void
double_fork() {
pid_t child, grandchild, wresult;
int status;
/* Fork once, then again, to disassociate the child from the command
shell process group. */
child = fork();
if (child < 0) {
/* Failure to fork. */
perror("fork");
exit(1);
}
if (child == 0) {
/* Child. Fork again. */
grandchild = fork();
if (grandchild < 0) {
perror("fork");
exit(1);
}
if (grandchild == 0) {
/* Grandchild. Begin useful work. */
do_autorestart();
/* Shouldn't get here. */
exit(1);
}
/* Child. Report the new pid, then terminate gracefully. */
fprintf(stderr, "Spawned, monitoring pid is %d.\n", grandchild);
exit(0);
}
/* Parent. Wait for the child to terminate, then return. */
wresult = waitpid(child, &status, 0);
if (wresult < 0) {
perror("waitpid");
exit(1);
}
if (!WIFEXITED(status)) {
if (WIFSIGNALED(status)) {
fprintf(stderr, "child caught signal %d unexpectedly.\n", WTERMSIG(status));
} else {
fprintf(stderr, "child exited with status %d.\n", WEXITSTATUS(status));
}
exit(1);
}
}
int
main(int argc, char *argv[]) {
extern char *optarg;
extern int optind;
/* The initial '+' instructs GNU getopt not to reorder switches. */
static const char *optflags = "+l:p:fntr:s:c:d:W:U:G:D:h";
int flag;
flag = getopt(argc, argv, optflags);
while (flag != EOF) {
switch (flag) {
case 'l':
logfile_name = optarg;
break;
case 'p':
pidfile_name = optarg;
break;
case 'f':
dont_fork = 1;
break;
case 'n':
stop_always = 1;
break;
case 't':
stop_on_terminate = 1;
break;
case 'r':
parse_int_triplet(optarg, &spam_respawn_count, &spam_respawn_time, &spam_restart_delay_time);
break;
case 's':
respawn_script = optarg;
break;
case 'c':
respawn_count_time = atoi(optarg);
break;
case 'd':
respawn_delay_time = atoi(optarg);
break;
case 'W':
parse_watchdog(optarg);
break;
case 'U':
startup_username = optarg;
break;
case 'G':
startup_groupname = optarg;
break;
case 'D':
startup_chdir = optarg;
break;
case 'h':
help();
return 1;
case '?':
case '+':
usage();
return 1;
default:
fprintf(stderr, "Unhandled switch: -%c\n", flag);
return 1;
}
flag = getopt(argc, argv, optflags);
}
argc -= (optind - 1);
argv += (optind - 1);
if (argc < 2) {
fprintf(stderr, "No program to execute given.\n");
usage();
return 1;
}
params = &argv[1];
if (logfile_name != NULL) {
logfile_fd = open(logfile_name, O_WRONLY | O_CREAT | O_TRUNC, 0666);
if (logfile_fd < 0) {
fprintf(stderr, "Cannot write to logfile %s: %s\n",
logfile_name, strerror(errno));
return 1;
}
fprintf(stderr, "Generating output to %s.\n", logfile_name);
}
if (startup_chdir != NULL) {
if (chdir(startup_chdir) != 0) {
perror(startup_chdir);
return 1;
}
}
if (startup_groupname != NULL) {
struct group *grp;
grp = getgrnam(startup_groupname);
if (grp == NULL) {
perror(startup_groupname);
return 1;
}
if (setgid(grp->gr_gid) != 0) {
perror(startup_groupname);
return 1;
}
}
if (startup_username != NULL) {
struct passwd *pwd;
pwd = getpwnam(startup_username);
if (pwd == NULL) {
perror(startup_username);
return 1;
}
if (setuid(pwd->pw_uid) != 0) {
perror(startup_username);
return 1;
}
}
if (dont_fork) {
do_autorestart();
} else {
double_fork();
}
return 0;
}
