_IOFBF
(void)setvbuf(fp, buf, buf ? _IOFBF : _IONBF, BUFSIZ);
(void)setvbuf(fp, buf, buf ? _IOFBF : _IONBF, (size_t)size);
if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
(void)setvbuf(screen->outfd, screen->stdbuf, _IOFBF, screen->len);
setvbuf(stderr, NULL, _IOFBF, 0); /* XXX */
case 2: return _IOFBF;
{ "IOFBF", _IOFBF },
setvbuf(stdout, msgbuf, _IOFBF, sizeof msgbuf);