fluke-45: avoid NULL dereference in the probe routine

The Fluke 45 probe routine tries to detect whether the serial port is
"in echo mode" (which already is questionable before the IDN query).
In the absence of a response, the library segfaults. Fix it.

diff --git a/src/hardware/fluke-45/api.c b/src/hardware/fluke-45/api.c
index e15adaad7b6cc7ef2928fd307538bff74eba4814..164cd5f9bceef01af51aae275091bb4affd47ee5 100644 (file)
--- a/src/hardware/fluke-45/api.c
+++ b/src/hardware/fluke-45/api.c
@@ -68,8 +68,9 @@ static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
        sdi->conn = scpi;
 
        /* Test for serial port ECHO enabled. */
+       response = NULL;
        sr_scpi_get_string(scpi, "ECHO-TEST", &response);
-       if (strcmp(response, "ECHO-TEST") == 0) {
+       if (response && strcmp(response, "ECHO-TEST") == 0) {
                sr_err("Serial port ECHO is ON. Please turn it OFF!");
                return NULL;
        }