/* getrusage replacement for systems which lack it.

   Copyright (C) 2012-2013 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible, 2012.  */

#include <config.h>

/* Specification.  */
#include <sys/resource.h>

#include <errno.h>
#include <string.h>

/* Get uint64_t.  */
#include <stdint.h>

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__

# define WIN32_LEAN_AND_MEAN
# include <windows.h>

#else

# include <sys/times.h>
# include <unistd.h>
#endif

int
getrusage (int who, struct rusage *usage_p)
{
  if (who == RUSAGE_SELF || who == RUSAGE_CHILDREN)
    {
      /* Clear all unsupported members of 'struct rusage'.  */
      memset (usage_p, '\0', sizeof (struct rusage));

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
      if (who == RUSAGE_SELF)
        {
          /* Fill in the ru_utime and ru_stime members.  */
          FILETIME creation_time;
          FILETIME exit_time;
          FILETIME kernel_time;
          FILETIME user_time;

          if (GetProcessTimes (GetCurrentProcess (),
                               &creation_time, &exit_time,
                               &kernel_time, &user_time))
            {
              /* Convert to microseconds, rounding.  */
              uint64_t kernel_usec =
                ((((uint64_t) kernel_time.dwHighDateTime << 32)
                  | (uint64_t) kernel_time.dwLowDateTime)
                 + 5) / 10;
              uint64_t user_usec =
                ((((uint64_t) user_time.dwHighDateTime << 32)
                  | (uint64_t) user_time.dwLowDateTime)
                 + 5) / 10;

              usage_p->ru_utime.tv_sec = user_usec / 1000000U;
              usage_p->ru_utime.tv_usec = user_usec % 1000000U;
              usage_p->ru_stime.tv_sec = kernel_usec / 1000000U;
              usage_p->ru_stime.tv_usec = kernel_usec % 1000000U;
            }
        }
#else
      /* Fill in the ru_utime and ru_stime members.  */
      {
        struct tms time;

        if (times (&time) != (clock_t) -1)
          {
            /* Number of clock ticks per second.  */
            unsigned int clocks_per_second = sysconf (_SC_CLK_TCK);

            if (clocks_per_second > 0)
              {
                clock_t user_ticks;
                clock_t system_ticks;

                uint64_t user_usec;
                uint64_t system_usec;

                if (who == RUSAGE_CHILDREN)
                  {
                    user_ticks   = time.tms_cutime;
                    system_ticks = time.tms_cstime;
                  }
                else
                  {
                    user_ticks   = time.tms_utime;
                    system_ticks = time.tms_stime;
                  }

                user_usec =
                  (((uint64_t) user_ticks * (uint64_t) 1000000U)
                   + clocks_per_second / 2) / clocks_per_second;
                system_usec =
                  (((uint64_t) system_ticks * (uint64_t) 1000000U)
                   + clocks_per_second / 2) / clocks_per_second;

                usage_p->ru_utime.tv_sec = user_usec / 1000000U;
                usage_p->ru_utime.tv_usec = user_usec % 1000000U;
                usage_p->ru_stime.tv_sec = system_usec / 1000000U;
                usage_p->ru_stime.tv_usec = system_usec % 1000000U;
              }
          }
      }
#endif

      return 0;
    }
  else
    {
      errno = EINVAL;
      return -1;
    }
}