oc-tasks: Add edit/delete own and Folder Contact/Owner sharing perm

By storing these custom MAPI roles in the ACL. Take into account that
a task folder is shared with a calendar folder with the same name, therefore
permissions are shared and overwritten from different Outlook sections.

The extension 'X-SOGO-COMPONENT-CREATED-BY' is used to store the task
creator in both Outlook and SOGo Webmail.

The PidLidTaskOwner is not yet properly managed and we are always returning
the folder owner but to effects of sharing that extension is used by now
which matches a little more with what the user expects until we fix
the task ownership defined in [MS-OXOTASK].

OpenChange/MAPIStoreTasksMessage.m

@@ -154,6 +154,9 @@
   return MAPISTORE_SUCCESS;
 }
 
+//------------------------------------
+// Specific task related properties
+//------------------------------------
 - (enum mapistore_error) getPidLidTaskComplete: (void **) data
                                       inMemCtx: (TALLOC_CTX *) memCtx
 {
@@ -323,6 +326,7 @@
 {
   NSString *owner;
 
+  /* FIXME: This is wrong when setting task's request */
   owner = [sogoObject ownerInContext: nil];
 
   *data = [owner asUnicodeInMemCtx: memCtx];
@@ -336,6 +340,25 @@
   return [self getLongZero: data inMemCtx: memCtx];
 }
 
+// ----------------------------------
+// Sharing
+// ----------------------------------
+- (NSString *) creator
+{
+  iCalToDo *task;
+
+  task = [sogoObject component: NO secure: YES];
+  return [[task uniqueChildWithTag: @"x-sogo-component-created-by"]
+            flattenedValuesForKey: @""];
+}
+
+- (NSString *) owner
+{
+  /* This is not true but to allow a user edit its own tasks is required.
+     FIXME: When PidLidTaskOwner getter is properly implemented for Task Requests */
+  return [self creator];
+}
+
 - (BOOL) subscriberCanReadMessage
 {
   return ([[self activeUserRoles]
@@ -354,6 +377,15 @@
     rc = ([roles containsObject: SOGoCalendarRole_ComponentModifier]
           || [roles containsObject: SOGoCalendarRole_ComponentResponder]);
 
+  /* Check if the message is owned and it has permission to edit it */
+  if (!rc && [roles containsObject: MAPIStoreRightEditOwn])
+    {
+      NSString *currentUser;
+
+      currentUser = [[container context] activeUser];
+      rc = [currentUser isEqual: [self ownerUser]];
+    }
+
   return rc;
 }
 
@@ -524,10 +556,16 @@
 	[vToDo setAccessClass: @"PUBLIC"];
     }
 
+  /* Creation */
   now = [NSCalendarDate date];
   if ([sogoObject isNew])
     {
       [vToDo setCreated: now];
+      /* Creator is used for sharing purposes */
+      value = [properties objectForKey: MAPIPropertyKey (PidTagLastModifierName)];
+      if (value)
+        [[vToDo uniqueChildWithTag: @"x-sogo-component-created-by"] setSingleValue: value
+                                                                            forKey: @""];
     }
   [vToDo setTimeStampAsDate: now];