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Delphi Programming with WinInet

FtpCommand Example

Using FtpCommand to list folder contents

The following code fragment shows how to use FtpCommand to list the contents of a folder. (To list the contents of a folder use FtpFindFirstFile and InternetFindNextFile - this code fragment is for illustration purposes only.)

function FtpCommandDirList(hFtpSession: HINTERNET): String;
var
  data_handle: HINTERNET;
  bytes_read: DWORD;
  text_buffer: PChar;
  buffer_size: DWORD;
begin
  result := '';
  data_handle := nil;
  if not FtpCommand(m_hFtpSession,true,FTP_TRANSFER_TYPE_ASCII,
    PChar('NLST'),0,@data_handle) then
  begin
    SetErrorCode(GetLastError());
    Application.MessageBox(PChar(SysErrorMessage(GetLastError())),'');
    exit;
  end;
  // Read the data.
  buffer_size := 1000;    // Arbitrary value.
  GetMem(text_buffer,buffer_size);
  bytes_read := 1;
  while bytes_read > 0 do
  begin
    InternetReadFile(data_handle,text_buffer,buffer_size, bytes_read);
    result := result + System.Copy(text_buffer,0,bytes_read);
  end;
  InternetCloseHandle(data_handle);
  FreeMem(text_buffer,buffer_size);
end;

Note:

• If (in this example) FtpCommand fails then the most likely cause is that the directory is empty.
• If you get an error from Delphi complaining that the number of arguments to FtpCommand is wrong then the definition for FtpCommand in WinInet is probably missing the last argument. The correct definition is provided at the bottom of my write-up on the FtpCommand.

These notes are believed to be correct for Delphi 6 and may apply to other versions as well.