1 /* vi: set sw=4 ts=4: */
3 * Sysctl 1.01 - A utility to read and manipulate the sysctl parameters
5 * Copyright 1999 George Staikos
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
10 * v1.01 - added -p <preload> to preload values from a file
11 * v1.01.1 - busybox applet aware by <solar@gentoo.org>
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"
19 //usage: "\n -n Don't print key names"
20 //usage: "\n -e Don't warn about unknown keys"
21 //usage: "\n -w Change sysctl setting"
22 //usage: "\n -p FILE Load sysctl settings from FILE (default /etc/sysctl.conf)"
23 //usage: "\n -a Display all values"
24 //usage: "\n -A Display all values in table form"
26 //usage:#define sysctl_example_usage
27 //usage: "sysctl [-n] [-e] variable...\n"
28 //usage: "sysctl [-n] [-e] -w variable=value...\n"
29 //usage: "sysctl [-n] [-e] -a\n"
30 //usage: "sysctl [-n] [-e] -p file (default /etc/sysctl.conf)\n"
31 //usage: "sysctl [-n] [-e] -A\n"
36 FLAG_SHOW_KEYS = 1 << 0,
37 FLAG_SHOW_KEY_ERRORS = 1 << 1,
38 FLAG_TABLE_FORMAT = 1 << 2, /* not implemented */
39 FLAG_SHOW_ALL = 1 << 3,
40 FLAG_PRELOAD_FILE = 1 << 4,
43 #define OPTION_STR "neAapw"
45 static void sysctl_dots_to_slashes(char *name)
47 char *cptr, *last_good, *end;
49 /* Convert minimum number of '.' to '/' so that
50 * we end up with existing file's name.
52 * Example from bug 3894:
53 * net.ipv4.conf.eth0.100.mc_forwarding ->
54 * net/ipv4/conf/eth0.100/mc_forwarding
55 * NB: net/ipv4/conf/eth0/mc_forwarding *also exists*,
56 * therefore we must start from the end, and if
57 * we replaced even one . -> /, start over again,
58 * but never replace dots before the position
59 * where last replacement occurred.
61 * Another bug we later had is that
62 * net.ipv4.conf.eth0.100
63 * (without .mc_forwarding) was mishandled.
65 * To set up testing: modprobe 8021q; vconfig add eth0 100
67 end = name + strlen(name);
69 *end = '.'; /* trick the loop into trying full name too */
73 while (cptr > last_good) {
76 //bb_error_msg("trying:'%s'", name);
77 if (access(name, F_OK) == 0) {
79 //bb_error_msg("replaced:'%s'", name);
90 static int sysctl_act_on_setting(char *setting)
92 int fd, retval = EXIT_SUCCESS;
94 char *value = value; /* for compiler */
96 outname = xstrdup(setting);
105 if (option_mask32 & FLAG_WRITE) {
106 cptr = strchr(setting, '=');
108 bb_error_msg("error: '%s' must be of the form name=value",
110 retval = EXIT_FAILURE;
113 value = cptr + 1; /* point to the value in name=value */
114 if (setting == cptr || !*value) {
115 bb_error_msg("error: malformed setting '%s'", outname);
116 retval = EXIT_FAILURE;
120 outname[cptr - setting] = '\0';
121 /* procps 3.2.7 actually uses these flags */
122 fd = open(setting, O_WRONLY|O_CREAT|O_TRUNC, 0666);
124 fd = open(setting, O_RDONLY);
130 if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
131 bb_error_msg("error: '%s' is an unknown key", outname);
134 bb_perror_msg("error %sing key '%s'",
135 option_mask32 & FLAG_WRITE ?
140 retval = EXIT_FAILURE;
144 if (option_mask32 & FLAG_WRITE) {
145 //TODO: procps 3.2.7 writes "value\n", note trailing "\n"
146 xwrite_str(fd, value);
148 if (option_mask32 & FLAG_SHOW_KEYS)
149 printf("%s = ", outname);
154 value = cptr = xmalloc_read(fd, NULL);
157 bb_perror_msg("error reading key '%s'", outname);
161 /* dev.cdrom.info and sunrpc.transports, for example,
162 * are multi-line. Try "sysctl sunrpc.transports"
164 while ((c = *cptr) != '\0') {
165 if (option_mask32 & FLAG_SHOW_KEYS)
166 printf("%s = ", outname);
184 static int sysctl_act_recursive(const char *path)
188 struct dirent *entry;
193 if (S_ISDIR(buf.st_mode) && !(option_mask32 & FLAG_WRITE)) {
194 dirp = opendir(path);
197 while ((entry = readdir(dirp)) != NULL) {
198 next = concat_subpath_file(path, entry->d_name);
200 continue; /* d_name is "." or ".." */
201 /* if path was ".", drop "./" prefix: */
202 retval |= sysctl_act_recursive((next[0] == '.' && next[1] == '/') ?
208 char *name = xstrdup(path);
209 retval |= sysctl_act_on_setting(name);
216 /* Set sysctl's from a conf file. Format example:
217 * # Controls IP packet forwarding
218 * net.ipv4.ip_forward = 0
220 static int sysctl_handle_preload_file(const char *filename)
225 parser = config_open(filename);
226 /* Must do it _after_ config_open(): */
228 /* xchroot(".") - if you are paranoid */
230 //TODO: ';' is comment char too
231 //TODO: comment may be only at line start. "var=1 #abc" - "1 #abc" is the value
232 // (but _whitespace_ from ends should be trimmed first (and we do it right))
233 //TODO: "var==1" is mishandled (must use "=1" as a value, but uses "1")
234 // can it be fixed by removing PARSE_COLLAPSE bit?
235 while (config_read(parser, token, 2, 2, "# \t=", PARSE_NORMAL)) {
237 sysctl_dots_to_slashes(token[0]);
238 tp = xasprintf("%s=%s", token[0], token[1]);
239 sysctl_act_recursive(tp);
242 if (ENABLE_FEATURE_CLEAN_UP)
243 config_close(parser);
247 int sysctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
248 int sysctl_main(int argc UNUSED_PARAM, char **argv)
253 opt = getopt32(argv, "+" OPTION_STR); /* '+' - stop on first non-option */
255 opt ^= (FLAG_SHOW_KEYS | FLAG_SHOW_KEY_ERRORS);
258 if (opt & FLAG_PRELOAD_FILE) {
259 option_mask32 |= FLAG_WRITE;
260 /* xchdir("/proc/sys") is inside */
261 return sysctl_handle_preload_file(*argv ? *argv : "/etc/sysctl.conf");
264 /* xchroot(".") - if you are paranoid */
265 if (opt & (FLAG_TABLE_FORMAT | FLAG_SHOW_ALL)) {
266 return sysctl_act_recursive(".");
271 sysctl_dots_to_slashes(*argv);
272 retval |= sysctl_act_recursive(*argv);