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1//===--- Linux absolute timeout ---------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_LIBC_SRC___SUPPORT_TIME_LINUX_ABS_TIMEOUT_H
10#define LLVM_LIBC_SRC___SUPPORT_TIME_LINUX_ABS_TIMEOUT_H
11
12#include "hdr/time_macros.h"
13#include "hdr/types/struct_timespec.h"
14#include "src/__support/CPP/expected.h"
15#include "src/__support/macros/config.h"
16#include "src/__support/time/units.h"
17
18namespace LIBC_NAMESPACE_DECL {
19namespace internal {
20// We use AbsTimeout to remind ourselves that the timeout is an absolute time.
21// This is a simple wrapper around the timespec struct that also keeps track of
22// whether the time is in realtime or monotonic time.
23class AbsTimeout {
24 timespec timeout;
25 bool realtime_flag;
26 LIBC_INLINE constexpr explicit AbsTimeout(timespec ts, bool realtime)
27 : timeout(ts), realtime_flag(realtime) {}
28
29public:
30 enum class Error { Invalid, BeforeEpoch };
31 LIBC_INLINE const timespec &get_timespec() const { return timeout; }
32 LIBC_INLINE bool is_realtime() const { return realtime_flag; }
33 LIBC_INLINE static constexpr cpp::expected<AbsTimeout, Error>
34 from_timespec(timespec ts, bool realtime) {
35 using namespace time_units;
36 if (ts.tv_nsec < 0 || ts.tv_nsec >= 1_s_ns)
37 return cpp::unexpected(Error::Invalid);
38
39 // POSIX allows tv_sec to be negative. We interpret this as an expired
40 // timeout.
41 if (ts.tv_sec < 0)
42 return cpp::unexpected(Error::BeforeEpoch);
43
44 return AbsTimeout{ts, realtime};
45 }
46};
47} // namespace internal
48} // namespace LIBC_NAMESPACE_DECL
49
50#endif // LLVM_LIBC_SRC___SUPPORT_TIME_LINUX_ABS_TIMEOUT_H
51

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source code of libc/src/__support/time/linux/abs_timeout.h