From 57c3afb8be3206e18abe535ad6896ef24ecb95c1 Mon Sep 17 00:00:00 2001
From: MarkRivers <rivers@cars.uchicago.edu>
Date: Fri, 20 Dec 2013 05:10:10 +0000
Subject: [PATCH] Protect against dereferencing null pointer, was crashing on
 Linux

---
 motorApp/MclennanSrc/devPM304.cc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/motorApp/MclennanSrc/devPM304.cc b/motorApp/MclennanSrc/devPM304.cc
index 63797b23..2cfb2e5d 100644
--- a/motorApp/MclennanSrc/devPM304.cc
+++ b/motorApp/MclennanSrc/devPM304.cc
@@ -175,8 +175,9 @@ STATIC RTN_STATUS PM304_build_trans(motor_cmnd command, double *parms, struct mo
 
     rtnval = OK;
     buff[0] = '\0';
-    dval = parms[0];
-    ival = NINT(parms[0]);
+    /* Protect against NULL pointer with WRTITE_MSG(GO/STOP_AXIS/GET_INFO, NULL). */
+    dval = (parms == NULL) ? 0.0 : *parms;
+    ival = NINT(dval);
 
     motor_call = &(trans->motor_call);
     card = motor_call->card;