Using IShellLink Interface to resolve a shortcut which has changed their drive letter

问题

According to MSDN Information here:

http://msdn.microsoft.com/en-us/library/windows/desktop/bb774952%28v=vs.85%29.aspx

And here:

http://msdn.microsoft.com/en-us/library/windows/desktop/bb774944%28v=vs.85%29.aspx

How I can resolve the fullpath of a link who has changed the driveletter on the shortcut Target?

Windows does this automatically in less than one second, but I need to work with a lot of shortcut files (.lnk files) in my application and I always get the raw old path, I can't resolve the path like windows does.

So for example if I have a shortcut file in this path:

C:\Test.lnk

And the target of the shortcut file is this

D:\Directory\Test.txt

Then If I rename the drive letter of the hard drive from "D:" to "F:" (the harddrive, not the target shortcut) Windows can still recognizing the shortcut as valid and can resolve the shortcut path instantly, so I know this can be possibly to do it with the IShellInterface but the problem is I don't know how to do it.

I don't understand what I need to do to resolve the shortcut, I don't know if I need to use GetPath method or Resolve Method, or both, also I don't know which window handle I need to pass to the resolve method...then is for launch a msgbox in a window or the method will return a string with the reoslved path?, all of this is getting me crazy, I need a code example.

I'm using this Class:

Imports System.Runtime.InteropServices
Imports System.Text

Public Class Form1

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    Dim TargetFilename As String = ResolveShortcut("C:\Test.lnk")
End Sub

<DllImport("shfolder.dll", CharSet:=CharSet.Auto)>
Friend Shared Function SHGetFolderPath(hwndOwner As IntPtr, nFolder As Integer, hToken As IntPtr, dwFlags As Integer, lpszPath As StringBuilder) As Integer
End Function

<Flags()>
Private Enum SLGP_FLAGS
    ''' <summary>Retrieves the standard short (8.3 format) file name</summary>
    SLGP_SHORTPATH = &H1
    ''' <summary>Retrieves the Universal Naming Convention (UNC) path name of the file</summary>
    SLGP_UNCPRIORITY = &H2
    ''' <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>
    SLGP_RAWPATH = &H4
End Enum

<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto)>
Private Structure WIN32_FIND_DATAW
    Public dwFileAttributes As UInteger
    Public ftCreationTime As Long
    Public ftLastAccessTime As Long
    Public ftLastWriteTime As Long
    Public nFileSizeHigh As UInteger
    Public nFileSizeLow As UInteger
    Public dwReserved0 As UInteger
    Public dwReserved1 As UInteger
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=260)>
    Public cFileName As String
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=14)>
    Public cAlternateFileName As String
End Structure

<Flags()>
Private Enum SLR_FLAGS
    ''' <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>
    SLR_NO_UI = &H1
    ''' <summary>Obsolete and no longer used</summary>
    SLR_ANY_MATCH = &H2
    ''' <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>
    SLR_UPDATE = &H4
    ''' <summary>Do not update the link information</summary>
    SLR_NOUPDATE = &H8
    ''' <summary>Do not execute the search heuristics</summary>
    SLR_NOSEARCH = &H10
    ''' <summary>Do not use distributed link tracking</summary>
    SLR_NOTRACK = &H20
    ''' <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>
    SLR_NOLINKINFO = &H40
    ''' <summary>Call the Microsoft Windows Installer</summary>
    SLR_INVOKE_MSI = &H80
End Enum

''' <summary>The IShellLink interface allows Shell links to be created, modified, and resolved</summary>
<ComImport(), InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("000214F9-0000-0000-C000-000000000046")>
Private Interface IShellLinkW
    ''' <summary>Retrieves the path and file name of a Shell link object</summary>
    Sub GetPath(<Out(), MarshalAs(UnmanagedType.LPWStr)> pszFile As StringBuilder, cchMaxPath As Integer, ByRef pfd As WIN32_FIND_DATAW, fFlags As SLGP_FLAGS)
    ''' <summary>Retrieves the list of item identifiers for a Shell link object</summary>
    Sub GetIDList(ByRef ppidl As IntPtr)
    ''' <summary>Sets the pointer to an item identifier list (PIDL) for a Shell link object.</summary>
    Sub SetIDList(pidl As IntPtr)
    ''' <summary>Retrieves the description string for a Shell link object</summary>
    Sub GetDescription(<Out(), MarshalAs(UnmanagedType.LPWStr)> pszName As StringBuilder, cchMaxName As Integer)
    ''' <summary>Sets the description for a Shell link object. The description can be any application-defined string</summary>
    Sub SetDescription(<MarshalAs(UnmanagedType.LPWStr)> pszName As String)
    ''' <summary>Retrieves the name of the working directory for a Shell link object</summary>
    Sub GetWorkingDirectory(<Out(), MarshalAs(UnmanagedType.LPWStr)> pszDir As StringBuilder, cchMaxPath As Integer)
    ''' <summary>Sets the name of the working directory for a Shell link object</summary>
    Sub SetWorkingDirectory(<MarshalAs(UnmanagedType.LPWStr)> pszDir As String)
    ''' <summary>Retrieves the command-line arguments associated with a Shell link object</summary>
    Sub GetArguments(<Out(), MarshalAs(UnmanagedType.LPWStr)> pszArgs As StringBuilder, cchMaxPath As Integer)
    ''' <summary>Sets the command-line arguments for a Shell link object</summary>
    Sub SetArguments(<MarshalAs(UnmanagedType.LPWStr)> pszArgs As String)
    ''' <summary>Retrieves the hot key for a Shell link object</summary>
    Sub GetHotkey(ByRef pwHotkey As Short)
    ''' <summary>Sets a hot key for a Shell link object</summary>
    Sub SetHotkey(wHotkey As Short)
    ''' <summary>Retrieves the show command for a Shell link object</summary>
    Sub GetShowCmd(ByRef piShowCmd As Integer)
    ''' <summary>Sets the show command for a Shell link object. The show command sets the initial show state of the window.</summary>
    Sub SetShowCmd(iShowCmd As Integer)
    ''' <summary>Retrieves the location (path and index) of the icon for a Shell link object</summary>
    Sub GetIconLocation(<Out(), MarshalAs(UnmanagedType.LPWStr)> pszIconPath As StringBuilder, cchIconPath As Integer, ByRef piIcon As Integer)
    ''' <summary>Sets the location (path and index) of the icon for a Shell link object</summary>
    Sub SetIconLocation(<MarshalAs(UnmanagedType.LPWStr)> pszIconPath As String, iIcon As Integer)
    ''' <summary>Sets the relative path to the Shell link object</summary>
    Sub SetRelativePath(<MarshalAs(UnmanagedType.LPWStr)> pszPathRel As String, dwReserved As Integer)
    ''' <summary>Attempts to find the target of a Shell link, even if it has been moved or renamed</summary>
    Sub Resolve(hwnd As IntPtr, fFlags As SLR_FLAGS)
    ''' <summary>Sets the path and file name of a Shell link object</summary>
    Sub SetPath(<MarshalAs(UnmanagedType.LPWStr)> pszFile As String)

End Interface

<ComImport(), Guid("0000010c-0000-0000-c000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)>
Public Interface IPersist
    <PreserveSig()>
    Sub GetClassID(ByRef pClassID As Guid)
End Interface


<ComImport(), Guid("0000010b-0000-0000-C000-000000000046"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)>
Public Interface IPersistFile
    Inherits IPersist
    Shadows Sub GetClassID(ByRef pClassID As Guid)
    <PreserveSig()>
    Function IsDirty() As Integer

    <PreserveSig()>
    Sub Load(<[In](), MarshalAs(UnmanagedType.LPWStr)> pszFileName As String, dwMode As UInteger)

    <PreserveSig()>
    Sub Save(<[In](), MarshalAs(UnmanagedType.LPWStr)> pszFileName As String, <[In](), MarshalAs(UnmanagedType.Bool)> fRemember As Boolean)

    <PreserveSig()>
    Sub SaveCompleted(<[In](), MarshalAs(UnmanagedType.LPWStr)> pszFileName As String)

    <PreserveSig()>
    Sub GetCurFile(<[In](), MarshalAs(UnmanagedType.LPWStr)> ppszFileName As String)
End Interface

Const STGM_READ As UInteger = 0
Const MAX_PATH As Integer = 260

' CLSID_ShellLink from ShlGuid.h 
<ComImport(), Guid("00021401-0000-0000-C000-000000000046")> Public Class ShellLink
End Class


Public Shared Function ResolveShortcut(filename As String) As String
    Dim link As New ShellLink()
    DirectCast(link, IPersistFile).Load(filename, STGM_READ)
    ' TODO: if I can get hold of the hwnd call resolve first. This handles moved and renamed files.  
    ' ((IShellLinkW)link).Resolve(hwnd, 0) 
    Dim sb As New StringBuilder(MAX_PATH)
    Dim data As New WIN32_FIND_DATAW()
    DirectCast(link, IShellLinkW).GetPath(sb, sb.Capacity, data, 0)
    Return sb.ToString()
End Function

End Class

EDIT:

If you know a simple but efficient way to get the fullpath when driveletter changes then just I will accept the answer.

But what I don't want is to use old vb6 methods or vbs or using external apps or For loops, that's why I've tried to use apis I think is the best way for performance.

回答1:

This is only tested with a connected network drive (i won`t change my local driveletters for testing):

Public Shared Function ResolveShortcut(filename As String,hwnd As IntPtr) As String
    Dim link As New ShellLink()
    DirectCast(link, IPersistFile).Load(filename, STGM_READ)

    DirectCast(link, IShellLinkW).Resolve(hwnd, SLR_FLAGS.SLR_UPDATE)

    Dim sb As New StringBuilder(MAX_PATH)
    Dim data As New WIN32_FIND_DATAW()
    DirectCast(link, IShellLinkW).GetPath(sb, sb.Capacity, data, 0)
    Return sb.ToString()
End Function

To be called like:

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    Dim TargetFilename As String = ResolveShortcut("C:\Test.lnk",Me.Handle)
End Sub

As the documentation, you have reffered to, states :

SLR_UPDATE (0x0004)
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 the link object has changed.

So passing the Handle of the form ( which the Shell will need if it needs to display some dialog ) for calling the Resolve method and passing SLR_UPDATE as second parameter, results for a connected networkdrive in the right path (at least on my site).

来源：https://stackoverflow.com/questions/18885865/using-ishelllink-interface-to-resolve-a-shortcut-which-has-changed-their-drive-l