use subprocess instead of forking for cosim

myhdl/_Cosimulation.py

@@ -21,12 +21,13 @@
 from __future__ import absolute_import
 
 
-import sys
 import os
+import shlex
+import subprocess
 
 from myhdl._intbv import intbv
 from myhdl import _simulator, CosimulationError
-from myhdl._compat import PY2, to_bytes, to_str
+from myhdl._compat import PY2, string_types, to_bytes, to_str
 
 _MAXLINE = 4096
 
@@ -67,26 +68,28 @@ class Cosimulation(object):
         self._toSizes = toSizes = []
         self._toSigs = toSigs = []
         self._toSigDict = toSigDict = {}
-
         self._hasChange = 0
         self._getMode = 1
 
-        child_pid = self._child_pid = os.fork()
-
-        if child_pid == 0:
+        def close_rt_wf():
             os.close(rt)
             os.close(wf)
-            os.environ['MYHDL_TO_PIPE'] = str(wt)
-            os.environ['MYHDL_FROM_PIPE'] = str(rf)
-            if isinstance(exe, list): arglist = exe
-            else: arglist = exe.split()
-            p = arglist[0]
-            arglist[0] = os.path.basename(p)
+
+        env = os.environ.copy()
+        env['MYHDL_TO_PIPE'] = str(wt)
+        env['MYHDL_FROM_PIPE'] = str(rf)
+
+        if isinstance(exe, string_types):
+            exe = shlex.split(exe)
+            
         try:
-                os.execvp(p, arglist)
+            sp = subprocess.Popen(exe, env=env, close_fds=False,
+                                  preexec_fn=close_rt_wf)
         except OSError as e:
             raise CosimulationError(_error.OSError, str(e))
-        else:
+
+        self._child = sp
+
         os.close(wt)
         os.close(rf)
         while 1:

myhdl/_Simulation.py

@@ -78,7 +78,7 @@ class Simulation(object):
             _simulator._cosim = 0
             os.close(cosim._rt)
             os.close(cosim._wf)
-            os.waitpid(cosim._child_pid, 0)
+            cosim._child.wait()
         if _simulator._tracing:
             _simulator._tracing = 0
             _simulator._tf.close()

myhdl/test/core/test_Cosimulation.py

@@ -60,7 +60,7 @@ class CosimulationTest(TestCase):
         try:
             Cosimulation("bla -x 45")
         except CosimulationError as e:
-            self.assertTrue(e.kind in(_error.OSError, _error.SimulationEnd))
+            self.assertEqual(e.kind, _error.OSError)
         else:
             self.fail()