Title: Playing with File Dates (Data Hiding)
Question: In my previous artice #1382 "How to get File Created,Modified and Accessed Dates" I demonstrated how to retieve these dates from a filename. This article extends this by allowing one to set ALL or just ONE of these file dates as well. The CREATED Datetime is interesting. This date is nice in that windows does not change this date as it does with MODIFIED and ACCESSED and it is not usually displayed in Explorers Grid (MODIFIED is Explorer's default)
Windows allows you to set the CREATED date to be GREATER than the MODIFIED or ACCESSED dates. You could use this date for a variety of uses such as to keep track of the HIGHEST system date to check whether the system clock has been set backwards.
If you are worried about this being greater than the MODIFIED date you could just use the HOURS:MINS:SECS of the datetime to store hidden data and leave the DD/MM/YYYY alone.
eg. To Set ALL DateTimes
SetFileTimes('c:\test.txt',Now,Now+3,Now+5);
eg. To Set Created Datetime only
SetFileTimes('c:\test.txt',Now,ftCreated);
eg. To Get All Datetimes
var dtC,dtM,dtA : TDateTime;
GetFileTimes('c:\test.txt',dtC,dtM,dtA);
eg. To Get Modified Dateime only
GetFileTimes('c:\test.txt',dtM,ftModified)
We are always looking for "Hidey Holes" to store data for copy protection and security schemes, this is another bullet for your ammo belt!
Answer:
unit PlayDates;
interface
uses Windows, SysUtils, DateUtils;
type
// Get-Set File Times
TFileTimes = (ftCreated,ftModified,ftAccessed);
function GetFileTimes(const AFileName : string;
out ACreated : TDateTime;
out AModified : TDateTime;
out AAccessed : TDateTime) : boolean; overload;
function GetFileTimes(const AFileName : string;
out AFileTime : TDateTime;
AGetFileTime : TFileTimes) : boolean; overload;
function SetFileTimes(const AFileName : string;
ACreated : TDateTime;
AModified : TDateTime;
AAccessed : TDateTime) : boolean; overload;
function SetFileTimes(const AFileName : string;
AFileTime : TDateTime;
ASetFileTime : TFileTimes) : boolean; overload;
// -----------------------------------------------------------------------
implementation
// ================================================================
// Return the three dates (Created,Modified,Accessed)
// of a given filename. Returns FALSE if file cannot
// be found or permissions denied. Results are returned
// in TdateTime VAR parameters
// Overloaded version is for get of single filetime only
// (Created OR Modified OR Accessed)
//
// To get extended error information, call GetLastError.
// ================================================================
// Get Filetime for ALL
function GetFileTimes(const AFileName : string;
out ACreated : TDateTime;
out AModified : TDateTime;
out AAccessed : TDateTime) : boolean;
var FileHandle : integer;
bResult : boolean;
FTimeC,FTimeA,FTimeM : TFileTime;
LTime : TFileTime;
STime : TSystemTime;
begin
FileHandle := FileOpen(AFileName,fmShareDenyNone);
ACreated := 0.0;
AModified := 0.0;
AAccessed := 0.0;
if FileHandle bResult := false
else begin
bResult := GetFileTime(FileHandle,@FTimeC,@FTimeA,@FTimeM);
FileClose(FileHandle);
if bResult then begin
// Created
FileTimeToLocalFileTime(FTimeC,LTime);
if FileTimeToSystemTime(LTime,STime) then
ACreated := EncodeDateTime(STime.wYear,STime.wMonth,STime.wDay,
STime.wHour,STime.wMinute,STime.wSecond,
STime.wMilliSeconds);
// Modified
FileTimeToLocalFileTime(FTimeM,LTime);
if FileTimeToSystemTime(LTime,STime) then
AModified := EncodeDateTime(STime.wYear,STime.wMonth,STime.wDay,
STime.wHour,STime.wMinute,STime.wSecond,
STime.wMilliSeconds);
// Accessed
FileTimeToLocalFileTime(FTimeA,LTime);
if FileTimeToSystemTime(LTime,STime) then
AAccessed := EncodeDateTime(STime.wYear,STime.wMonth,STime.wDay,
STime.wHour,STime.wMinute,STime.wSecond,
STime.wMilliSeconds);
end;
end;
Result := bResult;
end;
// Get Filetime for Created OR Modified OR Accessed
function GetFileTimes(const AFileName : string;
out AFileTime : TDateTime;
AGetFileTime : TFileTimes) : boolean; overload;
var dtCreated,
dtModified,dtAccessed : TDateTime;
bResult : boolean;
begin
if GetFileTimes(AFileName,dtCreated,dtModified,dtAccessed) then begin
case AGetFileTime of
ftCreated : AFileTime := dtCreated;
ftModified : AFileTime := dtModified;
ftAccessed : AFileTime := dtAccessed;
end;
bResult := true;
end
else begin
AFileTime := 0.0;
bResult := false;
end;
Result := bResult;
end;
// =====================================================
// Set FileTimes for (Created,Modified,Accessed)
// Overloaded for single Filetime
// (Created OR Modified OR Accessed)\
// Returns false if function fails.
// To get extended error information, call GetLastError.
// or just one status
// =====================================================
// Set file times for ALL
function SetFileTimes(const AFileName : string;
ACreated : TDateTime;
AModified : TDateTime;
AAccessed : TDateTime) : boolean;
var FileHandle : integer;
bResult : boolean;
FTimeC,FTimeA,FTimeM,
LTime : TFileTime;
STime : TSystemTime;
begin
FileHandle := FileOpen(AFileName,fmShareDenyWrite or fmOpenWrite);
if FileHandle bResult := false
else begin
// Created
DecodeDateTime(ACreated,STime.wYear,STime.wMonth,STime.wDay,
STime.wHour,STime.wMinute,STime.wSecond,
STime.wMilliSeconds);
SystemTimeToFileTime(STime,LTime);
LocalFileTimeToFileTime(LTime,FTimeC);
// Modified
DecodeDateTime(AModified,STime.wYear,STime.wMonth,STime.wDay,
STime.wHour,STime.wMinute,STime.wSecond,
STime.wMilliSeconds);
SystemTimeToFileTime(STime,LTime);
LocalFileTimeToFileTime(LTime,FTimeM);
// Accessed
DecodeDateTime(AAccessed,STime.wYear,STime.wMonth,STime.wDay,
STime.wHour,STime.wMinute,STime.wSecond,
STime.wMilliSeconds);
SystemTimeToFileTime(STime,LTime);
LocalFileTimeToFileTime(LTime,FTimeA);
bResult := SetFileTime(FileHandle,@FTimeC,@FTimeA,@FTimeM);
FileClose(FileHandle);
end;
Result := bResult;
end;
// Set Filetime for Created OR Modified OR Accessed
function SetFileTimes(const AFileName : string;
AFileTime : TDateTime;
ASetFileTime : TFileTimes) : boolean;
var FileHandle : integer;
bResult : boolean;
FTime,LTime : TFileTime;
STime : TSystemTime;
pCreated,pModified,pAccessed : PFileTime;
begin
pCreated := nil;
pModified := nil;
pAccessed := nil;
FileHandle := FileOpen(AFileName,fmShareDenyWrite or fmOpenWrite);
if FileHandle bResult := false
else begin
DecodeDateTime(AFileTime,STime.wYear,STime.wMonth,STime.wDay,
STime.wHour,STime.wMinute,STime.wSecond,
STime.wMilliSeconds);
SystemTimeToFileTime(STime,LTime);
LocalFileTimeToFileTime(LTime,FTime);
case ASetFileTime of
ftCreated : pCreated := @FTime;
ftModified : pModified := @FTime;
ftAccessed : pAccessed := @FTime;
end;
bResult := SetFileTime(FileHandle,pCreated,pModified,pAccessed);
FileClose(FileHandle);
end;
Result := bResult;
end;
end.