hal_hw_interface: Find HAL component directory from LD_LIBRARY_PATH

The RT HAL comp is installed in the `CMAKE_LIBRARY_OUTPUT_DIRECTORY`,
and that path was templated into the launch file at build time, to be
passed on through `hal_mgr` and into the .hal files.

@machinekoder discovered that using `configure_file()` to template the
launch file back into the source directory caused trouble in
`industrial-ci`, for obvious reasons.

He had the good idea to find the install directory at run time by
searching `LD_LIBRARY_PATH`, which is set in `setup.bash`.

This patch undoes the previous system and does the search directly
inside `hal_mgr`.

.gitignore

@@ -1,3 +1,2 @@
 autosave.halscope
-/hal_hw_interface/launch/hal_hw_interface.launch
 /simple_hardware_interfaces/doc/

README.md

@@ -175,8 +175,8 @@ position, velocity and acceleration, and connects them to the
 
 Because the `hal_hw_interface` component is installed outside the
 standard HAL component directory, its full path must be provided using
-the `$LIBDIR` environment variable:  `loadrt
-$(LIBDIR)/hal_hw_interface`.
+the `$COMP_DIR` environment variable:  `loadrt
+$(COMP_DIR)/hal_hw_interface`.
 
 When the `hal_hw_interface` component loads, it creates six HAL pins
 for each joint:  three command output pins and three feedback input

hal_hw_interface/CMakeLists.txt

@@ -44,12 +44,6 @@ install(
   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
   )
 
-# Launch file
-# - Add library path to help locate HAL comp
-configure_file(
-  ${CMAKE_CURRENT_SOURCE_DIR}/launch/${PROJECT_NAME}.in.launch
-  ${CMAKE_CURRENT_SOURCE_DIR}/launch/${PROJECT_NAME}.launch @ONLY)
-
 #######################
 # HAL component build definitions
 

hal_hw_interface/launch/hal_hw_interface.in.launch → hal_hw_interface/launch/hal_hw_interface.launch

@@ -17,10 +17,5 @@
       type="hal_mgr.py"
       output="screen"
       required="true"
-      >
-    <env
-        name="LIBDIR"
-        value="@CMAKE_LIBRARY_OUTPUT_DIRECTORY@"
-        />
-  </node>
+      />
 </launch>

hal_hw_interface/src/hal_mgr.py

@@ -40,6 +40,15 @@ def shutdown(msg = "Shutting down for unknown reason", res = 0):
     rate = rospy.Rate(1) # 1hz
     rospy.loginfo("hal_mgr:  Initialized node")
 
+    # Find the hal_hw_interface comp's directory in LD_LIBRARY_PATH and put it
+    # into $COMP_DIR
+    comp_dir = ""
+    for path in os.environ.get('LD_LIBRARY_PATH','').split(':'):
+        if os.path.exists(os.path.join(path, 'hal_hw_interface.so')):
+            comp_dir = path
+    os.environ['COMP_DIR'] = comp_dir
+    rospy.loginfo("hal_mgr:  COMP_DIR set to '%s'" % comp_dir)
+
     # Get parameters
     if not rospy.has_param(NAME):
         shutdown("No parameters set for '%s'" % NAME, 1)
@@ -51,8 +60,6 @@ def shutdown(msg = "Shutting down for unknown reason", res = 0):
         shutdown("%s has no 'hal_files' key" % NAME, 1)
     if 'hal_file_dir' not in hal_mgr_config:
         shutdown("%s has no 'hal_file_dir' key" % NAME, 1)
-    if 'LIBDIR' not in os.environ:
-        shutdown("No 'LIBDIR' environment variable defined", 1)
 
     # Set up HAL
     launcher.cleanup_session()  # kill any running Machinekit instances

hal_rrbot_control/halfiles/hal_hw_interface.hal

@@ -2,7 +2,7 @@
 newthread robot_hw_thread 10000000 fp
 
 # Load the hal_hw_interface component
-loadrt $(LIBDIR)/hal_hw_interface
+loadrt $(COMP_DIR)/hal_hw_interface
 addf hal_hw_interface robot_hw_thread
 
 # Connect position command to feedback via limit3 comp to simulate