Using UpdateResource in C#?

Question

I'm trying to change the icon of external executable programmatically. I've googled and found much information about this problem using C++. Basically, I need to use BeginUpdateResource, UpdateResource and EndUpdateResource. The problem is - I don't know what to pass to UpdateResource in C#.

Here's the code I have so far:

class IconChanger
{
    [DllImport("kernel32.dll", SetLastError = true)]
    static extern IntPtr BeginUpdateResource(string pFileName,
        [MarshalAs(UnmanagedType.Bool)]bool bDeleteExistingResources);

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern bool UpdateResource(IntPtr hUpdate, string lpType, string lpName, ushort wLanguage,
        IntPtr lpData, uint cbData);

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern bool EndUpdateResource(IntPtr hUpdate, bool fDiscard);

    public enum ICResult
    {
        Success,
        FailBegin,
        FailUpdate,
        FailEnd
    }

    public ICResult ChangeIcon(string exeFilePath, byte[] iconData)
    {
        // Load executable
        IntPtr handleExe = BeginUpdateResource(exeFilePath, false);

        if (handleExe == null)
            return ICResult.FailBegin;

        // Get language identifier
        CultureInfo currentCulture = CultureInfo.CurrentCulture;
        int pid = ((ushort)currentCulture.LCID) & 0x3ff;
        int sid = ((ushort)currentCulture.LCID) >> 10;
        ushort languageID = (ushort)((((ushort)pid) << 10) | ((ushort)sid));

        // Get pointer to data
        GCHandle iconHandle = GCHandle.Alloc(iconData, GCHandleType.Pinned);

        // Replace the icon
        if (UpdateResource(handleExe, "#3", "#1", languageID, iconHandle.AddrOfPinnedObject(), (uint)iconData.Length))
        {
            if (EndUpdateResource(handleExe, false))
                return ICResult.Success;
            else
                return ICResult.FailEnd;
        }
        else
            return ICResult.FailUpdate;
    }
}

Regarding lpType - in C++, you pass RT_ICON (or RT_GROUP_ICON). What value should I pass in C#? The same question goes for lpName parameter. I'm not sure about language identifier (I found this on Internet) since I cannot test it. I'm also not sure whether I'm providing appropriate icon data. Currently, iconData contains the bytes from .ico file.

Can anybody point me to right direction?

Thank you very much.

Answer 1

Just some pointers, this is quite hard to get right. Pass an RT_ICON by lying about the lpType argument. Change it from string to IntPtr and pass (IntPtr)3.

The lpData argument is quite tricky. You need to pass the data the way it is compiled by the resource compiler (rc.exe). I have no idea if it mangles the raw data of the .ico file. The only reasonable thing to try is to read the data from the .ico file with FileStream into a byte[], you already seem to be doing this. I think the function was really designed to copy a resource from one binary image to another. Odds of your approach working are not zero.

You are also ignoring another potential problem, the resource ID of the icon of the program isn't necessarily 1. It often is not, 100 tends to be a popular choice, but anything goes. EnumResourceNames would be required to make it reliable. The rule is that the lowest numbered ID sets the icon for the file. I'm not actually sure if that really means that the resource compiler puts the lowest number first, something that the API probably doesn't do.

A very small failure mode is that UpdateResource can only updated numbered resource items, not named ones. Using names instead of numbers is not uncommon but the vast majority of images use numbers for icons.

And of course, the odds that this will work without a UAC manifest are zero. You are hacking files that you don't normally have write access to.

Answer 2

This is the solution that worked for me. I was not able to write it in .NET, but have managed to write C++ DLL which I am referencing in my C# application.

C++ DLL

The contents of C++ solution I am building the DLL from:

#include <io.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <windows.h>

extern "C"
{
    #pragma pack(push, 2)
    typedef struct {
        WORD Reserved1;       // reserved, must be 0
        WORD ResourceType;    // type is 1 for icons
        WORD ImageCount;      // number of icons in structure (1)
        BYTE Width;           // icon width (32)
        BYTE Height;          // icon height (32)
        BYTE Colors;          // colors (0 means more than 8 bits per pixel)
        BYTE Reserved2;       // reserved, must be 0
        WORD Planes;          // color planes
        WORD BitsPerPixel;    // bit depth
        DWORD ImageSize;      // size of structure
        WORD ResourceID;      // resource ID
    } GROUPICON;
    #pragma pack(pop)

    __declspec(dllexport) void __stdcall ChangeIcon(char *executableFile, char *iconFile, INT16 imageCount)
    {
        int len = strlen(executableFile) + 1;
        wchar_t *executableFileEx = new wchar_t[len];
        memset(executableFileEx, 0, len);
        ::MultiByteToWideChar(CP_ACP, NULL, executableFile, -1, executableFileEx, len);

        len = strlen("MAINICON") + 1;
        wchar_t *mainIconEx = new wchar_t[len];
        memset(mainIconEx, 0, len);
        ::MultiByteToWideChar(CP_ACP, NULL, "MAINICON", -1, mainIconEx, len);

        HANDLE hWhere = BeginUpdateResource(executableFileEx, FALSE);

        char *buffer;    // Buffer to store raw icon data
        long buffersize; // Length of buffer
        int hFile;       // File handle

        hFile = open(iconFile, O_RDONLY | O_BINARY);
        if (hFile == -1)
            return; // If file doesn't exist, can't be opened etc. 

        // Calculate buffer length and load file into buffer
        buffersize = filelength(hFile);
        buffer = (char *)malloc(buffersize);
        read(hFile, buffer, buffersize);
        close(hFile);

        // Calculate header size
        int headerSize = 6 + imageCount * 16;

        UpdateResource(
            hWhere,  // Handle to executable
            RT_ICON, // Resource type - icon
            MAKEINTRESOURCE(1), // Make the id 1
            MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT), // Default language
            buffer + headerSize, // Skip the header bytes
            buffersize - headerSize  // Length of buffer
        );


        GROUPICON grData;

        grData.Reserved1 = 0;     // reserved, must be 0
        grData.ResourceType = 1;  // type is 1 for icons
        grData.ImageCount = 1;    // number of icons in structure (1)

        grData.Width = 32;        // icon width (32)
        grData.Height = 32;       // icon height (32)
        grData.Colors = 0;        // colors (256)
        grData.Reserved2 = 0;     // reserved, must be 0
        grData.Planes = 2;        // color planes
        grData.BitsPerPixel = 32; // bit depth
        grData.ImageSize = buffersize - 22; // size of image
        grData.ResourceID = 1;       // resource ID is 1

        UpdateResource(
            hWhere,
            RT_GROUP_ICON,
            // RT_GROUP_ICON resources contain information
            // about stored icons
            mainIconEx,
            // MAINICON contains information about the
            // application's displayed icon
            MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
            &grData,
            // Pointer to this structure
            sizeof(GROUPICON)
        );

        delete buffer; // free memory

        // Perform the update, don't discard changes
        EndUpdateResource(hWhere, FALSE);
    }
}

C# code

This is C# code which I'm using to import ChangeIcon function from previously written DLL:

[DllImport("IconChanger.dll")]
static extern void ChangeIcon(String executableFile, String iconFile, short imageCount);

/// <summary>
/// Changes the executable's icon
/// </summary>
/// <param name="exeFilePath">Path to executable file</param>
/// <param name="iconFilePath">Path to icon file</param>
static public void ChangeIcon(string exeFilePath, string iconFilePath)
{
    short imageCount = 0;

    using (StreamReader sReader = new StreamReader(iconFilePath))
    {
        using (BinaryReader bReader = new BinaryReader(sReader.BaseStream))
        {
            // Retrieve icon count inside icon file
            bReader.ReadInt16();
            bReader.ReadInt16();
            imageCount = bReader.ReadInt16();
        }
    }

    // Change the executable's icon
    ChangeIcon(exeFilePath, iconFilePath, imageCount);
}

Hope at least somebody will find this useful.

Answer 3

I managed to get this working in pure C# using ResourceHacker and this posting as an example. Just use a regular .ico as input. In ResourceHacker (http://www.angusj.com/resourcehacker/) you will see the icon identifier (in my case 1) and the language identifier (in my case 1043):

I used this code:

internal class IconChanger
{

    #region IconReader
    public class Icons : List<Icon>
    {
        public byte[] ToGroupData(int startindex = 1)
        {
            using (var ms = new MemoryStream())
            using (var writer = new BinaryWriter(ms))
            {
                var i = 0;

                writer.Write((ushort)0);  //reserved, must be 0
                writer.Write((ushort)1);  // type is 1 for icons
                writer.Write((ushort)this.Count);  // number of icons in structure(1)

                foreach (var icon in this)
                {

                    writer.Write(icon.Width);
                    writer.Write(icon.Height);
                    writer.Write(icon.Colors);

                    writer.Write((byte)0); // reserved, must be 0
                    writer.Write(icon.ColorPlanes);

                    writer.Write(icon.BitsPerPixel);

                    writer.Write(icon.Size);

                    writer.Write((ushort)(startindex + i));

                    i++;

                }
                ms.Position = 0;

                return ms.ToArray();
            }
        }
    }

    public class Icon
    {

        public byte Width { get; set; }
        public byte Height { get; set; }
        public byte Colors { get; set; }

        public uint Size { get; set; }

        public uint Offset { get; set; }

        public ushort ColorPlanes { get; set; }

        public ushort BitsPerPixel { get; set; }

        public byte[] Data { get; set; }

    }

    public class IconReader
    {

        public Icons Icons = new Icons();

        public IconReader(Stream input)
        {
            using (BinaryReader reader = new BinaryReader(input))
            {
                reader.ReadUInt16(); // ignore. Should be 0
                var type = reader.ReadUInt16();
                if (type != 1)
                {
                    throw new Exception("Invalid type. The stream is not an icon file");
                }
                var num_of_images = reader.ReadUInt16();

                for (var i = 0; i < num_of_images; i++)
                {
                    var width = reader.ReadByte();
                    var height = reader.ReadByte();
                    var colors = reader.ReadByte();
                    reader.ReadByte(); // ignore. Should be 0

                    var color_planes = reader.ReadUInt16(); // should be 0 or 1

                    var bits_per_pixel = reader.ReadUInt16();

                    var size = reader.ReadUInt32();

                    var offset = reader.ReadUInt32();

                    this.Icons.Add(new Icon()
                    {
                        Colors = colors,
                        Height = height,
                        Width = width,
                        Offset = offset,
                        Size = size,
                        ColorPlanes = color_planes,
                        BitsPerPixel = bits_per_pixel
                    });
                }

                // now get the Data
                foreach (var icon in Icons)
                {
                    if (reader.BaseStream.Position < icon.Offset)
                    {
                        var dummy_bytes_to_read = (int)(icon.Offset - reader.BaseStream.Position);
                        reader.ReadBytes(dummy_bytes_to_read);
                    }

                    var data = reader.ReadBytes((int)icon.Size);

                    icon.Data = data;
                }

            }
        }

    }
    #endregion

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern int UpdateResource(IntPtr hUpdate, uint lpType, ushort lpName, ushort wLanguage, byte[] lpData, uint cbData);

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern IntPtr BeginUpdateResource(string pFileName, [MarshalAs(UnmanagedType.Bool)]bool bDeleteExistingResources);

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern bool EndUpdateResource(IntPtr hUpdate, bool fDiscard);

    public enum ICResult
    {
        Success,
        FailBegin,
        FailUpdate,
        FailEnd
    }

    const uint RT_ICON = 3;
    const uint RT_GROUP_ICON = 14;

    public ICResult ChangeIcon(string exeFilePath, string iconFilePath)
    {
        using (FileStream fs = new FileStream(iconFilePath, FileMode.Open, FileAccess.Read))
        {
            var reader = new IconReader(fs);

            var iconChanger = new IconChanger();
            return iconChanger.ChangeIcon(exeFilePath, reader.Icons);
        }
    }

    public ICResult ChangeIcon(string exeFilePath, Icons icons)
    {
        // Load executable
        IntPtr handleExe = BeginUpdateResource(exeFilePath, false);

        if (handleExe == null) return ICResult.FailBegin;

        ushort startindex = 1;
        ushort index = startindex;
        ICResult result = ICResult.Success;

        var ret = 1;

        foreach (var icon in icons)
        {
            // Replace the icon
            // todo :Improve the return value handling of UpdateResource
            ret = UpdateResource(handleExe, RT_ICON, index, 0, icon.Data, icon.Size);

            index++;
        }

        var groupdata = icons.ToGroupData();

        // todo :Improve the return value handling of UpdateResource
        ret = UpdateResource(handleExe, RT_GROUP_ICON, startindex, 0, groupdata, (uint)groupdata.Length);
        if (ret == 1)
        {
            if (EndUpdateResource(handleExe, false))
                result = ICResult.Success;
            else
                result = ICResult.FailEnd;
        }
        else
            result = ICResult.FailUpdate;

        return result;
    }
}