Author: Christian Cristofori

I was using temporary files on the root of the disk, but the user could try to 
modify it when my application was open and I didn't want that. Here's how to 
prevent it.

Answer:

Solve 1:

There are two ways of doing that, but one, with the use of Windows' APIs 
(LockFileEx and UnlockFileEx) using the parameter LOCKFILE_EXCLUSIVE_LOCK was not 
good for my case, so I found that: 

Create the file with the OpenFile function and handle it: 
1   
2   hMyLockedFile := OpenFile('c:\variables.dat', ofStruct, OF_CREATE or OF_READWRITE or
3     OF_SHARE_EXCLUSIVE);


Now, you can work with your file, but users cannot change it! 

A last comment: 
I found that in Win32 SDK Reference, so if you need to know more (and there's more 
to know: believe me!) you should use it!


Solve 2:

4   var
5     SA: TSecurityAttributes;
6     MyText: array[0..500] of char;
7     BWritten: DWord;
8     OK: Boolean;
9   begin
10    MyText := 'Mark Halter' + chr(13) + Chr(10) + 'Südstr. 6';
11  
12    with SA do
13    begin
14      nLength := SizeOf(SA);
15      bInheritHandle := True;
16      lpSecurityDescriptor := nil;
17    end;
18  
19    Hndl := CreateFile('d:\temp\testfile.txt', // filename
20      GENERIC_READ or GENERIC_WRITE, // read/write access
21      0, // do not share file
22      @SA, // Security Attributes
23      CREATE_ALWAYS, // create file everytime
24      FILE_ATTRIBUTE_NORMAL, // set normal attributs
25      0);
26  
27    OK := WriteFile(Hndl,
28      MyText,
29      StrLen(MyText),
30      BWritten,
31      nil);
32  
33    CloseHandle(Hndl);
34  end;