Delphi 底層檔案操作實作：CopyFile、MoveFile、DeleteFile、RenameFile 核心代碼

CopyFile 完整實作（fmxutils 單元）

使用無型別檔案、檔案控制代碼、8KB 緩衝區、巢狀 try...finally 保護資源：

procedure CopyFile(const FileName, DestName: TFileName);
var CopyBuffer: Pointer; TimeStamp, BytesCopied: Longint; Source, Dest: Integer; Destination: TFileName;
const ChunkSize = 8192;
begin
  Destination := ExpandFileName(DestName);
  if HasAttr(Destination, faDirectory) then
    Destination := Destination + '\' + ExtractFileName(FileName);
  TimeStamp := FileAge(FileName);
  GetMem(CopyBuffer, ChunkSize);
  try
    Source := FileOpen(FileName, fmShareDenyWrite);
    if Source < 0 then raise EFOpenError.CreateFmt(SFOpenError, [FileName]);
    try
      Dest := FileCreate(Destination);
      if Dest < 0 then raise EFCreateError.CreateFmt(SFCreateError, [Destination]);
      try
        repeat
          BytesCopied := FileRead(Source, CopyBuffer^, ChunkSize);
          if BytesCopied > 0 then FileWrite(Dest, CopyBuffer^, BytesCopied);
        until BytesCopied < ChunkSize;
      finally
        FileSetDate(Dest, TimeStamp); FileClose(Dest);
      end;
    finally FileClose(Source); end;
  finally FreeMem(CopyBuffer, ChunkSize); end;
end;

FileSetDate 保留原檔時間戳，否則 Windows 寫入當前時間。

MoveFile 邏輯

優先嘗試 RenameFile（同磁碟機瞬間完成），失敗則「複製+刪除」：

procedure MoveFile(const FileName, DestName: TFileName);
var Destination: TFileName;
begin
  Destination := ExpandFileName(DestName);
  if not RenameFile(FileName, Destination) then
  begin
    if HasAttr(FileName, faReadOnly) then raise EFCantMove.CreateFmt(SFCantMove, [FileName]);
    CopyFile(FileName, Destination);
    DeleteFile(FileName);
  end;
end;

EFCantMove 為自訂例外類別（class(EStreamError)）。

DeleteFile / RenameFile

直接呼叫 RTL 常式，執行前確認對話框，畢 FileList.Update 刷新顯示。