PD_DAEMON
if (flags & PD_DAEMON)
#define PD_ALLOWED_AT_FORK (PD_DAEMON | PD_CLOEXEC)
int pid = pdfork(&pd, PD_DAEMON<<5);
PipePdforkDaemon() : PipePdforkBase(PD_DAEMON) {}
pid_t grandchild = PdforkParentDeath(PD_DAEMON);
rc = pdfork(&fd, PD_DAEMON);
dangle_pid = pdfork(&pd, PD_CLOEXEC | PD_DAEMON);