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Annotation of 41BSD/cmd/renice.c, revision 1.1.1.1

1.1       root        1: static char *sccsid = "@(#)renice.c    4.1 (Berkeley) 10/1/80";
                      2: #include <sys/param.h>
                      3: #include <sys/dir.h>
                      4: #include <sys/user.h>
                      5: #include <sys/proc.h>
                      6: #include <nlist.h>
                      7: #include <stdio.h>
                      8: 
                      9: struct proc proc[NPROC];
                     10: struct nlist nl[] = {
                     11:        {"_proc"}, {0}, 0,
                     12:        0, 0, 0, 0, 0, 0, 0, 0, 0, 0
                     13: };
                     14: 
                     15: /*
                     16:  * Change the running priority (nice) of a process which is already
                     17:  * running.
                     18:  *
                     19:  * Author: Kurt Shoens
                     20:  */
                     21: 
                     22: main(argc, argv)
                     23:        char **argv;
                     24: {
                     25:        register struct proc *pp;
                     26:        int pid, nice;
                     27:        int addr, mem, a1, a2, coreaddr;
                     28: 
                     29:        if (argc != 2 && argc != 3) {
                     30:                fprintf(stderr, "usage: renice pid [ priority ]\n");
                     31:                exit(1);
                     32:        }
                     33:        if (geteuid()) {
                     34:                fprintf(stderr, "NOT super user\n");
                     35:                exit(1);
                     36:        }
                     37:        pid = atoi(argv[1]);
                     38:        nice = atoi(argc == 3 ? argv[2] : "19");
                     39:        if (nice > 20)
                     40:                nice = 20;
                     41:        if (nice < -20)
                     42:                nice = -20;
                     43:        nice += NZERO;
                     44:        mem = open("/dev/kmem", 2);
                     45:        if (mem < 0) {
                     46:                perror("/dev/kmem");
                     47:                exit(1);
                     48:        }
                     49:        nlist("/vmunix", nl);
                     50:        addr = nl[0].n_value;
                     51:        if (addr == 0) {
                     52:                fprintf(stderr, "/vmunix: _proc not in namelist");
                     53:                exit(1);
                     54:        }
                     55:        lseek(mem, addr, 0);
                     56:        read(mem, &proc[0], sizeof proc);
                     57:        for (pp = &proc[0]; pp < &proc[NPROC]; pp++)
                     58:                if (pp->p_pid == pid)
                     59:                        break;
                     60:        if (pp >= &proc[NPROC]) {
                     61:                fprintf(stderr, "%d: process not found\n", pid);
                     62:                exit(1);
                     63:        }
                     64:        fprintf(stderr, "%d: old nice = %d, new nice = %d\n",
                     65:                        pid, 
                     66:                        pp->p_nice - NZERO,
                     67:                        nice - NZERO);
                     68:        a1 = (int)&pp->p_nice;
                     69:        a2 = (int)&proc[0];
                     70:        coreaddr = a1-a2+addr;
                     71:        lseek(mem, (long)coreaddr, 0);
                     72:        write(mem, &nice, 1);
                     73: }

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