minix/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  *   m_lsys_krn_sys_settime.now
   6  *   m_lsys_krn_sys_settime.clock_id
   7  *   m_lsys_krn_sys_settime.sec
   8  *   m_lsys_krn_sys_settime.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 boottime, timediff, timediff_ticks;
  23
  24   /* only realtime can change */
  25   if (m_ptr->m_lsys_krn_sys_settime.clock_id != CLOCK_REALTIME)
  26         return EINVAL;
  27
  28   /* user just wants to adjtime() */
  29   if (m_ptr->m_lsys_krn_sys_settime.now == 0) {
  30         /* convert delta value from seconds and nseconds to ticks */
  31         ticks = (m_ptr->m_lsys_krn_sys_settime.sec * system_hz) +
  32                 (m_ptr->m_lsys_krn_sys_settime.nsec/(1000000000/system_hz));
  33         set_adjtime_delta(ticks);
  34         return(OK);
  35   } /* else user wants to set the time */
  36
  37   boottime = get_boottime();
  38
  39   timediff = m_ptr->m_lsys_krn_sys_settime.sec - boottime;
  40   timediff_ticks = timediff * system_hz;
  41
  42   /* prevent a negative value for realtime */
  43   if (m_ptr->m_lsys_krn_sys_settime.sec <= boottime ||
  44       timediff_ticks < LONG_MIN/2 || timediff_ticks > LONG_MAX/2) {
  45         /* boottime was likely wrong, try to correct it. */
  46         set_boottime(m_ptr->m_lsys_krn_sys_settime.sec);
  47         set_realtime(1);
  48         return(OK);
  49   }
  50
  51   /* calculate the new value of realtime in ticks */
  52   newclock = timediff_ticks +
  53       (m_ptr->m_lsys_krn_sys_settime.nsec/(1000000000/system_hz));
  54
  55   set_realtime(newclock);
  56
  57   return(OK);
  58 }