summaryrefslogtreecommitdiff
path: root/procps/sysctl.c (plain)
blob: 16f91dcc2ec7f20a0a6ca7a0e2821b0155466b82
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//config:config BB_SYSCTL
14//config: bool "sysctl"
15//config: default y
16//config: help
17//config: Configure kernel parameters at runtime.
18
19//applet:IF_BB_SYSCTL(APPLET(sysctl, BB_DIR_SBIN, BB_SUID_DROP))
20
21//kbuild:lib-$(CONFIG_BB_SYSCTL) += sysctl.o
22
23//usage:#define sysctl_trivial_usage
24//usage: "[OPTIONS] [KEY[=VALUE]]..."
25//usage:#define sysctl_full_usage "\n\n"
26//usage: "Show/set kernel parameters\n"
27//usage: "\n -e Don't warn about unknown keys"
28//usage: "\n -n Don't show key names"
29//usage: "\n -a Show all values"
30/* Same as -a, no need to show it */
31/* //usage: "\n -A Show all values in table form" */
32//usage: "\n -w Set values"
33//usage: "\n -p FILE Set values from FILE (default /etc/sysctl.conf)"
34//usage: "\n -q Set values silently"
35//usage:
36//usage:#define sysctl_example_usage
37//usage: "sysctl [-n] [-e] variable...\n"
38//usage: "sysctl [-n] [-e] [-q] -w variable=value...\n"
39//usage: "sysctl [-n] [-e] -a\n"
40//usage: "sysctl [-n] [-e] [-q] -p file (default /etc/sysctl.conf)\n"
41//usage: "sysctl [-n] [-e] -A\n"
42
43#include "libbb.h"
44
45enum {
46 FLAG_SHOW_KEYS = 1 << 0,
47 FLAG_SHOW_KEY_ERRORS = 1 << 1,
48 FLAG_TABLE_FORMAT = 1 << 2, /* not implemented */
49 FLAG_SHOW_ALL = 1 << 3,
50 FLAG_PRELOAD_FILE = 1 << 4,
51/* TODO: procps 3.2.8 seems to not require -w for KEY=VAL to work: */
52 FLAG_WRITE = 1 << 5,
53 FLAG_QUIET = 1 << 6,
54};
55#define OPTION_STR "neAapwq"
56
57static void sysctl_dots_to_slashes(char *name)
58{
59 char *cptr, *last_good, *end;
60
61 /* Convert minimum number of '.' to '/' so that
62 * we end up with existing file's name.
63 *
64 * Example from bug 3894:
65 * net.ipv4.conf.eth0.100.mc_forwarding ->
66 * net/ipv4/conf/eth0.100/mc_forwarding
67 * NB: net/ipv4/conf/eth0/mc_forwarding *also exists*,
68 * therefore we must start from the end, and if
69 * we replaced even one . -> /, start over again,
70 * but never replace dots before the position
71 * where last replacement occurred.
72 *
73 * Another bug we later had is that
74 * net.ipv4.conf.eth0.100
75 * (without .mc_forwarding) was mishandled.
76 *
77 * To set up testing: modprobe 8021q; vconfig add eth0 100
78 */
79 end = name + strlen(name);
80 last_good = name - 1;
81 *end = '.'; /* trick the loop into trying full name too */
82
83 again:
84 cptr = end;
85 while (cptr > last_good) {
86 if (*cptr == '.') {
87 *cptr = '\0';
88 //bb_error_msg("trying:'%s'", name);
89 if (access(name, F_OK) == 0) {
90 *cptr = '/';
91 //bb_error_msg("replaced:'%s'", name);
92 last_good = cptr;
93 goto again;
94 }
95 *cptr = '.';
96 }
97 cptr--;
98 }
99 *end = '\0';
100}
101
102static int sysctl_act_on_setting(char *setting)
103{
104 int fd, retval = EXIT_SUCCESS;
105 char *cptr, *outname;
106 char *value = NULL;
107
108 outname = xstrdup(setting);
109
110 cptr = outname;
111 while (*cptr) {
112 if (*cptr == '/')
113 *cptr = '.';
114 cptr++;
115 }
116
117 if (option_mask32 & FLAG_WRITE) {
118 cptr = strchr(setting, '=');
119 if (cptr == NULL) {
120 bb_error_msg("error: '%s' must be of the form name=value",
121 outname);
122 retval = EXIT_FAILURE;
123 goto end;
124 }
125 value = cptr + 1; /* point to the value in name=value */
126 if (setting == cptr || !*value) {
127 bb_error_msg("error: malformed setting '%s'", outname);
128 retval = EXIT_FAILURE;
129 goto end;
130 }
131 *cptr = '\0';
132 outname[cptr - setting] = '\0';
133 /* procps 3.2.7 actually uses these flags */
134 fd = open(setting, O_WRONLY|O_CREAT|O_TRUNC, 0666);
135 } else {
136 fd = open(setting, O_RDONLY);
137 }
138
139 if (fd < 0) {
140 switch (errno) {
141 case EACCES:
142 /* Happens for write-only settings, e.g. net.ipv6.route.flush */
143 goto end;
144 case ENOENT:
145 if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
146 bb_error_msg("error: '%s' is an unknown key", outname);
147 break;
148 default:
149 bb_perror_msg("error %sing key '%s'",
150 option_mask32 & FLAG_WRITE ?
151 "sett" : "read",
152 outname);
153 break;
154 }
155 retval = EXIT_FAILURE;
156 goto end;
157 }
158
159 if (option_mask32 & FLAG_WRITE) {
160//TODO: procps 3.2.7 writes "value\n", note trailing "\n"
161 xwrite_str(fd, value);
162 close(fd);
163 if (!(option_mask32 & FLAG_QUIET)) {
164 if (option_mask32 & FLAG_SHOW_KEYS)
165 printf("%s = ", outname);
166 puts(value);
167 }
168 } else {
169 char c;
170
171 value = cptr = xmalloc_read(fd, NULL);
172 close(fd);
173 if (value == NULL) {
174 bb_perror_msg("error reading key '%s'", outname);
175 goto end;
176 }
177
178 /* dev.cdrom.info and sunrpc.transports, for example,
179 * are multi-line. Try "sysctl sunrpc.transports"
180 */
181 while ((c = *cptr) != '\0') {
182 if (option_mask32 & FLAG_SHOW_KEYS)
183 printf("%s = ", outname);
184 while (1) {
185 fputc(c, stdout);
186 cptr++;
187 if (c == '\n')
188 break;
189 c = *cptr;
190 if (c == '\0')
191 break;
192 }
193 }
194 free(value);
195 }
196 end:
197 free(outname);
198 return retval;
199}
200
201static int sysctl_act_recursive(const char *path)
202{
203 DIR *dirp;
204 struct stat buf;
205 struct dirent *entry;
206 char *next;
207 int retval = 0;
208
209 stat(path, &buf);
210 if (S_ISDIR(buf.st_mode) && !(option_mask32 & FLAG_WRITE)) {
211 dirp = opendir(path);
212 if (dirp == NULL)
213 return -1;
214 while ((entry = readdir(dirp)) != NULL) {
215 next = concat_subpath_file(path, entry->d_name);
216 if (next == NULL)
217 continue; /* d_name is "." or ".." */
218 /* if path was ".", drop "./" prefix: */
219 retval |= sysctl_act_recursive((next[0] == '.' && next[1] == '/') ?
220 next + 2 : next);
221 free(next);
222 }
223 closedir(dirp);
224 } else {
225 char *name = xstrdup(path);
226 retval |= sysctl_act_on_setting(name);
227 free(name);
228 }
229
230 return retval;
231}
232
233/* Set sysctl's from a conf file. Format example:
234 * # Controls IP packet forwarding
235 * net.ipv4.ip_forward = 0
236 */
237static int sysctl_handle_preload_file(const char *filename)
238{
239 char *token[2];
240 parser_t *parser;
241
242 parser = config_open(filename);
243 /* Must do it _after_ config_open(): */
244 xchdir("/proc/sys");
245 /* xchroot("/proc/sys") - if you are paranoid */
246
247//TODO: ';' is comment char too
248//TODO: comment may be only at line start. "var=1 #abc" - "1 #abc" is the value
249// (but _whitespace_ from ends should be trimmed first (and we do it right))
250//TODO: "var==1" is mishandled (must use "=1" as a value, but uses "1")
251// can it be fixed by removing PARSE_COLLAPSE bit?
252 while (config_read(parser, token, 2, 2, "# \t=", PARSE_NORMAL)) {
253 char *tp;
254 sysctl_dots_to_slashes(token[0]);
255 tp = xasprintf("%s=%s", token[0], token[1]);
256 sysctl_act_recursive(tp);
257 free(tp);
258 }
259 if (ENABLE_FEATURE_CLEAN_UP)
260 config_close(parser);
261 return 0;
262}
263
264int sysctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
265int sysctl_main(int argc UNUSED_PARAM, char **argv)
266{
267 int retval;
268 int opt;
269
270 opt = getopt32(argv, "+" OPTION_STR); /* '+' - stop on first non-option */
271 argv += optind;
272 opt ^= (FLAG_SHOW_KEYS | FLAG_SHOW_KEY_ERRORS);
273 option_mask32 = opt;
274
275 if (opt & FLAG_PRELOAD_FILE) {
276 option_mask32 |= FLAG_WRITE;
277 /* xchdir("/proc/sys") is inside */
278 return sysctl_handle_preload_file(*argv ? *argv : "/etc/sysctl.conf");
279 }
280 xchdir("/proc/sys");
281 /* xchroot("/proc/sys") - if you are paranoid */
282 if (opt & (FLAG_TABLE_FORMAT | FLAG_SHOW_ALL)) {
283 return sysctl_act_recursive(".");
284 }
285
286 retval = 0;
287 while (*argv) {
288 sysctl_dots_to_slashes(*argv);
289 retval |= sysctl_act_recursive(*argv);
290 argv++;
291 }
292
293 return retval;
294}
295
generated by cgit at 2024-05-15 00:36:58 (GMT)