Code to resolve Windows .lnk shortcuts and obtain the file path they refer to. Uses shfolder.dll.

Windows Shortcut Resolver.cs

using System;
using System.Runtime.InteropServices;
using System.Text;

namespace WindowsGameMetadataRetriever
{
    [Flags()]
    enum SlgpFlags
    {
        /// <summary>Retrieves the standard short (8.3 format) file name</summary>
        SlgpShortpath = 0x1,
        /// <summary>Retrieves the Universal Naming Convention (UNC) path name of the file</summary>
        SlgpUncpriority = 0x2,
        /// <summary>Retrieves the raw path name. A raw path is something that might not exist and may include environment variables that need to be expanded</summary>
        SlgpRawpath = 0x4
    }

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    struct Win32FindDataw
    {
        public uint dwFileAttributes;
        public long ftCreationTime;
        public long ftLastAccessTime;
        public long ftLastWriteTime;
        public uint nFileSizeHigh;
        public uint nFileSizeLow;
        public uint dwReserved0;
        public uint dwReserved1;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
        public string cFileName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]
        public string cAlternateFileName;
    }

    [Flags()]
    enum SlrFlags
    {
        /// <summary>
        /// Do not display a dialog box if the link cannot be resolved. When SLR_NO_UI is set,
        /// the high-order word of fFlags can be set to a time-out value that specifies the
        /// maximum amount of time to be spent resolving the link. The function returns if the
        /// link cannot be resolved within the time-out duration. If the high-order word is set
        /// to zero, the time-out duration will be set to the default value of 3,000 milliseconds
        /// (3 seconds). To specify a value, set the high word of fFlags to the desired time-out
        /// duration, in milliseconds.
        /// </summary>
        SlrNoUI = 0x1,
        /// <summary>Obsolete and no longer used</summary>
        SlrAnyMatch = 0x2,
        /// <summary>If the link object has changed, update its path and list of identifiers.
        /// If SLR_UPDATE is set, you do not need to call IPersistFile::IsDirty to determine
        /// whether or not the link object has changed.</summary>
        SlrUpdate = 0x4,
        /// <summary>Do not update the link information</summary>
        SlrNoupdate = 0x8,
        /// <summary>Do not execute the search heuristics</summary>
        SlrNosearch = 0x10,
        /// <summary>Do not use distributed link tracking</summary>
        SlrNotrack = 0x20,
        /// <summary>Disable distributed link tracking. By default, distributed link tracking tracks
        /// removable media across multiple devices based on the volume name. It also uses the
        /// Universal Naming Convention (UNC) path to track remote file systems whose drive letter
        /// has changed. Setting SLR_NOLINKINFO disables both types of tracking.</summary>
        SlrNolinkinfo = 0x40,
        /// <summary>Call the Microsoft Windows Installer</summary>
        SlrInvokeMsi = 0x80
    }


    /// <summary>The IShellLink interface allows Shell links to be created, modified, and resolved</summary>
    [ComImport(), InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("000214F9-0000-0000-C000-000000000046")]
    interface IShellLinkW
    {
        /// <summary>Retrieves the path and file name of a Shell link object</summary>
        void GetPath([Out(), MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszFile, int cchMaxPath, out Win32FindDataw pfd, SlgpFlags fFlags);
        /// <summary>Retrieves the list of item identifiers for a Shell link object</summary>
        void GetIDList(out IntPtr ppidl);
        /// <summary>Sets the pointer to an item identifier list (PIDL) for a Shell link object.</summary>
        void SetIDList(IntPtr pidl);
        /// <summary>Retrieves the description string for a Shell link object</summary>
        void GetDescription([Out(), MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszName, int cchMaxName);
        /// <summary>Sets the description for a Shell link object. The description can be any application-defined string</summary>
        void SetDescription([MarshalAs(UnmanagedType.LPWStr)] string pszName);
        /// <summary>Retrieves the name of the working directory for a Shell link object</summary>
        void GetWorkingDirectory([Out(), MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszDir, int cchMaxPath);
        /// <summary>Sets the name of the working directory for a Shell link object</summary>
        void SetWorkingDirectory([MarshalAs(UnmanagedType.LPWStr)] string pszDir);
        /// <summary>Retrieves the command-line arguments associated with a Shell link object</summary>
        void GetArguments([Out(), MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszArgs, int cchMaxPath);
        /// <summary>Sets the command-line arguments for a Shell link object</summary>
        void SetArguments([MarshalAs(UnmanagedType.LPWStr)] string pszArgs);
        /// <summary>Retrieves the hot key for a Shell link object</summary>
        void GetHotkey(out short pwHotkey);
        /// <summary>Sets a hot key for a Shell link object</summary>
        void SetHotkey(short wHotkey);
        /// <summary>Retrieves the show command for a Shell link object</summary>
        void GetShowCmd(out int piShowCmd);
        /// <summary>Sets the show command for a Shell link object. The show command sets the initial show state of the window.</summary>
        void SetShowCmd(int iShowCmd);
        /// <summary>Retrieves the location (path and index) of the icon for a Shell link object</summary>
        void GetIconLocation([Out(), MarshalAs(UnmanagedType.LPWStr)] StringBuilder pszIconPath,
                             int cchIconPath, out int piIcon);
        /// <summary>Sets the location (path and index) of the icon for a Shell link object</summary>
        void SetIconLocation([MarshalAs(UnmanagedType.LPWStr)] string pszIconPath, int iIcon);
        /// <summary>Sets the relative path to the Shell link object</summary>
        void SetRelativePath([MarshalAs(UnmanagedType.LPWStr)] string pszPathRel, int dwReserved);
        /// <summary>Attempts to find the target of a Shell link, even if it has been moved or renamed</summary>
        void Resolve(IntPtr hwnd, SlrFlags fFlags);
        /// <summary>Sets the path and file name of a Shell link object</summary>
        void SetPath([MarshalAs(UnmanagedType.LPWStr)] string pszFile);

    }



    [ComImport, Guid("0000010c-0000-0000-c000-000000000046"),
     InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IPersist
    {
        [PreserveSig]
        void GetClassID(out Guid pClassID);
    }



    [ComImport, Guid("0000010b-0000-0000-C000-000000000046"),
     InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IPersistFile : IPersist
    {

        new void GetClassID(out Guid pClassID);
        [PreserveSig]
        int IsDirty();

        [PreserveSig]
        void Load([In, MarshalAs(UnmanagedType.LPWStr)]
                      string pszFileName, uint dwMode);

        [PreserveSig]
        void Save([In, MarshalAs(UnmanagedType.LPWStr)] string pszFileName,
                  [In, MarshalAs(UnmanagedType.Bool)] bool fRemember);

        [PreserveSig]
        void SaveCompleted([In, MarshalAs(UnmanagedType.LPWStr)] string pszFileName);

        [PreserveSig]
        void GetCurFile([In, MarshalAs(UnmanagedType.LPWStr)] string ppszFileName);
    
    }



// CLSID_ShellLink from ShlGuid.h 
    [
        ComImport(),
        Guid("00021401-0000-0000-C000-000000000046")
    ]




    public class ShellLink
    {
    }


    internal class WindowsShortcutResolver
    {

        [DllImport("shfolder.dll", CharSet = CharSet.Auto)]
        static extern int SHGetFolderPath
            (IntPtr hwndOwner, int nFolder,
            IntPtr hToken, int dwFlags,
            StringBuilder lpszPath);



        const uint StgmRead = 0;
        const int MaxPath = 260;



        public static string ResolveShortcut(string filename)
        {

            var link = new ShellLink();

            ((IPersistFile)link).Load(filename, StgmRead);
            
            // TODO: if I can get hold of the hwnd call resolve first. This handles moved and renamed files.  
            // ((IShellLinkW)link).Resolve(hwnd, 0) 
            
            StringBuilder sb = new StringBuilder(MaxPath);
            
            Win32FindDataw data;
            new Win32FindDataw();
            
            ((IShellLinkW)link).GetPath(sb, sb.Capacity, out data, 0);
            
            
            return sb.ToString(); 
        }


    }



}