BSD 4_1c_2 release

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

static  char *sccsid = "@(#)renice.c    4.3 (Berkeley) 81/03/11";
#include <sys/param.h>
#include <sys/dir.h>
#include <sys/user.h>
#include <sys/proc.h>
#include <nlist.h>
#include <stdio.h>

struct  proc *proc;
struct nlist nl[] = {
       {"_proc"},
       { "_nproc" },
       {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, *pend;
       int pid, nice, nproc;
       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);
       if ((addr = nl[1].n_value) == 0) {
               fprintf(stderr, "/vmunix: _nproc not in namelist");
               exit(1);
       }
       lseek(mem, addr, 0);
       read(mem, &nproc, sizeof nproc);
       proc = (struct proc *) calloc(nproc, sizeof *proc);
       addr = nl[0].n_value;
       if (addr == 0) {
               fprintf(stderr, "/vmunix: _proc not in namelist");
               exit(1);
       }
       lseek(mem, addr, 0);
       read(mem, &addr, sizeof addr);
       lseek(mem, addr, 0);
       read(mem, proc, nproc * (sizeof *proc));
       pend = proc+nproc;
       for (pp = proc; pp < pend; pp++)
               if (pp->p_pid == pid)
                       break;
       if (pp >= pend) {
               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;
       coreaddr = a1-a2+addr;
       lseek(mem, (long)coreaddr, 0);
       write(mem, &nice, sizeof pp->p_nice);
}