File I/O permissions, the C# way

I believe the article I wrote here:

User Login For WinForm Applications[^]

will help you get the user group(s) the currently logged in user is a member of.

Right-click "My Computer", Click "Manage", then go to "Local Users and Groups", you'll see a list of Groups right there.

I suspect the group you want is simply called "Users".

Hope it helps.

Here is a link you may want to have a look at[^]

I think I found it:

// Create a new DirectoryInfo object.
System.IO.DirectoryInfo dInfo = new System.IO.DirectoryInfo(
    "X:\\Somewhere\\MyDirectory"
);

// Get a DirectorySecurity object that represents the
// current security settings.
DirectorySecurity dSecurity = dInfo.GetAccessControl();

// Add the FileSystemAccessRule to the security settings.
dSecurity.AddAccessRule(
    new FileSystemAccessRule(
        new System.Security.Principal.SecurityIdentifier(
            System.Security.Principal.WellKnownSidType.BuiltinUsersSid,
            null
        ),
        FileSystemRights.DeleteSubdirectoriesAndFiles,
        //FileSystemRights.FullControl,
        AccessControlType.Allow
    )
);

// Set the new access settings.
dInfo.SetAccessControl(dSecurity);

The BuiltinUsersSid should make this work for all normal users (in some cases WorldSid could be helpful as "Everyone"). Of course, whoever executes that code has to have the right to change those permissions in order to succeed.

In my case I would call above code right after creating a directory. The caller would therefore be the owner. So he should be able to do whatever he wants.

I tried above code by creating two user accounts on my windows XP. As admin, I created a directory and run above code. Then, I created a file inside the directory.
As user1, I wasn't able to change the test file, but to delete it and create another one. As user2, I again couldn't change the new file, but delete it and create yet another one.

So DeleteSubdirectoriesAndFiles seems to cause just what you would expect from its name.

private static DirectorySecurity RemoveExplicitSecurity(DirectorySecurity directorySecurity)
{
    AuthorizationRuleCollection rules = directorySecurity.GetAccessRules(true, false, typeof(System.Security.Principal.NTAccount));
    foreach (FileSystemAccessRule rule in rules)
        directorySecurity.RemoveAccessRule(rule);
    return directorySecurity;
}