文件传输错误，请高手帮忙，发送文件时出现I/O error 112,在BlockWrite(Tof,buf,sizeof(buf));出现错误提示(50分)

代码如下
unit main;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
Menus, StdCtrls, Buttons, ScktComp, ExtCtrls, ComCtrls;

type
TChatForm = class(TForm)
StatusBar1: TStatusBar;
Bevel1: TBevel;
Panel1: TPanel;
Memo1: TMemo;
Memo2: TMemo;
SpeedButton1: TSpeedButton;
ServerSocket: TServerSocket;
ClientSocket: TClientSocket;
SaveDialog1: TSaveDialog;
OpenDialog1: TOpenDialog;
SpeedButton2: TSpeedButton;
SpeedButton3: TSpeedButton;
procedure FileConnectItemClick(Sender: TObject);
procedure Exit1Click(Sender: TObject);


procedure CutFirst(denstr: string;scrstr: string);

procedure Memo1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
procedure FormCreate(Sender: TObject);
procedure ServerSocketError(Sender: TObject; Number: Smallint;
var Description: string; Scode: Integer; const Source,
HelpFile: string; HelpContext: Integer; var CancelDisplay: Wordbool);
procedure Disconnect1Click(Sender: TObject);
procedure ClientSocketConnect(Sender: TObject;
Socket: TCustomWinSocket);
procedure ClientSocketRead(Sender: TObject; Socket: TCustomWinSocket);
procedure ServerSocketClientRead(Sender: TObject;
Socket: TCustomWinSocket);
procedure ServerSocketAccept(Sender: TObject;
Socket: TCustomWinSocket);
procedure ServerSocketClientConnect(Sender: TObject;
Socket: TCustomWinSocket);
procedure ClientSocketError(Sender: TObject; Socket: TCustomWinSocket;
ErrorEvent: TErrorEvent; var ErrorCode: Integer);
procedure ServerSocketClientDisconnect(Sender: TObject;
Socket: TCustomWinSocket);
procedure ServerSocket1ClientRead(Sender: TObject;
Socket: TCustomWinSocket);
procedure SpeedButton2Click(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
procedure SpeedButton3Click(Sender: TObject);
protected
IsServer: Boolean;
end;


var
ChatForm: TChatForm;
Server: String;
stream : TMemoryStream; //定义内存流，其实用文件流也可以
size,count : integer; //文件大小
Tof : file;

implementation
uses tel;
{$R *.DFM}
procedure TChatForm.CutFirst(denstr: string;scrstr: string);
var
len :integer;
begin
len := length(scrstr);
denstr := copy(scrstr,2,(len-1));
end;


procedure TChatForm.FileConnectItemClick(Sender: TObject);
begin
if ClientSocket.Active then ClientSocket.Active := False;
if InputQuery('连接到计算机', '请输入要连接的计算机名字或IP地址:', Server) then
if Length(Server) > 0 then
with ClientSocket do
begin
Host := Server;
Active := True;
end;
end;

procedure TChatForm.Exit1Click(Sender: TObject);
begin
ServerSocket.Close;
ClientSocket.Close;
Close;
end;

procedure TChatForm.Memo1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
if Key = VK_Return then
if IsServer then
ServerSocket.Socket.Connections[0].SendText(Memo1.Lines[Memo1.Lines.Count - 1])
else
ClientSocket.Socket.SendText(Memo1.Lines[Memo1.Lines.Count - 1]);
end;

procedure TChatForm.FormCreate(Sender: TObject);
begin
ClientSocket.Active := False;
ServerSocket.Active := True;
Statusbar1.Panels[0].Text := '侦听...';
end;

procedure TChatForm.ServerSocketError(Sender: TObject; Number: Smallint;
var Description: string; Scode: Integer; const Source, HelpFile: string;
HelpContext: Integer; var CancelDisplay: Wordbool);
begin
ShowMessage(Description);
end;

procedure TChatForm.Disconnect1Click(Sender: TObject);
begin
ClientSocket.Active := False;
ServerSocket.Active := True;
Statusbar1.Panels[0].Text := '侦听...';
end;

procedure TChatForm.ClientSocketConnect(Sender: TObject;
Socket: TCustomWinSocket);
begin
Statusbar1.Panels[0].Text := '连接到: ' + Socket.RemoteHost;
end;

procedure TChatForm.ClientSocketRead(Sender: TObject;
Socket: TCustomWinSocket);
var
rcvtxt : string;
buf : array [1..2048] of char;
left : integer;
begin
rcvtxt := Socket.ReceiveText;
left := size-count; //未读字节数
if AnsiPos('go',rcvtxt)=1 then //收到响应则发
begin
if sizeof(buf)<left then //若满一块则读一块
begin
stream.Read(buf,sizeof(buf));
Socket.SendBuf(buf,sizeof(buf));
count := count + sizeof(buf);
end
else //不满则发剩余的
begin
stream.Read(buf,left);
Socket.SendBuf(buf,left);
end;
end;

end;

procedure TChatForm.ServerSocketClientRead(Sender: TObject;
Socket: TCustomWinSocket);
var
buf : array [1..2048] of char;
rcvtxt : string;
left,len : integer;
begin
len := Socket.ReceiveLength;
if len<10 then //若长度小于10则认为是文件长度
begin
rcvtxt := Socket.ReceiveText;
size := strtoint(rcvtxt);
count := 0;
if SaveDialog1.Execute then
begin
AssignFile(ToF, SaveDialog1.FileName);
Rewrite(ToF, 1);
end;
Socket.SendText('go'); //响应一块
end
else
begin
left := size - count; //未写的字节数
if sizeof(buf)<left then //满一块则写一块
begin
Socket.ReceiveBuf(buf,sizeof(buf));
BlockWrite(Tof,buf,sizeof(buf));
count := count + sizeof(buf);
Socket.SendText('go');
end
else //否则写剩余字节数
begin
Socket.ReceiveBuf(buf,left);
BlockWrite(Tof,buf,left);
CloseFile(Tof);
end;
end;
end;

procedure TChatForm.ServerSocketAccept(Sender: TObject;
Socket: TCustomWinSocket);
begin
IsServer := True;
Statusbar1.Panels[0].Text := '连接到: ' + Socket.RemoteAddress;
end;

procedure TChatForm.ServerSocketClientConnect(Sender: TObject;
Socket: TCustomWinSocket);
begin
Memo2.Lines.Clear;
end;

procedure TChatForm.ClientSocketError(Sender: TObject;
Socket: TCustomWinSocket; ErrorEvent: TErrorEvent;
var ErrorCode: Integer);
begin
Memo2.Lines.Add('连接到: ' + Server+'错误！');
ErrorCode := 0;
end;

procedure TChatForm.ServerSocketClientDisconnect(Sender: TObject;
Socket: TCustomWinSocket);
begin
Statusbar1.Panels[0].Text := '侦听...';
end;

procedure TChatForm.ServerSocket1ClientRead(Sender: TObject;
Socket: TCustomWinSocket);
begin
Memo2.Lines.Add(Socket.ReceiveText);
end;

procedure TChatForm.SpeedButton2Click(Sender: TObject);
begin
stream := TMemoryStream.Create;
if OpenDialog1.Execute then
begin
stream.LoadFromFile(OpenDialog1.FileName);
size := stream.Size; //获得文件大小
count := 0;
ClientSocket.Socket.SendText(inttostr(size)); //先发送大小
end;
end;

procedure TChatForm.FormClose(Sender: TObject; var Action: TCloseAction);
begin
ClientSocket.Active := False;
ServerSocket.Active := True;
// Statusbar1.Panels[0].Text := 'Listening...';
end;

procedure TChatForm.SpeedButton3Click(Sender: TObject);
begin
FTel:=TFtel.Create(application);
FTel.ShowModal;
end;

end.

gz

var
Len: Integer;
RecBuf:array of char;
begin
Len:=Socket.ReceiveLength;
SetLength(RecBuf, Len);
Socket.ReceiveBuf(RecBuf, Len);
{上一句出错，如果在定义时用： RecBuf:array[1..2048] of char;(静态数组，
并隐藏：SetLength(RecBuf, Len)则可以，请问这是为什么？？}
...
end;

动态数组的下标应该是从0开始的哦，否则会出错的！
如果定义静态数组，当然不能再setlength(recbuf,len)，也就是说
不能再]设定数组的长度了

{$I-}加在最前面！

帮你UP！