kernel/system/do_settime.c

   1 /* The kernel call implemented in this file:
   2  *   m_type:    SYS_SETTIME
   3  *
   4  * The parameters for this kernel call are:
   5  *    m4_l2:    T_SETTIME_NOW
   6  *    m4_l3:    T_CLOCK_ID
   7  *    m4_ll1:   T_TIME_SEC
   8  *    m4_l5:    T_TIME_NSEC
   9  */
  10
  11 #include "kernel/system.h"
  12 #include <minix/endpoint.h>
  13 #include <time.h>
  14
  15 /*===========================================================================*
  16  *                              do_settime                                   *
  17  *===========================================================================*/
  18 int do_settime(struct proc * caller, message * m_ptr)
  19 {
  20   clock_t newclock;
  21   int32_t ticks;
  22   time_t timediff, timediff_ticks;
  23
  24   if (m_ptr->T_CLOCK_ID != CLOCK_REALTIME) /* only realtime can change */
  25         return EINVAL;
  26
  27   if (m_ptr->T_SETTIME_NOW == 0) { /* user just wants to adjtime() */
  28         /* convert delta value from seconds and nseconds to ticks */
  29         ticks = (m_ptr->T_TIME_SEC * system_hz) +
  30                                 (m_ptr->T_TIME_NSEC/(1000000000/system_hz));
  31         set_adjtime_delta(ticks);
  32         return(OK);
  33   } /* else user wants to set the time */
  34
  35   timediff = m_ptr->T_TIME_SEC - boottime;
  36   timediff_ticks = timediff * system_hz;
  37
  38   /* prevent a negative value for realtime */
  39   if (m_ptr->T_TIME_SEC <= boottime ||
  40       timediff_ticks < LONG_MIN/2 || timediff_ticks > LONG_MAX/2) {
  41         /* boottime was likely wrong, try to correct it. */
  42         boottime = m_ptr->T_TIME_SEC;
  43         set_realtime(1);
  44         return(OK);
  45   }
  46
  47   /* calculate the new value of realtime in ticks */
  48   newclock = timediff_ticks + (m_ptr->T_TIME_NSEC/(1000000000/system_hz));
  49
  50   set_realtime(newclock);
  51
  52   return(OK);
  53 }