do some string conversions less hackish and address one review comment on how to call the callback and return results

python/src/deltachat/__init__.py

@@ -13,9 +13,10 @@ def py_dc_callback(ctx, evt, data1, data2):
     looks up the correct event handler for the given context.
     """
     callback = _DC_CALLBACK_MAP.get(ctx, lambda *a: 0)
-    ret = callback(ctx, evt, data1, data2)
+    try:
-    if ret is None:
+        ret = callback(ctx, evt, data1, data2)
-        return 0
+    except:
+        ret = 0
     return ret
 
 

python/src/deltachat/_build.py

@@ -29,12 +29,31 @@ def ffibuilder():
         'deltachat.capi',
         """
             #include <deltachat/deltachat.h>
+            const char * dupstring_helper(const char* string)
+            {
+                return strdup(string);
+            }
+            int dc_get_event_signature_types(int e)
+            {
+                int result = 0;
+                if (DC_EVENT_DATA1_IS_STRING(e))
+                    result |= 1;
+                if (DC_EVENT_DATA2_IS_STRING(e))
+                    result |= 2;
+                if (DC_EVENT_RETURNS_STRING(e))
+                    result |= 4;
+                if (DC_EVENT_RETURNS_INT(e))
+                    result |= 8;
+                return result;
+            }
         """,
         libraries=['deltachat'],
     )
     builder.cdef("""
         typedef int... time_t;
         void free(void *ptr);
+        extern const char * dupstring_helper(const char* string);
+        extern int dc_get_event_signature_types(int);
     """)
     cc = distutils.ccompiler.new_compiler(force=True)
     distutils.sysconfig.customize_compiler(cc)

python/tests/test_lowlevel.py

@@ -1,5 +1,6 @@
 from __future__ import print_function
 import deltachat
+import re
 import requests
 from deltachat import capi, get_dc_event_name
 from deltachat.capi import ffi
@@ -28,18 +29,30 @@ def test_cb(register_dc_callback):
 def test_basic_events(dc_context, dc_threads, register_dc_callback, tmpdir, userpassword):
     q = queue.Queue()
     def cb(dc_context, evt, data1, data2):
-        # print (evt1, data1, data2)
+        # the following code relates to the deltachat/_build.py's helper
-        data1 = try_cast_to_string(data1)
+        # function which provides us signature info of an event call
-        data2 = try_cast_to_string(data2)
+        event_sig_types = capi.lib.dc_get_event_signature_types(evt)
+        if data1 and event_sig_types & 1:
+            data1 = ffi.string(ffi.cast('char*', data1))
+        if data2 and event_sig_types & 2:
+            data2 = ffi.string(ffi.cast('char*', data2))
         evt_name = get_dc_event_name(evt)
         print (evt_name, data1, data2)
         if evt_name == "DC_EVENT_HTTP_GET":
             content =  read_url(data1)
-            # XXX how to give this string back to delta-core properly?
+            s = content.encode("utf-8")
-            # for now we just return nothing
+            # we need to return a pointer that the core owns
-        else:
+            dupped = capi.lib.dupstring_helper(s)
-            q.put((evt_name, data1, data2))
+            return ffi.cast('uintptr_t', dupped)
+        elif evt_name == "DC_EVENT_IS_OFFLINE":
+            return 0
+        elif event_sig_types & (4|8):  # returning string or int means it's a sync event
+            print ("dropping sync event: no handler for", evt_name)
+            return 0
+        # async event
+        q.put((evt_name, data1, data2))
         return 0
+
     register_dc_callback(dc_context, cb)
 
     dbfile = tmpdir.join("test.db")
@@ -48,25 +61,25 @@ def test_basic_events(dc_context, dc_threads, register_dc_callback, tmpdir, user
     capi.lib.dc_set_config(dc_context, "mail_pw", userpassword[1])
     capi.lib.dc_configure(dc_context)
 
-    while 1:
+    imap_ok = smtp_ok = False
-        evt_name, data1, data2 = q.get(timeout=2.0)
+    while not imap_ok or not smtp_ok:
+        evt_name, data1, data2 = q.get(timeout=5.0)
         if evt_name == "DC_EVENT_ERROR":
             assert 0
-        # XXX look for successful termination once we make things pass
+        if evt_name == "DC_EVENT_INFO":
+            if re.match("imap-login.*ok.", data2.lower()):
+                imap_ok = True
+            if re.match("smtp-login.*ok.", data2.lower()):
+                smtp_ok = True
+    assert 0
+    # assert capi.lib.dc_imap_is_connected(dc_context)
+    # assert capi.lib.dc_smtp_is_connected(dc_context)
 
 
 def read_url(url):
     try:
         r = requests.get(url)
     except requests.ConnectionError:
-        pass
+        return ''
     else:
         return r.content
-
-
-def try_cast_to_string(obj):
-    if isinstance(obj, long):
-        if obj > 100000:
-            return ffi.string(ffi.cast('char*', obj))
-    # print ("failed to convert", repr(obj))
-    return obj

src/deltachat.h

@@ -911,7 +911,7 @@ time_t          dc_lot_get_timestamp     (const dc_lot_t*);
 
 #define DC_EVENT_DATA1_IS_STRING(e)  ((e)==DC_EVENT_HTTP_GET || (e)==DC_EVENT_IMEX_FILE_WRITTEN || (e)==DC_EVENT_FILE_COPIED)
 #define DC_EVENT_DATA2_IS_STRING(e)  ((e)==DC_EVENT_INFO || (e)==DC_EVENT_WARNING || (e)==DC_EVENT_ERROR)
-#define DC_EVENT_RETURNS_INT         ((e)==DC_EVENT_IS_OFFLINE)
+#define DC_EVENT_RETURNS_INT(e)      ((e)==DC_EVENT_IS_OFFLINE)
 #define DC_EVENT_RETURNS_STRING(e)   ((e)==DC_EVENT_GET_QUANTITY_STRING || (e)==DC_EVENT_GET_STRING || (e)==DC_EVENT_HTTP_GET)