#include "cctk.h"
#include "cctk_WarnLevel.h"
#include "cctk_Arguments.h"
#include "cctk_Parameters.h"

/* manpage of getpriority:
   Including  <sys/time.h>  is  not  required  these days,
   but increases portability.
*/
#include <sys/time.h>
#include <errno.h>
#include <sys/resource.h>

int Nice_Renice(void);
int Nice_Renice(void)
{
    DECLARE_CCTK_PARAMETERS

    int old_nice, new_nice, nice_return_value;

    /* reset error variable */
    errno=0;
    /* save the old nice value */
    old_nice=getpriority(PRIO_PROCESS, 0);
    /* check errno */
    if (errno)
    {
        switch (errno)
        {
          case ESRCH  : /* this should never occur, since the 0 in getpriority
                           means this process, which should be found
                        */
                        CCTK_INFO("getpriority received ESTCH-error.");
                        break;
          case EINVAL : /* this should definitly not occur */
                        CCTK_INFO("getpriority received EINVAL-error.");
                        break;
          case EPERM  : /* this should never occur
                           It means, that the user of process did not match the
                           callers user */
                        CCTK_INFO("getpriority received EPERM-error.");
                        break;
          case EACCES : /* This cannot occur: non root user attemted to lower
                           priority (since we did not call setpriority here */
                        CCTK_INFO("getpriority received EACCES-error.");
                        break;
          default:      /* This should not occur, otherwise it is an
                           undocumented errno */
                        CCTK_VInfo(CCTK_THORNSTRING,
                                   "getpriority got undocumented errno %d",
                                   errno);
        }
        CCTK_WARN(0, "This should never occur.");
    }

    errno=0;
    /* try to set the new priority */
    nice_return_value=setpriority(PRIO_PROCESS, 0, Nice_nice);
    /* check return value */
    if (nice_return_value!=0)
    {
        switch (errno)
        {
          case ESRCH  : /* this should never occur, since the 0 in setpriority
                           means this process, which should be found
                        */
                        CCTK_INFO("setpriority received ESTCH-error.");
                        CCTK_WARN(0, "This should never occur.");
                        break;
          case EINVAL : /* this should definitly not occur */
                        CCTK_INFO("setpriority received EINVAL-error.");
                        CCTK_WARN(0, "This should never occur.");
                        break;
          case EPERM  : /* this should never occur
                           It means, that the user of process did not match the
                           callers user */
                        CCTK_INFO("setpriority received EPERM-error.");
                        CCTK_WARN(0, "This should never occur.");
                        break;
          case EACCES : /* This can occur: non root user attemted to lower
                           priority
                        */
                        CCTK_WARN(0, "Only root can lower priorities.");
                        break;
          default:      /* This should not occur, otherwise it is an
                           undocumented errno */
                        CCTK_VInfo(CCTK_THORNSTRING,
                                   "setpriority got undocumented errno %d",
                                   errno);
        }
        CCTK_WARN(0, "This should never occur.");
    }

    errno=0;
    /* It should ok, but check the new priority */
    new_nice=getpriority(PRIO_PROCESS, 0);
    /* check errno */
    if (errno)
    {
        switch (errno)
        {
          case ESRCH  : /* this should never occur, since the 0 in getpriority
                           means this process, which should be found */
                        CCTK_INFO("getpriority received ESTCH-error.");
                        break;
          case EINVAL : /* this should definitly not occur */
                        CCTK_INFO("getpriority received EINVAL-error.");
                        break;
          case EPERM  : /* this should never occur
                           It means, that the user of process did not match the
                           callers user */
                        CCTK_INFO("getpriority received EPERM-error.");
                        break;
          case EACCES : /* This cannot occur: non root user attemted to lower
                           priority (since we did not call setpriority here
                        */
                        CCTK_INFO("getpriority received EACCES-error.");
                        break;
          default:      /* This should not occur, otherwise it is an
                           undocumented errno */
                        CCTK_VInfo(CCTK_THORNSTRING,
                                   "getpriority got undocumented errno %d",
                                   errno);
        }
        CCTK_WARN(0, "This should never occur.");
    }

    if (new_nice == Nice_nice)
    {
        CCTK_VInfo(CCTK_THORNSTRING,"Process reniced from nice level %d to %d.",
                                    old_nice, new_nice);
    }
    else
    {
        /* this should never occur because of the error handling before */
        CCTK_VInfo(CCTK_THORNSTRING,
                   "Process reniced to nice level %d instead of %d.",
                   new_nice, Nice_nice);
    }

    return 0;
}