C# – Reading compound documents in c#

Here is my shot. This is an initial translation of this article.

namespace cs_console_app
{
    using System;
    using System.Runtime.InteropServices;
    using System.Runtime.InteropServices.ComTypes;

    [ComImport]
    [Guid("0000000d-0000-0000-C000-000000000046")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IEnumSTATSTG
    {
        // The user needs to allocate an STATSTG array whose size is celt.
        [PreserveSig]
        uint Next(
            uint celt,
            [MarshalAs(UnmanagedType.LPArray), Out]
            System.Runtime.InteropServices.ComTypes.STATSTG[] rgelt,
            out uint pceltFetched
        );

        void Skip(uint celt);

        void Reset();

        [return: MarshalAs(UnmanagedType.Interface)]
        IEnumSTATSTG Clone();
    }

    [ComImport]
    [Guid("0000000b-0000-0000-C000-000000000046")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    interface IStorage
    {
        void CreateStream(
            /* [string][in] */ string pwcsName,
            /* [in] */ uint grfMode,
            /* [in] */ uint reserved1,
            /* [in] */ uint reserved2,
            /* [out] */ out IStream ppstm);

        void OpenStream(
            /* [string][in] */ string pwcsName,
            /* [unique][in] */ IntPtr reserved1,
            /* [in] */ uint grfMode,
            /* [in] */ uint reserved2,
            /* [out] */ out IStream ppstm);

        void CreateStorage(
            /* [string][in] */ string pwcsName,
            /* [in] */ uint grfMode,
            /* [in] */ uint reserved1,
            /* [in] */ uint reserved2,
            /* [out] */ out IStorage ppstg);

        void OpenStorage(
            /* [string][unique][in] */ string pwcsName,
            /* [unique][in] */ IStorage pstgPriority,
            /* [in] */ uint grfMode,
            /* [unique][in] */ IntPtr snbExclude,
            /* [in] */ uint reserved,
            /* [out] */ out IStorage ppstg);

        void CopyTo(
            /* [in] */ uint ciidExclude,
            /* [size_is][unique][in] */ Guid rgiidExclude, // should this be an array?
            /* [unique][in] */ IntPtr snbExclude,
            /* [unique][in] */ IStorage pstgDest);

        void MoveElementTo(
            /* [string][in] */ string pwcsName,
            /* [unique][in] */ IStorage pstgDest,
            /* [string][in] */ string pwcsNewName,
            /* [in] */ uint grfFlags);

        void Commit(
            /* [in] */ uint grfCommitFlags);

        void Revert();

        void EnumElements(
            /* [in] */ uint reserved1,
            /* [size_is][unique][in] */ IntPtr reserved2,
            /* [in] */ uint reserved3,
            /* [out] */ out IEnumSTATSTG ppenum);

        void DestroyElement(
            /* [string][in] */ string pwcsName);

        void RenameElement(
            /* [string][in] */ string pwcsOldName,
            /* [string][in] */ string pwcsNewName);

        void SetElementTimes(
            /* [string][unique][in] */ string pwcsName,
            /* [unique][in] */ System.Runtime.InteropServices.ComTypes.FILETIME pctime,
            /* [unique][in] */ System.Runtime.InteropServices.ComTypes.FILETIME patime,
            /* [unique][in] */ System.Runtime.InteropServices.ComTypes.FILETIME pmtime);

        void SetClass(
            /* [in] */ Guid clsid);

        void SetStateBits(
            /* [in] */ uint grfStateBits,
            /* [in] */ uint grfMask);

        void Stat(
            /* [out] */ out System.Runtime.InteropServices.ComTypes.STATSTG pstatstg,
            /* [in] */ uint grfStatFlag);

    }

    [Flags]
    public enum STGM : int
    {
        DIRECT = 0x00000000,
        TRANSACTED = 0x00010000,
        SIMPLE = 0x08000000,
        READ = 0x00000000,
        WRITE = 0x00000001,
        READWRITE = 0x00000002,
        SHARE_DENY_NONE = 0x00000040,
        SHARE_DENY_READ = 0x00000030,
        SHARE_DENY_WRITE = 0x00000020,
        SHARE_EXCLUSIVE = 0x00000010,
        PRIORITY = 0x00040000,
        DELETEONRELEASE = 0x04000000,
        NOSCRATCH = 0x00100000,
        CREATE = 0x00001000,
        CONVERT = 0x00020000,
        FAILIFTHERE = 0x00000000,
        NOSNAPSHOT = 0x00200000,
        DIRECT_SWMR = 0x00400000,
    }

    public enum STATFLAG : uint
    {
        STATFLAG_DEFAULT = 0,
        STATFLAG_NONAME = 1,
        STATFLAG_NOOPEN = 2
    }

    public enum STGTY : int
    {
        STGTY_STORAGE = 1,
        STGTY_STREAM = 2,
        STGTY_LOCKBYTES = 3,
        STGTY_PROPERTY = 4
    }

    class Program
    {
        [DllImport("ole32.dll")]
        private static extern int StgIsStorageFile(
            [MarshalAs(UnmanagedType.LPWStr)] string pwcsName);

        [DllImport("ole32.dll")]
        static extern int StgOpenStorage(
            [MarshalAs(UnmanagedType.LPWStr)] string pwcsName,
            IStorage pstgPriority,
            STGM grfMode,
            IntPtr snbExclude,
            uint reserved,
            out IStorage ppstgOpen);

        static void Main(string[] args)
        {
            string filename = @"f:\temp\treta2.msg";
            if (StgIsStorageFile(filename) == 0)
            {
                IStorage storage = null;
                if (StgOpenStorage(
                    filename,
                    null,
                    STGM.DIRECT | STGM.READ | STGM.SHARE_EXCLUSIVE,
                    IntPtr.Zero,
                    0,
                    out storage) == 0)
                {
                    System.Runtime.InteropServices.ComTypes.STATSTG statstg;
                    storage.Stat(out statstg, (uint) STATFLAG.STATFLAG_DEFAULT);

                    IEnumSTATSTG pIEnumStatStg = null;
                    storage.EnumElements(0, IntPtr.Zero, 0, out pIEnumStatStg);

                    System.Runtime.InteropServices.ComTypes.STATSTG[] regelt = { statstg };
                    uint fetched = 0;
                    uint res = pIEnumStatStg.Next(1, regelt, out fetched);

                    if (res == 0)
                    {
                        while (res != 1)
                        {
                            string strNode = statstg.pwcsName;
                            bool bNodeFound = false;

                            Console.WriteLine(strNode);

                            if (strNode == "__substg1.0_0E04001E"
                                || strNode == "__substg1.0_0E1D001E"
                                || strNode == "__substg1.0_1000001E"
                                || strNode == "__substg1.0_1013001E")
                            {
                                bNodeFound = true;
                            }

                            if (bNodeFound)
                            {
                                switch (statstg.type)
                                {
                                    case (int) STGTY.STGTY_STORAGE:
                                        {
                                            IStorage pIChildStorage;
                                            storage.OpenStorage(statstg.pwcsName,
                                               null,
                                               (uint) (STGM.READ | STGM.SHARE_EXCLUSIVE),
                                               IntPtr.Zero,
                                               0,
                                               out pIChildStorage);
                                        }
                                        break;
                                    case (int) STGTY.STGTY_STREAM:
                                        {
                                            IStream pIStream;
                                            storage.OpenStream(statstg.pwcsName,
                                               IntPtr.Zero,
                                               (uint)(STGM.READ | STGM.SHARE_EXCLUSIVE),
                                               0,
                                               out pIStream);

                                            byte[] data = new byte[255];

                                            pIStream.Read(data, 255, IntPtr.Zero);
                                        }
                                        break;
                                }
                            }

                            if ((res = pIEnumStatStg.Next(1, regelt, out fetched)) != 1)
                            {
                                statstg = regelt[0];
                            }
                        }
                    }
                }
            }

            Console.ReadLine();
        }
    }
}