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 tarball for details.
   8  */
   9
  10 #include <sys/resource.h>
  11 #include "libbb.h"
  12
  13 int nice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  14 int 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 }