/* the echo service. stupid, but useful for testing */
static int qh_echo(int sd, char *buf, unsigned int len)
{
if (!strcmp(buf, "help")) {
nsock_printf_nul(sd,
"Query handler that simply echoes back what you send it.");
return 0;
}
return nsock_write_all(sd, buf, len);
}
int daemon_init(void)
{
int pid = 0;
int lockfile = 0;
int val = 0;
char buf[256];
struct flock lock;
if (set_working_directory() == (ERROR)) {
return (ERROR);
}
umask(S_IWGRP | S_IWOTH);
lockfile = open(lock_file, O_RDWR | O_CREAT, S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH);
if (lockfile < 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Failed to obtain lock on file %s: %s\n", lock_file, strerror(errno));
nm_log(NSLOG_PROCESS_INFO | NSLOG_RUNTIME_ERROR, "Bailing out due to errors encountered while attempting to daemonize... (PID=%d)", (int)getpid());
return (ERROR);
}
/* see if we can read the contents of the lockfile */
if ((val = read(lockfile, buf, (size_t)10)) < 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Lockfile exists but cannot be read");
return (ERROR);
}
/* we read something - check the PID */
if (val > 0) {
if ((val = sscanf(buf, "%d", &pid)) < 1) {
nm_log(NSLOG_RUNTIME_ERROR, "Lockfile '%s' does not contain a valid PID (%s)", lock_file, buf);
return (ERROR);
}
}
/* check for SIGHUP */
if (val == 1 && pid == (int)getpid()) {
return OK;
}
else {
lock.l_type = F_WRLCK;
lock.l_start = 0;
lock.l_whence = SEEK_SET;
lock.l_len = 0;
if (fcntl(lockfile, F_GETLK, &lock) == -1) {
nm_log(NSLOG_RUNTIME_ERROR, "Failed to access lockfile '%s'. %s. Bailing out...", lock_file, strerror(errno));
return (ERROR);
}
if (lock.l_type != F_UNLCK) {
nm_log(NSLOG_RUNTIME_ERROR, "Lockfile '%s' looks like its already held by another instance of Naemon (PID %d). Bailing out, pre-fork...", lock_file, (int)lock.l_pid);
return (ERROR);
}
}
/*
* set up a pipe used for sending a message from the child to the parent
* when initialization is complete.
*/
if (pipe(upipe_fd) < 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Failed to set up unnamned pipe: %s",
strerror(errno));
return (ERROR);
}
if ((pid = (int)fork()) < 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Unable to fork out the daemon process: %s",
strerror(errno));
return (ERROR);
} else if (pid != 0) {
/* parent stops - when child is done, we exit here */
int return_code = EXIT_FAILURE;
if (close(upipe_fd[PIPE_WRITE]) < 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Unable to close parent write end: %s",
strerror(errno));
return_code = EXIT_FAILURE;
}
/*
* wait for child to send the OK return code, if the child dies
* we stop blocking and the return code remains EXIT_FAILURE.
*/
if (read(upipe_fd[PIPE_READ], &return_code, sizeof(int)) < 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Unable to read from pipe: %s",
strerror(errno));
return_code = EXIT_FAILURE;
}
if (close(upipe_fd[PIPE_READ]) < 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Unable to close parent read end: %s",
strerror(errno));
return_code = EXIT_FAILURE;
}
if (return_code != OK) {
/* signal the child to die in case an error occurs in parent */
kill(pid, SIGTERM);
}
exit(return_code);
} else {
/* close read end of the pipe in the child */
if (close(upipe_fd[PIPE_READ]) < 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Unable to close child read end: %s",
strerror(errno));
return ERROR;
}
}
/* child becomes session leader... */
setsid();
/* place a file lock on the lock file */
lock.l_type = F_WRLCK;
lock.l_start = 0;
lock.l_whence = SEEK_SET;
lock.l_len = 0;
lock.l_pid = getpid();
if (fcntl(lockfile, F_SETLK, &lock) == -1) {
if (errno == EACCES || errno == EAGAIN) {
fcntl(lockfile, F_GETLK, &lock);
nm_log(NSLOG_RUNTIME_ERROR, "Lockfile '%s' looks like its already held by another instance of Naemon (PID %d). Bailing out, post-fork...", lock_file, (int)lock.l_pid);
} else
nm_log(NSLOG_RUNTIME_ERROR, "Cannot lock lockfile '%s': %s. Bailing out...", lock_file, strerror(errno));
return (ERROR);
}
/* write PID to lockfile... */
lseek(lockfile, 0, SEEK_SET);
if (ftruncate(lockfile, 0) != 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Cannot truncate lockfile '%s': %s. Bailing out...", lock_file, strerror(errno));
return (ERROR);
}
sprintf(buf, "%d\n", (int)getpid());
if (nsock_write_all(lockfile, buf, strlen(buf)) != 0) {
nm_log(NSLOG_RUNTIME_ERROR, "Cannot write PID to lockfile '%s': %s. Bailing out...", lock_file, strerror(errno));
return (ERROR);
}
/* make sure lock file stays open while program is executing... */
val = fcntl(lockfile, F_GETFD, 0);
val |= FD_CLOEXEC;
fcntl(lockfile, F_SETFD, val);
/* close existing stdin, stdout, stderr */
close(0);
close(1);
close(2);
/* THIS HAS TO BE DONE TO AVOID PROBLEMS WITH STDERR BEING REDIRECTED TO SERVICE MESSAGE PIPE! */
/* re-open stdin, stdout, stderr with known values */
open("/dev/null", O_RDONLY);
open("/dev/null", O_WRONLY);
open("/dev/null", O_WRONLY);
broker_program_state(NEBTYPE_PROCESS_DAEMONIZE, NEBFLAG_NONE, NEBATTR_NONE);
return OK;
}
