No change in behaviour, just make the code more obvious.
if (n_fds > 0 || have_pid) {
/* CMSG_SPACE(0) may return value different then zero, which results in miscalculated controllen. */
- msghdr.msg_controllen = (n_fds ? CMSG_SPACE(sizeof(int) * n_fds) : 0) +
- CMSG_SPACE(sizeof(struct ucred)) * have_pid;
+ msghdr.msg_controllen =
+ (n_fds > 0 ? CMSG_SPACE(sizeof(int) * n_fds) : 0) +
+ (have_pid ? CMSG_SPACE(sizeof(struct ucred)) : 0);
+
msghdr.msg_control = alloca(msghdr.msg_controllen);
cmsg = CMSG_FIRSTHDR(&msghdr);