1 /* nice -- run a program with modified niceness
2 Copyright (C) 1990-2023 Free Software Foundation, Inc.
3
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17 /* David MacKenzie <djm@gnu.ai.mit.edu> */
18
19 #include <config.h>
20 #include <stdio.h>
21 #include <getopt.h>
22 #include <sys/types.h>
23
24 #include "system.h"
25
26 #if ! HAVE_NICE
27 /* Include this after "system.h" so we're sure to have definitions
28 (from time.h or sys/time.h) required for e.g. the ru_utime member. */
29 # include <sys/resource.h>
30 #endif
31
32 #include "quote.h"
33 #include "xstrtol.h"
34
35 /* The official name of this program (e.g., no 'g' prefix). */
36 #define PROGRAM_NAME "nice"
37
38 #define AUTHORS proper_name ("David MacKenzie")
39
40 #if HAVE_NICE
41 # define GET_NICENESS() nice (0)
42 #else
43 # define GET_NICENESS() getpriority (PRIO_PROCESS, 0)
44 #endif
45
46 #ifndef NZERO
47 # define NZERO 20
48 #endif
49
50 /* This is required for Darwin Kernel Version 7.7.0. */
51 #if NZERO == 0
52 # undef NZERO
53 # define NZERO 20
54 #endif
55
56 static struct option const longopts[] =
57 {
58 {"adjustment", required_argument, nullptr, 'n'},
59 {GETOPT_HELP_OPTION_DECL},
60 {GETOPT_VERSION_OPTION_DECL},
61 {nullptr, 0, nullptr, 0}
62 };
63
64 void
65 usage (int status)
66 {
67 if (status != EXIT_SUCCESS)
68 emit_try_help ();
69 else
70 {
71 printf (_("Usage: %s [OPTION] [COMMAND [ARG]...]\n"), program_name);
72 printf (_("\
73 Run COMMAND with an adjusted niceness, which affects process scheduling.\n\
74 With no COMMAND, print the current niceness. Niceness values range from\n\
75 %d (most favorable to the process) to %d (least favorable to the process).\n\
76 "),
77 - NZERO, NZERO - 1);
78
79 emit_mandatory_arg_note ();
80
81 fputs (_("\
82 -n, --adjustment=N add integer N to the niceness (default 10)\n\
83 "), stdout);
84 fputs (HELP_OPTION_DESCRIPTION, stdout);
85 fputs (VERSION_OPTION_DESCRIPTION, stdout);
86 printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
87 emit_exec_status (PROGRAM_NAME);
88 emit_ancillary_info (PROGRAM_NAME);
89 }
90 exit (status);
91 }
92
93 static bool
94 perm_related_errno (int err)
95 {
96 return err == EACCES || err == EPERM;
97 }
98
99 int
100 main (int argc, char **argv)
101 {
102 int current_niceness;
103 int adjustment = 10;
104 char const *adjustment_given = nullptr;
105 bool ok;
106 int i;
107
108 initialize_main (&argc, &argv);
109 set_program_name (argv[0]);
110 setlocale (LC_ALL, "");
111 bindtextdomain (PACKAGE, LOCALEDIR);
112 textdomain (PACKAGE);
113
114 initialize_exit_failure (EXIT_CANCELED);
115 atexit (close_stdout);
116
117 for (i = 1; i < argc; /* empty */)
118 {
119 char const *s = argv[i];
120
121 if (s[0] == '-' && ISDIGIT (s[1 + (s[1] == '-' || s[1] == '+')]))
122 {
123 adjustment_given = s + 1;
124 ++i;
125 }
126 else
127 {
128 int c;
129 int fake_argc = argc - (i - 1);
130 char **fake_argv = argv + (i - 1);
131
132 /* Ensure that any getopt diagnostics use the right name. */
133 fake_argv[0] = argv[0];
134
135 /* Initialize getopt_long's internal state. */
136 optind = 0;
137
138 c = getopt_long (fake_argc, fake_argv, "+n:", longopts, nullptr);
139 i += optind - 1;
140
141 switch (c)
142 {
143 case 'n':
144 adjustment_given = optarg;
145 break;
146
147 case -1:
148 break;
149
150 case_GETOPT_HELP_CHAR;
151
152 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
153
154 default:
155 usage (EXIT_CANCELED);
156 break;
157 }
158
159 if (c == -1)
160 break;
161 }
162 }
163
164 if (adjustment_given)
165 {
166 /* If the requested adjustment is outside the valid range,
167 silently bring it to just within range; this mimics what
168 "setpriority" and "nice" do. */
169 enum { MIN_ADJUSTMENT = 1 - 2 * NZERO, MAX_ADJUSTMENT = 2 * NZERO - 1 };
170 long int tmp;
171 if (LONGINT_OVERFLOW < xstrtol (adjustment_given, nullptr, 10, &tmp, ""))
172 error (EXIT_CANCELED, 0, _("invalid adjustment %s"),
173 quote (adjustment_given));
174 adjustment = MAX (MIN_ADJUSTMENT, MIN (tmp, MAX_ADJUSTMENT));
175 }
176
177 if (i == argc)
178 {
179 if (adjustment_given)
180 {
181 error (0, 0, _("a command must be given with an adjustment"));
182 usage (EXIT_CANCELED);
183 }
184 /* No command given; print the niceness. */
185 errno = 0;
186 current_niceness = GET_NICENESS ();
187 if (current_niceness == -1 && errno != 0)
188 error (EXIT_CANCELED, errno, _("cannot get niceness"));
189 printf ("%d\n", current_niceness);
190 return EXIT_SUCCESS;
191 }
192
193 errno = 0;
194 #if HAVE_NICE
195 ok = (nice (adjustment) != -1 || errno == 0);
196 #else
197 current_niceness = GET_NICENESS ();
198 if (current_niceness == -1 && errno != 0)
199 error (EXIT_CANCELED, errno, _("cannot get niceness"));
200 ok = (setpriority (PRIO_PROCESS, 0, current_niceness + adjustment) == 0);
201 #endif
202 if (!ok)
203 {
204 error (perm_related_errno (errno) ? 0
205 : EXIT_CANCELED, errno, _("cannot set niceness"));
206 /* error() flushes stderr, but does not check for write failure.
207 Normally, we would catch this via our atexit() hook of
208 close_stdout, but execvp() gets in the way. If stderr
209 encountered a write failure, there is no need to try calling
210 error() again. */
211 if (ferror (stderr))
212 return EXIT_CANCELED;
213 }
214
215 execvp (argv[i], &argv[i]);
216
217 int exit_status = errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE;
218 error (0, errno, "%s", quote (argv[i]));
219 return exit_status;
220 }