Click here to Skip to main content
13,199,318 members (63,316 online)
Rate this:
Please Sign up or sign in to vote.
See more:

We have our application which is written in C++. At some places we check if any debugger is attached to the application by following code

char IsDbgPresent = 0;
__asm {
mov eax, fs:[30h]
mov al, [eax + 2h]
mov IsDbgPresent, al
 MessageBox(NULL, TEXT("Debugger Found!"), TEXT("Debugger Found!"), 0);
return true;

When i tried to use the same code for 64 bit version, I found that __asm is no longer supported for 64 bit . I am aware that i can use IsDebuggerPresent instead of above code.

Can anybody let me know if we can translate above code to C/C++.

Thanks in advance.
Posted 21-Feb-13 0:14am
Rate this: bad
Please Sign up or sign in to vote.

Solution 2

You're correct. Inline assembler is not supported by Microsoft's 64bit compilers and there is no direct equivalent in C or C++ for the inline assembler you show. Partly because there is no way to address the FS register even indirectly from C/C++ code. You can use MASM with a separate assembler source file and link the result.
There is one way to solve this which I am currently working on and that is to use a Just In Time (JIT) assembler to generate callable assembly language code at runtime. Such a JIT is available for free at the AsmJit[^] project and soon within the QOR[^] but it is a large ammount of code to inlclude within your project for the sake of 1 function.
I did not know that because I did not try it since I have 64-bit systems. It's a shame I think. My 5.
Rate this: bad
Please Sign up or sign in to vote.

Solution 3

Did you try Intrinsics[^]?

Something like this could work:
unsigned long tmp = __readfsdword(0x30);
IsDbgPresent = *((char *)(tmp + 0x2));

I'm not sure if the offsets would change for 64 bit code, I tried to search but couldn't find any info on that.
Matthew Faithfull 22-Feb-13 4:32am
Good call, Id'd forgetten all about __readfsdword
Rate this: bad
Please Sign up or sign in to vote.

Solution 1

The 32-bit registers are extended with 'r' registers, so 64-bit extensions of EAX, EBX, ECX, ESP are named RAX, RBX, RCX, RSP, etc. Please see:[^],[^].


This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

  Print Answers RSS
Top Experts
Last 24hrsThis month

Advertise | Privacy |
Web01 | 2.8.171020.1 | Last Updated 22 Feb 2013
Copyright © CodeProject, 1999-2017
All Rights Reserved. Terms of Service
Layout: fixed | fluid

CodeProject, 503-250 Ferrand Drive Toronto Ontario, M3C 3G8 Canada +1 416-849-8900 x 100