libc-bottom-half/cloudlibc/src/common/time.h

   1 // Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
   2 //
   3 // SPDX-License-Identifier: BSD-2-Clause
   4
   5 #ifndef COMMON_TIME_H
   6 #define COMMON_TIME_H
   7
   8 #include <common/limits.h>
   9
  10 #include <sys/time.h>
  11
  12 #include <wasi/api.h>
  13 #include <stdbool.h>
  14 #include <time.h>
  15
  16 #define NSEC_PER_SEC 1000000000
  17
  18 static inline bool timespec_to_timestamp_exact(
  19     const struct timespec *timespec, __wasi_timestamp_t *timestamp) {
  20   // Invalid nanoseconds field.
  21   if (timespec->tv_nsec < 0 || timespec->tv_nsec >= NSEC_PER_SEC)
  22     return false;
  23
  24   // Timestamps before the Epoch are not supported.
  25   if (timespec->tv_sec < 0)
  26     return false;
  27
  28   // Make sure our timestamp does not overflow.
  29   return !__builtin_mul_overflow(timespec->tv_sec, NSEC_PER_SEC, timestamp) &&
  30          !__builtin_add_overflow(*timestamp, timespec->tv_nsec, timestamp);
  31 }
  32
  33 static inline bool timespec_to_timestamp_clamp(
  34     const struct timespec *timespec, __wasi_timestamp_t *timestamp) {
  35   // Invalid nanoseconds field.
  36   if (timespec->tv_nsec < 0 || timespec->tv_nsec >= NSEC_PER_SEC)
  37     return false;
  38
  39   if (timespec->tv_sec < 0) {
  40     // Timestamps before the Epoch are not supported.
  41     *timestamp = 0;
  42   } else if (__builtin_mul_overflow(timespec->tv_sec, NSEC_PER_SEC, timestamp) ||
  43              __builtin_add_overflow(*timestamp, timespec->tv_nsec, timestamp)) {
  44     // Make sure our timestamp does not overflow.
  45     *timestamp = NUMERIC_MAX(__wasi_timestamp_t);
  46   }
  47   return true;
  48 }
  49
  50 static inline struct timespec timestamp_to_timespec(
  51     __wasi_timestamp_t timestamp) {
  52   // Decompose timestamp into seconds and nanoseconds.
  53   return (struct timespec){.tv_sec = timestamp / NSEC_PER_SEC,
  54                            .tv_nsec = timestamp % NSEC_PER_SEC};
  55 }
  56
  57 static inline struct timeval timestamp_to_timeval(
  58     __wasi_timestamp_t timestamp) {
  59   struct timespec ts = timestamp_to_timespec(timestamp);
  60   return (struct timeval){.tv_sec = ts.tv_sec, ts.tv_nsec / 1000};
  61 }
  62
  63 #endif