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//config:config NICE
  10//config:       bool "nice (2.1 kb)"
  11//config:       default y
  12//config:       help
  13//config:       nice runs a program with modified scheduling priority.
  14
  15//applet:IF_NICE(APPLET_NOEXEC(nice, nice, BB_DIR_BIN, BB_SUID_DROP, nice))
  16
  17//kbuild:lib-$(CONFIG_NICE) += nice.o
  18
  19//usage:#define nice_trivial_usage
  20//usage:       "[-n ADJUST] [PROG ARGS]"
  21//usage:#define nice_full_usage "\n\n"
  22//usage:       "Change scheduling priority, run PROG\n"
  23//usage:     "\n        -n ADJUST       Adjust priority by ADJUST"
  24
  25#include "libbb.h"
  26
  27int nice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  28int nice_main(int argc UNUSED_PARAM, char **argv)
  29{
  30        int old_priority, adjustment;
  31
  32        old_priority = getpriority(PRIO_PROCESS, 0);
  33
  34        if (!*++argv) { /* No args, so (GNU) output current nice value. */
  35                printf("%d\n", old_priority);
  36                fflush_stdout_and_exit(EXIT_SUCCESS);
  37        }
  38
  39        adjustment = 10;  /* Set default adjustment. */
  40
  41        if (argv[0][0] == '-') {
  42                char *nnn = argv[0] + 1;
  43                if (nnn[0] == 'n') { /* -n */
  44                        nnn += 1;
  45                        if (!nnn[0]) { /* "-n NNN" */
  46                                nnn = *++argv;
  47                        }
  48                        /* else: "-nNNN" (w/o space) */
  49                }
  50                /* else: "-NNN" (NNN may be negative) - same as "-n NNN" */
  51
  52                if (!nnn || !argv[1]) {  /* Missing priority or PROG! */
  53                        bb_show_usage();
  54                }
  55                adjustment = xatoi_range(nnn, INT_MIN/2, INT_MAX/2);
  56                argv++;
  57        }
  58
  59        {  /* Set our priority. */
  60                int prio = old_priority + adjustment;
  61
  62                if (setpriority(PRIO_PROCESS, 0, prio) < 0) {
  63                        bb_perror_msg_and_die("setpriority(%d)", prio);
  64                }
  65        }
  66
  67        BB_EXECVP_or_die(argv);
  68}
  69