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syslogd: Refactor backgrounding/daemonization w/ code from FreeBSD

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Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
This commit is contained in:
Joachim Nilsson 2019-12-07 20:39:32 +01:00
parent a3f3ed1833
commit f46850b000
1 changed files with 77 additions and 35 deletions
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110
src/syslogd.c
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@ -167,7 +167,6 @@ void domark(void *arg);
void doflush(void *arg);
void debug_switch();
void die(int sig);
void doexit(int sig);
void init();
static int strtobytes(char *arg);
static int cfparse(FILE *fp, struct files *newf);
@ -175,6 +174,9 @@ int decode(char *name, struct _code *codetab);
static void logit(char *, ...);
void sighup_handler(int);
static int validate(struct sockaddr *sa, const char *hname);
static int waitdaemon(int);
static void timedout(int);
static int addpeer(struct peer *pe0)
{
@ -248,7 +250,7 @@ int usage(int code)
int main(int argc, char *argv[])
{
pid_t ppid = getpid();
pid_t ppid = 1;
char *ptr;
int pflag = 0, bflag = 0;
int ch;
@ -376,30 +378,10 @@ int main(int argc, char *argv[])
else
kern_console_off();
if (!Foreground) {
chdir("/");
signal(SIGTERM, doexit);
if (fork()) {
/*
* Parent process
*/
sleep(300);
/*
* Not reached unless something major went wrong. 5
* minutes should be a fair amount of time to wait.
* Please note that this procedure is important since
* the father must not exit before syslogd isn't
* initialized or the klogd won't be able to flush its
* logs. -Joey
*/
exit(1);
}
signal(SIGTERM, SIG_DFL);
for (int i = 0; i < getdtablesize(); i++)
(void)close(i);
untty();
if (!Foreground && !Debug) {
ppid = waitdaemon(30);
if (ppid < 0)
err(1, "Failed daemonizing");
} else if (Debug) {
debugging_on = 1;
setlinebuf(stdout);
@ -434,18 +416,16 @@ int main(int argc, char *argv[])
debugging_on = 0;
}
/*
* Send a signal to the parent to it can terminate.
*/
if (getpid() != ppid)
kill(ppid, SIGTERM);
/*
* Tell system we're up and running by creating /run/syslogd.pid
*/
if (pidfile(PidFile))
logit("Failed creating %s: %s", PidFile, strerror(errno));
/* Tell parent we're up and running */
if (ppid != 1)
kill(ppid, SIGALRM);
/* Main loop begins here. */
for (;;) {
int rc;
@ -2009,11 +1989,73 @@ void die(int signo)
}
/*
* Signal handler to terminate the parent process.
* fork off and become a daemon, but wait for the child to come online
* before returning to the parent, or we get disk thrashing at boot etc.
* Set a timer so we don't hang forever if it wedges.
*/
void doexit(int signo)
static int waitdaemon(int maxwait)
{
int fd;
int status;
pid_t pid, childpid;
childpid = fork();
switch (childpid) {
case -1:
return -1;
case 0:
break;
default:
signal(SIGALRM, timedout);
alarm(maxwait);
while ((pid = wait3(&status, 0, NULL)) != -1) {
if (WIFEXITED(status))
errx(1, "child pid %d exited with return code %d",
pid, WEXITSTATUS(status));
if (WIFSIGNALED(status))
errx(1, "child pid %d exited on signal %d%s",
pid, WTERMSIG(status),
WCOREDUMP(status) ? " (core dumped)" :
"");
if (pid == childpid) /* it's gone... */
break;
}
exit(0);
}
if (setsid() == -1)
return -1;
(void)chdir("/");
fd = open(_PATH_DEVNULL, O_RDWR, 0);
if (fd != -1) {
(void)dup2(fd, STDIN_FILENO);
(void)dup2(fd, STDOUT_FILENO);
(void)dup2(fd, STDERR_FILENO);
if (fd > STDERR_FILENO)
(void)close(fd);
}
return getppid();
}
/*
* We get a SIGALRM from the child when it's running and finished doing it's
* fsync()'s or O_SYNC writes for all the boot messages.
*
* We also get a signal from the kernel if the timer expires, so check to
* see what happened.
*/
static void timedout(int signo)
{
int left;
left = alarm(0);
signal(SIGALRM, SIG_DFL);
if (left == 0)
errx(1, "timed out waiting for child");
_exit(0);
}
/* Create fallback .conf with err+panic sent to console */