1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * renice 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 | * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
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8 | */
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9 |
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10 | /* Notes:
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11 | * Setting an absolute priority was obsoleted in SUSv2 and removed
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12 | * in SUSv3. However, the common linux version of renice does
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13 | * absolute and not relative. So we'll continue supporting absolute,
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14 | * although the stdout logging has been removed since both SUSv2 and
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15 | * SUSv3 specify that stdout isn't used.
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16 | *
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17 | * This version is lenient in that it doesn't require any IDs. The
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18 | * options -p, -g, and -u are treated as mode switches for the
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19 | * following IDs (if any). Multiple switches are allowed.
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20 | */
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21 |
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22 | #include "busybox.h"
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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 |
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31 | #if (PRIO_PROCESS < CHAR_MIN) || (PRIO_PROCESS > CHAR_MAX)
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32 | #error Assumption violated : PRIO_PROCESS value
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33 | #endif
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34 | #if (PRIO_PGRP < CHAR_MIN) || (PRIO_PGRP > CHAR_MAX)
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35 | #error Assumption violated : PRIO_PGRP value
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36 | #endif
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37 | #if (PRIO_USER < CHAR_MIN) || (PRIO_USER > CHAR_MAX)
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38 | #error Assumption violated : PRIO_USER value
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39 | #endif
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40 |
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41 | static inline int int_add_no_wrap(int a, int b)
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42 | {
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43 | int s = a + b;
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44 |
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45 | if (b < 0) {
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46 | if (s > a) s = INT_MIN;
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47 | } else {
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48 | if (s < a) s = INT_MAX;
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49 | }
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50 |
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51 | return s;
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52 | }
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53 |
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54 | int renice_main(int argc, char **argv)
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55 | {
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56 | static const char Xetpriority_msg[] = "%d : %cetpriority";
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57 |
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58 | int retval = EXIT_SUCCESS;
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59 | int which = PRIO_PROCESS; /* Default 'which' value. */
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60 | int use_relative = 0;
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61 | int adjustment, new_priority;
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62 | id_t who;
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63 |
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64 | ++argv;
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65 |
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66 | /* Check if we are using a relative adjustment. */
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67 | if (argv[0] && (argv[0][0] == '-') && (argv[0][1] == 'n') && !argv[0][2]) {
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68 | use_relative = 1;
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69 | ++argv;
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70 | }
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71 |
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72 | if (!*argv) { /* No args? Then show usage. */
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73 | bb_show_usage();
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74 | }
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75 |
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76 | /* Get the priority adjustment (absolute or relative). */
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77 | adjustment = bb_xgetlarg(*argv, 10, INT_MIN, INT_MAX);
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78 |
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79 | while (*++argv) {
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80 | /* Check for a mode switch. */
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81 | if ((argv[0][0] == '-') && argv[0][1] && !argv[0][2]) {
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82 | static const char opts[]
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83 | = { 'p', 'g', 'u', 0, PRIO_PROCESS, PRIO_PGRP, PRIO_USER };
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84 | const char *p;
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85 | if ((p = strchr(opts, argv[0][1]))) {
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86 | which = p[4];
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87 | continue;
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88 | }
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89 | }
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90 |
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91 | /* Process an ID arg. */
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92 | if (which == PRIO_USER) {
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93 | struct passwd *p;
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94 | if (!(p = getpwnam(*argv))) {
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95 | bb_error_msg("unknown user: %s", *argv);
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96 | goto HAD_ERROR;
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97 | }
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98 | who = p->pw_uid;
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99 | } else {
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100 | char *e;
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101 | errno = 0;
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102 | who = strtoul(*argv, &e, 10);
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103 | if (*e || (*argv == e) || errno) {
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104 | bb_error_msg("bad value: %s", *argv);
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105 | goto HAD_ERROR;
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106 | }
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107 | }
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108 |
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109 | /* Get priority to use, and set it. */
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110 | if (use_relative) {
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111 | int old_priority;
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112 |
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113 | errno = 0; /* Needed for getpriority error detection. */
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114 | old_priority = getpriority(which, who);
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115 | if (errno) {
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116 | bb_perror_msg(Xetpriority_msg, who, 'g');
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117 | goto HAD_ERROR;
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118 | }
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119 |
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120 | new_priority = int_add_no_wrap(old_priority, adjustment);
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121 | } else {
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122 | new_priority = adjustment;
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123 | }
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124 |
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125 | if (setpriority(which, who, new_priority) == 0) {
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126 | continue;
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127 | }
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128 |
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129 | bb_perror_msg(Xetpriority_msg, who, 's');
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130 | HAD_ERROR:
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131 | retval = EXIT_FAILURE;
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132 | }
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133 |
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134 | /* No need to check for errors outputing to stderr since, if it
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135 | * was used, the HAD_ERROR label was reached and retval was set. */
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136 |
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137 | return retval;
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138 | }
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