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****************************************************************************/

#include "qcore_unix_p.h"

#ifndef Q_OS_VXWORKS

#  include <sys/select.h>

#  include <sys/time.h>

#else

#  include <selectLib.h>

#endif

#include <stdlib.h>

#ifdef Q_OS_MAC

#include <mach/mach_time.h>

#endif

#if !defined(QT_NO_CLOCK_MONOTONIC)

# if defined(QT_BOOTSTRAPPED)

#  define QT_NO_CLOCK_MONOTONIC

# endif

#endif

QT_BEGIN_NAMESPACE

bool qt_gettime_is_monotonic()

{

#if (_POSIX_MONOTONIC_CLOCK-0 > 0) || defined(Q_OS_MAC)

    return true;

#else

    static int returnValue = 0;

    if (returnValue == 0) {

#  if (_POSIX_MONOTONIC_CLOCK-0 < 0)

        returnValue = -1;

#  elif (_POSIX_MONOTONIC_CLOCK == 0)

        // detect if the system support monotonic timers

        long x = sysconf(_SC_MONOTONIC_CLOCK);

        returnValue = (x >= 200112L) ? 1 : -1;

#  endif

    }

    return returnValue != -1;

#endif

}

timeval qt_gettime()

{

    timeval tv;

#if defined(Q_OS_MAC)

    static mach_timebase_info_data_t info = {0,0};

    if (info.denom == 0)

        mach_timebase_info(&info);

    uint64_t cpu_time = mach_absolute_time();

    uint64_t nsecs = cpu_time * (info.numer / info.denom);

    tv.tv_sec = nsecs / 1000000000ull;

    tv.tv_usec = (nsecs / 1000) - (tv.tv_sec * 1000000);

    return tv;

#elif (_POSIX_MONOTONIC_CLOCK-0 > 0)

    timespec ts;

    clock_gettime(CLOCK_MONOTONIC, &ts);

    tv.tv_sec = ts.tv_sec;

    tv.tv_usec = ts.tv_nsec / 1000;

    return tv;

#else

#  if !defined(QT_NO_CLOCK_MONOTONIC) && !defined(QT_BOOTSTRAPPED)

    if (qt_gettime_is_monotonic()) {

        timespec ts;

        clock_gettime(CLOCK_MONOTONIC, &ts);

        tv.tv_sec = ts.tv_sec;

        tv.tv_usec = ts.tv_nsec / 1000;

        return tv;

    }

#  endif

    // use gettimeofday

    ::gettimeofday(&tv, 0);

    return tv;

#endif

}

static inline bool time_update(struct timeval *tv, const struct timeval &start,

                               const struct timeval &timeout)

{

    if (!qt_gettime_is_monotonic()) {

        // we cannot recalculate the timeout without a monotonic clock as the time may have changed

        return false;

    }

    // clock source is monotonic, so we can recalculate how much timeout is left

    struct timeval now = qt_gettime();

    *tv = timeout + start - now;

}

int qt_safe_select(int nfds, fd_set *fdread, fd_set *fdwrite, fd_set *fdexcept,

                   const struct timeval *orig_timeout)

{

    if (!orig_timeout) {

        // no timeout -> block forever

        register int ret;

        EINTR_LOOP(ret, select(nfds, fdread, fdwrite, fdexcept, 0));

        return ret;

    }

    timeval start = qt_gettime();

    timeval timeout = *orig_timeout;

    // loop and recalculate the timeout as needed

    int ret;

    forever {

        ret = ::select(nfds, fdread, fdwrite, fdexcept, &timeout);

        if (ret != -1 || errno != EINTR)

            return ret;

        // recalculate the timeout

        if (!time_update(&timeout, start, *orig_timeout)) {

            return 0;

        }

    }

}

QT_END_NAMESPACE