fix(ci): fix clang-21 static analyzer false positives

scan-build-21 reports false positive bugs in the posix eventloop code, causing some CI jobs to fail

arch/posix/eventloop_posix_eth.c

@@ -352,7 +352,7 @@ ETH_connectionSocketCallback(UA_ConnectionManager *cm, UA_RegisteredFD *rfd,
 
     /* Receive has failed */
     if(ret <= 0) {
-        if(UA_ERRNO == UA_INTERRUPTED)
+        if(ret < 0 && UA_ERRNO == UA_INTERRUPTED)
             return;
 
         /* Orderly shutdown of the socket. We can immediately close as no method

arch/posix/eventloop_posix_tcp.c

@@ -283,9 +283,9 @@ TCP_connectionSocketCallback(UA_ConnectionManager *cm, TCP_FD *conn,
 
     /* Receive has failed */
     if(ret <= 0) {
-        if(UA_ERRNO == UA_INTERRUPTED ||
-           UA_ERRNO == UA_WOULDBLOCK ||
-           UA_ERRNO == UA_AGAIN)
+        if(ret < 0 && (UA_ERRNO == UA_INTERRUPTED ||
+                        UA_ERRNO == UA_WOULDBLOCK ||
+                        UA_ERRNO == UA_AGAIN))
             return; /* Temporary error on an non-blocking socket */
 
         /* Orderly shutdown of the socket */

arch/posix/eventloop_posix_udp.c

@@ -695,7 +695,7 @@ UDP_connectionSocketCallback(UA_POSIXConnectionManager *pcm, UDP_FD *conn,
 
     /* Receive has failed */
     if(ret <= 0) {
-        if(UA_ERRNO == UA_INTERRUPTED)
+        if(ret < 0 && UA_ERRNO == UA_INTERRUPTED)
             return;
 
         /* Orderly shutdown of the socket. We can immediately close as no method

tools/ci/linux/ci.sh

@@ -531,10 +531,18 @@ function build_clang_analyzer {
           -DUA_FORCE_WERROR=ON \
           -DUA_NAMESPACE_ZERO=FULL \
           ..
+    # Disable checkers that produce false positives in the posix eventloop code
+    local checker_flags=""
+    if [ "$version" = "21" ]; then
+        checker_flags="-disable-checker unix.Errno -disable-checker unix.BlockInCriticalSection"
+    fi
     scan-build-$version \
           --status-bugs \
           --exclude ../src/util \
           --exclude ../tests \
+          --exclude ../examples \
+          --exclude ../deps \
+          $checker_flags \
           make ${MAKEOPTS}
 }