Send files using sockets in Delphi 2010 - delphi

Question

Hi I am sending a file via tsocket, I'm editing the first code to not use opendilalog but I want to use a string with the path of the file to send, the problem is that the second code that eh OpenDialog edited for not using shoot me an error saying the file to send is being used by another process.
The first source
procedure TForm1.Button2Click(Sender: TObject);
begin
if ClientSocket1.Active = True then
begin
OpenDialog1.Filter := 'All Files (*.*)'; // you can add more choices by adding | and followed by description and (*.extension)
OpenDialog1.FilterIndex := 1; // Here you follow which index number from above you want
if OpenDialog1.Execute then
begin
Edit1.Text := ExtractFileName(OpenDialog1.FileName); // To send as filename after
ClientSocket1.Socket.SendText('FILE!'+Edit1.Text);
sleep(2000); // Need to sleep so the other end has time to process the commands
Streamsize := TFileStream.Create(OpenDialog1.FileName, fmopenread); // Stream created just to Calculate size
Edit2.Text := inttostr(Streamsize.Size);
Sleep(2000);
ClientSocket1.Socket.SendText('SIZE!'+Edit2.Text); // Sends filesize through primary socket
Streamsize.Position := 0;
Streamsize.Free;
sleep(2000);
ClientSocket2.Address := Edit3.Text;
ClientSocket2.Open; // ready to send file on second socket
if ClientSocket2.Socket.SendStream(TFileStream.Create(OpenDialog1.FileName, fmopenRead)) then memo1.Lines.Add('File Sent');
// above creates a stream and sends as a stream its in a if line because this is the only way it will automatically check the byte order and send the whole stream
end;
end
else
MessageDlg('Error: You are not connected', mtError, [MbOK],0); // Error Check above code won't work until the socket is connected
end;
The second source
procedure TForm1.Button2Click(Sender: TObject);
var
archivo: string;
begin
archivo := 'c:/clap.jpg';
if ClientSocket1.Active = True then
begin
Edit1.Text := ExtractFileName(archivo);
// To send as filename after
ClientSocket1.Socket.SendText('FILE!' + Edit1.Text);
sleep(2000); // Need to sleep so the other end has time to process the commands
Streamsize := TFileStream.Create(archivo, fmopenread);
// Stream created just to Calculate size
Edit2.Text := inttostr(Streamsize.Size);
sleep(2000);
ClientSocket1.Socket.SendText('SIZE!' + Edit2.Text);
// Sends filesize through primary socket
Streamsize.Position := 0;
Streamsize.Free;
sleep(2000);
ClientSocket2.Address := '127.0.0.1';
ClientSocket2.Open; // ready to send file on second socket
if ClientSocket2.Socket.SendStream(TFileStream.Create(archivo, fmopenread))
then
Memo1.Lines.Add('File Sent');
// above creates a stream and sends as a stream its in a if line because this is the only way it will automatically check the byte order and send the whole stream
end
else
MessageDlg('Error: You are not connected', mtError, [MbOK], 0); // Error Check above code won't work until the socket is connected
end;
The server.
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ScktComp, ComCtrls, idglobal, ExtCtrls, ShellAPI;
type
TForm1 = class(TForm)
Button1: TButton;
Memo1: TMemo;
Label1: TLabel;
ServerSocket1: TServerSocket;
ServerSocket2: TServerSocket;
GroupBox1: TGroupBox;
Edit1: TEdit;
Edit2: TEdit;
Label2: TLabel;
Label3: TLabel;
ProgressBar1: TProgressBar;
Timer1: TTimer;
StatusBar1: TStatusBar;
procedure Button1Click(Sender: TObject);
procedure ServerSocket1Accept(Sender: TObject;
Socket: TCustomWinSocket);
procedure ServerSocket2Accept(Sender: TObject;
Socket: TCustomWinSocket);
procedure ServerSocket1ClientRead(Sender: TObject;
Socket: TCustomWinSocket);
procedure ServerSocket2ClientRead(Sender: TObject;
Socket: TCustomWinSocket);
procedure FormCreate(Sender: TObject);
procedure Timer1Timer(Sender: TObject);
private
{ Private declarations }
IncommingStream: TFileStream;
TimeTaken: integer;
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
// Written by me ColdFuzion
// All i ask is i be given some credit for coding this my e-mail is ColdFuzion#hushmail.com
// Program Usage: To recieve Files sent by the client
procedure TForm1.Button1Click(Sender: TObject);
begin
ServerSocket1.Open;
Memo1.Lines.Add('Server Listening on '+inttostr(ServerSocket1.Port) );
end;
procedure TForm1.ServerSocket1Accept(Sender: TObject;
Socket: TCustomWinSocket);
begin
Memo1.Lines.Add('Client connected From '+Socket.RemoteHost)
// Adds the clients host as it connects
end;
procedure TForm1.ServerSocket2Accept(Sender: TObject;
Socket: TCustomWinSocket);
begin
Memo1.Lines.Add('Incoming File Transfer');
end;
procedure TForm1.ServerSocket1ClientRead(Sender: TObject;
Socket: TCustomWinSocket);
var IncommingText, StrippedData, CommandName: string;
begin
IncommingText := socket.ReceiveText;
StrippedData := copy(IncommingText,6,length(IncommingText) );
CommandName := copy(IncommingText,0,5);
if CommandName = 'FILE!' then
begin
IncommingStream := TFileStream.Create(StrippedData, fmCREATE or fmOPENWRITE and fmsharedenywrite); // Once File name is recieved the stream to recieve
Edit1.Text := StrippedData; // The file is created
ServerSocket2.Open;
end
else
if CommandName = 'SIZE!' then
begin
Edit2.Text := StrippedData;
ProgressBar1.Max := StrToInt(StrippedData);
ProgressBar1.Min := 0;
Memo1.lines.Add('Recieving File '+Edit1.Text +' of size '+Edit2.Text);
end;
end;
procedure TForm1.ServerSocket2ClientRead(Sender: TObject;
// This is the secondary socket it is the most important part of the program
Socket: TCustomWinSocket);
// It processes the incomming file stream
var Buffer: array [0..9999] of Char;
IncommingLen, RecievedLen: integer;
Filepath: string;
begin
Timer1.Enabled := True;
IncommingLen := socket.ReceiveLength;
// If the size of any incomming data is the size of 0 then the process begins
Filepath := ExtractFilePath(Edit1.Text)+Edit1.Text;
// Sets a String Filepath for the actual directory with the filename so that the shellexecute can run this after
while IncommingLen > 0 do
// Must make sure the process ends
begin
RecievedLen := socket.ReceiveBuf(Buffer, Sizeof(Buffer));
// Changes the size of RecievedLen by the amount of incoming data recieved
if RecievedLen <= 0 then
// Small part of the code where once the buffer reaches 0 the code will exit
Break
else
IncommingStream.Write(Buffer, RecievedLen);
// Writes the Incoming data into a new stream by the filename and size which is recieved
ProgressBar1.StepBy(RecievedLen);
// through the primary socket Also this line increases the progess indicator bar
if IncommingStream.Size >= strtoint(Edit2.Text) then
// Onces the stream size begins to reach the size which was sent before sending the file then this
begin
// procedure will start
IncommingStream.Free;
// Free's the stream
memo1.Lines.Add('File '+Edit1.Text +' Recieved Successfuly');
memo1.Lines.Add('Time Taken to Recieve File ' +IntToStr(TimeTaken)+' seconds');
ServerSocket1.Socket.Connections[0].SendText('DONE!');
Edit1.Text := '';
// From here it starts setting the variables back
Edit2.Text := '';
ProgressBar1.Position := 0;
Timer1.Enabled := False;
TimeTaken := 0;
if Messagedlg('Would you Like to open the recieved file?', mtConfirmation, [MbYes,MbNo],0) = MrYes then // Simply asks the user if he wants to open the file if yes will execute if no break
begin
ShellExecute(Form1.Handle, 'open', pchar(Filepath),nil, nil, SW_NORMAL); // A shellapi was added to uses to beable to execute this line
end;
Break; // This line basically executes any file using the extension from the windows ini files.
end;
end;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
Memo1.Text := '';
end;
procedure TForm1.Timer1Timer(Sender: TObject);
begin
inc(TimeTaken,1);
// Counts number of seconds starts once the filestream begins
end;
end.
// This entire Program could use alot more Error checking but it simply is a very basic
// Example of how to do certain things using the basic components that come with Delphi
// There are hardly any examples of sending files with delphi on the internet so most of
// the code here had to be improvised i hope this helps people where i had to struggle with
I can correct as the second code to pull no more errors?

Answer 1

If the OS is complaining that the file is already in use, then it really is already in use.
You are creating multiple streams to the same file (you are also using the wrong path delimiter). Create one stream and reuse it multiple times instead, eg:
procedure TForm1.Button2Click(Sender: TObject);
var
archivo: string;
Strm: TFileStream;
begin
archivo := 'c:\clap.jpg';
if ClientSocket1.Active then
begin
Strm := TFileStream.Create(archivo, fmOpenRead or fmShareDenyWrite);
try
Edit1.Text := ExtractFileName(archivo);
Edit2.Text := IntToStr(Strm.Size);
ClientSocket1.Socket.SendText('FILE!' + Edit1.Text);
// Need to sleep so the other end has time to process the commands
Sleep(2000);
ClientSocket1.Socket.SendText('SIZE!' + Edit2.Text);
Sleep(2000);
ClientSocket2.Address := '127.0.0.1';
ClientSocket2.Open; // ready to send file on second socket
if ClientSocket2.Socket.SendStream(Strm) then
begin
// SendStream() takes ownership of the Stream, so don't free it!
Strm := nil;
Memo1.Lines.Add('File Sent');
end;
finally
Strm.Free;
end;
end
else
MessageDlg('Error: You are not connected', mtError, [MbOK], 0);
end;
As noted, SendStream() takes ownership of the stream. If you are using the socket in non-blocking mode, it may take time to transfer the whole stream. You would not be able to re-open the file again until that transfer is finished. That could account for the error you are seeing.
Now, with that said, the fact that you have to introduce sleeps into your protocol in order to get commands processed correctly means you did not design your protocol very well to begin with. It would be much more reliable to put a delimiter between your commands instead, eg:
procedure TForm1.Button2Click(Sender: TObject);
var
archivo: string;
Strm: TFileStream;
begin
archivo := 'c:\clap.jpg';
if ClientSocket1.Active then
begin
Strm := TFileStream.Create(archivo, fmOpenRead or fmShareDenyWrite);
try
Edit1.Text := ExtractFileName(archivo);
Edit2.Text := IntToStr(Strm.Size);
ClientSocket1.Socket.SendText('FILE!' + Edit1.Text + #13#10);
ClientSocket1.Socket.SendText('SIZE!' + Edit2.Text + #13#10);
ClientSocket2.Address := '127.0.0.1';
ClientSocket2.Open; // ready to send file on second socket
if ClientSocket2.Socket.SendStream(Strm) then
begin
// SendStream() takes ownership of the Stream and will free it
// after it is done sending, so don't free it yourself!
Strm := nil;
Memo1.Lines.Add('File Sent');
end;
finally
Strm.Free;
end;
end
else
MessageDlg('Error: You are not connected', mtError, [MbOK], 0);
end;
Then the receiver can simply read inbound data and split it on the delimiters as needed, no sleeps needed.
BTW, you are essentially recreating the FTP protocol, jut with a different syntax, so why not use the actual FTP protocol instead? There are plenty of FTP components/libraries readily available.