1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Sysctl 1.01 - A utility to read and manipulate the sysctl parameters
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4 | *
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5 | * Copyright 1999 George Staikos
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6 | *
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7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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8 | *
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9 | * Changelog:
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10 | * v1.01 - added -p <preload> to preload values from a file
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11 | * v1.01.1 - busybox applet aware by <solar@gentoo.org>
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12 | */
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13 |
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14 | //usage:#define sysctl_trivial_usage
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15 | //usage: "[OPTIONS] [KEY[=VALUE]]..."
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16 | //usage:#define sysctl_full_usage "\n\n"
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17 | //usage: "Show/set kernel parameters\n"
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18 | //usage: "\n -e Don't warn about unknown keys"
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19 | //usage: "\n -n Don't show key names"
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20 | //usage: "\n -a Show all values"
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21 | /* Same as -a, no need to show it */
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22 | /* //usage: "\n -A Show all values in table form" */
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23 | //usage: "\n -w Set values"
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24 | //usage: "\n -p FILE Set values from FILE (default /etc/sysctl.conf)"
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25 | //usage: "\n -q Set values silently"
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26 | //usage:
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27 | //usage:#define sysctl_example_usage
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28 | //usage: "sysctl [-n] [-e] variable...\n"
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29 | //usage: "sysctl [-n] [-e] [-q] -w variable=value...\n"
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30 | //usage: "sysctl [-n] [-e] -a\n"
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31 | //usage: "sysctl [-n] [-e] [-q] -p file (default /etc/sysctl.conf)\n"
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32 | //usage: "sysctl [-n] [-e] -A\n"
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33 |
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34 | #include "libbb.h"
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35 |
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36 | enum {
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37 | FLAG_SHOW_KEYS = 1 << 0,
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38 | FLAG_SHOW_KEY_ERRORS = 1 << 1,
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39 | FLAG_TABLE_FORMAT = 1 << 2, /* not implemented */
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40 | FLAG_SHOW_ALL = 1 << 3,
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41 | FLAG_PRELOAD_FILE = 1 << 4,
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42 | /* TODO: procps 3.2.8 seems to not require -w for KEY=VAL to work: */
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43 | FLAG_WRITE = 1 << 5,
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44 | FLAG_QUIET = 1 << 6,
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45 | };
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46 | #define OPTION_STR "neAapwq"
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47 |
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48 | static void sysctl_dots_to_slashes(char *name)
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49 | {
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50 | char *cptr, *last_good, *end;
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51 |
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52 | /* Convert minimum number of '.' to '/' so that
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53 | * we end up with existing file's name.
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54 | *
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55 | * Example from bug 3894:
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56 | * net.ipv4.conf.eth0.100.mc_forwarding ->
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57 | * net/ipv4/conf/eth0.100/mc_forwarding
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58 | * NB: net/ipv4/conf/eth0/mc_forwarding *also exists*,
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59 | * therefore we must start from the end, and if
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60 | * we replaced even one . -> /, start over again,
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61 | * but never replace dots before the position
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62 | * where last replacement occurred.
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63 | *
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64 | * Another bug we later had is that
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65 | * net.ipv4.conf.eth0.100
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66 | * (without .mc_forwarding) was mishandled.
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67 | *
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68 | * To set up testing: modprobe 8021q; vconfig add eth0 100
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69 | */
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70 | end = name + strlen(name);
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71 | last_good = name - 1;
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72 | *end = '.'; /* trick the loop into trying full name too */
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73 |
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74 | again:
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75 | cptr = end;
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76 | while (cptr > last_good) {
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77 | if (*cptr == '.') {
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78 | *cptr = '\0';
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79 | //bb_error_msg("trying:'%s'", name);
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80 | if (access(name, F_OK) == 0) {
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81 | *cptr = '/';
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82 | //bb_error_msg("replaced:'%s'", name);
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83 | last_good = cptr;
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84 | goto again;
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85 | }
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86 | *cptr = '.';
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87 | }
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88 | cptr--;
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89 | }
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90 | *end = '\0';
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91 | }
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92 |
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93 | static int sysctl_act_on_setting(char *setting)
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94 | {
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95 | int fd, retval = EXIT_SUCCESS;
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96 | char *cptr, *outname;
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97 | char *value = value; /* for compiler */
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98 |
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99 | outname = xstrdup(setting);
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100 |
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101 | cptr = outname;
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102 | while (*cptr) {
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103 | if (*cptr == '/')
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104 | *cptr = '.';
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105 | cptr++;
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106 | }
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107 |
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108 | if (option_mask32 & FLAG_WRITE) {
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109 | cptr = strchr(setting, '=');
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110 | if (cptr == NULL) {
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111 | bb_error_msg("error: '%s' must be of the form name=value",
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112 | outname);
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113 | retval = EXIT_FAILURE;
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114 | goto end;
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115 | }
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116 | value = cptr + 1; /* point to the value in name=value */
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117 | if (setting == cptr || !*value) {
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118 | bb_error_msg("error: malformed setting '%s'", outname);
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119 | retval = EXIT_FAILURE;
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120 | goto end;
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121 | }
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122 | *cptr = '\0';
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123 | outname[cptr - setting] = '\0';
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124 | /* procps 3.2.7 actually uses these flags */
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125 | fd = open(setting, O_WRONLY|O_CREAT|O_TRUNC, 0666);
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126 | } else {
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127 | fd = open(setting, O_RDONLY);
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128 | }
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129 |
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130 | if (fd < 0) {
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131 | switch (errno) {
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132 | case ENOENT:
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133 | if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
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134 | bb_error_msg("error: '%s' is an unknown key", outname);
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135 | break;
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136 | default:
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137 | bb_perror_msg("error %sing key '%s'",
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138 | option_mask32 & FLAG_WRITE ?
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139 | "sett" : "read",
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140 | outname);
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141 | break;
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142 | }
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143 | retval = EXIT_FAILURE;
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144 | goto end;
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145 | }
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146 |
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147 | if (option_mask32 & FLAG_WRITE) {
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148 | //TODO: procps 3.2.7 writes "value\n", note trailing "\n"
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149 | xwrite_str(fd, value);
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150 | close(fd);
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151 | if (!(option_mask32 & FLAG_QUIET)) {
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152 | if (option_mask32 & FLAG_SHOW_KEYS)
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153 | printf("%s = ", outname);
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154 | puts(value);
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155 | }
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156 | } else {
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157 | char c;
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158 |
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159 | value = cptr = xmalloc_read(fd, NULL);
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160 | close(fd);
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161 | if (value == NULL) {
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162 | bb_perror_msg("error reading key '%s'", outname);
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163 | goto end;
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164 | }
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165 |
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166 | /* dev.cdrom.info and sunrpc.transports, for example,
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167 | * are multi-line. Try "sysctl sunrpc.transports"
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168 | */
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169 | while ((c = *cptr) != '\0') {
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170 | if (option_mask32 & FLAG_SHOW_KEYS)
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171 | printf("%s = ", outname);
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172 | while (1) {
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173 | fputc(c, stdout);
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174 | cptr++;
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175 | if (c == '\n')
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176 | break;
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177 | c = *cptr;
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178 | if (c == '\0')
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179 | break;
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180 | }
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181 | }
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182 | free(value);
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183 | }
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184 | end:
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185 | free(outname);
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186 | return retval;
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187 | }
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188 |
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189 | static int sysctl_act_recursive(const char *path)
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190 | {
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191 | DIR *dirp;
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192 | struct stat buf;
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193 | struct dirent *entry;
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194 | char *next;
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195 | int retval = 0;
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196 |
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197 | stat(path, &buf);
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198 | if (S_ISDIR(buf.st_mode) && !(option_mask32 & FLAG_WRITE)) {
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199 | dirp = opendir(path);
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200 | if (dirp == NULL)
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201 | return -1;
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202 | while ((entry = readdir(dirp)) != NULL) {
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203 | next = concat_subpath_file(path, entry->d_name);
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204 | if (next == NULL)
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205 | continue; /* d_name is "." or ".." */
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206 | /* if path was ".", drop "./" prefix: */
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207 | retval |= sysctl_act_recursive((next[0] == '.' && next[1] == '/') ?
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208 | next + 2 : next);
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209 | free(next);
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210 | }
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211 | closedir(dirp);
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212 | } else {
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213 | char *name = xstrdup(path);
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214 | retval |= sysctl_act_on_setting(name);
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215 | free(name);
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216 | }
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217 |
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218 | return retval;
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219 | }
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220 |
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221 | /* Set sysctl's from a conf file. Format example:
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222 | * # Controls IP packet forwarding
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223 | * net.ipv4.ip_forward = 0
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224 | */
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225 | static int sysctl_handle_preload_file(const char *filename)
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226 | {
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227 | char *token[2];
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228 | parser_t *parser;
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229 |
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230 | parser = config_open(filename);
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231 | /* Must do it _after_ config_open(): */
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232 | xchdir("/proc/sys");
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233 | /* xchroot("/proc/sys") - if you are paranoid */
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234 |
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235 | //TODO: ';' is comment char too
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236 | //TODO: comment may be only at line start. "var=1 #abc" - "1 #abc" is the value
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237 | // (but _whitespace_ from ends should be trimmed first (and we do it right))
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238 | //TODO: "var==1" is mishandled (must use "=1" as a value, but uses "1")
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239 | // can it be fixed by removing PARSE_COLLAPSE bit?
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240 | while (config_read(parser, token, 2, 2, "# \t=", PARSE_NORMAL)) {
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241 | char *tp;
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242 | sysctl_dots_to_slashes(token[0]);
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243 | tp = xasprintf("%s=%s", token[0], token[1]);
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244 | sysctl_act_recursive(tp);
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245 | free(tp);
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246 | }
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247 | if (ENABLE_FEATURE_CLEAN_UP)
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248 | config_close(parser);
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249 | return 0;
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250 | }
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251 |
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252 | int sysctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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253 | int sysctl_main(int argc UNUSED_PARAM, char **argv)
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254 | {
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255 | int retval;
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256 | int opt;
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257 |
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258 | opt = getopt32(argv, "+" OPTION_STR); /* '+' - stop on first non-option */
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259 | argv += optind;
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260 | opt ^= (FLAG_SHOW_KEYS | FLAG_SHOW_KEY_ERRORS);
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261 | option_mask32 = opt;
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262 |
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263 | if (opt & FLAG_PRELOAD_FILE) {
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264 | option_mask32 |= FLAG_WRITE;
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265 | /* xchdir("/proc/sys") is inside */
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266 | return sysctl_handle_preload_file(*argv ? *argv : "/etc/sysctl.conf");
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267 | }
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268 | xchdir("/proc/sys");
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269 | /* xchroot("/proc/sys") - if you are paranoid */
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270 | if (opt & (FLAG_TABLE_FORMAT | FLAG_SHOW_ALL)) {
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271 | return sysctl_act_recursive(".");
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272 | }
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273 |
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274 | retval = 0;
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275 | while (*argv) {
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276 | sysctl_dots_to_slashes(*argv);
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277 | retval |= sysctl_act_recursive(*argv);
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278 | argv++;
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279 | }
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280 |
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281 | return retval;
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282 | }
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