Adding data to an exe

Seems to me that you should be able to initialize a string variable with a distinctive string set, then be able to change the string with relative impunity in the .exe

Since you know the path to the executable (app.path) getting the exe file to read in is not a problem. I don't have any idea what will happen when you re-write the the string back out.....

Care must be taken however:

1. You must have the exact same number of characters after the change as before

2. You have to be able to find the string in the executable

3. You have to know lots of high-level curses for when you screw it up.

In the DOS days, people would change the command.com using a hex editor. They did this to get distinctive (usually obscene) error messages. Same principle.

Good Luck
DerFarm

I think I can do it, if I don't modify the legth, but I need to modify the length.:(

If you have to modify the length of the program, then you're SOL.

You'll have to use an outside file to communicate from one session to another.

In actuality, while the scheme of using the .exe to hold data changes is intriguing, it isn't worth the effort for the return.

Good Luck
DefFarm

as far as I know, its not possible to do what you're describing. if the length is constant, it is easy, but with flexible lengths its not possible. only thing I know of is to store it in an external file.

Here's how:

1. Copy the stub exe into a new file
2. Store current offset
3. Append your data
4. At the end of the file, write the offset

Then, when the stub loads, it reads the last few bytes from the file, seeks to that offset, and loads the data. Depending on how you load it, you may need to chop the offset bytes off.

Lets say you want to write the user registered to the program into the exe file.

Code:

---

Type reg_t
    Name as string * 15
    ID as string * 5
End Type
Dim reg as reg_t


Open App.Path & "\" App.ExeName for binary as #1
    Seek #1, LOF(1) - 21 'Go to end of file munus
                          our type struct + 1 for the seek
    Get #1, reg
    If reg.ID <> "REGID" Then
          'Not registered
          MsgBox "Program not registered!"

          'Now promped the user to type in there name
          'and just seek back to where you saved the type
          'at the end of the file and save it using Put
    Else
          'Registered
          Msgbox "Thank you " & reg.name
    End If
Close #1

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[Edited by nkad on 09-29-2000 at 02:58 PM]

So you can just append it at the end of the file?

Yes, although I would suggest (to help discourage fiddling), that some kind of processing be done on the data. (Also, surrounding it in an arbitrary length of random data is often helpful).

Thanks for the help.:)

Does this really work?!?!?!? COOOLLL!!!

Yeah, I've used it in some of my software.

I posted a reply to a similar question a couple of days ago. The other question was about storing company logog in the exe, but the principal is the same.

The program should never ever get to your data so there would be no problem.

Virus checkers or innoculators are likely to pick up on the change and complain however. Also, in a LAN distribution (or any multi-user situation), such a thing is not recommended at all.

Cheers

In that situation, then it's not a good idea. In fact, I think I would probably say - never change the executable. You just can't tell if someone else is running it from somewhere else. There are usually much better ways of storing the data. (Unless the data will be inserted into the EXE statically)

ok, that's what I thought. I had read up on it and got a similar idea, so it seemed kind of interesting to me to think that it might work.

its still a cool technique tho. anybody know if you can use VS98 to edit resources (pics/strings/etc) in a compiled program (non vb)?

Quote:

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Originally posted by mlewis
ok, that's what I thought. I had read up on it and got a similar idea, so it seemed kind of interesting to me to think that it might work.

its still a cool technique tho. anybody know if you can use VS98 to edit resources (pics/strings/etc) in a compiled program (non vb)?

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