_IOFBF
setvbuf(fp, buf, buf ? _IOFBF : _IONBF, BUFSIZ);
setvbuf(fp, buf, buf ? _IOFBF : _IONBF, (size_t)size);
if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
mode = _IOFBF;
mode = _IOFBF;
setvbuf(conn->fpr, NULL, _IOFBF, 0);
setvbuf(conn->fpw, NULL, _IOFBF, 0);
setvbuf(conn->fpr, NULL, _IOFBF, 0);
setvbuf(conn->fpw, NULL, _IOFBF, 0);
setvbuf(f, NULL, _IOFBF, B_size);
if (setvbuf(ff, NULL, _IOFBF, cnt) != 0) {
if (setvbuf(ff, NULL, _IOFBF, cnt) != 0) {
#define setbuffer(f, b, s) setvbuf((f), (b), (b) ? _IOFBF : _IONBF, (s))
setvbuf(stdout, stdoutbuf, _IOFBF, BUFFERSIZE);