1/* vi: set sw=4 ts=4: */
2/*
3 * chrt - manipulate real-time attributes of a process
4 * Copyright (c) 2006-2007 Bernhard Fischer
5 *
6 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
7 */
8
9#include <sched.h>
10#include <getopt.h> /* optind */
11#include "libbb.h"
12#ifndef _POSIX_PRIORITY_SCHEDULING
13#warning your system may be foobared
14#endif
15static const struct {
16	const int policy;
17	const char const name[12];
18} policies[] = {
19	{SCHED_OTHER, "SCHED_OTHER"},
20	{SCHED_FIFO, "SCHED_FIFO"},
21	{SCHED_RR, "SCHED_RR"}
22};
23
24static void show_min_max(int pol)
25{
26	const char *fmt = "%s min/max priority\t: %d/%d\n\0%s not supported?\n";
27	int max, min;
28	max = sched_get_priority_max(pol);
29	min = sched_get_priority_min(pol);
30	if (max >= 0 && min >= 0)
31		printf(fmt, policies[pol].name, min, max);
32	else {
33		fmt += 29;
34		printf(fmt, policies[pol].name);
35	}
36}
37
38#define OPT_m (1<<0)
39#define OPT_p (1<<1)
40#define OPT_r (1<<2)
41#define OPT_f (1<<3)
42#define OPT_o (1<<4)
43
44int chrt_main(int argc, char** argv);
45int chrt_main(int argc, char** argv)
46{
47	pid_t pid = 0;
48	unsigned opt;
49	struct sched_param sp;
50	char *p_opt = NULL, *priority = NULL;
51	const char *state = "current\0new";
52	int prio = 0, policy = SCHED_RR;
53
54	opt_complementary = "r--fo:f--ro:r--fo"; /* only one policy accepted */
55	opt = getopt32(argv, "+mp:rfo", &p_opt);
56	if (opt & OPT_r)
57		policy = SCHED_RR;
58	if (opt & OPT_f)
59		policy = SCHED_FIFO;
60	if (opt & OPT_o)
61		policy = SCHED_OTHER;
62
63	if (opt & OPT_m) { /* print min/max */
64		show_min_max(SCHED_FIFO);
65		show_min_max(SCHED_RR);
66		show_min_max(SCHED_OTHER);
67		fflush_stdout_and_exit(EXIT_SUCCESS);
68	}
69	if (opt & OPT_p) {
70		if (argc == optind+1) { /* -p <priority> <pid> */
71			priority = p_opt;
72			p_opt = argv[optind];
73		}
74		argv += optind; /* me -p <arg> */
75		pid = xatoul_range(p_opt, 1, ULONG_MAX); /* -p <pid> */
76	} else {
77		argv += optind; /* me -p <arg> */
78		priority = *argv;
79	}
80	if (priority) {
81		/* from the manpage of sched_getscheduler:
82		   [...] sched_priority can have a value
83		   in the range 0 to 99.
84		   [...] SCHED_OTHER or SCHED_BATCH  must  be  assigned
85		   the  static  priority  0. [...] SCHED_FIFO  or
86		   SCHED_RR can have a static priority in the range 1 to 99.
87		 */
88		prio = xstrtol_range(priority, 0, policy == SCHED_OTHER
89													 ? 0 : 1, 99);
90	}
91
92	if (opt & OPT_p) {
93		int pol = 0;
94print_rt_info:
95		pol = sched_getscheduler(pid);
96		if (pol < 0)
97			bb_perror_msg_and_die("failed to %cet pid %d's policy", 'g', pid);
98		printf("pid %d's %s scheduling policy: %s\n",
99				pid, state, policies[pol].name);
100		if (sched_getparam(pid, &sp))
101			bb_perror_msg_and_die("failed to get pid %d's attributes", pid);
102		printf("pid %d's %s scheduling priority: %d\n",
103				pid, state, sp.sched_priority);
104		if (!*argv) /* no new prio given or we did print already, done. */
105			return EXIT_SUCCESS;
106	}
107
108	sp.sched_priority = prio;
109	if (sched_setscheduler(pid, policy, &sp) < 0)
110		bb_perror_msg_and_die("failed to %cet pid %d's policy", 's', pid);
111	if (opt & OPT_p) {
112		state += 8;
113		++argv;
114		goto print_rt_info;
115	}
116	++argv;
117	BB_EXECVP(*argv, argv);
118	bb_perror_msg_and_die("%s", *argv);
119}
120#undef OPT_p
121#undef OPT_r
122#undef OPT_f
123#undef OPT_o
124#undef OPT_m
125