1/* vi: set sw=4 ts=4: */
2/*
3 * renice implementation for busybox
4 *
5 * Copyright (C) 2005  Manuel Novoa III  <mjn3@codepoet.org>
6 *
7 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
8 */
9
10/* Notes:
11 *   Setting an absolute priority was obsoleted in SUSv2 and removed
12 *   in SUSv3.  However, the common linux version of renice does
13 *   absolute and not relative.  So we'll continue supporting absolute,
14 *   although the stdout logging has been removed since both SUSv2 and
15 *   SUSv3 specify that stdout isn't used.
16 *
17 *   This version is lenient in that it doesn't require any IDs.  The
18 *   options -p, -g, and -u are treated as mode switches for the
19 *   following IDs (if any).  Multiple switches are allowed.
20 */
21
22#include "libbb.h"
23#include <sys/resource.h>
24
25void BUG_bad_PRIO_PROCESS(void);
26void BUG_bad_PRIO_PGRP(void);
27void BUG_bad_PRIO_USER(void);
28
29int renice_main(int argc, char **argv);
30int renice_main(int argc, char **argv)
31{
32	static const char Xetpriority_msg[] ALIGN1 = "%cetpriority";
33
34	int retval = EXIT_SUCCESS;
35	int which = PRIO_PROCESS;	/* Default 'which' value. */
36	int use_relative = 0;
37	int adjustment, new_priority;
38	unsigned who;
39	char *arg;
40
41	/* Yes, they are not #defines in glibc 2.4! #if won't work */
42	if (PRIO_PROCESS < CHAR_MIN || PRIO_PROCESS > CHAR_MAX)
43		BUG_bad_PRIO_PROCESS();
44	if (PRIO_PGRP < CHAR_MIN || PRIO_PGRP > CHAR_MAX)
45		BUG_bad_PRIO_PGRP();
46	if (PRIO_USER < CHAR_MIN || PRIO_USER > CHAR_MAX)
47		BUG_bad_PRIO_USER();
48
49	arg = *++argv;
50
51	/* Check if we are using a relative adjustment. */
52	if (arg && arg[0] == '-' && arg[1] == 'n') {
53		use_relative = 1;
54		if (!arg[2])
55			arg = *++argv;
56		else
57			arg += 2;
58	}
59
60	if (!arg) {				/* No args?  Then show usage. */
61		bb_show_usage();
62	}
63
64	/* Get the priority adjustment (absolute or relative). */
65	adjustment = xatoi_range(arg, INT_MIN/2, INT_MAX/2);
66
67	while ((arg = *++argv) != NULL) {
68		/* Check for a mode switch. */
69		if (arg[0] == '-' && arg[1]) {
70			static const char opts[] ALIGN1 = {
71				'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER
72			};
73			const char *p = strchr(opts, arg[1]);
74			if (p) {
75				which = p[4];
76				if (!arg[2])
77					continue;
78				arg += 2;
79			}
80		}
81
82		/* Process an ID arg. */
83		if (which == PRIO_USER) {
84			struct passwd *p;
85			p = getpwnam(arg);
86			if (!p) {
87				bb_error_msg("unknown user: %s", arg);
88				goto HAD_ERROR;
89			}
90			who = p->pw_uid;
91		} else {
92			who = bb_strtou(arg, NULL, 10);
93			if (errno) {
94				bb_error_msg("bad value: %s", arg);
95				goto HAD_ERROR;
96			}
97		}
98
99		/* Get priority to use, and set it. */
100		if (use_relative) {
101			int old_priority;
102
103			errno = 0;	 /* Needed for getpriority error detection. */
104			old_priority = getpriority(which, who);
105			if (errno) {
106				bb_perror_msg(Xetpriority_msg, 'g');
107				goto HAD_ERROR;
108			}
109
110			new_priority = old_priority + adjustment;
111		} else {
112			new_priority = adjustment;
113		}
114
115		if (setpriority(which, who, new_priority) == 0) {
116			continue;
117		}
118
119		bb_perror_msg(Xetpriority_msg, 's');
120 HAD_ERROR:
121		retval = EXIT_FAILURE;
122	}
123
124	/* No need to check for errors outputing to stderr since, if it
125	 * was used, the HAD_ERROR label was reached and retval was set. */
126
127	return retval;
128}
129