CreateProcessAsUser fast user switching

[lars]

Hello all,

I am using a service to execute a executable.
This works fine with one user logged on but when a second user logs on the executable executes on the desktop from the first user.

Does anybody know how to solve this.

My gues is the code i am using gets the pid from explorer.exe (probably the first one found)this way the code gets the wrong explorer.exe (desktop)

the executable has to be executed on the users desktop thats currently active.

i posted a code snipped below

please help.

lars

function GetShellProcessName: string;
var
Reg: TRegistry;
begin
Reg := TRegistry.Create(KEY_READ);
try
Reg.RootKey := HKEY_LOCAL_MACHINE;
Reg.OpenKeyReadOnly('Software\Microsoft\Windows NT\CurrentVersion\WinLogon');
Result := Reg.ReadString('Shell');
finally
Reg.Free;
end;
end;

function GetShellProcessPid(const Name: string): Longword;
var
Snapshot: THandle;
Process: TProcessEntry32;
B: Boolean;
begin
Result := 0;
Snapshot := CreateToolHelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if Snapshot <> INVALID_HANDLE_VALUE then
try
FillChar(Process, SizeOf(Process), 0);
Process.dwSize := SizeOf(Process);
B := Process32First(Snapshot, Process);
while B do
begin
if CompareText(Process.szExeFile, Name) = 0 then
begin
Result := Process.th32ProcessID;
Break;
end;
B := Process32Next(Snapshot, Process);
end;
finally
CloseHandle(Snapshot);
end;
end;

function GetShellHandle: THandle;
var
Pid: Longword;
begin
Pid := GetShellProcessPid(GetShellProcessName);
Result := OpenProcess(PROCESS_ALL_ACCESS, False, Pid);
end;
procedure ExecuteProcessAsLoggedOnUser(FileName: string);
var
ph: THandle;
hToken, nToken: THandle;
ProcInfo: TProcessInformation;
StartInfo: TStartupInfo;
begin
ph := GetShellHandle;
if ph > 0 then
begin
if OpenProcessToken(ph, TOKEN_DUPLICATE or TOKEN_QUERY, hToken) then
begin
if DuplicateTokenEx(hToken, TOKEN_ASSIGN_PRIMARY or TOKEN_DUPLICATE or TOKEN_QUERY,
nil, SecurityImpersonation, TokenPrimary, nToken) then
begin
if ImpersonateLoggedOnUser(nToken) then
begin
// Initialize then STARTUPINFO structure
FillChar(StartInfo, SizeOf(TStartupInfo), 0);
StartInfo.cb := SizeOf(TStartupInfo);

// Specify that the process runs in the interactive desktop
StartInfo.lpDesktop := PChar('WinSta0\Default');

// Launch the process in the client's logon session
CreateProcessAsUser(nToken, nil, PChar(FileName), nil, nil, False,
CREATE_NEW_CONSOLE or NORMAL_PRIORITY_CLASS, nil, nil, StartInfo, ProcInfo);

// End impersonation of client
RevertToSelf();
end;
CloseHandle(nToken);
end;
CloseHandle(hToken);
end;
end;
end;