static ssize_t write_all(int fd, const char *buf, size_t count) {
	size_t rem = count;
	while (rem > 0) {
		ssize_t written = write(fd, buf, rem);
		if (written < 0) {
			if (errno == EAGAIN || errno == EINTR)
				continue;
			return -1;
		} else if (written == 0) {
			break;
		}
		rem -= written;
		buf += written;
	}
	return count - rem;
}