util: Don't overflow on errno in virFileAccessibleAs

If we need to virFork() to check assess() under different
UID+GID we need to translate returned status via WEXITSTATUS().
Otherwise, we may return values greater than 255 which is
obviously wrong.

src/util/util.c

@@ -724,8 +724,13 @@ virFileAccessibleAs(const char *path, int mode,
                 return -1;
         }
 
+        if (!WIFEXITED(status)) {
+            errno = EINTR;
+            return -1;
+        }
+
         if (status) {
-            errno = status;
+            errno = WEXITSTATUS(status);
             return -1;
         }