1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
24 */
25
26 #include "mt.h"
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <string.h>
30 #include <sys/param.h>
31 #include <sys/types.h>
32 #include <sys/stat.h>
33 #include <time.h>
34 #include <wait.h>
35 #include <fcntl.h>
36 #include <thread.h>
37 #include <unistd.h>
38 #include <errno.h>
39 #include <ucontext.h>
40 #include <syslog.h>
41 #include <rpcsvc/daemon_utils.h>
42
43 static int open_daemon_lock(const char *, int);
44
45 /*
46 * Use an advisory lock to ensure that only one daemon process is
47 * active in the system at any point in time. If the lock is held
48 * by another process, do not block but return the pid owner of
49 * the lock to the caller immediately. The lock is cleared if the
50 * holding daemon process exits for any reason even if the lock
51 * file remains, so the daemon can be restarted if necessary.
52 */
53
54 /*
55 * check if another process is holding lock on the lock file.
56 *
57 * return: 0 if file is not locked, else,
58 * 1 if file is locked by another process, else,
59 * -1 on any error.
60 */
61 int
_check_daemon_lock(const char * name)62 _check_daemon_lock(const char *name)
63 {
64 int fd, err;
65 struct flock lock;
66
67 if ((fd = open_daemon_lock(name, O_RDONLY)) == -1) {
68 if (errno == ENOENT)
69 return (0);
70 return (-1);
71 }
72
73 lock.l_type = F_WRLCK;
74 lock.l_whence = SEEK_SET;
75 lock.l_start = (off_t)0;
76 lock.l_len = (off_t)0;
77
78 err = fcntl(fd, F_GETLK, &lock);
79 (void) close(fd);
80
81 if (err == -1)
82 return (-1);
83
84 return ((lock.l_type == F_UNLCK) ? 0 : 1);
85 }
86
87 static int
open_daemon_lock(const char * name,int mode)88 open_daemon_lock(const char *name, int mode)
89 {
90 char lock_file[MAXPATHLEN], buf[MAXPATHLEN];
91 int fd;
92 char *p;
93
94 /*
95 * Our args look like this:
96 * svc:/network/nfs/status:default
97 * We want to create a lock file named like this:
98 * /etc/svc/volatile/nfs-status.lock
99 * i.e., we want the last two path components in the name.
100 */
101 (void) strncpy(buf, name, MAXPATHLEN);
102
103 /* First, strip off ":<instance>", if present. */
104 p = strrchr(buf, ':');
105 if (p != NULL)
106 *p = '\0';
107
108 /* Next, find final '/' and replace it with a dash */
109 p = strrchr(buf, '/');
110 if (p == NULL)
111 p = buf;
112 else {
113 *p = '-';
114 /* Now find the start of what we want our name to be */
115 p = strrchr(buf, '/');
116 if (p == NULL)
117 p = buf;
118 else
119 p++;
120 }
121
122 (void) snprintf(lock_file, MAXPATHLEN, "/etc/svc/volatile/%s.lock", p);
123
124 if ((fd = open(lock_file, mode, 0644)) == -1)
125 return (-1);
126
127 if (mode & O_CREAT)
128 (void) fchmod(fd, 0644);
129
130 return (fd);
131 }
132 /*
133 * lock the file, write caller's pid to the lock file
134 * return: 0 if caller can establish lock, else,
135 * pid of the current lock holder, else,
136 * -1 on any printable error.
137 */
138 pid_t
_enter_daemon_lock(const char * name)139 _enter_daemon_lock(const char *name)
140 {
141 int fd;
142 pid_t pid;
143 char line[BUFSIZ];
144 struct flock lock;
145
146 pid = getpid();
147 (void) snprintf(line, sizeof (line), "%ld\n", pid);
148
149 if ((fd = open_daemon_lock(name, O_RDWR|O_CREAT)) == -1)
150 return ((pid_t)-1);
151
152 lock.l_type = F_WRLCK;
153 lock.l_whence = SEEK_SET;
154 lock.l_start = (off_t)0;
155 lock.l_len = (off_t)0;
156
157 if (fcntl(fd, F_SETLK, &lock) == -1) {
158 if (fcntl(fd, F_GETLK, &lock) == -1) {
159 (void) close(fd);
160 return ((pid_t)-1);
161 }
162 (void) close(fd);
163 return (lock.l_pid);
164 }
165
166 if (write(fd, line, strlen(line)) == -1) {
167 (void) close(fd);
168 return ((pid_t)-1);
169 }
170
171 return ((pid_t)0);
172 }
173
174 int
_create_daemon_lock(const char * name,uid_t uid,gid_t gid)175 _create_daemon_lock(const char *name, uid_t uid, gid_t gid)
176 {
177 int fd = open_daemon_lock(name, O_CREAT);
178 int ret;
179
180 if (fd < 0)
181 return (-1);
182
183 ret = fchown(fd, uid, gid);
184 (void) close(fd);
185
186 return (ret);
187 }
188