How can I get a list of all open named pipes in Windows and avoiding possible exceptions?

Question

Getting the list of named pipes is in ideal case pretty simple and can be found here: How can I get a list of all open named pipes in Windows?

But mentioned solutio

Answer 1

I dug into Directory class source code and found an inspiration. Here is a working solution which gives you list of all opened named pipes. My result does not contain \\.\pipe\ prefix as it can be seen in result of Directory.GetFiles. I tested my solution on WinXp SP3, Win 7, Win 8.1.

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    struct WIN32_FIND_DATA
    {
        public uint dwFileAttributes;
        public System.Runtime.InteropServices.ComTypes.FILETIME ftCreationTime;
        public System.Runtime.InteropServices.ComTypes.FILETIME ftLastAccessTime;
        public System.Runtime.InteropServices.ComTypes.FILETIME ftLastWriteTime;
        public uint nFileSizeHigh;
        public uint nFileSizeLow;
        public uint dwReserved0;
        public uint dwReserved1;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
        public string cFileName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]
        public string cAlternateFileName;
    }

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    static extern IntPtr FindFirstFile(string lpFileName, out WIN32_FIND_DATA lpFindFileData);


    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    static extern bool FindNextFile(IntPtr hFindFile, out WIN32_FIND_DATA
       lpFindFileData);

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern bool FindClose(IntPtr hFindFile);

    private static void Main(string[] args)
    {
        var namedPipes = new List<string>();
        WIN32_FIND_DATA lpFindFileData;

        var ptr = FindFirstFile(@"\\.\pipe\*", out lpFindFileData);
        namedPipes.Add(lpFindFileData.cFileName);
        while (FindNextFile(ptr, out lpFindFileData))
        {
            namedPipes.Add(lpFindFileData.cFileName);
        }
        FindClose(ptr);

        namedPipes.Sort();

        foreach (var v in namedPipes)
            Console.WriteLine(v);

        Console.ReadLine();
     }

Answer 2

Using one of the .NET 4 APIs returning IEnumerable, you can catch those exceptions:

static IEnumerable<string> EnumeratePipes() {
    bool MoveNextSafe(IEnumerator enumerator) {

        // Pipes might have illegal characters in path. Seen one from IAR containing < and >.
        // The FileSystemEnumerable.MoveNext source code indicates that another call to MoveNext will return
        // the next entry.
        // Pose a limit in case the underlying implementation changes somehow. This also means that no more than 10
        // pipes with bad names may occur in sequence.
        const int Retries = 10;
        for (int i = 0; i < Retries; i++) {
            try {
                return enumerator.MoveNext();
            } catch (ArgumentException) {
            }
        }
        Log.Warn("Pipe enumeration: Retry limit due to bad names reached.");
        return false;
    }

    using (var enumerator = Directory.EnumerateFiles(@"\\.\pipe\").GetEnumerator()) {
        while (MoveNextSafe(enumerator)) {
            yield return enumerator.Current;
        }
    }
}

The badly named pipes are not enumerated in the end, of course. So, you cannot use this solution if you really want to list all of the pipes.