UnauthorizedAccessException：Winform拒绝访问路径

Question

I'm using FtpWebRequest to download my file from ftp. However, when the app goes to the line FileStream which I declare to write the file out.

Below is my Download function:

public void Download(List <string> path)
        {
            try
            {
                string timenow = DateTime.Today.Year.ToString() + "_" + DateTime.Today.Month.ToString() + "_" + DateTime.Today.Day.ToString() + "_" + DateTime.Today.Hour.ToString() + "_" + DateTime.Today.Minute.ToString() + "_" + DateTime.Today.Second.ToString();
                DirectoryInfo dir = new DirectoryInfo(@"C:\StudySystemFile\" + timenow);
                if (!dir.Exists)
                    dir.Create();

                foreach (string p in path)
                {
                    FtpWebRequest request;
                    request = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftp.Hostname + p));
                    request.Credentials = new System.Net.NetworkCredential(ftp.FtpAccount, ftp.FtpPassword);
                    request.Method = WebRequestMethods.Ftp.DownloadFile;
                    request.KeepAlive = false;
                    request.UseBinary = true;
                    FtpWebResponse response = (FtpWebResponse)request.GetResponse();

                    Stream reader = response.GetResponseStream();
                    FileStream file = new FileStream(@"C:\StudySystemFile\" + timenow, FileMode.Create, FileAccess.ReadWrite);

                    byte[] buffer = new byte[1024];
                    int bytesRead = reader.Read(buffer, 0, buffer.Length);

                    while (bytesRead > 0)
                    {
                        file.Write(buffer, 0, bytesRead);
                        bytesRead = reader.Read(buffer, 0, buffer.Length);
                    }

                    reader.Close();
                    file.Close();
                    response.Close();
                    Console.WriteLine(p);
                }
            }
            catch (Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);
            }
        }

Answer 1

The user running the program does not have permission to create the file at C:\\StudySystemFile\\ check that the folder exists and whatever user the program is running as can create files there without a UAC prompt.

Likely what is happening is when you create the folder with Create() it is inheriting permissions from C:\\ which does not have write permissions for files, you only get folder creation permissions.

You either need to create the folder outside the program or when you call Create() you need to set the permissions .

Answer 2

You must be getting UnauthorizedAccessException .The exception that is thrown when the operating system denies access because of an I/O error or a specific type of security error.

It is clearly a permission issue .

In case of Vista/Windows 7/8, C:\\ drive is considered as system drive, and need administrator privileges for your process in order to create files directly under it.

Try running your process with administrator or Run Visual Studio as Administrator , and it should work.

Answer 3

Your application doesn't have permission to write to that directory. You can force the UAC prompt by right-clicking on your project and adding a new Application Manifest File . In this file, replace

<requestedExecutionLevel level="asInvoker" uiAccess="false" />

with

<requestedExecutionLevel level="requireAdministrator" uiAccess="false" />

A better idea would be to write to a directory that doesn't require admin rights.

Answer 4

What version of Framework are you using? What installation/launch method are you using? (ie, clickonce) And like the other poster suggested, have you checked the permissions on that folder on your C: drive? Right click the folder and check the security tab, make sure the logged in user has modify as well as read access to the folder.

If you only need the file on a temporary basis, then look into writing to IsolatedStorage. How to store and retrieve data in Isolated Storage File?