Extension DLL callback function used for a Windows service and write to file

Hello, I have a problem with an extension DLL that has an exported function. The function is being exported ok, it is called by a Windows service. The Windows service is using the exported function, and everything works. I am trying to create a file with:

ofstream file;
file.open("C:\dir\to\file", ios::out);
file << "text";

But nothing happnes however. There are no errors, the file is just not created.
Also, if i try to call MessageBox() in the exported function, nothing happens as well :( . I have a .h file which exports the function with __declspec(dllexport) DWORD WINAPI functionName(), and also a .cpp file with the function definition. There is no main().

I appreciate help and suggestions about what I'm doing wrong.


oldejr.

Does the account the windows service is running under have write permissions to the folder?

Yes i think it's running as system account, but the folder has everyone permissions. And the MessageBox function is not being displayed when I try to call it in the exported function. I need that for debug messages.

You need to use two backslashes in a string when one is required. Try

Code:

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file.open("C:\\dir\\to\\file", ios:out);

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See http://msdn.microsoft.com/en-us/library/6aw8xdf2.aspx

Quote:

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Originally Posted by oldejr

Yes i think it's running as system account, but the folder has everyone permissions. And the MessageBox function is not being displayed when I try to call it in the exported function. I need that for debug messages.

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You need to check for errors and log them (try logging them to the event viewer). Lastly, you aren't going to see any MessageBox popups with a service by default - with services you need to use a different error reporting mechanism other than message boxes.