LXR busybox/coreutils/nice.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * nice implementation for busybox
   4 *
   5 * Copyright (C) 2005  Manuel Novoa III  <mjn3@codepoet.org>
   6 *
   7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8 */
   9
  10//usage:#define nice_trivial_usage
  11//usage:       "[-n ADJUST] [PROG ARGS]"
  12//usage:#define nice_full_usage "\n\n"
  13//usage:       "Change scheduling priority, run PROG\n"
  14//usage:     "\n        -n ADJUST       Adjust priority by ADJUST"
  15
  16#include <sys/resource.h>
  17#include "libbb.h"
  18
  19int nice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  20int nice_main(int argc, char **argv)
  21{
  22        int old_priority, adjustment;
  23
  24        old_priority = getpriority(PRIO_PROCESS, 0);
  25
  26        if (!*++argv) { /* No args, so (GNU) output current nice value. */
  27                printf("%d\n", old_priority);
  28                fflush_stdout_and_exit(EXIT_SUCCESS);
  29        }
  30
  31        adjustment = 10;  /* Set default adjustment. */
  32
  33        if (argv[0][0] == '-') {
  34                if (argv[0][1] == 'n') { /* -n */
  35                        if (argv[0][2]) { /* -nNNNN (w/o space) */
  36                                argv[0] += 2; argv--; argc++;
  37                        }
  38                } else { /* -NNN (NNN may be negative) == -n NNN */
  39                        argv[0] += 1; argv--; argc++;
  40                }
  41                if (argc < 4) {  /* Missing priority and/or utility! */
  42                        bb_show_usage();
  43                }
  44                adjustment = xatoi_range(argv[1], INT_MIN/2, INT_MAX/2);
  45                argv += 2;
  46        }
  47
  48        {  /* Set our priority. */
  49                int prio = old_priority + adjustment;
  50
  51                if (setpriority(PRIO_PROCESS, 0, prio) < 0) {
  52                        bb_perror_msg_and_die("setpriority(%d)", prio);
  53                }
  54        }
  55
  56        BB_EXECVP_or_die(argv);
  57}
  58