src/msw/utilsexc.cpp

/////////////////////////////////////////////////////////////////////////////
// Name:        msw/utilsexec.cpp
// Purpose:     wxExecute implementation for MSW
// Author:      Julian Smart
// Modified by:
// Created:     04/01/98
// RCS-ID:      $Id$
// Copyright:   (c) 1998-2002 wxWindows dev team
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

// ============================================================================
// declarations
// ============================================================================

// ----------------------------------------------------------------------------
// headers
// ----------------------------------------------------------------------------

#ifdef __GNUG__
    #pragma implementation
#endif

// For compilers that support precompilation, includes "wx.h".
#include "wx/wxprec.h"

#ifdef __BORLANDC__
    #pragma hdrstop
#endif

#ifndef WX_PRECOMP
    #include "wx/utils.h"
    #include "wx/app.h"
    #include "wx/intl.h"
    #include "wx/log.h"
    #if wxUSE_GUI // See 'dirty hack' below.
        #include "wx/frame.h"
    #endif
#endif

#ifdef __WIN32__
    #include "wx/stream.h"
    #include "wx/process.h"
#endif

#include "wx/msw/private.h"

#include <ctype.h>

#if !defined(__GNUWIN32__) && !defined(__SALFORDC__) && !defined(__WXMICROWIN__)
    #include <direct.h>
#ifndef __MWERKS__
    #include <dos.h>
#endif
#endif

#if defined(__GNUWIN32__) && !defined(__TWIN32__)
    #include <sys/unistd.h>
    #include <sys/stat.h>
#endif

#if defined(__WIN32__) && !defined(__WXMICROWIN__)
#ifndef __UNIX__
    #include <io.h>
#endif

#ifndef __GNUWIN32__
#include <shellapi.h>
#endif
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifndef __WATCOMC__
    #if !(defined(_MSC_VER) && (_MSC_VER > 800))
        #include <errno.h>
    #endif
#endif
#include <stdarg.h>

#if wxUSE_IPC
    #include "wx/dde.h"         // for WX_DDE hack in wxExecute
#endif // wxUSE_IPC

// ----------------------------------------------------------------------------
// constants
// ----------------------------------------------------------------------------

// this message is sent when the process we're waiting for terminates
#define wxWM_PROC_TERMINATED (WM_USER + 10000)

// ----------------------------------------------------------------------------
// this module globals
// ----------------------------------------------------------------------------

// we need to create a hidden window to receive the process termination
// notifications and for this we need a (Win) class name for it which we will
// register the first time it's needed
static const wxChar *gs_classForHiddenWindow = NULL;

// ----------------------------------------------------------------------------
// private types
// ----------------------------------------------------------------------------

// structure describing the process we're being waiting for
struct wxExecuteData
{
public:
    ~wxExecuteData()
    {
#ifndef __WIN16__
        if ( !::CloseHandle(hProcess) )
        {
            wxLogLastError(wxT("CloseHandle(hProcess)"));
        }
#endif
    }

    HWND       hWnd;          // window to send wxWM_PROC_TERMINATED to
    HANDLE     hProcess;      // handle of the process
    DWORD      dwProcessId;   // pid of the process
    wxProcess *handler;
    DWORD      dwExitCode;    // the exit code of the process
    bool       state;         // set to FALSE when the process finishes
};

#if defined(__WIN32__) && wxUSE_STREAMS

// ----------------------------------------------------------------------------
// wxPipeStreams
// ----------------------------------------------------------------------------

class wxPipeInputStream: public wxInputStream
{
public:
    wxPipeInputStream(HANDLE hInput);
    virtual ~wxPipeInputStream();

    // returns TRUE if the pipe is still opened
    bool IsOpened() const { return m_hInput != INVALID_HANDLE_VALUE; }

    // returns TRUE if there is any data to be read from the pipe
    virtual bool CanRead() const;

protected:
    size_t OnSysRead(void *buffer, size_t len);

protected:
    HANDLE m_hInput;

    DECLARE_NO_COPY_CLASS(wxPipeInputStream)
};

class wxPipeOutputStream: public wxOutputStream
{
public:
    wxPipeOutputStream(HANDLE hOutput);
    virtual ~wxPipeOutputStream();

protected:
    size_t OnSysWrite(const void *buffer, size_t len);

protected:
    HANDLE m_hOutput;

    DECLARE_NO_COPY_CLASS(wxPipeOutputStream)
};

// define this to let wxexec.cpp know that we know what we're doing
#define _WX_USED_BY_WXEXECUTE_
#include "../common/execcmn.cpp"

// ----------------------------------------------------------------------------
// wxPipe represents a Win32 anonymous pipe
// ----------------------------------------------------------------------------

class wxPipe
{
public:
    // the symbolic names for the pipe ends
    enum Direction
    {
        Read,
        Write
    };

    // default ctor doesn't do anything
    wxPipe() { m_handles[Read] = m_handles[Write] = INVALID_HANDLE_VALUE; }

    // create the pipe, return TRUE if ok, FALSE on error
    bool Create()
    {
        // default secutiry attributes
        SECURITY_ATTRIBUTES security;

        security.nLength              = sizeof(security);
        security.lpSecurityDescriptor = NULL;
        security.bInheritHandle       = TRUE; // to pass it to the child

        if ( !::CreatePipe(&m_handles[0], &m_handles[1], &security, 0) )
        {
            wxLogSysError(_("Failed to create an anonymous pipe"));

            return FALSE;
        }

        return TRUE;
    }

    // return TRUE if we were created successfully
    bool IsOk() const { return m_handles[Read] != INVALID_HANDLE_VALUE; }

    // return the descriptor for one of the pipe ends
    HANDLE operator[](Direction which) const
    {
        wxASSERT_MSG( which >= 0 && (size_t)which < WXSIZEOF(m_handles),
                      _T("invalid pipe index") );

        return m_handles[which];
    }

    // detach a descriptor, meaning that the pipe dtor won't close it, and
    // return it
    HANDLE Detach(Direction which)
    {
        wxASSERT_MSG( which >= 0 && (size_t)which < WXSIZEOF(m_handles),
                      _T("invalid pipe index") );

        HANDLE handle = m_handles[which];
        m_handles[which] = INVALID_HANDLE_VALUE;

        return handle;
    }

    // close the pipe descriptors
    void Close()
    {
        for ( size_t n = 0; n < WXSIZEOF(m_handles); n++ )
        {
            if ( m_handles[n] != INVALID_HANDLE_VALUE )
            {
                ::CloseHandle(m_handles[n]);
                m_handles[n] = INVALID_HANDLE_VALUE;
            }
        }
    }

    // dtor closes the pipe descriptors
    ~wxPipe() { Close(); }

private:
    HANDLE m_handles[2];
};

#endif // wxUSE_STREAMS

// ============================================================================
// implementation
// ============================================================================

#ifdef __WIN32__

// ----------------------------------------------------------------------------
// process termination detecting support
// ----------------------------------------------------------------------------

// thread function for the thread monitoring the process termination
static DWORD __stdcall wxExecuteThread(void *arg)
{
    wxExecuteData * const data = (wxExecuteData *)arg;

    if ( ::WaitForSingleObject(data->hProcess, INFINITE) != WAIT_OBJECT_0 )
    {
        wxLogDebug(_T("Waiting for the process termination failed!"));
    }

    // get the exit code
    if ( !::GetExitCodeProcess(data->hProcess, &data->dwExitCode) )
    {
        wxLogLastError(wxT("GetExitCodeProcess"));
    }

    wxASSERT_MSG( data->dwExitCode != STILL_ACTIVE,
                  wxT("process should have terminated") );

    // send a message indicating process termination to the window
    ::SendMessage(data->hWnd, wxWM_PROC_TERMINATED, 0, (LPARAM)data);

    return 0;
}

// window procedure of a hidden window which is created just to receive
// the notification message when a process exits
LRESULT APIENTRY _EXPORT wxExecuteWindowCbk(HWND hWnd, UINT message,
                                            WPARAM wParam, LPARAM lParam)
{
    if ( message == wxWM_PROC_TERMINATED )
    {
        DestroyWindow(hWnd);    // we don't need it any more

        wxExecuteData * const data = (wxExecuteData *)lParam;
        if ( data->handler )
        {
            data->handler->OnTerminate((int)data->dwProcessId,
                                       (int)data->dwExitCode);
        }

        if ( data->state )
        {
            // we're executing synchronously, tell the waiting thread
            // that the process finished
            data->state = 0;
        }
        else
        {
            // asynchronous execution - we should do the clean up
            delete data;
        }

        return 0;
    }
    else
    {
        return ::DefWindowProc(hWnd, message, wParam, lParam);
    }
}

// ============================================================================
// implementation of IO redirection support classes
// ============================================================================

#if wxUSE_STREAMS

// ----------------------------------------------------------------------------
// wxPipeInputStreams
// ----------------------------------------------------------------------------

wxPipeInputStream::wxPipeInputStream(HANDLE hInput)
{
    m_hInput = hInput;
}

wxPipeInputStream::~wxPipeInputStream()
{
    if ( m_hInput != INVALID_HANDLE_VALUE )
        ::CloseHandle(m_hInput);
}

bool wxPipeInputStream::CanRead() const
{
    if ( !IsOpened() )
        return FALSE;

    DWORD nAvailable;

    // function name is misleading, it works with anon pipes as well
    DWORD rc = ::PeekNamedPipe
                    (
                      m_hInput,     // handle
                      NULL, 0,      // ptr to buffer and its size
                      NULL,         // [out] bytes read
                      &nAvailable,  // [out] bytes available
                      NULL          // [out] bytes left
                    );

    if ( !rc )
    {
        if ( ::GetLastError() != ERROR_BROKEN_PIPE )
        {
            // unexpected error
            wxLogLastError(_T("PeekNamedPipe"));
        }

        // don't try to continue reading from a pipe if an error occured or if
        // it had been closed
        ::CloseHandle(m_hInput);

        wxPipeInputStream *self = wxConstCast(this, wxPipeInputStream);

        self->m_hInput = INVALID_HANDLE_VALUE;
        self->m_lasterror = wxSTREAM_EOF;

        nAvailable = 0;
    }

    return nAvailable != 0;
}

size_t wxPipeInputStream::OnSysRead(void *buffer, size_t len)
{
    if ( !IsOpened() )
    {
        m_lasterror = wxSTREAM_EOF;

        return 0;
    }

    DWORD bytesRead;
    if ( !::ReadFile(m_hInput, buffer, len, &bytesRead, NULL) )
    {
        m_lasterror = ::GetLastError() == ERROR_BROKEN_PIPE
                        ? wxSTREAM_EOF
                        : wxSTREAM_READ_ERROR;
    }

    // bytesRead is set to 0, as desired, if an error occured
    return bytesRead;
}

// ----------------------------------------------------------------------------
// wxPipeOutputStream
// ----------------------------------------------------------------------------

wxPipeOutputStream::wxPipeOutputStream(HANDLE hOutput)
{
    m_hOutput = hOutput;
}

wxPipeOutputStream::~wxPipeOutputStream()
{
    ::CloseHandle(m_hOutput);
}

size_t wxPipeOutputStream::OnSysWrite(const void *buffer, size_t len)
{
    DWORD bytesWritten;

    m_lasterror = wxSTREAM_NO_ERROR;
    if ( !::WriteFile(m_hOutput, buffer, len, &bytesWritten, NULL) )
    {
        m_lasterror = ::GetLastError() == ERROR_BROKEN_PIPE
                            ? wxSTREAM_EOF
                            : wxSTREAM_WRITE_ERROR;
    }

    return bytesWritten;
}

#endif // wxUSE_STREAMS

#endif // Win32

// ============================================================================
// wxExecute functions family
// ============================================================================

#if wxUSE_IPC

// connect to the given server via DDE and ask it to execute the command
static bool wxExecuteDDE(const wxString& ddeServer,
                         const wxString& ddeTopic,
                         const wxString& ddeCommand)
{
    bool ok = FALSE;

    wxDDEClient client;
    wxConnectionBase *conn = client.MakeConnection(_T(""),
                                                   ddeServer,
                                                   ddeTopic);
    if ( !conn )
    {
        ok = FALSE;
    }
    else // connected to DDE server
    {
        // the added complication here is that although most
        // programs use XTYP_EXECUTE for their DDE API, some
        // important ones - like IE and other MS stuff - use
        // XTYP_REQUEST!
        //
        // so we try one first and then the other one if it
        // failed
        {
            wxLogNull noErrors;
            ok = conn->Execute(ddeCommand);
        }

        if ( !ok )
        {
            // now try request - but show the errors
            ok = conn->Request(ddeCommand) != NULL;
        }
    }

    return ok;
}

#endif // wxUSE_IPC

long wxExecute(const wxString& cmd, int flags, wxProcess *handler)
{
    wxCHECK_MSG( !!cmd, 0, wxT("empty command in wxExecute") );

#if wxUSE_THREADS
    // for many reasons, the code below breaks down if it's called from another
    // thread -- this could be fixed, but as Unix versions don't support this
    // neither I don't want to waste time on this now
    wxASSERT_MSG( wxThread::IsMain(),
                    _T("wxExecute() can be called only from the main thread") );
#endif // wxUSE_THREADS

    wxString command;

#if wxUSE_IPC
    // DDE hack: this is really not pretty, but we need to allow this for
    // transparent handling of DDE servers in wxMimeTypesManager. Usually it
    // returns the command which should be run to view/open/... a file of the
    // given type. Sometimes, however, this command just launches the server
    // and an additional DDE request must be made to really open the file. To
    // keep all this well hidden from the application, we allow a special form
    // of command: WX_DDE#<command>#DDE_SERVER#DDE_TOPIC#DDE_COMMAND in which
    // case we execute just <command> and process the rest below
    wxString ddeServer, ddeTopic, ddeCommand;
    static const size_t lenDdePrefix = 7;   // strlen("WX_DDE:")
    if ( cmd.Left(lenDdePrefix) == _T("WX_DDE#") )
    {
        // speed up the concatenations below
        ddeServer.reserve(256);
        ddeTopic.reserve(256);
        ddeCommand.reserve(256);

        const wxChar *p = cmd.c_str() + 7;
        while ( *p && *p != _T('#') )
        {
            command += *p++;
        }

        if ( *p )
        {
            // skip '#'
            p++;
        }
        else
        {
            wxFAIL_MSG(_T("invalid WX_DDE command in wxExecute"));
        }

        while ( *p && *p != _T('#') )
        {
            ddeServer += *p++;
        }

        if ( *p )
        {
            // skip '#'
            p++;
        }
        else
        {
            wxFAIL_MSG(_T("invalid WX_DDE command in wxExecute"));
        }

        while ( *p && *p != _T('#') )
        {
            ddeTopic += *p++;
        }

        if ( *p )
        {
            // skip '#'
            p++;
        }
        else
        {
            wxFAIL_MSG(_T("invalid WX_DDE command in wxExecute"));
        }

        while ( *p )
        {
            ddeCommand += *p++;
        }

        // if we want to just launch the program and not wait for its
        // termination, try to execute DDE command right now, it can succeed if
        // the process is already running - but as it fails if it's not
        // running, suppress any errors it might generate
        if ( !(flags & wxEXEC_SYNC) )
        {
            wxLogNull noErrors;
            if ( wxExecuteDDE(ddeServer, ddeTopic, ddeCommand) )
            {
                // a dummy PID - this is a hack, of course, but it's well worth
                // it as we don't open a new server each time we're called
                // which would be quite bad
                return -1;
            }
        }
    }
    else
#endif // wxUSE_IPC
    {
        // no DDE
        command = cmd;
    }

#if defined(__WIN32__) && !defined(__TWIN32__)

    // the IO redirection is only supported with wxUSE_STREAMS
    BOOL redirect = FALSE;

#if wxUSE_STREAMS
    wxPipe pipeIn, pipeOut, pipeErr;

    // we'll save here the copy of pipeIn[Write]
    HANDLE hpipeStdinWrite = INVALID_HANDLE_VALUE;

    // open the pipes to which child process IO will be redirected if needed
    if ( handler && handler->IsRedirected() )
    {
        // create pipes for redirecting stdin, stdout and stderr
        if ( !pipeIn.Create() || !pipeOut.Create() || !pipeErr.Create() )
        {
            wxLogSysError(_("Failed to redirect the child process IO"));

            // indicate failure: we need to return different error code
            // depending on the sync flag
            return flags & wxEXEC_SYNC ? -1 : 0;
        }

        redirect = TRUE;
    }
#endif // wxUSE_STREAMS

    // create the process
    STARTUPINFO si;
    wxZeroMemory(si);
    si.cb = sizeof(si);

#if wxUSE_STREAMS
    if ( redirect )
    {
        si.dwFlags = STARTF_USESTDHANDLES;

        si.hStdInput = pipeIn[wxPipe::Read];
        si.hStdOutput = pipeOut[wxPipe::Write];
        si.hStdError = pipeErr[wxPipe::Write];

        // when the std IO is redirected, we don't show the (console) process
        // window by default, but this can be overridden by the caller by
        // specifying wxEXEC_NOHIDE flag
        if ( !(flags & wxEXEC_NOHIDE) )
        {
            si.dwFlags |= STARTF_USESHOWWINDOW;
            si.wShowWindow = SW_HIDE;
        }

        // we must duplicate the handle to the write side of stdin pipe to make
        // it non inheritable: indeed, we must close the writing end of pipeIn
        // before launching the child process as otherwise this handle will be
        // inherited by the child which will never close it and so the pipe
        // will never be closed and the child will be left stuck in ReadFile()
        HANDLE pipeInWrite = pipeIn.Detach(wxPipe::Write);
        if ( !::DuplicateHandle
                (
                    ::GetCurrentProcess(),
                    pipeInWrite,
                    ::GetCurrentProcess(),
                    &hpipeStdinWrite,
                    0,                      // desired access: unused here
                    FALSE,                  // not inherited
                    DUPLICATE_SAME_ACCESS   // same access as for src handle
                ) )
        {
            wxLogLastError(_T("DuplicateHandle"));
        }

        ::CloseHandle(pipeInWrite);
    }
#endif // wxUSE_STREAMS

    PROCESS_INFORMATION pi;
    DWORD dwFlags = CREATE_DEFAULT_ERROR_MODE | CREATE_SUSPENDED;

    bool ok = ::CreateProcess
                (
                 NULL,              // application name (use only cmd line)
                 (wxChar *)
                 command.c_str(),   // full command line
                 NULL,              // security attributes: defaults for both
                 NULL,              //   the process and its main thread
                 redirect,          // inherit handles if we use pipes
                 dwFlags,           // process creation flags
                 NULL,              // environment (use the same)
                 NULL,              // current directory (use the same)
                 &si,               // startup info (unused here)
                 &pi                // process info
                ) != 0;

#if wxUSE_STREAMS
    // we can close the pipe ends used by child anyhow
    if ( redirect )
    {
        ::CloseHandle(pipeIn.Detach(wxPipe::Read));
        ::CloseHandle(pipeOut.Detach(wxPipe::Write));
        ::CloseHandle(pipeErr.Detach(wxPipe::Write));
    }
#endif // wxUSE_STREAMS

    if ( !ok )
    {
#if wxUSE_STREAMS
        // close the other handles too
        if ( redirect )
        {
            ::CloseHandle(pipeOut.Detach(wxPipe::Read));
            ::CloseHandle(pipeErr.Detach(wxPipe::Read));
        }
#endif // wxUSE_STREAMS

        wxLogSysError(_("Execution of command '%s' failed"), command.c_str());

        return flags & wxEXEC_SYNC ? -1 : 0;
    }

#if wxUSE_STREAMS
    // the input buffer bufOut is connected to stdout, this is why it is
    // called bufOut and not bufIn
    wxStreamTempInputBuffer bufOut,
                            bufErr;

    if ( redirect )
    {
        // We can now initialize the wxStreams
        wxPipeInputStream *
            outStream = new wxPipeInputStream(pipeOut.Detach(wxPipe::Read));
        wxPipeInputStream *
            errStream = new wxPipeInputStream(pipeErr.Detach(wxPipe::Read));
        wxPipeOutputStream *
            inStream = new wxPipeOutputStream(hpipeStdinWrite);

        handler->SetPipeStreams(outStream, inStream, errStream);

        bufOut.Init(outStream);
        bufErr.Init(errStream);
    }
#endif // wxUSE_STREAMS

    // register the class for the hidden window used for the notifications
    if ( !gs_classForHiddenWindow )
    {
        gs_classForHiddenWindow = _T("wxHiddenWindow");

        WNDCLASS wndclass;
        wxZeroMemory(wndclass);
        wndclass.lpfnWndProc   = (WNDPROC)wxExecuteWindowCbk;
        wndclass.hInstance     = wxGetInstance();
        wndclass.lpszClassName = gs_classForHiddenWindow;

        if ( !::RegisterClass(&wndclass) )
        {
            wxLogLastError(wxT("RegisterClass(hidden window)"));
        }
    }

    // create a hidden window to receive notification about process
    // termination
    HWND hwnd = ::CreateWindow(gs_classForHiddenWindow, NULL,
                               WS_OVERLAPPEDWINDOW,
                               0, 0, 0, 0, NULL,
                               (HMENU)NULL, wxGetInstance(), 0);
    wxASSERT_MSG( hwnd, wxT("can't create a hidden window for wxExecute") );

    // Alloc data
    wxExecuteData *data = new wxExecuteData;
    data->hProcess    = pi.hProcess;
    data->dwProcessId = pi.dwProcessId;
    data->hWnd        = hwnd;
    data->state       = (flags & wxEXEC_SYNC) != 0;
    if ( flags & wxEXEC_SYNC )
    {
        // handler may be !NULL for capturing program output, but we don't use
        // it wxExecuteData struct in this case
        data->handler = NULL;
    }
    else
    {
        // may be NULL or not
        data->handler = handler;
    }

    DWORD tid;
    HANDLE hThread = ::CreateThread(NULL,
                                    0,
                                    wxExecuteThread,
                                    (void *)data,
                                    0,
                                    &tid);

    // resume process we created now - whether the thread creation succeeded or
    // not
    if ( ::ResumeThread(pi.hThread) == (DWORD)-1 )
    {
        // ignore it - what can we do?
        wxLogLastError(wxT("ResumeThread in wxExecute"));
    }

    // close unneeded handle
    if ( !::CloseHandle(pi.hThread) )
        wxLogLastError(wxT("CloseHandle(hThread)"));

    if ( !hThread )
    {
        wxLogLastError(wxT("CreateThread in wxExecute"));

        DestroyWindow(hwnd);
        delete data;

        // the process still started up successfully...
        return pi.dwProcessId;
    }

    ::CloseHandle(hThread);

#if wxUSE_IPC
    // second part of DDE hack: now establish the DDE conversation with the
    // just launched process
    if ( !ddeServer.empty() )
    {
        bool ok;

        // give the process the time to init itself
        //
        // we use a very big timeout hoping that WaitForInputIdle() will return
        // much sooner, but not INFINITE just in case the process hangs
        // completely - like this we will regain control sooner or later
        switch ( ::WaitForInputIdle(pi.hProcess, 10000 /* 10 seconds */) )
        {
            default:
                wxFAIL_MSG( _T("unexpected WaitForInputIdle() return code") );
                // fall through

            case -1:
                wxLogLastError(_T("WaitForInputIdle() in wxExecute"));

            case WAIT_TIMEOUT:
                wxLogDebug(_T("Timeout too small in WaitForInputIdle"));

                ok = FALSE;
                break;

            case 0:
                // ok, process ready to accept DDE requests
                ok = wxExecuteDDE(ddeServer, ddeTopic, ddeCommand);
        }
    }
#endif // wxUSE_IPC

    if ( !(flags & wxEXEC_SYNC) )
    {
        // clean up will be done when the process terminates

        // return the pid
        return pi.dwProcessId;
    }

    // disable all app windows while waiting for the child process to finish
#if wxUSE_GUI

    /*
       We use a dirty hack here to disable all application windows (which we
       must do because otherwise the calls to wxYield() could lead to some very
       unexpected reentrancies in the users code) but to avoid losing
       focus/activation entirely when the child process terminates which would
       happen if we simply disabled everything using wxWindowDisabler. Indeed,
       remember that Windows will never activate a disabled window and when the
       last childs window is closed and Windows looks for a window to activate
       all our windows are still disabled. There is no way to enable them in
       time because we don't know when the childs windows are going to be
       closed, so the solution we use here is to keep one special tiny frame
       enabled all the time. Then when the child terminates it will get
       activated and when we close it below -- after reenabling all the other
       windows! -- the previously active window becomes activated again and
       everything is ok.
     */
    wxWindow *winActive;
    {
        wxBusyCursor bc;

        // first disable all existing windows
        wxWindowDisabler wd;

        // then create an "invisible" frame: it has minimal size, is positioned
        // (hopefully) outside the screen and doesn't appear on the taskbar
        winActive = new wxFrame
                        (
                            wxTheApp->GetTopWindow(),
                            -1,
                            _T(""),
                            wxPoint(32600, 32600),
                            wxSize(1, 1),
                            wxDEFAULT_FRAME_STYLE | wxFRAME_NO_TASKBAR
                        );
        winActive->Show();
#endif // wxUSE_GUI

        // wait until the child process terminates
        while ( data->state )
        {
#if wxUSE_STREAMS
            bufOut.Update();
            bufErr.Update();
#endif // wxUSE_STREAMS

            // don't eat 100% of the CPU -- ugly but anything else requires
            // real async IO which we don't have for the moment
            ::Sleep(50);

#if wxUSE_GUI
            // repaint the GUI
            wxYield();
#else // !GUI
            // dispatch the messages to the hidden window so that it could
            // process the wxWM_PROC_TERMINATED notification
            MSG msg;
            ::PeekMessage(&msg, hwnd, 0, 0, PM_REMOVE);
#endif // GUI/!GUI
        }

#if wxUSE_GUI
    }

    // finally delete the dummy frame and, as wd has been already destroyed and
    // the other windows reenabled, the activation is going to return to the
    // window which had it before
    winActive->Destroy();
#endif // wxUSE_GUI

    DWORD dwExitCode = data->dwExitCode;
    delete data;

    // return the exit code
    return dwExitCode;
#else // Win16
    long instanceID = WinExec((LPCSTR) WXSTRINGCAST command, SW_SHOW);
    if (instanceID < 32)
        return flags & wxEXEC_SYNC ? -1 : 0;

    if ( flags & wxEXEC_SYNC )
    {
        int running;
        do
        {
            wxYield();
            running = GetModuleUsage((HINSTANCE)instanceID);
        } while (running);
    }

    return instanceID;
#endif // Win16/32
}

long wxExecute(wxChar **argv, int flags, wxProcess *handler)
{
    wxString command;

    for ( ;; )
    {
        command += *argv++;
        if ( !*argv )
            break;

        command += _T(' ');
    }

    return wxExecute(command, flags, handler);
}