Question

Given a file, I need to list all the users that have read access to that file using C# and .NET framework 4. Not interested in adding or listing any other permissions.
Assume the directory is a local directory and local users are enough.

Answer 1

I’m not sure if there’s an easy way to get that list, but here’s an idea. You can loop through the access control rules and check which users can read the file. Beware that some rules allow access while others deny it. Here’s a starting point:

using System.IO;
using System.Security.AccessControl;

...

FileSecurity security = File.GetAccessControl(@"C:\MyFolder\My File.txt");

AuthorizationRuleCollection acl = security.GetAccessRules(
   true, true, typeof(System.Security.Principal.NTAccount));
foreach (FileSystemAccessRule ace in acl)
{
   var user = ace.IdentityReference.Value;
   var rights = ace.FileSystemRights;
   var allowOrDeny = ace.AccessControlType;
   // ...
}

Check FileSystemAccessRule for further information.