TaskScheduler ExecAction put_WorkingDirectory fails to update its value - c++

Question

I'm working on a project that needs to install a series of Windows Task Scheduler tasks and for that I created a Wix project and a Custom Action that takes care of all the details. That Custom Action was created using C++ to avoid dependencies on the .NET Framework.
At first I started executing SCHTASKS.EXE from a Wix custom action but, after I managed to create the correct command line to install a task correctly, I realized I couldn't set the Action's Working Directory ('Start in' in the Task Scheduler UI) from the SCHTASKS.EXE command line, because it simply didn't have the option...
I decided then to use COM in C++ (#import <taskschd.dll> raw_interfaces_only) to get to the Task Scheduler and tweak the WorkingFolder using the API after installing the Task using SCHTASKS.EXE which was working fine besides that detail.
I managed to get to the task and read its values after installing the task correctly but when I executed put_WorkingDirectory method with the current value that didn't fail actually, but the value wasn't saved into the task.
Does anyone have a clue why I couldn't get there? This is part of the code I used to get to the ExecAction and set the value successfully. Remember this is within a Wix Custom action so some of the methods calls are Wix's.
This code is actually working and the log shows the correct path I intend to set, but the task doesn't get changed. What am I doing wrong?
HRESULT UpdateWorkingDirectory(TaskScheduler::ITaskFolderPtr rootFolder, BSTR taskName, BSTR installFolder)
{
HRESULT hr = S_OK;
TaskScheduler::IRegisteredTaskCollectionPtr taskCollection;
LONG numTasks = 0;
TaskScheduler::IRegisteredTaskPtr thisTask;
TaskScheduler::ITaskDefinitionPtr definition;
TaskScheduler::IActionCollectionPtr actions;
TaskScheduler::IActionPtr action;
TaskScheduler::IExecActionPtr execAction;
long actionCount;
hr = rootFolder->GetTasks(NULL, &taskCollection);
ExitOnFailure(hr, "Cannot get task collection pointer");
hr = taskCollection->get_Count(&numTasks);
ExitOnFailure(hr, "Cannot get task collection item count");
for (LONG taskIdx = 0; taskIdx < numTasks; taskIdx++) {
TaskScheduler::IRegisteredTaskPtr registeredTask;
bstr_t taskIdxName;
hr = taskCollection->get_Item(variant_t(taskIdx + 1), &registeredTask);
ExitOnFailure(hr, "Cannot get task item %d", taskIdx + 1);
hr = registeredTask->get_Name(&taskIdxName.GetBSTR());
ExitOnFailure(hr, "Cannot get task name");
WcaLog(LOGMSG_STANDARD, " registered task name = %s", (LPCSTR)taskIdxName);
if (strcmp(bstr_t(taskName), taskIdxName) == 0) {
thisTask = registeredTask;
break;
}
}
if (thisTask == NULL) {
hr = E_FAIL;
ExitOnFailure(hr, "task {%S} not found", taskName);
}
hr = thisTask->get_Definition(&definition);
ExitOnFailure(hr, "error getting task definition for {%S}", taskName);
hr = definition->get_Actions(&actions);
ExitOnFailure(hr, "error getting actions for {%S}", taskName);
WcaLog(LOGMSG_STANDARD, " got actions from %S", taskName);
hr = actions->get_Count(&actionCount);
ExitOnFailure(hr, "error getting action count for {%S}", taskName);
WcaLog(LOGMSG_STANDARD, " got count = %d from {%S}", actionCount, taskName);
if (actionCount > 0) {
bstr_t actionId;
bstr_t arguments;
bstr_t path;
hr = actions->get_Item(1, &action);
ExitOnFailure(hr, "error getting action[1] for {%S}", taskName);
hr = action->QueryInterface(&execAction);
ExitOnFailure(hr, "error getting ExecAction for {%S}", taskName);
hr = execAction->get_Id(&actionId.GetBSTR());
ExitOnFailure(hr, "error getting Exec Action id for first exec action of {%S}", taskName);
WcaLog(LOGMSG_STANDARD, " first Exec Action Id is %s", (LPCSTR)actionId);
hr = execAction->get_Arguments(&arguments.GetBSTR());
ExitOnFailure(hr, "error getting Exec Action arguments for first exec action of {%S}", taskName);
WcaLog(LOGMSG_STANDARD, " first Exec Action arguments are %s", (LPCSTR)arguments);
hr = execAction->get_Path(&path.GetBSTR());
ExitOnFailure(hr, "error getting Exec Action path for first exec action of {%S}", taskName);
WcaLog(LOGMSG_STANDARD, " first Exec Action path is %s", (LPCSTR)path);
hr = execAction->put_WorkingDirectory(installFolder);
ExitOnFailure(hr, "error putting working directory for {%S}", taskName);
WcaLog(LOGMSG_STANDARD, " successful put working directory to %S", installFolder);
}
LExit:
return hr;
}
NOTE: All C++ samples I found used simple interface pointers instead of smart pointers, I preferred smart pointers to avoid taking care of release by myself

Answer 1

It seems to me that this is a good example:
https://msdn.microsoft.com/en-us/library/windows/desktop/aa446854(v=vs.85).aspx
More specifically, it shows that you call ITask::Activate before changing things like the working directory, and that you call IPersistFile to save the changes. I can't see any of these in that posted code sample. I've not looked at these interfaces for a while, but that might be the issue.

Answer 2

I found the answer
I had to change my method signature to accommodate username and password
HRESULT UpdateWorkingDirectory(TaskScheduler::ITaskFolderPtr rootFolder, BSTR taskName, BSTR installFolder, variant_t username, variant_t password)
and add these five lines
thisTask = NULL;
hr = rootFolder->RegisterTaskDefinition(taskName, definition, TaskScheduler::_TASK_CREATION::TASK_UPDATE, username, password, TaskScheduler::_TASK_LOGON_TYPE::TASK_LOGON_PASSWORD, variant_t(), &thisTask);
ExitOnFailure(hr, "error updating task regisration for {%S}", taskName);
WcaLog(LOGMSG_STANDARD, " successful update of task regisration to %S", taskName);
after executing put_WorkingDirectory.
This updates the registration of the task definition with the updated value, that was what I wanted to do, and it worked!!!!