BSD 3 development

[unix-history] / usr / src / cmd / renice.c

#include <sys/param.h>
#include <sys/proc.h>
#include <stdio.h>

struct  proc proc[NPROC];
struct  {
       char            name[8];
       int             type;
       unsigned        value;
} nl[] = {
       "_proc", 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/*
* Change the running priority (nice) of a process which is already
* running.
*
* Author: Kurt Shoens
*/

main(argc, argv)
       char **argv;
{
       register struct proc *pp;
       int pid, nice;
       int addr, mem, a1, a2, coreaddr;

       if (argc != 2 && argc != 3) {
               fprintf(stderr, "usage: renice pid [ priority ]\n");
               exit(1);
       }
       if (geteuid()) {
               fprintf(stderr, "NOT super user\n");
               exit(1);
       }
       pid = atoi(argv[1]);
       nice = atoi(argc == 3 ? argv[2] : "19");
       if (nice > 20)
               nice = 20;
       if (nice < -20)
               nice = -20;
       nice += NZERO;
       mem = open("/dev/kmem", 2);
       if (mem < 0) {
               perror("/dev/kmem");
               exit(1);
       }
       nlist("/vmunix", nl);
       addr = nl[0].value;
       if (addr == 0) {
               fprintf(stderr, "/vmunix: _proc not in namelist");
               exit(1);
       }
       lseek(mem, addr, 0);
       read(mem, &proc[0], sizeof proc);
       for (pp = &proc[0]; pp < &proc[NPROC]; pp++)
               if (pp->p_pid == pid)
                       break;
       if (pp >= &proc[NPROC]) {
               fprintf(stderr, "%d: process not found\n", pid);
               exit(1);
       }
       fprintf(stderr, "%d: old nice = %d, new nice = %d\n",
                       pid, 
                       pp->p_nice - NZERO,
                       nice - NZERO);
       a1 = (int)&pp->p_nice;
       a2 = (int)&proc[0];
       coreaddr = a1-a2+addr;
       lseek(mem, (long)coreaddr, 0);
       write(mem, &nice, 1);
}