// C:\\a.txt に、aaa という名前でファイルストリームを作成し、読み込むサンプル
// NTFS フォーマットのドライブでのみ実行可能

#include <windows.h>
#include <tchar.h>

#include <io.h>
#include <fcntl.h>
#include <sys/stat.h>

// エントリポイント
int WINAPI _tWinMain ( HINSTANCE hThisInstance,
    HINSTANCE,
    _TCHAR *,
    int )
{
    const _TCHAR cszPath[] = _TEXT ( "C:\\a.txt" );

// C:\\a.txt がない場合は、作成
    WIN32_FIND_DATA win32FindData;
    memset ( &win32FindData, 0, sizeof ( WIN32_FIND_DATA ) );
    HANDLE hFindFile;
    hFindFile = FindFirstFile ( cszPath, &win32FindData );
    if ( INVALID_HANDLE_VALUE == hFindFile )
    {
        // "C:\\a.txt" の中身は、"ABC"
        int nHandle;
        nHandle = _topen ( cszPath, _O_BINARY | _O_CREAT | _O_WRONLY, _S_IWRITE );
        if ( -1 == nHandle )
        {
            MessageBox ( NULL,
                _TEXT ( "open failed - C:\\a.txt" ),
                _TEXT ( "Error" ),
                MB_OK | MB_ICONSTOP );
            return 0;
        }
        const _TCHAR cszABC[] = _TEXT ( "ABC" );
        if ( -1 == _write ( nHandle, cszABC, lstrlen ( cszABC ) * sizeof ( _TCHAR ) ) )
        {
            _close ( nHandle );
            MessageBox ( NULL,
                _TEXT ( "write failed - C:\\a.txt" ),
                _TEXT ( "Error" ),
                MB_OK | MB_ICONSTOP );
            return 0;
        }
        _close ( nHandle );
    }
    else
    {
        // 検索終了
        FindClose ( hFindFile );
    }

// "C:\\a.txt"に ファイルストリーム "aaa" を作成 ( 中身は、"DEFG" )
    const _TCHAR cszPath2[] = _TEXT ( "C:\\a.txt:aaa" );
    int nHandle;
    nHandle = _topen ( cszPath2, _O_BINARY | _O_CREAT | _O_WRONLY, _S_IWRITE );
    if ( -1 == nHandle )
    {
        MessageBox ( NULL,
            _TEXT ( "open failed - C:\\a.txt:aaa" ),
            _TEXT ( "Error" ),
            MB_OK | MB_ICONSTOP );
        return 0;
    }
    const _TCHAR cszDEF[] = _TEXT ( "DEFG" );
    if ( -1 == _write ( nHandle, cszDEF, lstrlen ( cszDEF ) * sizeof ( _TCHAR ) ) )
    {
        _close ( nHandle );
        MessageBox ( NULL,
            _TEXT ( "write failed - C:\\a.txt:aaa" ),
            _TEXT ( "Error" ),
            MB_OK | MB_ICONSTOP );
        return 0;
    }
    _close ( nHandle );

// 書き込んだ内容を閲覧
    nHandle = _topen ( cszPath2, _O_BINARY | _O_RDONLY );
    int nFileLength = _filelength ( nHandle );
    _TCHAR *pszData = new _TCHAR[ nFileLength + 1 ];
    memset ( pszData, 0, ( nFileLength + 1 ) * sizeof ( _TCHAR ) );
    if ( -1 == _read ( nHandle, pszData, nFileLength ) )
    {
        delete[] pszData;
        _close ( nHandle );
        MessageBox ( NULL,
            _TEXT ( "read failed - C:\\a.txt:aaa" ),
            _TEXT ( "Error" ),
            MB_OK | MB_ICONSTOP );
        return 0;
    }

    _close ( nHandle );

    MessageBox ( NULL,
        pszData,
        _TEXT ( "C:\\a.txt:aaa の内容は" ),
        MB_OK );

    delete[] pszData;

    return 0;
}