Annotate return_overflow in fr_writev() (CID #1604625) (#5438)

In theory, iovcnt and the amounts written could total to more than
SSIZE_MAX, and when Coverity is looking at fr_writev() rather than
its callers it can't tell. We therefore annotate.

diff --git a/src/lib/util/iovec.c b/src/lib/util/iovec.c
index ce65a28ed43999cd68ecf632d2fdf5846c5be42e..acbbb1cdc606ba41c6dd8e6f7922a991d2034526 100644 (file)
--- a/src/lib/util/iovec.c
+++ b/src/lib/util/iovec.c
@@ -75,13 +75,6 @@ ssize_t fr_writev(int fd, struct iovec vector[], int iovcnt, fr_time_delta_t tim
 
                wrote = writev(fd, vector_p, iovcnt);
                if (wrote > 0) {
-#ifdef __COVERITY__
-                       /*
-                        *      Coverity thinks that total += wrote might underflow,
-                        *      which causes an issue at the return.
-                        */
-                       if (total + wrote < total) return -1;
-#endif
                        total += wrote;
                        while (wrote > 0) {
                                /*
@@ -102,7 +95,10 @@ ssize_t fr_writev(int fd, struct iovec vector[], int iovcnt, fr_time_delta_t tim
                                break;
                        }
                        continue;
-               } else if (wrote == 0) return total;
+               } else if (wrote == 0) {
+                       /* coverity[return_overflow] */
+                       return total;
+               }
 
                switch (errno) {
                /* Write operation would block, use select() to implement a timeout */