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     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

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    16 ** GNU Lesser General Public License Usage

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    18 ** General Public License version 2.1 as published by the Free Software

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    38 ** $QT_END_LICENSE$

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    40 ****************************************************************************/

    41 

    42 #include "qcore_unix_p.h"

    43 

    44 #ifndef Q_OS_VXWORKS

    45 #  include <sys/select.h>

    46 #  include <sys/time.h>

    47 #else

    48 #  include <selectLib.h>

    49 #endif

    50 

    51 #include <stdlib.h>

    52 

    53 #ifdef Q_OS_MAC

    54 #include <mach/mach_time.h>

    55 #endif

    56 

    57 #if !defined(QT_NO_CLOCK_MONOTONIC)

    58 # if defined(QT_BOOTSTRAPPED)

    59 #  define QT_NO_CLOCK_MONOTONIC

    60 # endif

    61 #endif

    62 

    63 QT_BEGIN_NAMESPACE

    64 

    65 bool qt_gettime_is_monotonic()

    66 {

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

    68     return true;

    69 #else

    70     static int returnValue = 0;

    71 

    72     if (returnValue == 0) {

    73 #  if (_POSIX_MONOTONIC_CLOCK-0 < 0)

    74         returnValue = -1;

    75 #  elif (_POSIX_MONOTONIC_CLOCK == 0)

    76         // detect if the system support monotonic timers

    77         long x = sysconf(_SC_MONOTONIC_CLOCK);

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

    79 #  endif

    80     }

    81 

    82     return returnValue != -1;

    83 #endif

    84 }

    85 

    86 timeval qt_gettime()

    87 {

    88     timeval tv;

    89 #if defined(Q_OS_MAC)

    90     static mach_timebase_info_data_t info = {0,0};

    91     if (info.denom == 0)

    92         mach_timebase_info(&info);

    93 

    94     uint64_t cpu_time = mach_absolute_time();

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

    96     tv.tv_sec = nsecs / 1000000000ull;

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

    98     return tv;

    99 #elif (_POSIX_MONOTONIC_CLOCK-0 > 0)

   100     timespec ts;

   101     clock_gettime(CLOCK_MONOTONIC, &ts);

   102     tv.tv_sec = ts.tv_sec;

   103     tv.tv_usec = ts.tv_nsec / 1000;

   104     return tv;

   105 #else

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

   107     if (qt_gettime_is_monotonic()) {

   108         timespec ts;

   109         clock_gettime(CLOCK_MONOTONIC, &ts);

   110         tv.tv_sec = ts.tv_sec;

   111         tv.tv_usec = ts.tv_nsec / 1000;

   112         return tv;

   113     }

   114 #  endif

   115     // use gettimeofday

   116     ::gettimeofday(&tv, 0);

   117     return tv;

   118 #endif

   119 }

   120 

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

   122                                const struct timeval &timeout)

   123 {

   124     if (!qt_gettime_is_monotonic()) {

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

   126         return false;

   127     }

   128 

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

   130     struct timeval now = qt_gettime();

   131     *tv = timeout + start - now;

   132     return true;

   133 }

   134 

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

   136                    const struct timeval *orig_timeout)

   137 {

   138     if (!orig_timeout) {

   139         // no timeout -> block forever

   140         register int ret;

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

   142         return ret;

   143     }

   144 

   145     timeval start = qt_gettime();

   146     timeval timeout = *orig_timeout;

   147 

   148     // loop and recalculate the timeout as needed

   149     int ret;

   150     forever {

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

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

   153             return ret;

   154 

   155         // recalculate the timeout

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

   157             // clock reset, fake timeout error

   158             return 0;

   159         }

   160     }

   161 }

   162 

   163 QT_END_NAMESPACE