Fix changing env vars on Windows, allows to load LV2 plugins

source/carla_backend.py

@@ -20,6 +20,7 @@
 # Imports (Global)
 
 from ctypes import *
+from os import environ
 from platform import architecture
 from sys import platform, maxsize
 
@@ -1742,6 +1743,14 @@ class Host(object):
     def get_host_osc_url_udp(self):
         return charPtrToString(self.lib.carla_get_host_osc_url_udp())
 
+    # extra
+    def setenv(self, key, value):
+        environ[key] = value
+
+        if WINDOWS:
+            keyvalue = "%s=%s" % (key, value)
+            self.msvcrt._putenv(keyvalue.encode("utf-8"))
+
     def _init(self, libName):
         self.lib = cdll.LoadLibrary(libName)
 
@@ -2008,3 +2017,8 @@ class Host(object):
 
         self.lib.carla_get_host_osc_url_udp.argtypes = None
         self.lib.carla_get_host_osc_url_udp.restype = c_char_p
+
+        if WINDOWS:
+            self.msvcrt = cdll.msvcrt
+            self.msvcrt._putenv.argtypes = [c_char_p]
+            self.msvcrt._putenv.restype = None

source/carla_host.py

@@ -711,7 +711,7 @@ class HostWindow(QMainWindow):
 
         # ---------------------------------------------
 
-        if not gCarla.isPlugin:
+        if gCarla.host is not None and not gCarla.isPlugin:
             # engine
             self.setEngineSettings(settings)
 
@@ -725,14 +725,14 @@ class HostWindow(QMainWindow):
             SF2_PATH    = toList(settings.value("Paths/SF2",    gCarla.DEFAULT_SF2_PATH))
             SFZ_PATH    = toList(settings.value("Paths/SFZ",    gCarla.DEFAULT_SFZ_PATH))
 
-            os.environ["LADSPA_PATH"] = splitter.join(LADSPA_PATH)
-            os.environ["DSSI_PATH"]   = splitter.join(DSSI_PATH)
-            os.environ["LV2_PATH"]    = splitter.join(LV2_PATH)
-            os.environ["VST_PATH"]    = splitter.join(VST_PATH)
-            os.environ["AU_PATH"]     = splitter.join(AU_PATH)
-            os.environ["GIG_PATH"]    = splitter.join(GIG_PATH)
-            os.environ["SF2_PATH"]    = splitter.join(SF2_PATH)
-            os.environ["SFZ_PATH"]    = splitter.join(SFZ_PATH)
+            gCarla.host.setenv("LADSPA_PATH", splitter.join(LADSPA_PATH))
+            gCarla.host.setenv("DSSI_PATH",   splitter.join(DSSI_PATH))
+            gCarla.host.setenv("LV2_PATH",    splitter.join(LV2_PATH))
+            gCarla.host.setenv("VST_PATH",    splitter.join(VST_PATH))
+            gCarla.host.setenv("AU_PATH",     splitter.join(AU_PATH))
+            gCarla.host.setenv("GIG_PATH",    splitter.join(GIG_PATH))
+            gCarla.host.setenv("SF2_PATH",    splitter.join(SF2_PATH))
+            gCarla.host.setenv("SFZ_PATH",    splitter.join(SFZ_PATH))
 
         # ---------------------------------------------