How to write to Program Files (x86) in C#?

Question

A requirement of the application I am developing is to be able to install a plugin for an external program. Installing a plugin consists of dropping a dll into a plugins directory. The trouble is that the plugins directory is located in a folder in Program Files (x86). When attempting to write to it via File.WriteAllBytes, I encounter an UnauthorizedAccessException.

• This error occurs even if the program is Run as administrator.
• I have tried modifying my manifest to level requireAdministrator.
• I have also tried spawning a new process with with runas.

How can I drop my dll into a folder inside Program Files (x86)?

Answer 1

Try adding

[PermissionSet(SecurityAction.Demand, Name="FullTrust")]

above your method that involves the IO activity. F/E, the following copies "myFile" to the program files directory:

[PermissionSet(SecurityAction.Demand, Name="FullTrust")]
public void copyFile(string myFile){
    System.IO.File.Copy(myFile,Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles);
}