Re: Please please help with this simple Q from a C++ newbie - C / C++ / MFC Discussion Boards

Re: How To Execute Raw Binary From Within A Binary

Luc Pattyn19-Feb-09 11:39

19-Feb-09 11:39

Hi,

an EXE file does not contain just executable code, it is a complex thing describing all that is needed to load several segments of code and data, load other required DLL files, etc.

You can launch an EXE file to run in a separate process by calling the Win32 function ShellExecute[^].

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

- before you ask a question here, search CodeProject, then Google
- the quality and detail of your question reflects on the effectiveness of the help you are likely to get
- use the code block button (PRE tags) to preserve formatting when showing multi-line code snippets

Re: How To Execute Raw Binary From Within A Binary

Stuart Dootson19-Feb-09 12:00

Stuart Dootson

19-Feb-09 12:00

That's very likely not going to work. Executables rely on the OS loader to a) load the executables at a specific address (40000 hex), b) load DLLs and perform relocations on them, c) make data available at specific addresses. You could try to perform functionality equivalent to the OS loader, but I don't think it would work.

One approach that would involve a lot of work, but could well work, would be to implement a virtual process within the host process, a bit like how software like VMWare lets you run an OS on a virtual machine.

The first thing to do is get a very good understanding of the Windows OS loader and the PE executable format. This Wndows internals book[^] is an excellent place to start.

This article[^] is a good description of what's contained in a PE executable file, which shows you what the OS loader has to deal with when loading an executable.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: How To Execute Raw Binary From Within A Binary

Rick York19-Feb-09 12:51

Rick York

19-Feb-09 12:51

Several years ago I had the task of writing a machine code generator for a script engine. In other words, a JIT mechanism to accelerate the execution speed of our scripts. I didn't have the first clue of how to even start but I figured out a test for the proof of principle.

First, I decided to implement a simple little function. It doesn't really matter what this is but it needs to be simple. Here is one to compare two integers :

int CompareValues( int valueA, int valueB )
{
    int rc = 0;
    if( valueA < valueB )
        rc = -1;
    else if( valueA > valueB )
        rc = 1;
    return rc;
}

Then I defined a type that is a pointer to a function with that prototype signature :

typedef int (*CompareFunc)( int valueA, int valueB );

Next I wrote a test program to do something like the following :

int TestMethod()
{
    CompareFunc func = CompareValues;
    int valueA = 42;
    int valueB = 96;
    int returnValue = (*func)( valueA, valueB );
    return returnValue;
}

The next step is a little more involved. You have to go to the settings for your project and in the C++ section select Output Files and then enable the Assembly, Machine Code, and Source option. Now rebuild your test app and take a look at the machine code for the CompareValues function. Copy the machine code bytes and place them into an array of BYTEs :

static BYTE codeBytes[] = { ... };

Now you should be able to "invoke" this code with something like the following :

int TestMethod()
{
    CompareFunc func = (CompareFunc)codeBytes;
    int valueA = 42;
    int valueB = 96;
    int returnValue = (*func)( valueA, valueB );
    return returnValue;
}

and that's basically it. You will probably have to experiment a little to make things work right like possibly using assembly statements to push your variables onto the stack before invoking the function and things like that.

It has been a long time, ten years or so, since I did this but I used a technique just like this to get started. My JIT compiler would emit the code bytes into a buffer and then execute them using a mechanism nearly identical to this.

You should be able to get the basics of this down fairly quickly. If you can't then this could be a very difficult project for you to accomplish.

Re: How To Execute Raw Binary From Within A Binary

V3RO19-Feb-09 13:30

V3RO

19-Feb-09 13:30

THANKS!! THAT IS EXACTLY What Im looking to do, and the same sort of project actually. THANKS AGAIN

Please please help with this simple Q from a C++ newbie

meixiang619-Feb-09 10:11

meixiang6

19-Feb-09 10:11

Please please help with this simple Q from a C++ newbie....I spent hours trying to find the answer online...

I want to run this on a linux box. Open a file containing a list of file names and then run a linux commands on each of the list for example:
The file contains a list of files names eg:

test
test1
test2
test3

How do I code in C so that it opens the file and then foreach of the elements do a system command eg: ls

in perl it would be something like:

#!/usr/local/bin/perl

while(<>){
chomp;

$cmd="ls $_";
system($cmd);
print "$cmd\n";
}

Thanks in advance!

Re: Please please help with this simple Q from a C++ newbie

Stuart Dootson19-Feb-09 10:35

Stuart Dootson

19-Feb-09 10:35

Use fgets to read individual lines from a file.

Use strcat to append the file name to the command (just make sure the command is in a long enough string to start with).

C has a system function just like Perl as well.

It's easier in C++, using std::getline to read lines from a file and the std::string class to build the command:

#include <stdlib.h>
#include <iostream>
#include <fstream>
#include <string>

int main(int argc, char** argv)
{
  std::ifstream f(argv[1]);
  
  std::string s;
  while (std::getline(f, s))
  {
    system((std::string("ls -l ") + s).c_str());
  }
}

Easy enough (and works on OS X, which is close enough to Linux)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: Please please help with this simple Q from a C++ newbie

meixiang619-Feb-09 10:53

meixiang6

19-Feb-09 10:53

Thanks very much Stuart!

Any chance of typing the entire code in C as well?

thanks a lot again!

Re: Please please help with this simple Q from a C++ newbie

Stuart Dootson19-Feb-09 11:42

Stuart Dootson

19-Feb-09 11:42

meixiang6 wrote:
Any chance of typing the entire code in C as well?

I'll leave that as an exercise for the reader...you remember I said it was easier in C++ Smile | :)

It's not too much different - fgets is roughly equivalent to getline. Rather than adding string objects together, you use strcpy to copy the command into a character buffer, then strcat to add the line you've read from the file to the end of the buffer. Then you pass the buffer to the system command.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: Please please help with this simple Q from a C++ newbie

meixiang619-Feb-09 12:00

meixiang6

19-Feb-09 12:00

thanks Stuart for the information, I am a very new newbie and have no idea how that looks like in C, any chance of someone writing that in C ?

apologizes for the inconvenience

Re: Please please help with this simple Q from a C++ newbie

Stuart Dootson19-Feb-09 12:17

Stuart Dootson

19-Feb-09 12:17

You'll gain a lot more learning how to do it yourself.

This page[^] has code that reads a file line by line (search for 'fgets').

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

Re: Please please help with this simple Q from a C++ newbie [modified]

meixiang619-Feb-09 14:39

meixiang6

19-Feb-09 14:39

Thanks Stuart, I got it working with this, not sure if the code is right thou but it works...

#include <stdio.h>
#include <string.h>

int main()
{
FILE *f;
char string[1000];
char str[1000];
f = fopen("file.txt", "r");
if(!f) {
printf("Couldn't open file.txtn");
return 1;
}
while(fgets(str, 1000, f)) {
/* printf("%s", str); */
strcpy (string, "ls -la ");
strcat (string, str);
system (string);

}
fclose(f);
return 0;
}

<div class="ForumMod">modified on Thursday, February 19, 2009 8:56 PM</div>

Re: Please please help with this simple Q from a C++ newbie

David Crow19-Feb-09 17:08

David Crow

19-Feb-09 17:08

meixiang6 wrote:
char string[1000];

I know this is being nit-picky, but you might want to make this 7 bytes larger than str. If str contains 999 bytes, copying that plus "ls -la " is going to overflow string.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

Re: Please please help with this simple Q from a C++ newbie

Stuart Dootson19-Feb-09 21:43

Stuart Dootson

19-Feb-09 21:43

Aside from what David said, that code's fine Smile | :)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

urgent : I need help

D_Isaac19-Feb-09 9:38

D_Isaac

19-Feb-09 9:38

am a newbie to win32 console programming and i was given
to
Create the editor of resources files of application, which allows to form the following facility

-the icon
- the menu
- the text
- the dialogue windows

i was able to write a code to for the text but i cant for the icon , i really dont have idea.

Please help so we could share ideas together thanks

Re: urgent : I need help

CPallini19-Feb-09 11:01

CPallini

19-Feb-09 11:01

As newbie, they could give you as well the task to discover the origin of the Universe, I suppose.
My solidarity. Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: urgent : I need help

Luc Pattyn19-Feb-09 11:41

Luc Pattyn

19-Feb-09 11:41