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 *ppfh, *pfh; 57 sigset_t mask, oldmask; 58 int ch, nochdir, noclose, restart, serrno; 59 const char *pidfile, *ppidfile, *user; 60 pid_t otherpid, pid; 61 62 nochdir = noclose = 1; 63 restart = 0; 64 ppidfile = pidfile = user = NULL; 65 while ((ch = getopt(argc, argv, "cfp:P: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 'P': 77 ppidfile = optarg; 78 break; 79 case 'r': 80 restart = 1; 81 break; 82 case 'u': 83 user = optarg; 84 break; 85 default: 86 usage(); 87 } 88 } 89 argc -= optind; 90 argv += optind; 91 92 if (argc == 0) 93 usage(); 94 95 ppfh = pfh = NULL; 96 /* 97 * Try to open the pidfile before calling daemon(3), 98 * to be able to report the error intelligently 99 */ 100 if (pidfile != NULL) { 101 pfh = pidfile_open(pidfile, 0600, &otherpid); 102 if (pfh == NULL) { 103 if (errno == EEXIST) { 104 errx(3, "process already running, pid: %d", 105 otherpid); 106 } 107 err(2, "pidfile ``%s''", pidfile); 108 } 109 } 110 /* Do the same for actual daemon process. */ 111 if (ppidfile != NULL) { 112 ppfh = pidfile_open(ppidfile, 0600, &otherpid); 113 if (ppfh == NULL) { 114 serrno = errno; 115 pidfile_remove(pfh); 116 errno = serrno; 117 if (errno == EEXIST) { 118 errx(3, "process already running, pid: %d", 119 otherpid); 120 } 121 err(2, "ppidfile ``%s''", ppidfile); 122 } 123 } 124 125 if (daemon(nochdir, noclose) == -1) { 126 warn("daemon"); 127 goto exit; 128 } 129 /* Write out parent pidfile if needed. */ 130 pidfile_write(ppfh); 131 132 /* 133 * If the pidfile or restart option is specified the daemon 134 * executes the command in a forked process and wait on child 135 * exit to remove the pidfile or restart the command. Normally 136 * we don't want the monitoring daemon to be terminated 137 * leaving the running process and the stale pidfile, so we 138 * catch SIGTERM and forward it to the children expecting to 139 * get SIGCHLD eventually. 140 */ 141 pid = -1; 142 if (pidfile != NULL || ppidfile != NULL || restart) { 143 /* 144 * Restore default action for SIGTERM in case the 145 * parent process decided to ignore it. 146 */ 147 if (signal(SIGTERM, SIG_DFL) == SIG_ERR) { 148 warn("signal"); 149 goto exit; 150 } 151 /* 152 * Because SIGCHLD is ignored by default, setup dummy handler 153 * for it, so we can mask it. 154 */ 155 if (signal(SIGCHLD, dummy_sighandler) == SIG_ERR) { 156 warn("signal"); 157 goto exit; 158 } 159 /* 160 * Block interesting signals. 161 */ 162 sigemptyset(&mask); 163 sigaddset(&mask, SIGTERM); 164 sigaddset(&mask, SIGCHLD); 165 if (sigprocmask(SIG_SETMASK, &mask, &oldmask) == -1) { 166 warn("sigprocmask"); 167 goto exit; 168 } 169 /* 170 * Try to protect against pageout kill. Ignore the 171 * error, madvise(2) will fail only if a process does 172 * not have superuser privileges. 173 */ 174 (void)madvise(NULL, 0, MADV_PROTECT); 175 restart: 176 /* 177 * Spawn a child to exec the command, so in the parent 178 * we could wait for it to exit and remove pidfile. 179 */ 180 pid = fork(); 181 if (pid == -1) { 182 warn("fork"); 183 goto exit; 184 } 185 } 186 if (pid <= 0) { 187 if (pid == 0) { 188 /* Restore old sigmask in the child. */ 189 if (sigprocmask(SIG_SETMASK, &oldmask, NULL) == -1) 190 err(1, "sigprocmask"); 191 } 192 /* Now that we are the child, write out the pid. */ 193 pidfile_write(pfh); 194 195 if (user != NULL) 196 restrict_process(user); 197 198 execvp(argv[0], argv); 199 200 /* 201 * execvp() failed -- report the error. The child is 202 * now running, so the exit status doesn't matter. 203 */ 204 err(1, "%s", argv[0]); 205 } 206 207 setproctitle("%s[%d]", argv[0], pid); 208 if (wait_child(pid, &mask) == 0 && restart) { 209 sleep(1); 210 goto restart; 211 } 212 exit: 213 pidfile_remove(pfh); 214 pidfile_remove(ppfh); 215 exit(1); /* If daemon(3) succeeded exit status does not matter. */ 216 } 217 218 static void 219 dummy_sighandler(int sig __unused) 220 { 221 /* Nothing to do. */ 222 } 223 224 static void 225 restrict_process(const char *user) 226 { 227 struct passwd *pw = NULL; 228 229 pw = getpwnam(user); 230 if (pw == NULL) 231 errx(1, "unknown user: %s", user); 232 233 if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0) 234 errx(1, "failed to set user environment"); 235 } 236 237 static int 238 wait_child(pid_t pid, sigset_t *mask) 239 { 240 int terminate, signo; 241 242 terminate = 0; 243 for (;;) { 244 if (sigwait(mask, &signo) == -1) { 245 warn("sigwaitinfo"); 246 return (-1); 247 } 248 switch (signo) { 249 case SIGCHLD: 250 if (waitpid(pid, NULL, WNOHANG) == -1) { 251 warn("waitpid"); 252 return (-1); 253 } 254 return (terminate); 255 case SIGTERM: 256 terminate = 1; 257 if (kill(pid, signo) == -1) { 258 warn("kill"); 259 return (-1); 260 } 261 continue; 262 default: 263 warnx("sigwaitinfo: invalid signal: %d", signo); 264 return (-1); 265 } 266 } 267 } 268 269 static void 270 usage(void) 271 { 272 (void)fprintf(stderr, 273 "usage: daemon [-cfr] [-p child_pidfile] [-P supervisor_pidfile] " 274 "[-u user]\n command arguments ...\n"); 275 exit(1); 276 } 277