How to see if a file is being mutually accessed (via FTP)

[Alex Chumbley]

I am accessing a remote directory using FTP, then I am doing three separate functions on them: get, rename, and delete. However, I do not want to do any of the functions if the file in question is being accessed by something else (mutually accessed). It can be accessed by the FTP feed and the process which drops the file. Is there a way to check this?

Also, at the risk of asking more than one question in one post, is there any way to do those three functions using the same FTPRequest? Right now, I have to use an FTPRequest to get a list of files, the I have to use one fore each one I am downloading, then one for each renaming, and one for each deletion. So, if I have 100 files, I am using 306 connections, quite a few, and I worry that it will affect performance.


Thanks in advance for the help!

For reference, here is an example of my code. I am downloading all the files:

public void mget()
{
ftp client = new ftp(ftpIP, ftpUsername, ftpPassword);
foreach (string str in GetFileList())
{
client.download(str, localFilePath);
}
client = null;
}


public string[] GetFileList()
{
string[] downloadFiles;
StringBuilder result = new StringBuilder();
WebResponse response = null;
StreamReader reader = null;
try
{
FtpWebRequest reqFTP;
reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + ftpIP + "/"));
reqFTP.UseBinary = true;
reqFTP.Credentials = new NetworkCredential(ftpUsername, ftpPassword);
reqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
reqFTP.Proxy = null;
reqFTP.KeepAlive = false;
reqFTP.UsePassive = false;
response = reqFTP.GetResponse();
reader = new StreamReader(response.GetResponseStream());
string line = reader.ReadLine();
while (line != null)
{
result.Append(line);
result.Append("\n");
line = reader.ReadLine();
}
// to remove the trailing \n
result.Remove(result.ToString().LastIndexOf(\n), 1);
return result.ToString().Split(\n);
}
catch (Exception ex)
{
Console.WriteLine(ex);
if (reader != null)
{
reader.Close();
}
if (response != null)
{
response.Close();
}
downloadFiles = null;
return downloadFiles;
}
}


/* Download File */
public void download(string remoteFile, string localFile)
{
try
{
/* Create an FTP Request */
ftpRequest = (FtpWebRequest)FtpWebRequest.Create(host + "/" + remoteFile);
/* Log in to the FTP Server with the User Name and Password Provided */
ftpRequest.Credentials = new NetworkCredential(user, pass);
/* When in doubt, use these options */
ftpRequest.UseBinary = true;
ftpRequest.UsePassive = true;
ftpRequest.KeepAlive = true;
/* Specify the Type of FTP Request */
ftpRequest.Method = WebRequestMethods.Ftp.DownloadFile;
/* Establish Return Communication with the FTP Server */
ftpResponse = (FtpWebResponse)ftpRequest.GetResponse();
/* Get the FTP Servers Response Stream */
ftpStream = ftpResponse.GetResponseStream();
/* Open a File Stream to Write the Downloaded File */
FileStream localFileStream = new FileStream(localFile, FileMode.Create);
/* Buffer for the Downloaded Data */
byte[] byteBuffer = new byte[bufferSize];
int bytesRead = ftpStream.Read(byteBuffer, 0, bufferSize);
/* Download the File by Writing the Buffered Data Until the Transfer is Complete */
try
{
while (bytesRead > 0)
{
localFileStream.Write(byteBuffer, 0, bytesRead);
bytesRead = ftpStream.Read(byteBuffer, 0, bufferSize);
}
}
catch (Exception ex) { Console.WriteLine(ex.ToString()); }
/* Resource Cleanup */
localFileStream.Close();
ftpStream.Close();
ftpResponse.Close();
ftpRequest = null;
}
catch (Exception ex) { Console.WriteLine(ex.ToString()); }
return;
}

Continue reading...