How to read link (.lnk) files?

[Wayne Diamond]

Has anybody been able to read .lnk files yet? According to POFFS2 many people have tried but no source has apparently been posted All I need to find out is what file the .lnk file is pointing to so I could probably write a neanderthal routine to scan for it but it'd be nice to do it the proper way if anybody knows how?


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[Sven Blumenstein]

I just took a look on a lnk file under Linux :-)
It's binary but the path of the source file is
in plain-text. But I think, there is a Windows
API to get the path.

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E-Mail (home): mailto:[email protected][email protected]</A>
E-Mail (work): mailto:[email protected][email protected]</A>

[Wayne Diamond]

I found some C and C++ source code to do exactly what Im after and it seems to do it "properly" (using Co* APIs) - http://sparksoft.363.net/Info/Info15.htm
It seems fairly straightforward but still beyond my C translation abilities! so ill continue looking i think

It's been a while since i've messed with that, but i dug up the following
source code. it has been so long that i can't remember if this was the file
i got working, so someone should test it out (i don't have time). however,
it basically decodes the windows .lnk file format to find out what it is a
shortcut to, and determines if that is a directory (i was going to write a
unix type ln command using .lnk file formats.....). there are 2 files here.
one is a c version, the other is a c++ version.... hope this helps....
-donald murray

============================================
c version
============================================
#include <windows.h>
#include <windowsx.h>
#include <objbase.h>
#include <shlobj.h>
#include <stdio.h>
#include <initguid.h>
#include <string.h>
main(int ac, char *av[])
{
ishelllink *psl;
hresult hres;
win32_find_data wfd;
char szgotpath[max_path];
ipersistfile *ppf;
    if (ac != 2)
{
printf("syntax: ln <pathname>\n");
return 0;
}
    hres = coinitialize(null);
if (!succeeded(hres))
printf("could not open the com library\n");
    hres = cocreateinstance(&clsid_shelllink, null, clsctx_inproc_server,
&iid_ishelllink, (lpvoid *)&psl);
if (succeeded(hres))
{
hres = psl->lpvtbl->queryinterface(psl, &iid_ipersistfile, &ppf);
        if (succeeded(hres))
{
word wsz[max_path];
            multibytetowidechar(cp_acp, 0, av[1], -1, wsz, max_path);
            hres = ppf->lpvtbl->load(ppf, wsz, stgm_read);
if (succeeded(hres))
{
hres = psl->lpvtbl->resolve(psl, 0, slr_any_match);
                if (succeeded(hres))
{
strcpy(szgotpath, av[1]);
                   hres = psl->lpvtbl->getpath(psl, szgotpath, max_path,
(win32_find_data *)&wfd, slgp_shortpath );
if (!succeeded(hres))
printf("getpath failed!\n");
                   printf("this points to %s\n", wfd.cfilename);
if (wfd.dwfileattributes & file_attribute_directory)
printf("this is a directory\n");
}
}
else
printf("ipersistfile load error\n");
ppf->lpvtbl->release(ppf);
}
else
printf("queryinterface error\n");
psl->lpvtbl->release(psl);
}
else
printf("cocreateinstance error - hres = %08x\n", hres);
return 0;
}
==================================
c++ version
==================================
#include <windowsx.h>
#include <objbase.h>
#include <shlobj.h>
#include <stdio.h>
#include <initguid.h>
#include <stdlib.h>
#include <io.h>
#include <string.h>
// this program should print out whether the file is a link and where it
// points to and whether it is a directory or not.
//
main(int ac, char *av[])
{
if (ac != 2)
{
printf("syntax: ln <pathname>\n");
return 0;
}
    ishelllink *psl;                            // pointer to ishelllink i/f
hresult hres;
win32_find_data wfd;
char szgotpath[max_path];
    // get pointer to the ishelllink interface.
    hres = cocreateinstance(clsid_shelllink, null, clsctx_inproc_server,
iid_ishelllink, (lpvoid *)&psl);
    if (succeeded(hres))
{
// get pointer to the ipersistfile interface.
        ipersistfile *ppf;
hres = psl->queryinterface(iid_ipersistfile, (lpvoid *)&ppf);
        if (succeeded(hres))
{
word wsz[max_path];
            // ensure string is unicode.
multibytetowidechar(cp_acp, 0, av[1], -1, wsz, max_path);
            // load the shell link
hres = ppf->load(wsz, stgm_read);
if (succeeded(hres))
{
// resolve the link.
                hres = psl->resolve(0, slr_any_match);
//                  ^
// using 0 instead -| of hwnd, as hwnd is only used if
// interface needs to prompt for more information. should use
// hwnd from current console in the long run.
                if (succeeded(hres))
{
strcpy(szgotpath, av[1]);
                    hres = psl->getpath(szgotpath, max_path,
(win32_find_data *)&wfd, slgp_shortpath );
if (!succeeded(hres))
printf("getpath failed!\n");
                    printf("this points to %s\n", wfd.cfilename);
if (wfd.dwfileattributes & file_attribute_directory)
printf("this is a directory\n");
}
}
else
printf("ipersistfile load error\n");
ppf->release();
}
else
printf("queryinterface error\n");
psl->release();
}
else
printf("cocreateinstance error - hres = %08x\n", hres);
return 0;
}

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[Peter P Stephensen]

have a look at http://www.powerbasic.com/support/pb...ad.php?t=23774

regards
peter

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[Wayne Diamond]

Thanks very much, Semen just alerted me to that URL, thanks Semen, thanks Peter, and thanks to author-of-the-piece Florent Heyworth and George Bleck for his mods that code works beautifully and seems to be the right way to do this - saves me writing a pathetic hack with binary file access
it escaped my POFFS searches because I was searching for link instead of shortcut... *duh*


[This message has been edited by Wayne Diamond (edited June 25, 2001).]

[Peter P Stephensen]

Wayne,

Just for fun I rewrote George Bleck's code. Here you have a
OOP-version:

Test Code:

#compile exe
#dim all
#register none
#include "win32api.inc"
#include "link.inc"
 
function pbmain
 
    if LinkOpen("C:\PBDLL60\Projects\SendTo\RunGAMS.lnk") = 0 then
        msgbox "Could not open link" : exit function
    end if		
  
    msgbox LinkGetFilePath,, "LinkGetFilePath"
    msgbox LinkGetWorkingDirectory,, "LinkGetWorkingDirectory"
    msgbox LinkGetArguments,, "LinkGetArguments"
 
    LinkClose
 
end function

Here is the include-file:

DECLARE FUNCTION CoInitialize Lib "ole32.dll" ALIAS "CoInitialize"( BYVAL pvReserved AS DWORD ) AS DWORD
DECLARE FUNCTION CoCreateInstance Lib "ole32.dll" ALIAS "CoCreateInstance"( rclsid AS STRING * 16, BYVAL pUnkOuter AS ANY, BYVAL dwClsContext AS DWORD, riid AS STRING * 16, ppv AS DWORD ) AS DWORD
DECLARE SUB CoUninitialize Lib "ole32.dll" ALIAS "CoUninitialize"
DECLARE SUB CoTaskMemFree Lib "ole32.dll" ALIAS "CoTaskMemFree"( pv AS DWORD )
DECLARE FUNCTION Sub1( p1 AS ANY ) AS DWORD
DECLARE FUNCTION Sub2( p1 AS ANY, p2 AS ANY ) AS DWORD
DECLARE FUNCTION Sub3( p1 AS ANY, p2 AS ANY, p3 AS ANY ) AS DWORD
DECLARE FUNCTION Sub5( p1 AS ANY, p2 AS ANY, p3 AS ANY, p4 AS ANY, p5 AS ANY ) AS DWORD
  
%LinkOpen = 1
%LinkClose = 2
%LinkGetFilePath = 3
%LinkGetWorkingDirectory = 4
%LinkGetArguments = 5
  
function LinkMainFunction(byval func_id as long, byval s as string) as string
  
    LOCAL CLSCTX_INPROC_SERVER AS DWORD
    LOCAL CLSID_ShellLink AS STRING * 16
    LOCAL FileData AS WIN32_FIND_DATA
    LOCAL Flags AS DWORD
    LOCAL IID_IShellLink AS STRING * 16
    LOCAL IID_Persist AS STRING * 16
    LOCAL lResult AS DWORD
    LOCAL outvalue AS ASCIIZ * 128
    local pp AS DWORD PTR
    static ppf AS DWORD PTR
    static psl AS DWORD PTR
    LOCAL TmpAsciiz AS ASCIIZ * %MAX_PATH
    LOCAL TmpWide AS ASCIIZ * ( 2 * %MAX_PATH )
 
    select case func_id
    case %LinkOpen
	CLSID_ShellLink = MKL$( &H00021401 ) + CHR$( 0, 0, 0, 0, &HC0, 0, 0, 0, 0, 0, 0, &H46 )
	IID_IShellLink = MKL$( &H000214EE ) + CHR$( 0, 0, 0, 0, &HC0, 0, 0, 0, 0, 0, 0, &H46 )
	IID_Persist = MKL$( &H0000010B ) + CHR$( 0, 0, 0, 0, &HC0, 0, 0, 0, 0, 0, 0, &H46 )
	CLSCTX_INPROC_SERVER = 1
 
	CoInitialize %Null
 
	if CoCreateInstance( CLSID_ShellLink, %Null, CLSCTX_INPROC_SERVER, IID_IShellLink, psl ) <> %S_OK then
	    function = "" : exit function
	end if
  
	pp = @psl: CALL DWORD @pp USING Sub3( BYVAL psl, IID_Persist, ppf ) TO lResult
	TmpAsciiz = s
	MultiByteToWideChar %CP_ACP, 0, TmpAsciiz, - 1, TmpWide, %MAX_PATH
	pp = @ppf + 20: CALL DWORD @pp USING Sub3( BYVAL ppf, TmpWide, BYVAL %True )
 
	function = "OK" : exit function
  
	case %LinkClose
	    'Release the persistant file
	    pp = @ppf + 8: CALL DWORD @pp USING Sub1( BYVAL ppf )
	    'Unbind the shell link object from the persistent file
	    pp = @psl + 8: CALL DWORD @pp USING Sub1( BYVAL psl )
 
	    CoUninitialize : exit function
 	
	case %LinkGetFilePath
	    pp = @psl + 12: CALL DWORD @pp USING Sub5( BYVAL psl, outvalue, BYVAL %MAX_PATH, FileData, Flags )	
	    function = outvalue : exit function
 
	case %LinkGetWorkingDirectory
	    pp = @psl + 32: CALL DWORD @pp USING Sub3( BYVAL psl, outvalue, BYVAL %MAX_PATH )	
	    function = outvalue : exit function
 
	case %LinkGetArguments
	    pp = @psl + 40: CALL DWORD @pp USING Sub3( BYVAL psl, outvalue, BYVAL %MAX_PATH )	
	    function = outvalue : exit function
 
	end select 
 
end function
 
function LinkOpen(byval LinkPath as string) as long
    if LinkMainFunction(%LinkOpen, LinkPath) = "" then exit function
    function = 1
end function	
  
sub LinkClose()
    LinkMainFunction %LinkClose, ""
end sub
 
function LinkGetFilePath() as string
    function = LinkMainFunction(%LinkGetFilePath, "")
end function	
 
function LinkGetWorkingDirectory() as string
    function = LinkMainFunction(%LinkGetWorkingDirectory, "")
end function	
 
function LinkGetArguments() as string
    function = LinkMainFunction(%LinkGetArguments, "")
end function

Regards
Peter


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[Scott Turchin]

I just checked out the source code in the forum that was re-written (Nice job both of you)...

Question!


We have need to look at a specific .LNK file to determine what the UNC name is inside the .LNK file.

MS has a tool that does this, but seems like it would just be one more function to add, if so how do you do that?


Reason I ask is that for some reason after a Dr watson that part gets changed, but you don't see that part unless you open the .LNK file with a hex editor...

In other words if we dr watson ONE time our problems multiply exponentially because of that.
So this code will help build a tool to validate the UNC name did not infact change...


Thanks!


Scott


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Scott