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 tarball for details.
   8 */
   9
  10#include <sys/resource.h>
  11#include "libbb.h"
  12
  13int nice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  14int nice_main(int argc, char **argv)
  15{
  16        int old_priority, adjustment;
  17
  18        old_priority = getpriority(PRIO_PROCESS, 0);
  19
  20        if (!*++argv) { /* No args, so (GNU) output current nice value. */
  21                printf("%d\n", old_priority);
  22                fflush_stdout_and_exit(EXIT_SUCCESS);
  23        }
  24
  25        adjustment = 10;                        /* Set default adjustment. */
  26
  27        if (argv[0][0] == '-') {
  28                if (argv[0][1] == 'n') { /* -n */
  29                        if (argv[0][2]) { /* -nNNNN (w/o space) */
  30                                argv[0] += 2; argv--; argc++;
  31                        }
  32                } else { /* -NNN (NNN may be negative) == -n NNN */
  33                        argv[0] += 1; argv--; argc++;
  34                }
  35                if (argc < 4) {                 /* Missing priority and/or utility! */
  36                        bb_show_usage();
  37                }
  38                adjustment = xatoi_range(argv[1], INT_MIN/2, INT_MAX/2);
  39                argv += 2;
  40        }
  41
  42        {  /* Set our priority. */
  43                int prio = old_priority + adjustment;
  44
  45                if (setpriority(PRIO_PROCESS, 0, prio) < 0) {
  46                        bb_perror_msg_and_die("setpriority(%d)", prio);
  47                }
  48        }
  49
  50        BB_EXECVP(*argv, argv);         /* Now exec the desired program. */
  51
  52        /* The exec failed... */
  53        xfunc_error_retval = (errno == ENOENT) ? 127 : 126; /* SUSv3 */
  54        bb_simple_perror_msg_and_die(*argv);
  55}
  56