C# – Add permission in folder via SharePoint Web Services

Example of using the WSS "Copy" Web service to upload a document to a library...

public static void UploadFile2007(string destinationUrl, byte[] fileData)
{
    // List of desination Urls, Just one in this example.
    string[] destinationUrls = { Uri.EscapeUriString(destinationUrl) };

    // Empty Field Information. This can be populated but not for this example.
    SharePoint2007CopyService.FieldInformation information = new 
        SharePoint2007CopyService.FieldInformation();
    SharePoint2007CopyService.FieldInformation[] info = { information };

    // To receive the result Xml.
    SharePoint2007CopyService.CopyResult[] result;

    // Create the Copy web service instance configured from the web.config file.
    SharePoint2007CopyService.CopySoapClient
    CopyService2007 = new CopySoapClient("CopySoap");
    CopyService2007.ClientCredentials.Windows.ClientCredential = 
        CredentialCache.DefaultNetworkCredentials;
    CopyService2007.ClientCredentials.Windows.AllowedImpersonationLevel = 
        System.Security.Principal.TokenImpersonationLevel.Delegation;

    CopyService2007.CopyIntoItems(destinationUrl, destinationUrls, info, fileData, out result);

    if (result[0].ErrorCode != SharePoint2007CopyService.CopyErrorCode.Success)
    {
        // ...
    }
}

WSS has a basic UI for setting item-level permission on list items, but they hide that from the UI for document libraries. If you go into Settings->List Settings->Avanced settings for a list, you'll see the options to do pretty much what you're asking for. However, on document libraries, that UI is not available. The settings it drives, though are avaiable via the object model.

You could set those same properties for a document library like this:

SPDocumentLibrary onlyOwnLib = theWeb.Lists["DocLibName"]  
onlyOwnLib.WriteSecurity = 2;  
onlyOwnLib.Update();  

And that should about do it. However, apparently that doesn't really set permissions; it just controls what the user can do via the UI. If they had another interface to the library (like via WebDAV) or list (like via the web services), it wouldn't prevent them from editing items they didn't create. If you want true item-level permissions, I think you need to go the event handler route.

This post from Matt Morse explains it in more detail, and he even wrote a command line tool to set the property (plus the .ReadSecurity property) for lists and libraries.