Delphi DLL

Write Text at a 64-bit Offset in a Remote SFTP File

Demonstrates the Chilkat SFtp.WriteFileText64 method, which encodes text and writes it at a specific 64-bit byte offset in an open handle. The arguments are the handle, the offset, the charset, and the text. The 64-bit offset supports very large files.

Background: A 32-bit offset tops out at about 4 GB, so files larger than that require the 64-bit form to address positions beyond that boundary. The behavior is otherwise identical to the 32-bit version — the only difference is the width of the offset argument, chosen to match the size of the file you are working with.

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var
success: Boolean;
sftp: HCkSFtp;
port: Integer;
password: PWideChar;
handle: PWideChar;
offset: HCkint64;

begin
success := False;

//  Demonstrates the SFtp.WriteFileText64 method, which encodes text and writes it at a specific
//  64-bit byte offset in an open handle.  The 1st argument is the handle, the 2nd is the offset,
//  the 3rd is the charset, and the 4th is the text.  The 64-bit offset supports very large files.

sftp := CkSFtp_Create();

//  Connect, authenticate, and initialize the SFTP subsystem.
port := 22;
success := CkSFtp_Connect(sftp,'sftp.example.com',port);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
password := 'mySshPassword';

success := CkSFtp_AuthenticatePw(sftp,'mySshLogin',password);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

success := CkSFtp_InitializeSftp(sftp);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

handle := CkSFtp__openFile(sftp,'subdir/hugefile.dat','readWrite','openOrCreate');
if (CkSFtp_getLastMethodSuccess(sftp) = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

//  Write at a byte offset beyond the 32-bit (4 GB) range.
offset := 5000000000;
success := CkSFtp_WriteFileText64(sftp,handle,offset,'utf-8','MARKER');
if (success = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;

success := CkSFtp_CloseHandle(sftp,handle);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSFtp__lastErrorText(sftp));
    Exit;
  end;
Memo1.Lines.Add('Wrote at the 64-bit offset.');

CkSFtp_Disconnect(sftp);

CkSFtp_Dispose(sftp);