ClamD: Log an error message and exit 1 for bad temp dir

If `TemporaryDirectory` in `clamd.conf` does not exist, ClamD will now
print an error message and exit with exit code 1. 

Fixes: #1028

clamd/clamd.c

@@ -568,6 +568,13 @@ int main(int argc, char **argv)
                 ret = 1;
                 break;
             }
+
+            STATBUF sb;
+            if (CLAMSTAT(opt->strarg, &sb) != 0 && !S_ISDIR(sb.st_mode)) {
+                logg(LOGG_ERROR, "Current configuration of TemporaryDirectory: %s does not exist, or is not valid \n", opt->strarg);
+                ret = 1;
+                break;
+            }
         }
 
         cl_engine_set_clcb_hash(engine, hash_callback);

clamd/session.c

@@ -591,8 +591,9 @@ int execute_or_dispatch_command(client_conn_t *conn, enum commands cmd, const ch
         }
         case COMMAND_INSTREAM: {
             int rc = cli_gentempfd(optget(conn->opts, "TemporaryDirectory")->strarg, &conn->filename, &conn->scanfd);
-            if (rc != CL_SUCCESS)
-                return rc;
+            if (rc != CL_SUCCESS) {
+                return 1;
+            }
             conn->quota = optget(conn->opts, "StreamMaxLength")->numarg;
             conn->mode  = MODE_STREAM;
             return 0;