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 GPLv2 or later, see file LICENSE in this source tree.
8 */
9 /* Notes:
10 * Setting an absolute priority was obsoleted in SUSv2 and removed
11 * in SUSv3. However, the common linux version of renice does
12 * absolute and not relative. So we'll continue supporting absolute,
13 * although the stdout logging has been removed since both SUSv2 and
14 * SUSv3 specify that stdout isn't used.
15 *
16 * This version is lenient in that it doesn't require any IDs. The
17 * options -p, -g, and -u are treated as mode switches for the
18 * following IDs (if any). Multiple switches are allowed.
19 */
20 //config:config RENICE
21 //config: bool "renice (4.2 kb)"
22 //config: default y
23 //config: help
24 //config: Renice alters the scheduling priority of one or more running
25 //config: processes.
26
27 //applet:IF_RENICE(APPLET_NOEXEC(renice, renice, BB_DIR_USR_BIN, BB_SUID_DROP, renice))
28
29 //kbuild:lib-$(CONFIG_RENICE) += renice.o
30
31 //usage:#define renice_trivial_usage
32 //usage: "[-n] PRIORITY [[-p|g|u] ID...]..."
33 //usage:#define renice_full_usage "\n\n"
34 //usage: "Change scheduling priority of a running process\n"
35 //usage: "\n -n Add PRIORITY to current nice value"
36 //usage: "\n Without -n, nice value is set to PRIORITY"
37 //usage: "\n -p Process ids (default)"
38 //usage: "\n -g Process group ids"
39 //usage: "\n -u Process user names"
40
41 #include "libbb.h"
42
43 int renice_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
renice_main(int argc UNUSED_PARAM,char ** argv)44 int renice_main(int argc UNUSED_PARAM, char **argv)
45 {
46 static const char Xetpriority_msg[] ALIGN1 = "%cetpriority";
47
48 int retval = EXIT_SUCCESS;
49 int which = PRIO_PROCESS; /* Default 'which' value. */
50 int use_relative = 0;
51 int adjustment, new_priority;
52 unsigned who;
53 char *arg;
54
55 /* Yes, they are not #defines in glibc 2.4! #if won't work */
56 BUILD_BUG_ON(PRIO_PROCESS < CHAR_MIN || PRIO_PROCESS > CHAR_MAX);
57 BUILD_BUG_ON(PRIO_PGRP < CHAR_MIN || PRIO_PGRP > CHAR_MAX);
58 BUILD_BUG_ON(PRIO_USER < CHAR_MIN || PRIO_USER > CHAR_MAX);
59
60 arg = *++argv;
61
62 /* Check if we are using a relative adjustment. */
63 if (arg && arg[0] == '-' && arg[1] == 'n') {
64 use_relative = 1;
65 if (!arg[2])
66 arg = *++argv;
67 else
68 arg += 2;
69 }
70
71 if (!arg) { /* No args? Then show usage. */
72 bb_show_usage();
73 }
74
75 /* Get the priority adjustment (absolute or relative). */
76 adjustment = xatoi_range(arg, INT_MIN/2, INT_MAX/2);
77
78 while ((arg = *++argv) != NULL) {
79 /* Check for a mode switch. */
80 if (arg[0] == '-' && arg[1]) {
81 static const char opts[] ALIGN1 = {
82 'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER
83 };
84 const char *p = strchr(opts, arg[1]);
85 if (p) {
86 which = p[4];
87 if (!arg[2])
88 continue;
89 arg += 2;
90 }
91 }
92
93 /* Process an ID arg. */
94 if (which == PRIO_USER) {
95 struct passwd *p;
96 /* NB: use of getpwnam makes it risky to be NOFORK, switch to getpwnam_r? */
97 p = getpwnam(arg);
98 if (!p) {
99 bb_error_msg("unknown user %s", arg);
100 goto HAD_ERROR;
101 }
102 who = p->pw_uid;
103 } else {
104 who = bb_strtou(arg, NULL, 10);
105 if (errno) {
106 bb_error_msg("invalid number '%s'", arg);
107 goto HAD_ERROR;
108 }
109 }
110
111 /* Get priority to use, and set it. */
112 if (use_relative) {
113 int old_priority;
114
115 errno = 0; /* Needed for getpriority error detection. */
116 old_priority = getpriority(which, who);
117 if (errno) {
118 bb_perror_msg(Xetpriority_msg, 'g');
119 goto HAD_ERROR;
120 }
121
122 new_priority = old_priority + adjustment;
123 } else {
124 new_priority = adjustment;
125 }
126
127 if (setpriority(which, who, new_priority) == 0) {
128 continue;
129 }
130
131 bb_perror_msg(Xetpriority_msg, 's');
132 HAD_ERROR:
133 retval = EXIT_FAILURE;
134 }
135
136 /* No need to check for errors outputting to stderr since, if it
137 * was used, the HAD_ERROR label was reached and retval was set. */
138
139 return retval;
140 }
141