openssl/include/internal/time.h

/*
 * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#ifndef OSSL_INTERNAL_TIME_H
# define OSSL_INTERNAL_TIME_H
# pragma once

# include <openssl/e_os2.h>     /* uint64_t */
# include "internal/e_os.h"     /* for struct timeval */
# include "internal/safe_math.h"

/* The precision of times allows this many values per second */
# define OSSL_TIME_SECOND ((uint64_t)1000000000)

/* One millisecond. */
# define OSSL_TIME_MS     (OSSL_TIME_SECOND / 1000)

/* One microsecond. */
# define OSSL_TIME_US     (OSSL_TIME_MS     / 1000)

/* Macro representing the most distant future time */
# define OSSL_TIME_INFINITY (~(OSSL_TIME)0)

/* Macro that's guaranteed to be now or before */
# define OSSL_TIME_IMMEDIATE    0

/* Macro representing the zero value */
# define OSSL_TIME_ZERO         0

/*
 * Internal type defining a time.
 * The time datum is Unix's 1970 and at nanosecond precision, this gives
 * a range of 584 years roughly.
 */
typedef uint64_t OSSL_TIME;

/* Get current time */
OSSL_TIME ossl_time_now(void);

/* Convert time to timeval */
static ossl_unused ossl_inline
void ossl_time_time_to_timeval(OSSL_TIME t, struct timeval *out)
{
#ifdef _WIN32
    out->tv_sec = (long int)(t / OSSL_TIME_SECOND);
#else
    out->tv_sec = (time_t)(t / OSSL_TIME_SECOND);
#endif
    out->tv_usec = (t % OSSL_TIME_SECOND) / (OSSL_TIME_SECOND / 1000000);
}

/* Compare two time values, return -1 if less, 1 if greater and 0 if equal */
static ossl_unused ossl_inline
int ossl_time_compare(OSSL_TIME a, OSSL_TIME b)
{
    if (a > b)
        return 1;
    if (a < b)
        return -1;
    return 0;
}

/*
 * Arithmetic operations on times.
 * These operations are saturating, in that an overflow or underflow returns
 * the largest or smallest value respectively.
 */
OSSL_SAFE_MATH_UNSIGNED(time, OSSL_TIME)

static ossl_unused ossl_inline
OSSL_TIME ossl_time_add(OSSL_TIME a, OSSL_TIME b)
{
    OSSL_TIME r;
    int err = 0;

    r = safe_add_time(a, b, &err);
    return err ? OSSL_TIME_INFINITY : r;
}

static ossl_unused ossl_inline
OSSL_TIME ossl_time_subtract(OSSL_TIME a, OSSL_TIME b)
{
    OSSL_TIME r;
    int err = 0;

    r = safe_sub_time(a, b, &err);
    return err ? 0 : r;
}

/* Returns |a - b|. */
static ossl_unused ossl_inline
OSSL_TIME ossl_time_abs_difference(OSSL_TIME a, OSSL_TIME b)
{
    return a > b ? ossl_time_subtract(a, b) : ossl_time_subtract(b, a);
}

static ossl_unused ossl_inline
OSSL_TIME ossl_time_multiply(OSSL_TIME a, uint64_t b)
{
    OSSL_TIME r;
    int err = 0;

    r = safe_mul_time(a, b, &err);
    return err ? OSSL_TIME_INFINITY : r;
}

static ossl_unused ossl_inline
OSSL_TIME ossl_time_divide(OSSL_TIME a, uint64_t b)
{
    OSSL_TIME r;
    int err = 0;

    r = safe_div_time(a, b, &err);
    return err ? 0 : r;
}

/* Return higher of the two given time values. */
static ossl_unused ossl_inline
OSSL_TIME ossl_time_max(OSSL_TIME a, OSSL_TIME b)
{
    return a > b ? a : b;
}

/* Return the lower of the two given time values. */
static ossl_unused ossl_inline
OSSL_TIME ossl_time_min(OSSL_TIME a, OSSL_TIME b)
{
    return a < b ? a : b;
}

#endif