Is there a way to check for "exclusive" access to a file?

  • Thread starter Thread starter Kent P. Iler
  • Start date Start date
K

Kent P. Iler

Hi,

I have an application that watches a directory using FileSystemWatcher.
When a specific type of files comes over, I want to parse it and then move
it.

However, these files can be somewhat large, and the FTP process isn't
complete when I try to access the files. In those instances, an exception
is thrown when I try to access the file.

Is there a way that I can check to see if the files is ready for reading and
moving before I read it? That way I can wait until it's ready instead of
having the exception thrown.

Thanks.

-- Kent Iler
 
The OS should not allow you to open it exclusively until it has been written
and closed. You can trap the error and keep trying, in a loop with a timer,
until you get exclusive access. Another way I used to use was to try renaming
it and trapping the error in a loop until it worked. The OS will not allow
you to rename it until you have exclusive access.
 
Well the best way without resorting to unmanaged API calls is to wrap
the function which opens the file in a try catch block and use
FileShare.None as the share parameter to a FileStream object.

Example:

try {
using (FileStream fs = new FileStream (@"C:\MyFile.txt",
FileMode.Open, FileAccess.Read, FileShare.None)) {
//Code here...
}
} catch (IOException ioEx) {
//Exception handling here.
}

Using FileShare.None flag will make sure that when opening a file, the
process has exclusive access to the file.
 
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