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16Aug/100

Reading from C:\ProgramData without requiring UAC elevation

When trying to read some user settings from C:\ProgramData in my .NET app, I was getting an Access Denied exception, even though I was only attempting to read the configuration file, not write anything:

System.UnauthorizedAccessException: Access to the path 'C:\ProgramData\YourApp\1.0.0.0\settings.xml' is denied.

Even though I was only reading the file, and not writing anything, it still wanted elevation before it let me read it. It turns out that I need to signify my intent not to write anything when I open the stream. This code generated the exception (the "Using" statement actually threw the exception):

Using f As New FileStream(MySettingsFilePath, FileMode.Open)
    Dim formatter As New Formatters.Binary.BinaryFormatter
    MySettings = formatter.Deserialize(f)
    f.Close()
End Using

However, by changing the "FileStream" to a "StreamReader", I signify my intent to read and not write, so the code runs without an issue (there are two changes):

Using f As New StreamReader(MySettingsFilePath)
    Dim formatter As New Formatters.Binary.BinaryFormatter
    MySettings = formatter.Deserialize(f.BaseStream)
    f.Close()
End Using
MORAL - Elevation isn't required to read common application settings, only to write them, but you need to be clear about what you intend to do!
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