python: Robust exception handling in callbacks.

* lang/python/helpers.c (pygpgme_stash_callback_exception): New
function.
(pygpgme_raise_callback_exception): Likewise.
(pyPassphraseCb): Stash python errors.
* lang/python/helpers.h (pygpgme_raise_callback_exception): New
prototype.
* lang/python/pyme/core.py ({Context,Data}.__init__): Move common
initialization to superclass.
(Context.set_progress_cb): Hand in 'self'.
* lang/python/pyme/util.py (GpgmeWrapper.__init__): New function.
(GpgmeWrapper.__getattr__): Raise stashed exceptions.
* lang/python/tests/Makefile.am (py_tests): Add new test.
* lang/python/tests/t-callbacks.py: New file.

Signed-off-by: Justus Winter <[email protected]>

2 files changed, 18 insertions, 8 deletions

diff --git a/lang/python/pyme/core.py b/lang/python/pyme/core.py
index 2a0ca072..8a4c197e 100644
--- a/lang/python/pyme/core.py
+++ b/lang/python/pyme/core.py
@@ -54,14 +54,14 @@ class Context(GpgmeWrapper):
 
     def __init__(self, wrapped=None):
         if wrapped:
-            self.wrapped = wrapped
             self.own = False
         else:
             tmp = pygpgme.new_gpgme_ctx_t_p()
             errorcheck(pygpgme.gpgme_new(tmp))
-            self.wrapped = pygpgme.gpgme_ctx_t_p_value(tmp)
+            wrapped = pygpgme.gpgme_ctx_t_p_value(tmp)
             pygpgme.delete_gpgme_ctx_t_p(tmp)
             self.own = True
+        super().__init__(wrapped)
         self.last_passcb = None
         self.last_progresscb = None
 
@@ -167,9 +167,9 @@ class Context(GpgmeWrapper):
         else:
             self.last_passcb = pygpgme.new_PyObject_p_p()
             if hook == None:
-                hookdata = func
+                hookdata = (self, func)
             else:
-                hookdata = (func, hook)
+                hookdata = (self, func, hook)
         pygpgme.pygpgme_set_passphrase_cb(self.wrapped, hookdata, self.last_passcb)
 
     def set_progress_cb(self, func, hook=None):
@@ -282,7 +282,7 @@ class Data(GpgmeWrapper):
         that file.
 
         Any other use will result in undefined or erroneous behavior."""
-        self.wrapped = None
+        super().__init__(None)
         self.last_readcb = None
 
         if cbs != None:
diff --git a/lang/python/pyme/util.py b/lang/python/pyme/util.py
index 3c34c79e..b54cd4dc 100644
--- a/lang/python/pyme/util.py
+++ b/lang/python/pyme/util.py
@@ -32,6 +32,11 @@ def process_constants(starttext, dict):
 class GpgmeWrapper(object):
     """Base class all Pyme wrappers for GPGME functionality.  Not to be
     instantiated directly."""
+
+    def __init__(self, wrapped):
+        self._callback_excinfo = None
+        self.wrapped = wrapped
+
     def __repr__(self):
         return '<instance of %s.%s with GPG object at %s>' % \
                (__name__, self.__class__.__name__,
@@ -78,11 +83,16 @@ class GpgmeWrapper(object):
 
         if self._errorcheck(name):
             def _funcwrap(slf, *args, **kwargs):
-                return errorcheck(func(slf.wrapped, *args, **kwargs),
-                                  "Invocation of " + name)
+                result = func(slf.wrapped, *args, **kwargs)
+                if slf._callback_excinfo:
+                    pygpgme.pygpgme_raise_callback_exception(slf)
+                return errorcheck(result, "Invocation of " + name)
         else:
             def _funcwrap(slf, *args, **kwargs):
-                return func(slf.wrapped, *args, **kwargs)
+                result = func(slf.wrapped, *args, **kwargs)
+                if slf._callback_excinfo:
+                    pygpgme.pygpgme_raise_callback_exception(slf)
+                return result
 
         _funcwrap.__doc__ = getattr(func, "__doc__")