Lock reading, opening and editing file

Question

How to block the opening, reading and editing of a file by the user during the period the application is running?

An application has a relatively long data collection period. This application reads data in real time. The data read is recorded in file every minute. At the end of the data collection, I must release the file to the user. Use the code below to save the data every minute. The file attributes Hidden and read only don’t help me!

string diret=saveFileDialog1.FileName;
Encoding sjisX=Encoding.GetEncoding("Shift_JIS");
StreamWriter arquivo=new StreamWriter(diret,true,sjisX);
arquivo.Write(tb_csv.Text); //salva os dados.
arquivo.Close(); // fecha o arquivo.

//fileProtec.Attributes=FileAttributes.Hidden; permite sua abertura, logo, não serve!

Answer 1

Instead of creating the object StreamWriter with the file path, create a FilesTream and the pass to the StreamWriter.

For example:

string diret = saveFileDialog1.FileName;
using (FileStream arquivo =  // Isso é o que realmente abre o arquivo. Não esqueça o using.
        File.Open(diret,
                  FileMode.OpenOrCreate,
                  FileAccess.ReadWrite,
                  FileShare.None)) {

    using (StreamWriter escritor = new StreamWriter(arquivo)) // esse objeto não é o arquivo, é quem escreve nele.
    {
        escritor.BaseStream.Seek(0, SeekOrigin.End); // Posicionamos o cursor de escrita no final do arquivo.

        escritor.Write(tb_csv.Text);
        escritor.flush(); // Caso hajam dados em buffer ainda não escritos, forçamos sua escrita.

        escritor.Close();
    }
}

This blocks reading by other processes because of the signature of Open method of the File class. This method can inform the operating system that you do not want to share the file with other processes, through its last parameter. Of official documentation:

Fileshare.None: Decline current file sharing. Any request to open the file (by this process or another) will fail until the file is closed.