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
16enum {
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
26static 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				*cptr = '/';
60				//bb_error_msg("replaced:'%s'", name);
61				last_good = cptr;
62				goto again;
63			}
64			*cptr = '.';
65		}
66		cptr--;
67	}
68	*end = '\0';
69}
70
71static int sysctl_act_on_setting(char *setting)
72{
73	int fd, retval = EXIT_SUCCESS;
74	char *cptr, *outname;
75	char *value = value; /* for compiler */
76
77	outname = xstrdup(setting);
78
79	cptr = outname;
80	while (*cptr) {
81		if (*cptr == '/')
82			*cptr = '.';
83		cptr++;
84	}
85
86	if (option_mask32 & FLAG_WRITE) {
87		cptr = strchr(setting, '=');
88		if (cptr == NULL) {
89			bb_error_msg("error: '%s' must be of the form name=value",
90				outname);
91			retval = EXIT_FAILURE;
92			goto end;
93		}
94		value = cptr + 1;	/* point to the value in name=value */
95		if (setting == cptr || !*value) {
96			bb_error_msg("error: malformed setting '%s'", outname);
97			retval = EXIT_FAILURE;
98			goto end;
99		}
100		*cptr = '\0';
101		outname[cptr - setting] = '\0';
102		/* procps 3.2.7 actually uses these flags */
103		fd = open(setting, O_WRONLY|O_CREAT|O_TRUNC, 0666);
104	} else {
105		fd = open(setting, O_RDONLY);
106	}
107
108	if (fd < 0) {
109		switch (errno) {
110		case ENOENT:
111			if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
112				bb_error_msg("error: '%s' is an unknown key", outname);
113			break;
114		default:
115			bb_perror_msg("error %sing key '%s'",
116					option_mask32 & FLAG_WRITE ?
117						"sett" : "read",
118					outname);
119			break;
120		}
121		retval = EXIT_FAILURE;
122		goto end;
123	}
124
125	if (option_mask32 & FLAG_WRITE) {
126//TODO: procps 3.2.7 writes "value\n", note trailing "\n"
127		xwrite_str(fd, value);
128		close(fd);
129		if (option_mask32 & FLAG_SHOW_KEYS)
130			printf("%s = ", outname);
131		puts(value);
132	} else {
133		char c;
134
135		value = cptr = xmalloc_read(fd, NULL);
136		close(fd);
137		if (value == NULL) {
138			bb_perror_msg("error reading key '%s'", outname);
139			goto end;
140		}
141
142		/* dev.cdrom.info and sunrpc.transports, for example,
143		 * are multi-line. Try "sysctl sunrpc.transports"
144		 */
145		while ((c = *cptr) != '\0') {
146			if (option_mask32 & FLAG_SHOW_KEYS)
147				printf("%s = ", outname);
148			while (1) {
149				fputc(c, stdout);
150				cptr++;
151				if (c == '\n')
152					break;
153				c = *cptr;
154				if (c == '\0')
155					break;
156			}
157		}
158		free(value);
159	}
160 end:
161	free(outname);
162	return retval;
163}
164
165static int sysctl_act_recursive(const char *path)
166{
167	DIR *dirp;
168	struct stat buf;
169	struct dirent *entry;
170	char *next;
171	int retval = 0;
172
173	stat(path, &buf);
174	if (S_ISDIR(buf.st_mode) && !(option_mask32 & FLAG_WRITE)) {
175		dirp = opendir(path);
176		if (dirp == NULL)
177			return -1;
178		while ((entry = readdir(dirp)) != NULL) {
179			next = concat_subpath_file(path, entry->d_name);
180			if (next == NULL)
181				continue; /* d_name is "." or ".." */
182			/* if path was ".", drop "./" prefix: */
183			retval |= sysctl_act_recursive((next[0] == '.' && next[1] == '/') ?
184					    next + 2 : next);
185			free(next);
186		}
187		closedir(dirp);
188	} else {
189		char *name = xstrdup(path);
190		retval |= sysctl_act_on_setting(name);
191		free(name);
192	}
193
194	return retval;
195}
196
197/* Set sysctl's from a conf file. Format example:
198 * # Controls IP packet forwarding
199 * net.ipv4.ip_forward = 0
200 */
201static int sysctl_handle_preload_file(const char *filename)
202{
203	char *token[2];
204	parser_t *parser;
205
206	parser = config_open(filename);
207	/* Must do it _after_ config_open(): */
208	xchdir("/proc/sys");
209	/* xchroot(".") - if you are paranoid */
210
211//TODO: ';' is comment char too
212//TODO: comment may be only at line start. "var=1 #abc" - "1 #abc" is the value
213// (but _whitespace_ from ends should be trimmed first (and we do it right))
214//TODO: "var==1" is mishandled (must use "=1" as a value, but uses "1")
215// can it be fixed by removing PARSE_COLLAPSE bit?
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
228int sysctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
229int 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}
259