Check if Word document is already open before opening it in C#

Question

I'm doing several things with a Word document in the background and sometimes, if the app fails, an instance of MS Word is left running in the background. Upon restart, it tries to open the same file and there's a stream of issues related to that.

I'd like to understand (couldn't quite find an applicable answer here) how to check if the file I'm trying to open is already open.

My code:

Microsoft.Office.Interop.Word.Application wordApp = new Microsoft.Office.Interop.Word.Application();
Document wordDoc = new Document();
wordDoc = wordApp.Documents.Open(ref oTemplatePath, ref oMissing, ref oMissing, ref oMissing);
wordApp.Visible = false;

How can I check for the file being already open before executing wordApp.Documents.Open?

Thanks!

Answer 1

You can try to open the file, if the file is already open IOException will be thrown and indicate that the file is open:

public bool fileIsOpen(string path)
{
    System.IO.FileStream a = null;

    try
    {
        a = System.IO.File.Open(path,
        System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.None);
        return false;
    }
    catch (System.IO.IOException ex)
    {
        return true;
    }

    finally
    {
        if (a != null)
        {
            a.Close();
            a.Dispose();
        }
    }
}

Answer 2

You can enumerate all Word windows and try to find one with that document. Also if you try to open this file, while it's opened in Word, you will get IOException. But it's not perfect solution :( Here is solution:

using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;

namespace WordExampleApp
{
    class Program
    {
        const int ERROR_SHARING_VIOLATION = -2147024864;
        static readonly string WORD_CLASS_NAME = "OpusApp";
        static readonly string WORD_DOCUMENT_CLASS_NAME = "_WwB";

        delegate bool EnumWindowProc(IntPtr hWnd, IntPtr parameter);

        static void Main(string[] args)
        {
            // Path to exist word document
            string filePath = @"C:\temp\asdasd.docx";

            string documentName = Path.GetFileNameWithoutExtension(filePath);
            var isDocOpened = IsDocumentOpened(documentName);
            Console.WriteLine("Is document opened: {0}", isDocOpened);

            bool canRead = CanReadFile(filePath);
            Console.WriteLine("Can read file: {0}", canRead);
        }
        private static bool CanReadFile(string path)
        {
            try {
                using (var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.None)) { }
                return true;
            }
            catch (IOException ex) {
                if (ex.HResult == ERROR_SHARING_VIOLATION)
                    return false;
                else throw;
            }
        }

        private static bool IsDocumentOpened(string documentName)
        {
            IntPtr hwnd = FindWindow(WORD_CLASS_NAME, documentName + " - Word");
            List<IntPtr> childs = GetChildWindows(hwnd);
            var classText = new StringBuilder("", 1024);
            var windowText = new StringBuilder("", 1024);

            foreach (var childHwnd in childs)
            {
                if (0 == GetClassName(childHwnd, classText, 1024)) {
                    // something wrong
                }
                if (0 == GetWindowText(childHwnd, windowText, 1024)) {
                    // something wrong
                }
                var className = classText.ToString();
                var windowName = windowText.ToString();
                if (className == WORD_DOCUMENT_CLASS_NAME && windowName == documentName)
                    return true;

                classText.Clear();
                windowText.Clear();
            }
            return false;
        }
        public static List<IntPtr> GetChildWindows(IntPtr parent)
        {
            List<IntPtr> result = new List<IntPtr>();
            GCHandle gcHandle = GCHandle.Alloc(result);
            try {
                EnumWindowProc childProc = new EnumWindowProc(EnumWindow);
                EnumChildWindows(parent, childProc, GCHandle.ToIntPtr(gcHandle));
            }
            finally {
                if (gcHandle.IsAllocated)
                    gcHandle.Free();
            }
            return result;
        }
        private static bool EnumWindow(IntPtr handle, IntPtr pointer)
        {
            GCHandle gch = GCHandle.FromIntPtr(pointer);
            List<IntPtr> list = gch.Target as List<IntPtr>;
            if (list == null)
                throw new InvalidCastException("GCHandle Target could not be cast as List<IntPtr>");
            list.Add(handle);
            return true;
        }

        [DllImport("user32", ExactSpelling = false, CharSet = CharSet.Auto)]
        internal static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool EnumChildWindows(IntPtr hwndParent, EnumWindowProc lpEnumFunc, IntPtr lParam);

        [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount);

        [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        public static extern int GetWindowText(IntPtr hWnd, StringBuilder lpWindowText, int nMaxCount);
    }
}