CLEANUP: quic: replace ALREADY_CHECKED() with ASSUME_NONNULL() at a few places

There were 4 instances of ALREADY_CHECKED() used to tell the compiler that
the argument couldn't be NULL by design. Let's change them to the cleaner
ASSUME_NONNULL(). Functions like qc_snd_buf() were slightly reduced in
size (-24 bytes).

Apparently gcc-13 sees a potential case that others don't see, and it's
likely a bug since depending what is masked, it will completely change
the output warnings to the point of contradicting itself. After many
attempts, it appears that just checking that CMSG_FIRSTHDR(msg) is not
null suffices to calm it down, so the strange warnings might have been
the result of an overoptimization based on a supposed UB in the first
place. At least now all versions up to 13.2 as well as clang are happy.

diff --git a/src/quic_loss.c b/src/quic_loss.c
index affa6f2064097c9c1cd2075d1642be4e68ad1e9e..1c32d92c4a85e68bc3ac88268cd85ae3e4228330 100644 (file)
--- a/src/quic_loss.c
+++ b/src/quic_loss.c
@@ -317,7 +317,7 @@ int qc_release_lost_pkts(struct quic_conn *qc, struct quic_pktns *pktns,
         * that <pkts> list is not empty. Without this, GCC 12.2.0 reports a
         * possible overflow on a 0 byte region with O2 optimization.
         */
-       ALREADY_CHECKED(oldest_lost);
+       ASSUME_NONNULL(oldest_lost);
        quic_tx_packet_refdec(oldest_lost);
        if (newest_lost != oldest_lost)
                quic_tx_packet_refdec(newest_lost);

diff --git a/src/quic_sock.c b/src/quic_sock.c
index 327deb492fcd9364fd7c329d684960c47d623f93..b7ee8f8f48d7a5ed61f8851eb4764013658b50b7 100644 (file)
--- a/src/quic_sock.c
+++ b/src/quic_sock.c
@@ -613,8 +613,11 @@ static void cmsg_set_saddr(struct msghdr *msg, struct cmsghdr **cmsg,
        /* Set first msg_controllen to be able to use CMSG_* macros. */
        msg->msg_controllen += CMSG_SPACE(sz);
 
+       /* seems necessary to please gcc-13 */
+       ASSUME_NONNULL(CMSG_FIRSTHDR(msg));
+
        *cmsg = !(*cmsg) ? CMSG_FIRSTHDR(msg) : CMSG_NXTHDR(msg, *cmsg);
-       ALREADY_CHECKED(*cmsg);
+       ASSUME_NONNULL(*cmsg);
        c = *cmsg;
        c->cmsg_len = CMSG_LEN(sz);
 
@@ -666,8 +669,11 @@ static void cmsg_set_gso(struct msghdr *msg, struct cmsghdr **cmsg,
        /* Set first msg_controllen to be able to use CMSG_* macros. */
        msg->msg_controllen += CMSG_SPACE(sz);
 
+       /* seems necessary to please gcc-13 */
+       ASSUME_NONNULL(CMSG_FIRSTHDR(msg));
+
        *cmsg = !(*cmsg) ? CMSG_FIRSTHDR(msg) : CMSG_NXTHDR(msg, *cmsg);
-       ALREADY_CHECKED(*cmsg);
+       ASSUME_NONNULL(*cmsg);
        c = *cmsg;
        c->cmsg_len = CMSG_LEN(sz);
 
@@ -884,7 +890,7 @@ int qc_rcv_buf(struct quic_conn *qc)
                        TRACE_STATE("datagram for other connection on quic-conn socket, requeue it", QUIC_EV_CONN_RCV, qc);
 
                        rxbuf = MT_LIST_POP(&l->rx.rxbuf_list, typeof(rxbuf), rxbuf_el);
-                       ALREADY_CHECKED(rxbuf);
+                       ASSUME_NONNULL(rxbuf);
                        cspace = b_contig_space(&rxbuf->buf);
 
                        tmp_dgram = quic_rxbuf_purge_dgrams(rxbuf);