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
27 int nice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
nice_main(int argc UNUSED_PARAM,char ** argv)28 int 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