release/src/router/busybox/procps/sysctl.c

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