defined.c revision 270096 
1/*-
2 * Copyright (c) 2014 The FreeBSD Foundation
3 * All rights reserved.
4 *
5 * This software was developed by Edward Tomasz Napierala under sponsorship
6 * from the FreeBSD Foundation.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD: head/usr.sbin/autofs/defined.c 270096 2014-08-17 09:44:42Z trasz $
30 */
31
32/*
33 * All the "defined" stuff is for handling variables,
34 * such as ${OSNAME}, in maps.
35 */
36
37#include <sys/types.h>
38#include <sys/time.h>
39#include <sys/ioctl.h>
40#include <sys/param.h>
41#include <sys/linker.h>
42#include <sys/mount.h>
43#include <sys/socket.h>
44#include <sys/stat.h>
45#include <sys/wait.h>
46#include <sys/utsname.h>
47#include <assert.h>
48#include <ctype.h>
49#include <errno.h>
50#include <fcntl.h>
51#include <libgen.h>
52#include <netdb.h>
53#include <signal.h>
54#include <stdbool.h>
55#include <stdint.h>
56#include <stdio.h>
57#include <stdlib.h>
58#include <string.h>
59#include <unistd.h>
60
61#include <libutil.h>
62
63#include "common.h"
64
65static TAILQ_HEAD(, defined_value)	defined_values;
66
67static const char *
68defined_find(const char *name)
69{
70	struct defined_value *d;
71
72	TAILQ_FOREACH(d, &defined_values, d_next) {
73		if (strcmp(d->d_name, name) == 0)
74			return (d->d_value);
75	}
76
77	return (NULL);
78}
79
80char *
81defined_expand(const char *string)
82{
83	const char *value;
84	char c, *expanded, *name;
85	int i, ret, before_len = 0, name_off = 0, name_len = 0, after_off = 0;
86	bool backslashed = false, bracketed = false;
87
88	expanded = checked_strdup(string);
89
90	for (i = 0; string[i] != '\0'; i++) {
91		c = string[i];
92		if (c == '\\' && backslashed == false) {
93			backslashed = true;
94			continue;
95		}
96		if (backslashed) {
97			backslashed = false;
98			continue;
99		}
100		backslashed = false;
101		if (c != '$')
102			continue;
103
104		/*
105		 * The 'before_len' variable contains the number
106		 * of characters before the '$'.
107		 */
108		before_len = i;
109		assert(i + 1 < (int)strlen(string));
110		if (string[i + 1] == '{')
111			bracketed = true;
112
113		if (string[i + 1] == '\0') {
114			log_warnx("truncated variable");
115			return (NULL);
116		}
117
118		/*
119		 * Skip '$'.
120		 */
121		i++;
122
123		if (bracketed) {
124			if (string[i + 1] == '\0') {
125				log_warnx("truncated variable");
126				return (NULL);
127			}
128
129			/*
130			 * Skip '{'.
131			 */
132			i++;
133		}
134
135		/*
136		 * The 'name_off' variable contains the number
137		 * of characters before the variable name,
138		 * including the "$" or "${".
139		 */
140		name_off = i;
141
142		for (; string[i] != '\0'; i++) {
143			c = string[i];
144			/*
145			 * XXX: Decide on the set of characters that can be
146			 *	used in a variable name.
147			 */
148			if (isalnum(c) || c == '_')
149				continue;
150
151			/*
152			 * End of variable name.
153			 */
154			if (bracketed) {
155				if (c != '}')
156					continue;
157
158				/*
159				 * The 'after_off' variable contains the number
160				 * of characters before the rest of the string,
161				 * i.e. after the variable name.
162				 */
163				after_off = i + 1;
164				assert(i > 1);
165				assert(i - 1 > name_off);
166				name_len = i - name_off;
167				break;
168			}
169
170			after_off = i;
171			assert(i > 1);
172			assert(i > name_off);
173			name_len = i - name_off;
174			break;
175		}
176
177		name = strndup(string + name_off, name_len);
178		if (name == NULL)
179			log_err(1, "strndup");
180		value = defined_find(name);
181		if (value == NULL) {
182			log_warnx("undefined variable ${%s}", name);
183			return (NULL);
184		}
185
186		/*
187		 * Concatenate it back.
188		 */
189		ret = asprintf(&expanded, "%.*s%s%s",
190		    before_len, string, value, string + after_off);
191		if (ret < 0)
192			log_err(1, "asprintf");
193
194		//log_debugx("\"%s\" expanded to \"%s\"", string, expanded);
195		free(name);
196
197		/*
198		 * Figure out where to start searching for next variable.
199		 */
200		string = expanded;
201		i = before_len + strlen(value);
202		backslashed = bracketed = false;
203		before_len = name_off = name_len = after_off = 0;
204		assert(i <= (int)strlen(string));
205	}
206
207	if (before_len != 0 || name_off != 0 || name_len != 0 || after_off != 0) {
208		log_warnx("truncated variable");
209		return (NULL);
210	}
211
212	return (expanded);
213}
214
215static void
216defined_add(const char *name, const char *value)
217{
218	struct defined_value *d;
219	const char *found;
220
221	found = defined_find(name);
222	if (found != NULL)
223		log_errx(1, "variable %s already defined", name);
224
225	log_debugx("defining variable %s=%s", name, value);
226
227	d = calloc(sizeof(*d), 1);
228	if (d == NULL)
229		log_err(1, "calloc");
230	d->d_name = checked_strdup(name);
231	d->d_value = checked_strdup(value);
232
233	TAILQ_INSERT_TAIL(&defined_values, d, d_next);
234}
235
236void
237defined_parse_and_add(char *def)
238{
239	char *name, *value;
240
241	value = def;
242	name = strsep(&value, "=");
243
244	if (value == NULL || value[0] == '\0')
245		log_errx(1, "missing variable value");
246	if (name == NULL || name[0] == '\0')
247		log_errx(1, "missing variable name");
248
249	defined_add(name, value);
250}
251
252void
253defined_init(void)
254{
255	struct utsname name;
256	int error;
257
258	TAILQ_INIT(&defined_values);
259
260	error = uname(&name);
261	if (error != 0)
262		log_err(1, "uname");
263
264	defined_add("ARCH", name.machine);
265	defined_add("CPU", name.machine);
266	defined_add("HOST", name.nodename);
267	defined_add("OSNAME", name.sysname);
268	defined_add("OSREL", name.release);
269	defined_add("OSVERS", name.version);
270}
271