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c#impersonationnetworkcredentials

Copying a file, using impersonator, throw an Unauthorized Access Exception

I am using this Impersonator class to copy files to a Directory with access rights.

public void CopyFile(string sourceFullFileName,string targetFullFileName)
{
    var fileInfo = new FileInfo(sourceFullFileName);

    try
    {
        using (new Impersonator("username", "domain", "pwd"))
        {
            // The following code is executed under the impersonated user.
            fileInfo.CopyTo(targetFullFileName, true);
        }
    }
    catch (IOException)
    {
        throw;
    }
}

This code work almost perfectly. The problem I am facing is when the sourceFullFileName is a file located in folder like C:\Users\username\Documents where the original user has access but the impersonator not.

The exception I am getting while trying to copy a file from such location is:

An unhandled exception of type 'System.UnauthorizedAccessException' occurred in mscorlib.dll Additional information: Access to the path 'C:\Users\username\Documents\file.txt' is denied.

Solution

  • Before impersonation, the current user has access to the source file path but not to the destination file path.

    After impersonation, it is quite the opposite: the impersonated user has access to the destination file path but not to the source file path.

    If the files are not too large, my idea would be the following:

    public void CopyFile(string sourceFilePath, string destinationFilePath)
{
    var content = File.ReadAllBytes(sourceFilePath);

    using (new Impersonator("username", "domain", "pwd"))
    {
        File.WriteAllBytes(destinationFilePath, content);
    }
}

    I.e.:

    1. Read all content from the source file path into a byte array in memory.
    2. Do the impersonation.
    3. Write all content from the byte array in memory into the destination file path.

    Methods and classes used here: