/*

 * Copyright 2022-2025 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

 */

#include <openssl/crypto.h>

#include "internal/e_os.h"

#include "internal/time.h"

/* system-specific variants defining OSSL_sleep() */

#if (defined(OPENSSL_SYS_UNIX) || defined(__DJGPP__)) && !defined(OPENSSL_USE_SLEEP_BUSYLOOP)

# if defined(OPENSSL_USE_USLEEP)                        \

    || defined(__DJGPP__)                               \

    || (defined(__TANDEM) && defined(_REENTRANT))

/*

 * usleep() was made obsolete by POSIX.1-2008, and nanosleep()

 * should be used instead.  However, nanosleep() isn't implemented

 * on the platforms given above, so we still use it for those.

 * Also, OPENSSL_USE_USLEEP can be defined to enable the use of

 * usleep, if it turns out that nanosleep() is unavailable.

 */

#  include <unistd.h>

static void ossl_sleep_millis(uint64_t millis)

{

    unsigned int s = (unsigned int)(millis / 1000);

    unsigned int us = (unsigned int)((millis % 1000) * 1000);

    if (s > 0)

        sleep(s);

    /*

     * On NonStop with the PUT thread model, thread context switch is

     * cooperative, with usleep() being a "natural" context switch point.

     * We avoid checking us > 0 here, to allow that context switch to

     * happen.

     */

    usleep(us);

}

# elif defined(__TANDEM) && !defined(_REENTRANT)

#  include <cextdecs.h(PROCESS_DELAY_)>

static void ossl_sleep_millis(uint64_t millis)

{

    /* HPNS does not support usleep for non threaded apps */

    PROCESS_DELAY_(millis * 1000);

}

# else

/* nanosleep is defined by POSIX.1-2001 */

#  include <time.h>

static void ossl_sleep_millis(uint64_t millis)

{

    struct timespec ts;

    ts.tv_sec = (long int) (millis / 1000);

    ts.tv_nsec = (long int) (millis % 1000) * 1000000ul;

    nanosleep(&ts, NULL);

}

# endif

#elif defined(_WIN32) && !defined(OPENSSL_SYS_UEFI)

# include <windows.h>

static void ossl_sleep_millis(uint64_t millis)

{

    /*

     * Windows' Sleep() takes a DWORD argument, which is smaller than

     * a uint64_t, so we need to limit it to 49 days, which should be enough.

     */

    DWORD limited_millis = (DWORD)-1;

    if (millis < limited_millis)

        limited_millis = (DWORD)millis;

    Sleep(limited_millis);

}

#else

/* Fallback to a busy wait */

# define USE_SLEEP_SECS

static void ossl_sleep_secs(uint64_t secs)

{

    /*

     * sleep() takes an unsigned int argument, which is smaller than

     * a uint64_t, so it needs to be limited to 136 years which

     * should be enough even for Sleeping Beauty.

     */

    unsigned int limited_secs = UINT_MAX;

    if (secs < limited_secs)

        limited_secs = (unsigned int)secs;

    sleep(limited_secs);

}

static void ossl_sleep_millis(uint64_t millis)

{

    const OSSL_TIME finish

        = ossl_time_add(ossl_time_now(), ossl_ms2time(millis));

    while (ossl_time_compare(ossl_time_now(), finish) < 0)

        /* busy wait */ ;

}

#endif /* defined(OPENSSL_SYS_UNIX) || defined(__DJGPP__) */

void OSSL_sleep(uint64_t millis)

{

    OSSL_TIME now = ossl_time_now();

    OSSL_TIME finish = ossl_time_add(now, ossl_ms2time(millis));

    uint64_t left = millis;

#if defined(USE_SLEEP_SECS)

    do {

        ossl_sleep_secs(left / 1000);

        now = ossl_time_now();

        left = ossl_time2ms(ossl_time_subtract(finish, now));

    } while (ossl_time_compare(now, finish) < 0 && left > 1000);

    if (ossl_time_compare(now, finish) >= 0)

        return;

#endif

    do {

        ossl_sleep_millis(left);

        now = ossl_time_now();

        left = ossl_time2ms(ossl_time_subtract(finish, now));

    } while (ossl_time_compare(now, finish) < 0);

}