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 tarball for details.
11 * - added -p <preload> to preload values from a file
13 * - busybox applet aware by <solar@gentoo.org>
19 static int sysctl_read_setting(const char *setting);
20 static int sysctl_write_setting(const char *setting);
21 static int sysctl_display_all(const char *path);
22 static int sysctl_preload_file_and_exit(const char *filename);
23 static void sysctl_dots_to_slashes(char *name);
25 static const char ETC_SYSCTL_CONF[] ALIGN1 = "/etc/sysctl.conf";
26 static const char PROC_SYS[] ALIGN1 = "/proc/sys/";
27 enum { strlen_PROC_SYS = sizeof(PROC_SYS) - 1 };
29 static const char msg_unknown_key[] ALIGN1 =
30 "error: '%s' is an unknown key";
32 static void dwrite_str(int fd, const char *buf)
34 write(fd, buf, strlen(buf));
38 FLAG_SHOW_KEYS = 1 << 0,
39 FLAG_SHOW_KEY_ERRORS = 1 << 1,
40 FLAG_TABLE_FORMAT = 1 << 2, /* not implemented */
41 FLAG_SHOW_ALL = 1 << 3,
42 FLAG_PRELOAD_FILE = 1 << 4,
46 int sysctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
47 int sysctl_main(int argc UNUSED_PARAM, char **argv)
52 opt = getopt32(argv, "+neAapw"); /* '+' - stop on first non-option */
54 opt ^= (FLAG_SHOW_KEYS | FLAG_SHOW_KEY_ERRORS);
55 option_mask32 ^= (FLAG_SHOW_KEYS | FLAG_SHOW_KEY_ERRORS);
57 if (opt & (FLAG_TABLE_FORMAT | FLAG_SHOW_ALL))
58 return sysctl_display_all(PROC_SYS);
59 if (opt & FLAG_PRELOAD_FILE)
60 return sysctl_preload_file_and_exit(*argv ? *argv : ETC_SYSCTL_CONF);
65 retval |= sysctl_write_setting(*argv);
67 retval |= sysctl_read_setting(*argv);
72 } /* end sysctl_main() */
74 /* Set sysctl's from a conf file. Format example:
75 * # Controls IP packet forwarding
76 * net.ipv4.ip_forward = 0
78 static int sysctl_preload_file_and_exit(const char *filename)
83 parser = config_open(filename);
84 // TODO: ';' is comment char too
85 while (config_read(parser, token, 2, 2, "# \t=", PARSE_NORMAL)) {
87 char *s = xasprintf("%s=%s", token[0], token[1]);
88 sysctl_write_setting(s);
90 #else /* Save ~4 bytes by using parser internals */
91 sprintf(parser->line, "%s=%s", token[0], token[1]); // must have room by definition
92 sysctl_write_setting(parser->line);
95 if (ENABLE_FEATURE_CLEAN_UP)
98 } /* end sysctl_preload_file_and_exit() */
100 static int sysctl_write_setting(const char *setting)
106 char *tmpname, *outname, *cptr;
110 equals = strchr(setting, '=');
112 bb_error_msg("error: '%s' must be of the form name=value", setting);
116 value = equals + 1; /* point to the value in name=value */
117 if (name == equals || !*value) {
118 bb_error_msg("error: malformed setting '%s'", setting);
122 tmpname = xasprintf("%s%.*s", PROC_SYS, (int)(equals - name), name);
123 outname = xstrdup(tmpname + strlen_PROC_SYS);
125 sysctl_dots_to_slashes(tmpname);
127 while ((cptr = strchr(outname, '/')) != NULL)
130 fd = open(tmpname, O_WRONLY | O_CREAT | O_TRUNC, 0666);
134 if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
135 bb_error_msg(msg_unknown_key, outname);
138 bb_perror_msg("error setting key '%s'", outname);
141 retval = EXIT_FAILURE;
143 dwrite_str(fd, value);
145 if (option_mask32 & FLAG_SHOW_KEYS) {
146 printf("%s = ", outname);
149 retval = EXIT_SUCCESS;
155 } /* end sysctl_write_setting() */
157 static int sysctl_read_setting(const char *name)
160 char *tmpname, *outname, *cptr;
165 if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
166 bb_error_msg(msg_unknown_key, name);
170 tmpname = concat_path_file(PROC_SYS, name);
171 outname = xstrdup(tmpname + strlen_PROC_SYS);
173 sysctl_dots_to_slashes(tmpname);
175 while ((cptr = strchr(outname, '/')) != NULL)
178 fp = fopen_for_read(tmpname);
182 if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
183 bb_error_msg(msg_unknown_key, outname);
186 bb_perror_msg("error reading key '%s'", outname);
189 retval = EXIT_FAILURE;
191 while (fgets(inbuf, sizeof(inbuf) - 1, fp)) {
192 if (option_mask32 & FLAG_SHOW_KEYS) {
193 printf("%s = ", outname);
195 fputs(inbuf, stdout);
198 retval = EXIT_SUCCESS;
204 } /* end sysctl_read_setting() */
206 static int sysctl_display_all(const char *path)
208 int retval = EXIT_SUCCESS;
218 while ((de = readdir(dp)) != NULL) {
219 tmpdir = concat_subpath_file(path, de->d_name);
221 continue; /* . or .. */
222 if (stat(tmpdir, &ts) != 0) {
223 bb_perror_msg(tmpdir);
224 } else if (S_ISDIR(ts.st_mode)) {
225 retval |= sysctl_display_all(tmpdir);
227 retval |= sysctl_read_setting(tmpdir + strlen_PROC_SYS);
234 } /* end sysctl_display_all() */
236 static void sysctl_dots_to_slashes(char *name)
238 char *cptr, *last_good, *end;
240 /* It can be good as-is! */
241 if (access(name, F_OK) == 0)
244 /* Example from bug 3894:
245 * net.ipv4.conf.eth0.100.mc_forwarding ->
246 * net/ipv4/conf/eth0.100/mc_forwarding. NB:
247 * net/ipv4/conf/eth0/mc_forwarding *also exists*,
248 * therefore we must start from the end, and if
249 * we replaced even one . -> /, start over again,
250 * but never replace dots before the position
251 * where replacement occurred. */
252 end = name + strlen(name) - 1;
253 last_good = name - 1;
256 while (cptr > last_good) {
259 if (access(name, F_OK) == 0) {
268 } /* end sysctl_dots_to_slashes() */