assembly language

Show_Date_Time_of_File (Chapter 11, Pr 9)

Write a procedure named AccessFileDateTime that fills a SYSTEMTIME structure with date/time stamps of a file. Pass the offset of a filename in EDX, and pass the offset of two SYSTEMTIME structures in ESI and EDI.

; Receives: EDX offset of filename, ; ESI points to a SYSTEMTIME structure of sysTimeCreated ; EDI points to a SYSTEMTIME structure of sysTimeLastWritten ; Returns: If successful, CF=0 and two SYSTEMTIME structures contain the file's date/time data. ; If it fails, CF=1. AccessFileDateTime

When you implement this function, you will need to open the file to read, get its handle, pass the handle to GetFileTime, pass its results to FileTimeToSystemTime, and close the file. You can create whenCreated and lastWritten two local variables as intermediate arguments. Since we are only interested in two time stamps, you can simply supply NULL for the middle parameter of the Last Accessed structure:

INVOKE GetFileTime, fileHandle, ADDR whenCreated, NULL, ADDR lastWritten

Write a test program that calls AccessFileDateTime, make sure it return correctly:

... mov edx, OFFSET filename mov ecx, Len_filename-1 call ReadString mov esi, OFFSET sysTimeCreated mov edi, OFFSET sysTimeLastWritten call AccessFileDateTime ...

and then print out the date/time when a particular file was created and last written, such as sysTimeCreated.wMonth, sysTimeCreated.wDay, ..., until sysTimeCreated.wSecond. You may need a helper to call twice like

WriteDateTime PROC, DateTime:SYSTEMTIME

or

WriteDateTime2 PROC datetimeAddr: PTR SYSTEMTIME

Try ch11_09r.exe , to see the result like this:

Input your file name: ch11_09.lst ch11_09.lst was created on: 10/14/2010 9:40:31 And it was last written on: 10/28/2008 5:27:1

While comparing with the Windows file property here

You certainly notice the difference, which is the difference between UTC system time and local time . How to fix it by converting the UTC system to local time? This leaves a little more work to consider. A good reference in C/C++ can be seen at CreateFile(), GetFileTime(), FileTimeToSystemTime(), Syst... You can use SystemTimeToTzSpecificLocalTime , a Win API prototype:

BOOL WINAPI SystemTimeToTzSpecificLocalTime( __in_opt LPTIME_ZONE_INFORMATION lpTimeZone, __in LPSYSTEMTIME lpUniversalTime, __out LPSYSTEMTIME lpLocalTime );

Since the first parameter of a pointer to TIME_ZONE_INFORMATION will be NULL, you can simply make it as DWORD without caring about that structure type. But unfortunately, it's not defined in SmallWin.inc. In order to use it, you have to declare a PROTO in assembly language format accordingly and add it to your source code.