/** Signal handler callback for writing signals to pipe
*
* @param sig the signal number to pass to mainloop via pipe
*/
static void mce_tx_signal_cb(int sig)
{
/* NOTE: this function must be kept async-signal-safe! */
static volatile int exit_tries = 0;
static const char msg[] = "\n*** BREAK ***\n";
static const char die[] = "\n*** UNRECOVERABLE FAILURE ***\n";
switch( sig )
{
case SIGUSR1:
case SIGUSR2:
case SIGHUP:
/* Just pass to mainloop */
break;
case SIGINT:
case SIGQUIT:
case SIGTERM:
/* Make sure that a stuck or non-existing mainloop does
* not stop us from handling at least repeated terminating
signals ... */
#ifdef ENABLE_WAKELOCKS
/* We are on exit path -> block suspend for good */
wakelock_block_suspend_until_exit();
#endif
no_error_check_write(STDERR_FILENO, msg, sizeof msg - 1);
if( !mainloop || ++exit_tries >= 2 ) {
mce_abort();
}
break;
default:
/* Assume unrecoverable failure that can't be handled in
* the mainloop - disable autosuspend and then terminate
* via default signal handler. */
no_error_check_write(STDERR_FILENO, die, sizeof die - 1);
mce_exit_via_signal(sig);
break;
}
/* transfer the signal to mainloop via pipe */
int did = TEMP_FAILURE_RETRY(write(signal_pipe[1], &sig, sizeof sig));
if( did != (int)sizeof sig ) {
mce_abort();
}
}
/**
* Daemonize the program
*
* @return TRUE if MCE is started during boot, FALSE otherwise
*/
static gboolean daemonize(void)
{
gint retries = 0;
gint i = 0;
gchar str[10];
if (getppid() == 1)
goto EXIT; /* Already daemonized */
/* Detach from process group */
switch (fork()) {
case -1:
/* Parent - Failure */
mce_log(LL_CRIT, "daemonize: fork failed: %s",
g_strerror(errno));
exit(EXIT_FAILURE);
case 0:
/* Child */
break;
default:
/* Parent -- Success */
/* One main() one exit() - in this case the parent
* must not call atexit handlers etc */
_exit(EXIT_SUCCESS);
}
/* Detach TTY */
setsid();
/* Close all file descriptors and redirect stdio to /dev/null */
if ((i = getdtablesize()) == -1)
i = 256;
while (--i >= 0) {
if (close(i) == -1) {
if (retries > 10) {
mce_log(LL_CRIT,
"close() was interrupted more than "
"10 times. Exiting.");
exit(EXIT_FAILURE);
}
if (errno == EINTR) {
mce_log(LL_INFO,
"close() was interrupted; retrying.");
errno = 0;
i++;
retries++;
} else if (errno == EBADF) {
/* Ignore invalid file descriptors */
errno = 0;
} else {
mce_log(LL_CRIT,
"Failed to close() fd %d; %s. "
"Exiting.",
i + 1, g_strerror(errno));
exit(EXIT_FAILURE);
}
} else {
retries = 0;
}
}
if ((i = open("/dev/null", O_RDWR)) == -1) {
mce_log(LL_CRIT,
"Cannot open `/dev/null'; %s. Exiting.",
g_strerror(errno));
exit(EXIT_FAILURE);
}
if ((dup(i) == -1)) {
mce_log(LL_CRIT,
"Failed to dup() `/dev/null'; %s. Exiting.",
g_strerror(errno));
exit(EXIT_FAILURE);
}
if ((dup(i) == -1)) {
mce_log(LL_CRIT,
"Failed to dup() `/dev/null'; %s. Exiting.",
g_strerror(errno));
exit(EXIT_FAILURE);
}
/* Set umask */
umask(022);
/* Set working directory */
if ((chdir("/tmp") == -1)) {
mce_log(LL_CRIT,
"Failed to chdir() to `/tmp'; %s. Exiting.",
g_strerror(errno));
exit(EXIT_FAILURE);
}
/* Single instance */
if ((i = open(MCE_LOCKFILE, O_RDWR | O_CREAT, 0640)) == -1) {
mce_log(LL_CRIT,
"Cannot open lockfile; %s. Exiting.",
g_strerror(errno));
exit(EXIT_FAILURE);
}
if (lockf(i, F_TLOCK, 0) == -1) {
mce_log(LL_CRIT, "Already running. Exiting.");
exit(EXIT_FAILURE);
}
sprintf(str, "%d\n", getpid());
no_error_check_write(i, str, strlen(str));
close(i);
/* Ignore TTY signals */
signal(SIGTSTP, SIG_IGN);
signal(SIGTTOU, SIG_IGN);
signal(SIGTTIN, SIG_IGN);
/* Ignore child terminate signal */
signal(SIGCHLD, SIG_IGN);
EXIT:
return 0;
}
/** Signal handler callback for writing signals to pipe
*
* @param sig the signal number to pass to mainloop via pipe
*/
static void mce_tx_signal_cb(int sig)
{
/* NOTE: this function must be kept async-signal-safe! */
static volatile int exit_tries = 0;
static const char msg[] = "\n*** BREAK ***\n";
#ifdef ENABLE_WAKELOCKS
static const char die[] = "\n*** UNRECOVERABLE FAILURE ***\n";
#endif
/* FIXME: Should really use sigaction() to avoid having
* the default handler active until we manage to restore
* our handler here ... */
signal(sig, mce_tx_signal_cb);
switch( sig )
{
case SIGINT:
case SIGQUIT:
case SIGTERM:
/* Make sure that a stuck or non-existing mainloop does
* not stop us from handling at least repeated terminating
signals ... */
#ifdef ENABLE_WAKELOCKS
/* We are on exit path -> block suspend for good */
wakelock_block_suspend_until_exit();
#endif
no_error_check_write(STDERR_FILENO, msg, sizeof msg - 1);
if( !mainloop || ++exit_tries >= 2 ) {
mce_abort();
}
break;
#ifdef ENABLE_WAKELOCKS
case SIGABRT:
case SIGILL:
case SIGFPE:
case SIGSEGV:
case SIGALRM:
case SIGBUS:
/* Unrecoverable failures can't be handled in the mainloop
* Terminate but disable suspend first */
no_error_check_write(STDERR_FILENO, die, sizeof die - 1);
mce_exit_via_signal(sig);
break;
case SIGTSTP:
/* Stopping mce could also lead to unrecoverable suspend */
break;
#endif
default:
break;
}
/* transfer the signal to mainloop via pipe */
int did = TEMP_FAILURE_RETRY(write(signal_pipe[1], &sig, sizeof sig));
if( did != (int)sizeof sig ) {
mce_abort();
}
}