Prepend LD_LIBRARY_PATH instead of overwritting it

My current distribution ships a newer libcrypto and libssl which are not
ABI compatible with the ones generated by Jenkins. I had to copy those
libraries locally and use LD_LIBRARY_PATH to be able to run binaries
compiled coming from the jenkins slave. Without this patch I am not
able to run it because it is overwriting the previous variable.

Change-Id: Id9b16d13d343616cbf87b9da8a99e3fae48da6bd

src/osmo_gsm_tester/bts_octphy.py

@@ -50,7 +50,7 @@ class OsmoBtsOctphy(log.Origin):
         lib = self.inst.child('lib')
         if not os.path.isdir(lib):
             raise RuntimeError('No lib/ in %r' % self.inst)
-        self.env = { 'LD_LIBRARY_PATH': lib }
+        self.env = { 'LD_LIBRARY_PATH': util.prepend_library_path(lib) }
 
         self.launch_process(OsmoBtsOctphy.BIN_BTS_OCTPHY, '-r', '1', '-c', os.path.abspath(self.config_file))
         self.suite_run.poll()

src/osmo_gsm_tester/bts_osmotrx.py

@@ -54,7 +54,7 @@ class OsmoBtsTrx(log.Origin):
         lib = self.inst.child('lib')
         if not os.path.isdir(lib):
             raise RuntimeError('No lib/ in %r' % self.inst)
-        self.env = { 'LD_LIBRARY_PATH': lib }
+        self.env = { 'LD_LIBRARY_PATH': util.prepend_library_path(lib) }
 
         self.proc_trx = self.launch_process(OsmoBtsTrx.BIN_TRX, '-x')
         self.log('Waiting for osmo-trx to start up...')

src/osmo_gsm_tester/osmo_nitb.py

@@ -50,7 +50,9 @@ class OsmoNitb(log.Origin):
         lib = inst.child('lib')
         if not os.path.isdir(lib):
             raise RuntimeError('No lib/ in %r' % inst)
-        env = { 'LD_LIBRARY_PATH': lib }
+
+        env = { 'LD_LIBRARY_PATH': util.prepend_library_path(lib) }
+
         self.dbg(run_dir=self.run_dir, binary=binary, env=env)
         self.process = process.Process(self.name(), self.run_dir,
                                        (binary, '-c',

src/osmo_gsm_tester/util.py

@@ -32,6 +32,12 @@ import tty
 import readline
 
 
+def prepend_library_path(path):
+    lp = os.getenv('LD_LIBRARY_PATH')
+    if not lp:
+        return path
+    return path + ':' + lp
+
 class listdict:
     'a dict of lists { "a": [1, 2, 3],  "b": [1, 2] }'
     def __getattr__(ld, name):