1 /*- 2 * Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. Berkeley Software Design Inc's name may not be used to endorse or 13 * promote products derived from this software without specific prior 14 * written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * From BSDI: daemon.c,v 1.2 1996/08/15 01:11:09 jch Exp 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #include <sys/param.h> 35 #include <sys/mman.h> 36 #include <sys/wait.h> 37 38 #include <err.h> 39 #include <errno.h> 40 #include <libutil.h> 41 #include <login_cap.h> 42 #include <pwd.h> 43 #include <signal.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <unistd.h> 47 48 static void dummy_sighandler(int); 49 static void restrict_process(const char *); 50 static int wait_child(pid_t pid, sigset_t *mask); 51 static void usage(void); 52 53 int 54 main(int argc, char *argv[]) 55 { 56 struct pidfh *pfh = NULL; 57 sigset_t mask, oldmask; 58 int ch, nochdir, noclose, restart; 59 const char *pidfile, *user; 60 pid_t otherpid, pid; 61 62 nochdir = noclose = 1; 63 restart = 0; 64 pidfile = user = NULL; 65 while ((ch = getopt(argc, argv, "cfp:ru:")) != -1) { 66 switch (ch) { 67 case 'c': 68 nochdir = 0; 69 break; 70 case 'f': 71 noclose = 0; 72 break; 73 case 'p': 74 pidfile = optarg; 75 break; 76 case 'r': 77 restart = 1; 78 break; 79 case 'u': 80 user = optarg; 81 break; 82 default: 83 usage(); 84 } 85 } 86 argc -= optind; 87 argv += optind; 88 89 if (argc == 0) 90 usage(); 91 92 pfh = NULL; 93 /* 94 * Try to open the pidfile before calling daemon(3), 95 * to be able to report the error intelligently 96 */ 97 if (pidfile != NULL) { 98 pfh = pidfile_open(pidfile, 0600, &otherpid); 99 if (pfh == NULL) { 100 if (errno == EEXIST) { 101 errx(3, "process already running, pid: %d", 102 otherpid); 103 } 104 err(2, "pidfile ``%s''", pidfile); 105 } 106 } 107 108 if (daemon(nochdir, noclose) == -1) 109 err(1, NULL); 110 111 /* 112 * If the pidfile or restart option is specified the daemon 113 * executes the command in a forked process and wait on child 114 * exit to remove the pidfile or restart the command. Normally 115 * we don't want the monitoring daemon to be terminated 116 * leaving the running process and the stale pidfile, so we 117 * catch SIGTERM and forward it to the children expecting to 118 * get SIGCHLD eventually. 119 */ 120 pid = -1; 121 if (pidfile != NULL || restart) { 122 /* 123 * Restore default action for SIGTERM in case the 124 * parent process decided to ignore it. 125 */ 126 if (signal(SIGTERM, SIG_DFL) == SIG_ERR) 127 err(1, "signal"); 128 /* 129 * Because SIGCHLD is ignored by default, setup dummy handler 130 * for it, so we can mask it. 131 */ 132 if (signal(SIGCHLD, dummy_sighandler) == SIG_ERR) 133 err(1, "signal"); 134 /* 135 * Block interesting signals. 136 */ 137 sigemptyset(&mask); 138 sigaddset(&mask, SIGTERM); 139 sigaddset(&mask, SIGCHLD); 140 if (sigprocmask(SIG_SETMASK, &mask, &oldmask) == -1) 141 err(1, "sigprocmask"); 142 /* 143 * Try to protect against pageout kill. Ignore the 144 * error, madvise(2) will fail only if a process does 145 * not have superuser privileges. 146 */ 147 (void)madvise(NULL, 0, MADV_PROTECT); 148 restart: 149 /* 150 * Spawn a child to exec the command, so in the parent 151 * we could wait for it to exit and remove pidfile. 152 */ 153 pid = fork(); 154 if (pid == -1) { 155 pidfile_remove(pfh); 156 err(1, "fork"); 157 } 158 } 159 if (pid <= 0) { 160 if (pid == 0) { 161 /* Restore old sigmask in the child. */ 162 if (sigprocmask(SIG_SETMASK, &oldmask, NULL) == -1) 163 err(1, "sigprocmask"); 164 } 165 /* Now that we are the child, write out the pid. */ 166 pidfile_write(pfh); 167 168 if (user != NULL) 169 restrict_process(user); 170 171 execvp(argv[0], argv); 172 173 /* 174 * execvp() failed -- report the error. The child is 175 * now running, so the exit status doesn't matter. 176 */ 177 err(1, "%s", argv[0]); 178 } 179 setproctitle("%s[%d]", argv[0], pid); 180 if (wait_child(pid, &mask) == 0 && restart) { 181 sleep(1); 182 goto restart; 183 } 184 pidfile_remove(pfh); 185 exit(0); /* Exit status does not matter. */ 186 } 187 188 static void 189 dummy_sighandler(int sig __unused) 190 { 191 /* Nothing to do. */ 192 } 193 194 static void 195 restrict_process(const char *user) 196 { 197 struct passwd *pw = NULL; 198 199 pw = getpwnam(user); 200 if (pw == NULL) 201 errx(1, "unknown user: %s", user); 202 203 if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0) 204 errx(1, "failed to set user environment"); 205 } 206 207 static int 208 wait_child(pid_t pid, sigset_t *mask) 209 { 210 int terminate, signo; 211 212 terminate = 0; 213 for (;;) { 214 if (sigwait(mask, &signo) == -1) { 215 warn("sigwaitinfo"); 216 return (-1); 217 } 218 switch (signo) { 219 case SIGCHLD: 220 if (waitpid(pid, NULL, WNOHANG) == -1) { 221 warn("waitpid"); 222 return (-1); 223 } 224 return (terminate); 225 case SIGTERM: 226 terminate = 1; 227 if (kill(pid, signo) == -1) { 228 warn("kill"); 229 return (-1); 230 } 231 continue; 232 default: 233 warnx("sigwaitinfo: invalid signal: %d", signo); 234 return (-1); 235 } 236 } 237 } 238 239 static void 240 usage(void) 241 { 242 (void)fprintf(stderr, 243 "usage: daemon [-cfr] [-p pidfile] [-u user] command " 244 "arguments ...\n"); 245 exit(1); 246 } 247