Emulate waiting on File.Open in C# when file is locked


I have, essentially, the same problem as this poster, but in C#: Waiting until a file is available for reading with Win32

More information: we have code that calls File.Open in one of our projects, that occasionally dies when the file is already opened by another process (EDIT: or thread):

FileStream stream = File.Open(m_fileName, m_mode, m_access);
/* do stream-type-stuff */

File.Open will throw an IOException (which is currently quietly swallowed somewhere), whose HResult property is 0x80070020 (ERROR_SHARING_VIOLATION). What I would like to do is this:

FileStream stream = null;
while (stream == null) {
    try {
        stream = File.Open(m_fileName, m_mode, m_access, FileShare.Read);
    } catch (IOException e) {
        const int ERROR_SHARING_VIOLATION = int(0x80070020);
        if (e.HResult != ERROR_SHARING_VIOLATION)
/* do stream-type-stuff */

However, HResult is a protected member of Exception, and cannot be accessed -- the code does not compile. Is there another way of accessing the HResult, or perhaps, another part of .NET I might use to do what I want?

Oh, one final caveat, and it's a doozy: I'm limited to using Visual Studio 2005 and .NET 2.0.

asked on Stack Overflow Jun 29, 2010 by Blair Holloway • edited May 23, 2017 by Community

2 Answers


You can call Marshal.GetHRForException() within the catch clause to get the error code. No need for reflection:

using System.Runtime.InteropServices;

if (Marshal.GetHRForException(e) == ERROR_SHARING_VIOLATION)
answered on Stack Overflow Jun 29, 2010 by Igal Tabachnik • edited Jun 29, 2010 by Igal Tabachnik

Your best bet is using reflection unfortunately. Of course, since you sleep for 1sec between attempts, the performance costs will most likely go unnoticed.

answered on Stack Overflow Jun 29, 2010 by Blindy

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