Finding module name from the window handle

• Download source code - 21 Kb

Introduction

A few days back, in one of my projects, I needed to enumerate all the visible windows, and then needed to determine if a given application was running or not. I first struggled a little, but soon found a simple method to do that.

Enumerating the windows

With the EnumWindows API, I filtered out the visible windows. Next, with GetWindowThreadProcessId, I found the process ID of that window, and with that, I found the name of the executable file.

Below is the callback function for EnumWindows:

BOOL CALLBACK CProcessDlg::EnumWindowsProc (HWND hWnd, LPARAM lParam)
{
    CProcessDlg *pDlg = (CProcessDlg *)lParam;

    int nItem = 0;

    //Make sure that the window is visible
    TCHAR szWindowText [MAX_PATH];
    if (!::IsWindowVisible (hWnd))
        return TRUE;

    //Get the text on the title bar
    ::GetWindowText (hWnd, szWindowText, MAX_PATH);

    //If the window is Process Manager then don't display it
    if (_tcsstr (_T("Program Manager"), szWindowText))
        return TRUE;

    //Get process ID
    DWORD dwProcessID;
    GetWindowThreadProcessId (hWnd, &dwProcessID);
    
    //Get the name of the executable file
    CString strEXEName = pDlg->GetEXEName (dwProcessID);

    //Add the info to the list control
    nItem = pDlg->m_List.InsertItem (0, szWindowText);
    pDlg->m_List.SetItemText (nItem, 1, strEXEName);    

    return TRUE;
}

Finding module name

The GetEXEName procedure returns the name of the executable file from its process ID:

#include "psapi.h"
#pragma comment(lib, "psapi.lib")

CString GetEXEName(DWORD dwProcessID)
{
    DWORD aProcesses [1024], cbNeeded, cProcesses;
    unsigned int i;
        
    //Enumerate all processes
    if (!EnumProcesses(aProcesses, sizeof(aProcesses), &cbNeeded))
        return NULL;

    // Calculate how many process identifiers were returned.
    cProcesses = cbNeeded / sizeof(DWORD);

    TCHAR szEXEName[MAX_PATH];
    //Loop through all process to find the one that matches
    //the one we are looking for
    for (i = 0; i < cProcesses; i++)
    {
        if (aProcesses [i] == dwProcessID)
        {
            // Get a handle to the process
            HANDLE hProcess = OpenProcess(PROCESS_QUERY_INFORMATION |
                              PROCESS_VM_READ, FALSE, dwProcessID);
        
            // Get the process name
            if (NULL != hProcess)
            {
                HMODULE hMod;
                DWORD cbNeeded;
            
                if(EnumProcessModules(hProcess, &hMod, 
                                      sizeof(hMod), &cbNeeded))
                {
                    //Get the name of the exe file
                    GetModuleBaseName(hProcess, hMod, szEXEName, 
                        sizeof(szEXEName)/sizeof(TCHAR));

                    return CString (szEXEName);
                }
            }
        }    
    }

    return NULL;
}

Conclusion

The code is very easy to understand and follow, please see the demo project if you have any trouble using it.

I hope you find it useful.

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here