C# – way to check if a file is in use

.netc++filefile-iofile-locking

I'm writing a program in C# that needs to repeatedly access 1 image file. Most of the time it works, but if my computer's running fast, it will try to access the file before it's been saved back to the filesystem and throw an error:

"File in use by another process"

I would like to find a way around this, but all my Googling has only yielded creating checks by using exception handling. This is against my religion, so I was wondering if anyone has a better way of doing it?

Best Solution

Updated NOTE on this solution: Checking with FileAccess.ReadWrite will fail for Read-Only files so the solution has been modified to check with FileAccess.Read.

ORIGINAL: I've used this code for the past several years, and I haven't had any issues with it.

Understand your hesitation about using exceptions, but you can't avoid them all of the time:

protected virtual bool IsFileLocked(FileInfo file)
{
    try
    {
        using(FileStream stream = file.Open(FileMode.Open, FileAccess.Read, FileShare.None))
        {
            stream.Close();
        }
    }
    catch (IOException)
    {
        //the file is unavailable because it is:
        //still being written to
        //or being processed by another thread
        //or does not exist (has already been processed)
        return true;
    }

    //file is not locked
    return false;
}