Ignore folders/files when Directory.GetFiles() is

Question

I am trying to display a list of all files found in the selected directory (and optionally any subdirectories). The problem I am having is that when the GetFiles() method comes across a folder that it cannot access, it throws an exception and the process stops.

How do I ignore this exception (and ignore the protected folder/file) and continue adding accessible files to the list?

try
{
    if (cbSubFolders.Checked == false)
    {
        string[] files = Directory.GetFiles(folderBrowserDialog1.SelectedPath);
        foreach (string fileName in files)
            ProcessFile(fileName);
    }
    else
    {
        string[] files = Directory.GetFiles(folderBrowserDialog1.SelectedPath, "*.*", SearchOption.AllDirectories);
        foreach (string fileName in files)
            ProcessFile(fileName);
    }
    lblNumberOfFilesDisplay.Enabled = true;
}
catch (UnauthorizedAccessException) { }
finally {}

Answer 1

Here's a full-featured, .NET 2.0-compatible implementation.

You can even alter the yielded List of files to skip over directories in the FileSystemInfo version!

(Beware null values!)

public static IEnumerable<KeyValuePair<string, string[]>> GetFileSystemInfosRecursive(string dir, bool depth_first)
{
    foreach (var item in GetFileSystemObjectsRecursive(new DirectoryInfo(dir), depth_first))
    {
        string[] result;
        var children = item.Value;
        if (children != null)
        {
            result = new string[children.Count];
            for (int i = 0; i < result.Length; i++)
            { result[i] = children[i].Name; }
        }
        else { result = null; }
        string fullname;
        try { fullname = item.Key.FullName; }
        catch (IOException) { fullname = null; }
        catch (UnauthorizedAccessException) { fullname = null; }
        yield return new KeyValuePair<string, string[]>(fullname, result);
    }
}

public static IEnumerable<KeyValuePair<DirectoryInfo, List<FileSystemInfo>>> GetFileSystemInfosRecursive(DirectoryInfo dir, bool depth_first)
{
    var stack = depth_first ? new Stack<DirectoryInfo>() : null;
    var queue = depth_first ? null : new Queue<DirectoryInfo>();
    if (depth_first) { stack.Push(dir); }
    else { queue.Enqueue(dir); }
    for (var list = new List<FileSystemInfo>(); (depth_first ? stack.Count : queue.Count) > 0; list.Clear())
    {
        dir = depth_first ? stack.Pop() : queue.Dequeue();
        FileSystemInfo[] children;
        try { children = dir.GetFileSystemInfos(); }
        catch (UnauthorizedAccessException) { children = null; }
        catch (IOException) { children = null; }
        if (children != null) { list.AddRange(children); }
        yield return new KeyValuePair<DirectoryInfo, List<FileSystemInfo>>(dir, children != null ? list : null);
        if (depth_first) { list.Reverse(); }
        foreach (var child in list)
        {
            var asdir = child as DirectoryInfo;
            if (asdir != null)
            {
                if (depth_first) { stack.Push(asdir); }
                else { queue.Enqueue(asdir); }
            }
        }
    }
}

Answer 2

see https://stackoverflow.com/a/10728792/89584 for a solution that handles the UnauthorisedAccessException problem.

All the solutions above will miss files and/or directories if any calls to GetFiles() or GetDirectories() are on folders with a mix of permissions.