Delphi ActiveX

Read Text at a String Offset from a Remote SFTP File

Demonstrates the Chilkat SFtp.ReadFileText64s method, which is like ReadFileText64 but takes the byte offset as a decimal string. The arguments are the handle, the offset string, the maximum number of bytes, and the charset.

Background: The string-offset read exists for the same reason as its write counterpart: it lets code in languages without convenient 64-bit integers still address positions in very large files by supplying the offset as text. Functionally it is identical to the int64 version.

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var
success: Integer;
sftp: TChilkatSFtp;
port: Integer;
password: WideString;
handle: WideString;
offset: WideString;
numBytes: Integer;
text: WideString;

begin
success := 0;

//  Demonstrates the SFtp.ReadFileText64s method, which is like ReadFileText64 but takes the byte
//  offset as a decimal string.  The 1st argument is the handle, the 2nd is the offset string, the
//  3rd is the maximum number of bytes, and the 4th is the charset.

sftp := TChilkatSFtp.Create(Self);

//  Connect, authenticate, and initialize the SFTP subsystem.
port := 22;
success := sftp.Connect('sftp.example.com',port);
if (success = 0) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    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 := sftp.AuthenticatePw('mySshLogin',password);
if (success = 0) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    Exit;
  end;

success := sftp.InitializeSftp();
if (success = 0) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    Exit;
  end;

handle := sftp.OpenFile('subdir/hugefile.dat','readOnly','openExisting');
if (sftp.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    Exit;
  end;

//  Supplying the offset as a string is convenient in languages without a native 64-bit integer.
offset := '5000000000';
numBytes := 6;
text := sftp.ReadFileText64s(handle,offset,numBytes,'utf-8');
if (sftp.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    Exit;
  end;
Memo1.Lines.Add(text);

success := sftp.CloseHandle(handle);
if (success = 0) then
  begin
    Memo1.Lines.Add(sftp.LastErrorText);
    Exit;
  end;

sftp.Disconnect();