fsshare.c revision 209757 
1/*-
2 * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/cddl/compat/opensolaris/misc/fsshare.c 209757 2010-07-07 07:09:33Z mm $");
29
30#include <sys/param.h>
31#include <stdio.h>
32#include <unistd.h>
33#include <fcntl.h>
34#include <string.h>
35#include <errno.h>
36#include <libutil.h>
37#include <assert.h>
38#include <pathnames.h>	/* _PATH_MOUNTDPID */
39#include <fsshare.h>
40
41#define	FILE_HEADER	"# !!! DO NOT EDIT THIS FILE MANUALLY !!!\n\n"
42#define	OPTSSIZE	1024
43#define	MAXLINESIZE	(PATH_MAX + OPTSSIZE)
44
45static void
46restart_mountd(void)
47{
48	struct pidfh *pfh;
49	pid_t mountdpid;
50
51	pfh = pidfile_open(_PATH_MOUNTDPID, 0600, &mountdpid);
52	if (pfh != NULL) {
53		/* Mountd is not running. */
54		pidfile_remove(pfh);
55		return;
56	}
57	if (errno != EEXIST) {
58		/* Cannot open pidfile for some reason. */
59		return;
60	}
61	/* We have mountd(8) PID in mountdpid varible. */
62	kill(mountdpid, SIGHUP);
63}
64
65/*
66 * Read one line from a file. Skip comments, empty lines and a line with a
67 * mountpoint specified in the 'skip' argument.
68 */
69static char *
70getline(FILE *fd, const char *skip)
71{
72	static char line[MAXLINESIZE];
73	size_t len, skiplen;
74	char *s, last;
75
76	if (skip != NULL)
77		skiplen = strlen(skip);
78	for (;;) {
79		s = fgets(line, sizeof(line), fd);
80		if (s == NULL)
81			return (NULL);
82		/* Skip empty lines and comments. */
83		if (line[0] == '\n' || line[0] == '#')
84			continue;
85		len = strlen(line);
86		if (line[len - 1] == '\n')
87			line[len - 1] = '\0';
88		last = line[skiplen];
89		/* Skip the given mountpoint. */
90		if (skip != NULL && strncmp(skip, line, skiplen) == 0 &&
91		    (last == '\t' || last == ' ' || last == '\0')) {
92			continue;
93		}
94		break;
95	}
96	return (line);
97}
98
99/*
100 * Function translate options to a format acceptable by exports(5), eg.
101 *
102 *	-ro -network=192.168.0.0 -mask=255.255.255.0 -maproot=0 freefall.freebsd.org 69.147.83.54
103 *
104 * Accepted input formats:
105 *
106 *	ro,network=192.168.0.0,mask=255.255.255.0,maproot=0,freefall.freebsd.org
107 *	ro network=192.168.0.0 mask=255.255.255.0 maproot=0 freefall.freebsd.org
108 *	-ro,-network=192.168.0.0,-mask=255.255.255.0,-maproot=0,freefall.freebsd.org
109 *	-ro -network=192.168.0.0 -mask=255.255.255.0 -maproot=0 freefall.freebsd.org
110 *
111 * Recognized keywords:
112 *
113 *	ro, maproot, mapall, mask, network, sec, alldirs, public, webnfs, index, quiet
114 *
115 */
116static const char *known_opts[] = { "ro", "maproot", "mapall", "mask",
117    "network", "sec", "alldirs", "public", "webnfs", "index", "quiet", NULL };
118static char *
119translate_opts(const char *shareopts)
120{
121	static char newopts[OPTSSIZE];
122	char oldopts[OPTSSIZE];
123	char *o, *s = NULL;
124	unsigned int i;
125	size_t len;
126
127	strlcpy(oldopts, shareopts, sizeof(oldopts));
128	newopts[0] = '\0';
129	s = oldopts;
130	while ((o = strsep(&s, "-, ")) != NULL) {
131		if (o[0] == '\0')
132			continue;
133		for (i = 0; known_opts[i] != NULL; i++) {
134			len = strlen(known_opts[i]);
135			if (strncmp(known_opts[i], o, len) == 0 &&
136			    (o[len] == '\0' || o[len] == '=')) {
137				strlcat(newopts, "-", sizeof(newopts));
138				break;
139			}
140		}
141		strlcat(newopts, o, sizeof(newopts));
142		strlcat(newopts, " ", sizeof(newopts));
143	}
144	return (newopts);
145}
146
147static int
148fsshare_main(const char *file, const char *mountpoint, const char *shareopts,
149    int share)
150{
151	char tmpfile[PATH_MAX];
152	char *line;
153	FILE *newfd, *oldfd;
154	int fd, error;
155
156	newfd = oldfd = NULL;
157	error = 0;
158
159	/*
160	 * Create temporary file in the same directory, so we can atomically
161	 * rename it.
162	 */
163	if (strlcpy(tmpfile, file, sizeof(tmpfile)) >= sizeof(tmpfile))
164		return (ENAMETOOLONG);
165	if (strlcat(tmpfile, ".XXXXXXXX", sizeof(tmpfile)) >= sizeof(tmpfile))
166		return (ENAMETOOLONG);
167	fd = mkstemp(tmpfile);
168	if (fd == -1)
169		return (errno);
170	/*
171	 * File name is random, so we don't really need file lock now, but it
172	 * will be needed after rename(2).
173	 */
174	error = flock(fd, LOCK_EX);
175	assert(error == 0 || (error == -1 && errno == EOPNOTSUPP));
176	newfd = fdopen(fd, "r+");
177	assert(newfd != NULL);
178	/* Open old exports file. */
179	oldfd = fopen(file, "r");
180	if (oldfd == NULL) {
181		if (share) {
182			if (errno != ENOENT) {
183				error = errno;
184				goto out;
185			}
186		} else {
187			/* If there is no exports file, ignore the error. */
188			if (errno == ENOENT)
189				errno = 0;
190			error = errno;
191			goto out;
192		}
193	} else {
194		error = flock(fileno(oldfd), LOCK_EX);
195		assert(error == 0 || (error == -1 && errno == EOPNOTSUPP));
196		error = 0;
197	}
198
199	/* Place big, fat warning at the begining of the file. */
200	fprintf(newfd, "%s", FILE_HEADER);
201	while (oldfd != NULL && (line = getline(oldfd, mountpoint)) != NULL)
202		fprintf(newfd, "%s\n", line);
203	if (oldfd != NULL && ferror(oldfd) != 0) {
204		error = ferror(oldfd);
205		goto out;
206	}
207	if (ferror(newfd) != 0) {
208		error = ferror(newfd);
209		goto out;
210	}
211	if (share) {
212		fprintf(newfd, "%s\t%s\n", mountpoint,
213		    translate_opts(shareopts));
214	}
215
216out:
217	if (error != 0)
218		unlink(tmpfile);
219	else {
220		if (rename(tmpfile, file) == -1) {
221			error = errno;
222			unlink(tmpfile);
223		} else {
224			/*
225			 * Send SIGHUP to mountd, but unlock exports file later.
226			 */
227			restart_mountd();
228		}
229	}
230	if (oldfd != NULL) {
231		flock(fileno(oldfd), LOCK_UN);
232		fclose(oldfd);
233	}
234	if (newfd != NULL) {
235		flock(fileno(newfd), LOCK_UN);
236		fclose(newfd);
237	}
238	return (error);
239}
240
241/*
242 * Add the given mountpoint to the given exports file.
243 */
244int
245fsshare(const char *file, const char *mountpoint, const char *shareopts)
246{
247
248	return (fsshare_main(file, mountpoint, shareopts, 1));
249}
250
251/*
252 * Remove the given mountpoint from the given exports file.
253 */
254int
255fsunshare(const char *file, const char *mountpoint)
256{
257
258	return (fsshare_main(file, mountpoint, NULL, 0));
259}
260