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