I get an JVM exit code -1073740940 when running this icon extractor code on Windows. Please advise.

[Dávid Karnok]

The following code enumerates windows and tries to get their icons, or tries to extract one from their exe file. For some reason, the JVM crashes with exit code -1073740940, which is 0xC0000374 - heap corruption on Windows 10 x64. The code itself worked fine back in 2010 on Windows 7 x86. When I step through it, it fails after random rounds. The Windows API definitions I use are here. JNA 5.2.0, Java 8u202.

Please advise.

Native.setProtected(true);

List<ProcessData> result = new ArrayList<ProcessData>();
User32 u32 = User32.INSTANCE;
Kernel32 k32 = Kernel32.INSTANCE;
char[] strOut = new char[1024];
int nxt = u32.GetTopWindow(0);

do {
    if (nxt != 0 && u32.IsWindowVisible(nxt)) {
        ProcessData pd = new ProcessData();

        pd.Handle = nxt;
        u32.GetWindowTextW(nxt, strOut, strOut.length);

        pd.WindowText = Native.toString(strOut);
        if (pd.WindowText.length() > 0) {
            u32.GetClassNameW(nxt, strOut, strOut.length);

            pd.ClassName = Native.toString(strOut);
            pd.Instance = u32.GetWindowLongW(nxt, User32.GWL_HINSTANCE);

            if (!u32.GetClassInfoExW(pd.Instance, new WString(
                    pd.ClassName), pd.ClassWindowEx)) {
                pd.Error = k32.GetLastError();
                pd.ErrorStr = getLastErrorStr(pd.Error);
            }
            IntByReference iref = new IntByReference();
            u32.GetWindowThreadProcessId(nxt, iref);

            pd.ProcessID = iref.getValue();
            int hIconSm = u32.SendMessageW(nxt, User32.WM_GETICON, User32.ICON_SMALL2, 0);

            if (hIconSm == 0) {
                hIconSm = u32.SendMessageW(nxt, User32.WM_GETICON, User32.ICON_SMALL, 0);

            }
            boolean destroyIcon = false;
            if (hIconSm == 0) {
                Psapi ps = Psapi.INSTANCE;
                Arrays.fill(strOut, '\0');
                int hProcess = k32.OpenProcess(Kernel32.PROCESS_VM_READ | Kernel32.PROCESS_QUERY_INFORMATION, false, pd.ProcessID);

                if (hProcess != 0) {
                    ps.GetModuleFileNameExW(hProcess, 0, strOut, strOut.length);

                    k32.CloseHandle(hProcess);

                    pd.exeFile = Native.toString(strOut);
                    int[] ints = new int[1];
                    if (Shell32.INSTANCE.ExtractIconExW(new WString(pd.exeFile), 0, null, ints, 1) == 1) {

                        hIconSm = ints[0];
                        destroyIcon = true;
                    }
                } else {
                    printLastError();
                }
            }
            int size = 16;

            int[] iconBits = getIconBits(hIconSm, size);
            if (iconBits != null) {
                BufferedImage bi = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
                bi.setRGB(0, 0, size, size, iconBits, 0, size);
                pd.icon16 = new ImageIcon(bi);
            }
            if (destroyIcon) {
                u32.DestroyIcon(hIconSm);

            }
            result.add(pd);
        }
    }
    nxt = u32.GetWindow(nxt, User32.GW_HWNDNEXT);

} while (nxt != 0);

The getIconBits is defined as follows:

    public static int[] getIconBits(int hIcon, int size) {
        User32 u32 = User32.INSTANCE;
        GDI32 g32 = GDI32.INSTANCE;
        IconInfo iconinfo = new IconInfo();
        // get icon information
        if (!u32.GetIconInfo(hIcon, iconinfo)) {
            return null;
        }
        int dc = u32.GetDC(0);
        if (dc == 0) {
            g32.DeleteObject(iconinfo.hbmColor);
            g32.DeleteObject(iconinfo.hbmMask);
            return null;
        }
        int nBits = size * size * 4;
        BitmapInfo bmi = new BitmapInfo();
        bmi.initColors(1);
        bmi.bmiHeader.biWidth = size;
        bmi.bmiHeader.biHeight = -size;
        bmi.bmiHeader.biPlanes = 1;
        bmi.bmiHeader.biBitCount = 32;
        bmi.bmiHeader.biCompression = GDI32.BI_RGB;
        Memory colorBitsMem = new Memory(nBits);
        // Extract the color bitmap
        int result = g32.GetDIBits(dc, iconinfo.hbmColor, 0, size, colorBitsMem, bmi,
                GDI32.DIB_RGB_COLORS);
        if (result == 0) {
            result = Kernel32.INSTANCE.GetLastError();
            System.err.println("hbmColor:" + result + " - " + getLastErrorStr(result));
        }
       
        int[] colorBits = colorBitsMem.getIntArray(0, size * size);
        Memory maskBitsMem = new Memory(nBits);
        // Extract the mask bitmap
        result = g32.GetDIBits(dc, iconinfo.hbmMask, 0, size, maskBitsMem, bmi,
                GDI32.DIB_RGB_COLORS);


        /*
        if (result == 0) {
            result = Kernel32.INSTANCE.GetLastError();
            System.err.println("hbmMask:" + result + " - " + getLastErrorStr(result));
        }
        */


        int[] maskBits = maskBitsMem.getIntArray(0, size * size);
        // Copy the mask alphas into the color bits
        for (int i = 0; i < colorBits.length; i++) {
            colorBits[i] = colorBits[i] | (maskBits[i] != 0 ? 0 : 0xFF000000);
        }
        // Release DC
        u32.ReleaseDC(0, dc);


        // Release bitmap handle in icon info
        g32.DeleteObject(iconinfo.hbmColor); // add
        g32.DeleteObject(iconinfo.hbmMask); // add


        return colorBits;
    }

[Matthias Bläsing]

Hey Dávid,

some people on this list might recognise my answer: Java got more aggressive in recent 

time regarding memory management. GC memory is faster reclaimed and thus code that

worked in the past by sheer luck fails today. Oh and platforms are also a good failure 

source.

You will need to check all datatypes you are using, whether they depend on the platform

and if they correctly adapt.

In you case I spottet:

int nxt = u32.GetTopWindow(0);

HWND is a pointer and as such is 32bit wide on x86 and 64bit wide on x64. On the latter

platform, you will get an invalid value and you will damage the heap, because 32bit are

allocated for the value and 64bit are written.

The same holds true for structures and such. You need to use the correct datatypes.

I suggest to have a look at the platform package JNA provides. There is a huge number

of functions already bound. I won't claim it is bug free (I was already bitten hard by it),

but that being common code, there is a pretty good chance that someone before

you already found the bugs.

Greetings

Matthias

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[Dávid Karnok]

Thanks! My experience with the Windows API dates back to the 32bit era and I haven't been keeping up or needing to talk to it up until now.

--

Best regards,

David Karnok