alarm_timer = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) Timer));
35 }
36 auto timer_was_added = TimerQueue::the().add_timer_without_id(*m_alarm_timer, CLOCK_REALTIME_COARSE, deadline, [this]() {
37 MUST(send_signal(SIGALRM, nullptr));
38 });
39 if (!timer_was_added)
40 return ENOMEM;
41 }
42 return previous_alarm_remaining;
43}
44
45}