C / C++ / MFC Discussion Boards

Arm5523-Dec-13 7:01

23-Dec-13 7:01

Hello. Thanks for the answer. No, the SampleSub() function is inside a VB6 program, an executable. Then I build a C DLL with the code above and inject it on the VB6 process. Sorry if I don't explain that very well.

Thanks again. Smile | :)

Re: Can't call a VB6 function from C

Richard Andrew x6423-Dec-13 9:13

Richard Andrew x64

23-Dec-13 9:13

How are you determining the address of the VB6 function?

The difficult we do right away...
...the impossible takes slightly longer.

Re: Can't call a VB6 function from C

Arm5523-Dec-13 10:08

Arm55

23-Dec-13 10:08

Hi, thanks for your answer. I'm using:

AddressOf SampleSub

Also OllyDbg gives me that address.

Re: Can't call a VB6 function from C

Richard Andrew x6423-Dec-13 16:43

Richard Andrew x64

23-Dec-13 16:43

I would experiment with calling other VB6 functions to see if they give the same result. Especially try calling a function that takes no parameters to see if the problem might be the parameter passing.

Have you ever had success calling a VB6 function from C?

The difficult we do right away...
...the impossible takes slightly longer.

Re: Can't call a VB6 function from C

Arm5524-Dec-13 4:41

Arm55

24-Dec-13 4:41

Hi, thanks for your answer. I tried calling a function without parameters and without return value and it doesn't work. This is the VB function now:

Public Sub SampleSub()
    MsgBox "Hello world!"
End Sub

And the new C prototype:

C++

typedef void (__stdcall *SampleSubPtr)(void);

But the same Access violation error (that says OllyDbg).

In the past I was able to call a VB6 function from C, that's why I'm so angry! Frown | :(

But I just can't remeber how I did it. I'm sure I did it like I'm doing now, but I don't know why it doesn't work Hmmm | :|

. Now SampleSub() is at 0x00401BC0.

Do you think that the way of compiling, the language (if C or C++) or something like that is causing errors? Because I'm 90% sure that the code is the same that the one I used in the past to call a VB6 function, so I need to think that I'm compiling wrong or something like that. I'm compiling like this (or that's what CodeBlocks does for me Poke tongue | ;-P

mingw32-g++.exe  -Wall -DBUILD_DLL -O2     -c "C:\Path\main.cpp" -o obj\Release\main.o

And using extern "C" in the main function.

Thanks again Smile | :)

modified 24-Dec-13 10:49am.

Re: Can't call a VB6 function from C

Richard Andrew x6424-Dec-13 6:51

Richard Andrew x64

24-Dec-13 6:51

I'm afraid I don't know what it could be. However, I had always believed that it was not possible to arbitrarily call into a VB6 executable.

I was under the impression that the old VB worked on a, sort of, virtual execution scheme, and the VB program was under the control of a supervisor thread.

I wish I could be more helpful!

The difficult we do right away...
...the impossible takes slightly longer.

Re: Can't call a VB6 function from C

Arm5524-Dec-13 7:11

Arm55

24-Dec-13 7:11

Ok thank you very much, I'll keep trying and tell you if I could make the trick. If anybody have any idea please tell me!!

Thanks again! Smile | :)

Re: Can't call a VB6 function from C

Randor 24-Dec-13 18:12

Randor

24-Dec-13 18:12

Hmmm,

Btw, your original code has several bugs. The Visual Basic 6 Boolean is actually a VARIANT_BOOL[^] from the C++ programmers point of view. This is a difference of sizeof(short) versus sizeof(int). Also... most VB6 data types are actually VARIANTS ^

Best Wishes,
-David Delaune

[edit]
I remembered helping someone with this many years ago... searched a bit and found it:
VC++ & VB Inter Process Communication Plus Introduction To VB Subclassing[^]

Re: Can't call a VB6 function from C

Arm5525-Dec-13 9:25

Arm55

25-Dec-13 9:25

Hi Randor, thank you very much for your reply. I'm actually just using a VB6 "function" with no return value and that takes no parameters. This one:

Public Sub SampleSub()
    MsgBox "Hello world!"
End Sub

With the typedef void (__stdcall *SampleSubPtr)(void); prototype. What should I use instead of void? I think it will be better to start calling a simple function with no parameters, that's why I delete the old function that returns a VB boolean and takes two Integers as it params. Poke tongue | ;-P

I checked out the link your provided but that's for a Variant type in VB6, do you mean I should use VARIANT in C++ for any VB6 type?

I was thinking... I always get the Access violation when reading... error, do you think that a type incompatibility can cause this?

What would you do in my place? This problem is driving me crazy! Frown | :(

Thanks again! Smile | :)

From where start?

Le@rner20-Dec-13 21:15

Le@rner

20-Dec-13 21:15

hi all,

please guide me and provide me a right direction.

currently I m using office automation and random password generation for this but is to time taking and slow process.

please help me to start for ms office file password recovery type application?

thanks in advance.

Re: From where start?

Richard MacCutchan20-Dec-13 22:05

Richard MacCutchan

20-Dec-13 22:05

Le@rner wrote:
please guide me and provide me a right direction.

Learn how to do basic research[^].

Veni, vidi, abiit domum

Re: From where start?

Le@rner20-Dec-13 22:34

Le@rner

20-Dec-13 22:34

I already do this this search list all recovery application.

not about the how to implement of code for this..

Re: From where start?

Richard MacCutchan20-Dec-13 22:40

Richard MacCutchan

20-Dec-13 22:40

Then I guess you need to try contacting one of the authors of those packages.

Veni, vidi, abiit domum

Re: From where start?

Le@rner20-Dec-13 22:44

Le@rner

20-Dec-13 22:44

really why those authors disclose their logics..

it means codeproject not help me for this...

Re: From where start?

Richard MacCutchan20-Dec-13 23:12

Richard MacCutchan

20-Dec-13 23:12

Le@rner wrote:
it means codeproject not help me for this...

No, it means we don't have the answer.

Veni, vidi, abiit domum

Re: From where start?

Le@rner20-Dec-13 23:58

Le@rner

20-Dec-13 23:58

can u please suggest me any other option or way to move on.

Re: From where start?

Richard MacCutchan21-Dec-13 0:18

Richard MacCutchan

21-Dec-13 0:18

The only thing I can suggest is more Googling, and maybe some initiative. You also need to consider why passwords exist; if it was easy to crack them then there would be no reason to use them in the first place.

Veni, vidi, abiit domum

how to detect ms office files are password protected?

Le@rner19-Dec-13 20:26

Le@rner

19-Dec-13 20:26

hi all,

is there any option to know the office file is password protected or not?

thanks in advance.

Re: how to detect ms office files are password protected?

Richard Andrew x6420-Dec-13 9:38

Richard Andrew x64

20-Dec-13 9:38

Try opening it? Poke tongue | ;-P

The difficult we do right away...
...the impossible takes slightly longer.

Re: how to detect ms office files are password protected?

Le@rner20-Dec-13 17:23

Le@rner

20-Dec-13 17:23

I m using excel and word automation to open files is there any other method to chk file without opening the file is password protected or not.

coz other than excel and word files I m not able to open using automation....

and also if the file open function is inside the loop of random password generator and try with every new password to open the file the program becomes slower.

please help me,

Re: how to detect ms office files are password protected?

Richard MacCutchan20-Dec-13 22:03

Richard MacCutchan

20-Dec-13 22:03

Le@rner wrote:
if the file open function is inside the loop of random password generator and try with every new password to open the file the program becomes slower.

If you do not know the password then maybe you are not supposed to be opening the file.

Veni, vidi, abiit domum

Re: how to detect ms office files are password protected?

Le@rner20-Dec-13 22:45

Le@rner

20-Dec-13 22:45

yes file is not open and return exception of wrong password until the correct password is generated.

that's y I m taking help for another approach..

Re: how to detect ms office files are password protected?

David Crow23-Dec-13 5:47

David Crow

23-Dec-13 5:47

Le@rner wrote:
...return exception of wrong password until the correct password is generated.

That seems to be the answer to your "is there any option to know the office file is password protected or not" question.

"One man's wage rise is another man's price increase." - Harold Wilson

"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

"Show me a community that obeys the Ten Commandments and I'll show you a less crowded prison system." - Anonymous

Re: how to detect ms office files are password protected?

Le@rner23-Dec-13 21:19

Le@rner

23-Dec-13 21:19

not I m trying to open the file with different password if password is correct its open otherwise its generate the exception...

in my question "to identify the file is password protected or not" I m want to chk just before open the document.

Basic Question About Interfaces

Django_Untaken19-Dec-13 19:07

Django_Untaken

19-Dec-13 19:07

In object-oriented languages, the term "interface" is often used to define an abstract type that contains no data, but exposes behaviors defined as methods. A class having all the methods corresponding to that interface is said to implement that interface. Source: WIKIPEDIA

I do not understand that how certain interfaces of Media Foundation APIs are getting created and working. Take IMFSourceReader for example. I understand that it gets created using MFCreateSourceReaderFromXXXX functions. But just a function call and nothing else?

- It should not be working in the first place.
- What class creates and implements it in the system?

Thanks for any info.

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