1 /* vi: set sw=4 ts=4: */
3 * nice implementation for busybox
5 * Copyright (C) 2005 Manuel Novoa III <mjn3@codepoet.org>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
29 #include <sys/resource.h>
32 static inline int int_add_no_wrap(int a, int b)
37 if (s > a) s = INT_MIN;
39 if (s < a) s = INT_MAX;
45 int nice_main(int argc, char **argv)
47 static const char Xetpriority_msg[] = "cannot %cet priority";
49 int old_priority, adjustment;
51 errno = 0; /* Needed for getpriority error detection. */
52 old_priority = getpriority(PRIO_PROCESS, 0);
54 bb_perror_msg_and_die(Xetpriority_msg, 'g');
57 if (!*++argv) { /* No args, so (GNU) output current nice value. */
58 bb_printf("%d\n", old_priority);
59 bb_fflush_stdout_and_exit(EXIT_SUCCESS);
62 adjustment = 10; /* Set default adjustment. */
64 if ((argv[0][0] == '-') && (argv[0][1] == 'n') && !argv[0][2]) { /* "-n" */
65 if (argc < 4) { /* Missing priority and/or utility! */
68 adjustment = bb_xgetlarg(argv[1], 10, INT_MIN, INT_MAX);
72 { /* Set our priority. Handle integer wrapping for old + adjust. */
73 int new_priority = int_add_no_wrap(old_priority, adjustment);
75 if (setpriority(PRIO_PROCESS, 0, new_priority) < 0) {
76 bb_perror_msg_and_die(Xetpriority_msg, 's');
80 execvp(*argv, argv); /* Now exec the desired program. */
82 /* The exec failed... */
83 bb_default_error_retval = (errno == ENOENT) ? 127 : 126; /* SUSv3 */
84 bb_perror_msg_and_die("%s", *argv);