gzwrite
ZEXTERN int ZEXPORT gzwrite(gzFile file, voidpc buf, unsigned len);
len = gzwrite(out, (char *)buf, (unsigned)buf_len);
if (gzwrite(out, buf, (unsigned)len) != len) error(gzerror(out, &err));
ZEXTERN int ZEXPORT gzwrite(gzFile file, voidpc buf, unsigned len);
if (gzwrite(gzf, ibuf, r) != r)