[PATCH] build/utils: Allow python functions to execute with real exception handling

[Richard Purdie <richard.purdie@linuxfoundation.org>]

With the code as it stands today it not possible to execute a python function
and get "normal" python exception handling behaviour. If a python function 
raises an exception, it forces a traceback to be printed and the exception
becomes a FuncFailed exception.

This adds in a parameter 'pythonexception' which allows standard python
exceptions to be passed unchanged with no traceback. Ultimately we may want
to change to this convention in various places but at least it means we can
start to add sane functions now.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/bitbake/lib/bb/build.py b/bitbake/lib/bb/build.py
index 1d2df81..1d0dcde 100644
--- a/bitbake/lib/bb/build.py
+++ b/bitbake/lib/bb/build.py
@@ -156,7 +156,12 @@ class LogTee(object):
     def flush(self):
         self.outfile.flush()
 
-def exec_func(func, d, dirs = None):
+#
+# pythonexception allows the python exceptions generated to be raised
+# as the real exceptions (not FuncFailed) and without a backtrace at the 
+# origin of the failure.
+#
+def exec_func(func, d, dirs = None, pythonexception=False):
     """Execute a BB 'function'"""
 
     body = d.getVar(func, False)
@@ -224,7 +229,7 @@ def exec_func(func, d, dirs = None):
 
     with bb.utils.fileslocked(lockfiles):
         if ispython:
-            exec_func_python(func, d, runfile, cwd=adir)
+            exec_func_python(func, d, runfile, cwd=adir, pythonexception=pythonexception)
         else:
             exec_func_shell(func, d, runfile, cwd=adir)
 
@@ -232,7 +237,7 @@ _functionfmt = """
 {function}(d)
 """
 logformatter = bb.msg.BBLogFormatter("%(levelname)s: %(message)s")
-def exec_func_python(func, d, runfile, cwd=None):
+def exec_func_python(func, d, runfile, cwd=None, pythonexception=False):
     """Execute a python BB 'function'"""
 
     code = _functionfmt.format(function=func)
@@ -256,10 +261,12 @@ def exec_func_python(func, d, runfile, cwd=None):
         bb.methodpool.insert_method(func, text, fn, lineno - 1)
 
         comp = utils.better_compile(code, func, "exec_python_func() autogenerated")
-        utils.better_exec(comp, {"d": d}, code, "exec_python_func() autogenerated")
+        utils.better_exec(comp, {"d": d}, code, "exec_python_func() autogenerated", pythonexception=pythonexception)
     except (bb.parse.SkipRecipe, bb.build.FuncFailed):
         raise
     except:
+        if pythonexception:
+            raise
         raise FuncFailed(func, None)
     finally:
         bb.debug(2, "Python function %s finished" % func)
diff --git a/bitbake/lib/bb/utils.py b/bitbake/lib/bb/utils.py
index 7ab8927..e9ad68f 100644
--- a/bitbake/lib/bb/utils.py
+++ b/bitbake/lib/bb/utils.py
@@ -372,7 +372,7 @@ def _print_exception(t, value, tb, realfile, text, context):
     finally:
         logger.error("\n".join(error))
 
-def better_exec(code, context, text = None, realfile = "<code>"):
+def better_exec(code, context, text = None, realfile = "<code>", pythonexception=False):
     """
     Similiar to better_compile, better_exec will
     print the lines that are responsible for the
@@ -389,6 +389,8 @@ def better_exec(code, context, text = None, realfile = "<code>"):
         # Error already shown so passthrough, no need for traceback
         raise
     except Exception as e:
+        if pythonexception:
+            raise
         (t, value, tb) = sys.exc_info()
         try:
             _print_exception(t, value, tb, realfile, text, context)