执行一组Windows API调用以读取任务栏图标工具提示时的内存泄漏

Question

我正在使用以下代码示例来扫描任务栏中的任务栏图标，然后提取其工具提示并将其作为字符串列表返回。

class TrayTooltip
{
    public static List<String> ScanToolbarButtons()
    {
        List<string> tooltips = new List<string>();

        var handle = GetSystemTrayHandle();
        if (handle == IntPtr.Zero)
            return null;

        var count = SendMessage(handle, TB_BUTTONCOUNT, IntPtr.Zero, IntPtr.Zero).ToInt32();
        if (count == 0)
            return null;

        int pid;
        GetWindowThreadProcessId(handle, out pid);
        var hProcess = OpenProcess(PROCESS_ALL_ACCESS, false, pid);
        if (hProcess == IntPtr.Zero)
            throw new Win32Exception(Marshal.GetLastWin32Error());

        var size = (IntPtr)Marshal.SizeOf<TBBUTTONINFOW>();
        var buffer = VirtualAllocEx(hProcess, IntPtr.Zero, size, MEM_COMMIT, PAGE_READWRITE);
        if (buffer == IntPtr.Zero)
        {
            CloseHandle(hProcess);
            throw new Win32Exception(Marshal.GetLastWin32Error());
        }

        for (int i = 0; i < count; i++)
        {
            var btn = new TBBUTTONINFOW();
            btn.cbSize = size.ToInt32();
            btn.dwMask = TBIF_BYINDEX | TBIF_COMMAND;

            IntPtr written;
            if (WriteProcessMemory(hProcess, buffer, ref btn, size, out written))
            {
                // we want the identifier
                var res = SendMessage(handle, TB_GETBUTTONINFOW, (IntPtr)i, buffer);
                if (res.ToInt32() >= 0)
                {
                    IntPtr read;
                    if (ReadProcessMemory(hProcess, buffer, ref btn, size, out read))
                    {
                        // now get display text using the identifier
                        // first pass we ask for size
                        var textSize = SendMessage(handle, TB_GETBUTTONTEXTW, (IntPtr)btn.idCommand, IntPtr.Zero);
                        if (textSize.ToInt32() != -1)
                        {
                            // we need to allocate for the terminating zero and unicode
                            var utextSize = (IntPtr)((1 + textSize.ToInt32()) * 2);
                            var textBuffer = VirtualAllocEx(hProcess, IntPtr.Zero, utextSize, MEM_COMMIT, PAGE_READWRITE);
                            if (textBuffer != IntPtr.Zero)
                            {
                                res = SendMessage(handle, TB_GETBUTTONTEXTW, (IntPtr)btn.idCommand, textBuffer);
                                if (res == textSize)
                                {
                                    var localBuffer = Marshal.AllocHGlobal(utextSize.ToInt32());
                                    if (ReadProcessMemory(hProcess, textBuffer, localBuffer, utextSize, out read))
                                    {
                                        var text = Marshal.PtrToStringUni(localBuffer);
                                        tooltips.Add(text);
                                        Marshal.FreeHGlobal(localBuffer);
                                    }
                                }
                                VirtualFreeEx(hProcess, textBuffer, size, MEM_RELEASE);
                            }
                        }
                    }
                }
            }
        }

        VirtualFreeEx(hProcess, buffer, size, MEM_RELEASE);
        CloseHandle(hProcess);

        return tooltips;
    }

    private static IntPtr GetSystemTrayHandle()
    {
        var hwnd = FindWindowEx(IntPtr.Zero, IntPtr.Zero, "Shell_TrayWnd", null);
        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "TrayNotifyWnd", null);
        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "SysPager", null);
        return FindWindowEx(hwnd, IntPtr.Zero, "ToolbarWindow32", null);
    }

    [DllImport("kernel32", SetLastError = true)]
    private static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool CloseHandle(IntPtr hObject);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref TBBUTTONINFOW lpBuffer, IntPtr nSize, out IntPtr lpNumberOfBytesWritten);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref TBBUTTONINFOW lpBuffer, IntPtr nSize, out IntPtr lpNumberOfBytesRead);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, IntPtr lpBuffer, IntPtr nSize, out IntPtr lpNumberOfBytesRead);

    [DllImport("user32", SetLastError = true)]
    private static extern int GetWindowThreadProcessId(IntPtr hWnd, out int lpdwProcessId);

    [DllImport("kernel32", SetLastError = true)]
    private static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, IntPtr dwSize, int flAllocationType, int flProtect);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool VirtualFreeEx(IntPtr hProcess, IntPtr lpAddress, IntPtr dwSize, int dwFreeType);

    [DllImport("user32")]
    private static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32", SetLastError = true)]
    private static extern IntPtr FindWindowEx(IntPtr hWndParent, IntPtr hWndChildAfter, string lpClassName, string lpWindowName);

    private const int TBIF_BYINDEX = unchecked((int)0x80000000); // this specifies that the wparam in Get/SetButtonInfo is an index, not id
    private const int TBIF_COMMAND = 0x20;
    private const int MEM_COMMIT = 0x1000;
    private const int MEM_RELEASE = 0x8000;
    private const int PAGE_READWRITE = 0x4;
    private const int TB_GETBUTTONINFOW = 1087;
    private const int TB_GETBUTTONTEXTW = 1099;
    private const int TB_BUTTONCOUNT = 1048;

    private static bool IsWindowsVistaOrAbove() => Environment.OSVersion.Platform == PlatformID.Win32NT && Environment.OSVersion.Version.Major >= 6;
    private static int PROCESS_ALL_ACCESS => IsWindowsVistaOrAbove() ? 0x001FFFFF : 0x001F0FFF;

    [StructLayout(LayoutKind.Sequential)]
    private struct TBBUTTONINFOW
    {
        public int cbSize;
        public int dwMask;
        public int idCommand;
        public int iImage;
        public byte fsState;
        public byte fsStyle;
        public short cx;
        public IntPtr lParam;
        public IntPtr pszText;
        public int cchText;
    }
}

特别是，我正在使用此代码来监视正在其工具提示文本中显示其状态（将文本文件转换为MP3）的程序。 然后，我从下面的代码调用ScanToolbarButtons（）函数以检索更新的转换进度百分比：

/// <summary>
/// Returns the conversion status of the MP3 conversion using the tooltip text from the Balabolka command line utility
/// </summary>
/// <returns>Number from 0-100 representing status, or -1 if the text wasn't found.</returns>
private int GetMP3ConversionStatus()
{
    try
    {
        // Return a list of tooltips for all active tray icons
        List<string> tooltips = TrayTooltip.ScanToolbarButtons();

        // Iterate through the list to find the one for the Balabolka commandline app
        foreach (string text in tooltips)
        {
            if (text.Contains("Balabolka ["))
            {
                // Split the string into sections to extract the numbers
                string[] splitText = text.Split(new char[] { '[', '%' });

                // Extract the number from the correct element and return it
                return Convert.ToInt32(splitText[1]);
            }
        }
    }
    catch (Exception)
    {
        return -1;
    }

    return -1;
}

该代码似乎很好用，但是问题在于，当我在循环中连续调用GetMP3ConversionStatus函数以查询百分比时，我注意到任务管理器中的explorer.exe使用越来越多的RAM，直到它填满了所有内存。在我的计算机上，程序崩溃。

显然，内存没有释放到某个地方，但是我不确定从代码中看什么。 似乎其中有些功能可以关闭打开的句柄并释放内存，但是我不确定发生了什么或如何最好地解决此问题。

Answer 1

好的，我终于解决了问题，问题在于，对于VirtualFreeEx函数，将第四个参数设置为IntPtr.Zero时，需要将第三个参数size设置为MEM_RELEASE 。 对函数调用的两个实例进行此更改可解决内存泄漏问题。

对于那些感兴趣的人，这是我现在使用的代码的最终版本。 一切归功于Simon Mourier，他为提供原始工作代码示例提供了极大的帮助。

class TrayTooltip
{
    public static List<string> ScanToolbarButtons()
    {
        List<string> tooltips = new List<string>();

        var handle = GetSystemTrayHandle();
        if (handle == IntPtr.Zero)
        {
            return null;
        }

        var count = SendMessage(handle, TB_BUTTONCOUNT, IntPtr.Zero, IntPtr.Zero).ToInt32();
        if (count == 0)
        {
            return null;
        }

        GetWindowThreadProcessId(handle, out var pid);
        var hProcess = OpenProcess(PROCESS_ALL_ACCESS, false, pid);
        if (hProcess == IntPtr.Zero)
        {
            throw new Win32Exception(Marshal.GetLastWin32Error());
        }

        var size = (IntPtr)Marshal.SizeOf<TBBUTTONINFOW>();
        var buffer = VirtualAllocEx(hProcess, IntPtr.Zero, size, MEM_COMMIT, PAGE_READWRITE);
        if (buffer == IntPtr.Zero)
        {
            CloseHandle(hProcess);
            throw new Win32Exception(Marshal.GetLastWin32Error());
        }

        for (int i = 0; i < count; i++)
        {
            var btn = new TBBUTTONINFOW();
            btn.cbSize = size.ToInt32();
            btn.dwMask = TBIF_BYINDEX | TBIF_COMMAND;
            if (WriteProcessMemory(hProcess, buffer, ref btn, size, out var written))
            {
                // we want the identifier
                var res = SendMessage(handle, TB_GETBUTTONINFOW, (IntPtr)i, buffer);
                if (res.ToInt32() >= 0)
                {
                    if (ReadProcessMemory(hProcess, buffer, ref btn, size, out var read))
                    {
                        // now get display text using the identifier
                        // first pass we ask for size
                        var textSize = SendMessage(handle, TB_GETBUTTONTEXTW, (IntPtr)btn.idCommand, IntPtr.Zero);
                        if (textSize.ToInt32() != -1)
                        {
                            // we need to allocate for the terminating zero and unicode
                            var utextSize = (IntPtr)((1 + textSize.ToInt32()) * 2);
                            var textBuffer = VirtualAllocEx(hProcess, IntPtr.Zero, utextSize, MEM_COMMIT, PAGE_READWRITE);
                            if (textBuffer != IntPtr.Zero)
                            {
                                res = SendMessage(handle, TB_GETBUTTONTEXTW, (IntPtr)btn.idCommand, textBuffer);
                                if (res == textSize)
                                {
                                    var localBuffer = Marshal.AllocHGlobal(utextSize.ToInt32());
                                    if (ReadProcessMemory(hProcess, textBuffer, localBuffer, utextSize, out read))
                                    {
                                        var text = Marshal.PtrToStringUni(localBuffer);
                                        tooltips.Add(text);
                                    }
                                    Marshal.FreeHGlobal(localBuffer);
                                }
                                VirtualFreeEx(hProcess, textBuffer, IntPtr.Zero, MEM_RELEASE);
                            }
                        }
                    }
                }
            }
        }

        VirtualFreeEx(hProcess, buffer, IntPtr.Zero, MEM_RELEASE);
        CloseHandle(hProcess);

        return tooltips;
    }

    private static IntPtr GetSystemTrayHandle()
    {
        var hwnd = FindWindowEx(IntPtr.Zero, IntPtr.Zero, "Shell_TrayWnd", null);
        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "TrayNotifyWnd", null);
        hwnd = FindWindowEx(hwnd, IntPtr.Zero, "SysPager", null);
        return FindWindowEx(hwnd, IntPtr.Zero, "ToolbarWindow32", null);
    }

    [DllImport("kernel32", SetLastError = true)]
    private static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool CloseHandle(IntPtr hObject);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref TBBUTTONINFOW lpBuffer, IntPtr nSize, out IntPtr lpNumberOfBytesWritten);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref TBBUTTONINFOW lpBuffer, IntPtr nSize, out IntPtr lpNumberOfBytesRead);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, IntPtr lpBuffer, IntPtr nSize, out IntPtr lpNumberOfBytesRead);

    [DllImport("user32", SetLastError = true)]
    private static extern int GetWindowThreadProcessId(IntPtr hWnd, out int lpdwProcessId);

    [DllImport("kernel32", SetLastError = true)]
    private static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, IntPtr dwSize, int flAllocationType, int flProtect);

    [DllImport("kernel32", SetLastError = true)]
    private static extern bool VirtualFreeEx(IntPtr hProcess, IntPtr lpAddress, IntPtr dwSize, int dwFreeType);

    [DllImport("user32")]
    private static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32", SetLastError = true)]
    private static extern IntPtr FindWindowEx(IntPtr hWndParent, IntPtr hWndChildAfter, string lpClassName, string lpWindowName);

    private const int TBIF_BYINDEX = unchecked((int)0x80000000); // this specifies that the wparam in Get/SetButtonInfo is an index, not id
    private const int TBIF_COMMAND = 0x20;
    private const int MEM_COMMIT = 0x1000;
    private const int MEM_RELEASE = 0x8000;
    private const int PAGE_READWRITE = 0x4;
    private const int TB_GETBUTTONINFOW = 1087;
    private const int TB_GETBUTTONTEXTW = 1099;
    private const int TB_BUTTONCOUNT = 1048;

    private static bool IsWindowsVistaOrAbove() => Environment.OSVersion.Platform == PlatformID.Win32NT && Environment.OSVersion.Version.Major >= 6;
    private static int PROCESS_ALL_ACCESS => IsWindowsVistaOrAbove() ? 0x001FFFFF : 0x001F0FFF;

    [StructLayout(LayoutKind.Sequential)]
    private struct TBBUTTONINFOW
    {
        public int cbSize;
        public int dwMask;
        public int idCommand;
        public int iImage;
        public byte fsState;
        public byte fsStyle;
        public short cx;
        public IntPtr lParam;
        public IntPtr pszText;
        public int cchText;
    }
}