Add a coverity-only check to pacify Coverity (CID #1604620)

diff --git a/src/listen/control/proto_control_unix.c b/src/listen/control/proto_control_unix.c
index 54f7aceaf0ea7a07f8c772506cf75751b9f7c0b4..0c3acde40a47b3a82baa1f936cd457f9eecb4356 100644 (file)
--- a/src/listen/control/proto_control_unix.c
+++ b/src/listen/control/proto_control_unix.c
@@ -359,6 +359,20 @@ static ssize_t mod_write(fr_listen_t *li, UNUSED void *packet_ctx, UNUSED fr_tim
         */
        if (data_size <= 0) return data_size;
 
+#ifdef __COVERITY__
+       /*
+        *      data_size and written have type size_t, so
+        *      their sum can at least in theory exceed SSIZE_MAX.
+        *      We add this check to placate Coverity.
+        *
+        *      When Coverity examines this function it doesn't have
+        *      the caller context to see that it's honoring needed
+        *      preconditions (buffer_len <=SSIZE_MAX, and the loop
+        *      schema needed to use this function).
+        */
+       if (data_size + written > SSIZE_MAX) return -1;
+#endif
+
        return data_size + written;
 }