1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * nice implementation for busybox
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4 | *
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5 | * Copyright (C) 2005 Manuel Novoa III <mjn3@codepoet.org>
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6 | *
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7 | * This program is free software; you can redistribute it and/or modify
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8 | * it under the terms of the GNU General Public License as published by
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9 | * the Free Software Foundation; either version 2 of the License, or
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10 | * (at your option) any later version.
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11 | *
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12 | * This program is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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15 | * General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with this program; if not, write to the Free Software
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19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 | *
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21 | */
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22 |
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23 | #include <stdio.h>
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24 | #include <stdlib.h>
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25 | #include <string.h>
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26 | #include <limits.h>
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27 | #include <errno.h>
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28 | #include <unistd.h>
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29 | #include <sys/resource.h>
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30 | #include "busybox.h"
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31 |
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32 | static inline int int_add_no_wrap(int a, int b)
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33 | {
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34 | int s = a + b;
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35 |
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36 | if (b < 0) {
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37 | if (s > a) s = INT_MIN;
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38 | } else {
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39 | if (s < a) s = INT_MAX;
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40 | }
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41 |
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42 | return s;
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43 | }
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44 |
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45 | int nice_main(int argc, char **argv)
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46 | {
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47 | static const char Xetpriority_msg[] = "cannot %cet priority";
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48 |
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49 | int old_priority, adjustment;
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50 |
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51 | errno = 0; /* Needed for getpriority error detection. */
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52 | old_priority = getpriority(PRIO_PROCESS, 0);
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53 | if (errno) {
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54 | bb_perror_msg_and_die(Xetpriority_msg, 'g');
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55 | }
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56 |
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57 | if (!*++argv) { /* No args, so (GNU) output current nice value. */
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58 | bb_printf("%d\n", old_priority);
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59 | bb_fflush_stdout_and_exit(EXIT_SUCCESS);
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60 | }
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61 |
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62 | adjustment = 10; /* Set default adjustment. */
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63 |
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64 | if ((argv[0][0] == '-') && (argv[0][1] == 'n') && !argv[0][2]) { /* "-n" */
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65 | if (argc < 4) { /* Missing priority and/or utility! */
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66 | bb_show_usage();
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67 | }
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68 | adjustment = bb_xgetlarg(argv[1], 10, INT_MIN, INT_MAX);
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69 | argv += 2;
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70 | }
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71 |
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72 | { /* Set our priority. Handle integer wrapping for old + adjust. */
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73 | int new_priority = int_add_no_wrap(old_priority, adjustment);
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74 |
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75 | if (setpriority(PRIO_PROCESS, 0, new_priority) < 0) {
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76 | bb_perror_msg_and_die(Xetpriority_msg, 's');
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77 | }
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78 | }
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79 |
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80 | execvp(*argv, argv); /* Now exec the desired program. */
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81 |
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82 | /* The exec failed... */
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83 | bb_default_error_retval = (errno == ENOENT) ? 127 : 126; /* SUSv3 */
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84 | bb_perror_msg_and_die("%s", *argv);
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85 | }
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