release/src/router/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
  19 int nice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  20 int 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 }