/* $Id: elevate.c 4233 2012-02-04 01:01:58Z flaterco $ */
/* Elevate a process to realtime priority. */

/* This has to be suid root to work. */

/* gcc -O2 -Wall -Wextra -pedantic -s -o elevate elevate.c */
/* chown root. elevate */
/* chmod 4755 elevate */

#include <sched.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>

int main (int argc, char **argv) {
  struct sched_param sp;
  pid_t pid;
  if (argc != 2 || sscanf (argv[1], "%d", &pid) != 1) {
    fprintf (stderr, "Usage: elevate pid\n");
    return EXIT_FAILURE;
  }
  sp.sched_priority = sched_get_priority_min(SCHED_FIFO);
  if (sched_setscheduler (pid, SCHED_FIFO, &sp)) {
    perror ("elevate");
    return EXIT_FAILURE;
  }
  return EXIT_SUCCESS;
}