I have a mexfile that i succed to have it dll file to use it in a c++ program. The problem that i dont have any information about the name and parameter of functions in the dll file. I try to use dependance walker program to get information about dll file. the program give this:
Function Name Address Relative Address Ordinal
mexFunction 0x10004fc0 0x00004fc0 1 (0x1)
The problem is that i'm sure that the dll file has many function not only one, i dont know how to do to call this functions and have their parameter.
Any help please.
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I know this is a frequently asked question, but most solutions I have found are from 6-10 years ago and don't seem to work.
As a part of the C program I am writing in Visual Studio, I need to find a function that is able to return a boolean value - whether or not a file with a given name exists (the file in question is located in the debug directory, which is why I am saying file name and not file path).
I need to implement it using a library I am able to include in VS, hence using access() from the unistd.h library will not work.
Also, it has to be a safe function.
If there's a function in the WINAPI that does all of that - that would be best.
Thanks in advance for the help.
PathFileExistsW should do the job. It takes the path of the file or directory, which you want to check the existence of, as the first argument. It returns BOOL (TRUE, if the file or directory exists, and FALSE, if it doesn't. You have to include shlwapi.h as header and link against Shlwapi.lib in order to use this function.
This question already has answers here:
"Undefined function 'function_name' for input arguments of type 'double'."
(3 answers)
Closed 5 years ago.
I'm a new user of Matlab, can you please help:
I have the following code in an .M file:
function f = divrat(w, C)
S=sqrt(diag(diag(C)));
s=diag(S);
f=sqrt(w'*C*w)/(w'*s);
I have stored this file (divrat.M) in the normal Matlab path, and therefore I'm assuming that Matlab will read the function when it's starting and that this function therefore should be available to use.
However, when I type
>> divrat(w, C)
I get the following error
??? Undefined function or method 'divrat' for input arguments of type 'double'.
What is the error message telling me to do, I can't see any error in the code or the function call?
You get this error when the function isn't on the MATLAB path or in pwd.
First, make sure that you are able to find the function using:
>> which divrat
c:\work\divrat\divrat.m
If it returns:
>> which divrat
'divrat' not found.
It is not on the MATLAB path or in PWD.
Second, make sure that the directory that contains divrat is on the MATLAB path using the PATH command. It may be that a directory that you thought was on the path isn't actually on the path.
Finally, make sure you aren't using a "private" directory. If divrat is in a directory named private, it will be accessible by functions in the parent directory, but not from the MATLAB command line:
>> foo
ans =
1
>> divrat(1,1)
??? Undefined function or method 'divrat' for input arguments of type 'double'.
>> which -all divrat
c:\work\divrat\private\divrat.m % Private to divrat
As others have pointed out, this is very probably a problem with the path of the function file not being in Matlab's 'path'.
One easy way to verify this is to open your function in the Editor and press the F5 key. This would make the Editor try to run the file, and in case the file is not in path, it will prompt you with a message box. Choose Add to Path in that, and you must be fine to go.
One side note: at the end of the above process, Matlab command window will give an error saying arguments missing: obviously, we didn't provide any arguments when we tried to run from the editor. But from now on you can use the function from the command line giving the correct arguments.
The most common cause of this problem is that Matlab cannot find the file on it's search path. Basically, Matlab looks for files in:
The current directory (pwd);
Directly in a directory on the path (to see the path, type path at the command line)
In a directory named #(whatever the class of the first argument is) that is in any directory above.
As someone else suggested, you can use the command which, but that is often unhelpful in this case - it tells you Matlab can't find the file, which you knew already.
So the first thing to do is make sure the file is locatable on the path.
Next thing to do is make sure that the file that matlab is finding (use which) requires the same type as the first argument you are actually passing. I.el, If w is supposed to be different class, and there is a divrat function there, but w is actually empty, [], so matlab is looking for Double/divrat, when there is only a #(yourclass)/divrat. This is just speculation on my part, but this often bites me.
The function itself is valid matlab-code. The problem must be something else.
Try calling the function from within the directory it is located or add that directory to your searchpath using addpath('pathname').
The error code indicates the function definition cannot be found. Make sure you're calling the function from the same workspace as the divrat.m file is stored. And make sure divrat function is not a subfunction, it should be first function declaration in the file. You can also try to call the function from the same divrat.m file in order to see if the problem is with workspace selection or the function.
By the way, why didn't you simply say
s = sqrt(diag(C));
Wouldn't it be the same?
Also, name it divrat.m, not divrat.M. This shouldn't matter on most OSes, but who knows...
You can also test whether matlab can find a function by using the which command, i.e.
which divrat
I am pretty sure that the reason why this problem happened is because of the license of the toolbox (package) in which this function belongs in. Write which divrat and see what will be the result. If it returns path of the function and the comment Has no license available, then the problem is related to the license. That means, license of the package is not set correctly. Mostly it happens if the package (toolbox) of this function is added later, i.e., after installation of the original matlab. Please check and solve the license issue, then it will work fine.
How to write function at particular memory location in flash memory? Is there any directive for that? Do i need particular linker?
If you are using keil ide you can place a function at a specific address using .ARM.__at_address as the section name. To place the function add at 0x20000, specify:
int add(int n1,int n2) __attribute__((section(".ARM.__at_0x20000")));
int add(int n1,int n2)
{
return n1+n2;
}
Do you use the keil toolchain?
If yes, perhaps http://www.keil.com/support/docs/359.htm helps.
Edit:
The .obj file is generated by the compiler. I am not sure what you mean with 'how can i configure .obj file'.
The linker mentioned above takes the obj files, links them together and places code and variables.
You should start with a project which compiles and links without errors.
Then you have:
- Some c files. One of them with your function.
- A linkfile with the settings for the linker.
- A makefile or some kind of batchfile which calls compiler and linker with the necessary arguments.
If you have that, you can look into the m51 file for the name of the symbol for your function.
The m51 file is a textfile generated by the lx51 linker with interesting information about which symbols are there and what the linker has done with them.
The keil documentation for the linker I mentioned says: The compiler creates a symbol name for the function using the following format: ?PR?function_name?file_name.
This means: You will find the names of all functions of your project in the m51 file. If your function is in file file_x and named func_x. The symbol name will be PR?func_x?file_x
In http://www.keil.com/support/man/docs/lx51/lx51_segments.htm you can find some information about the usage of the SEGMENTS directive of the lx51 linker. According to that:
SEGMENTS (PR?func_x?file_x(C:0x1234))
should place your function to address 0x1234 in code memory.
Actually I have no keil toolchain. Therefore I cannot test all that myself.
But I am sure that you can manage that yourself if you start with a simple working example, change things step by step and check what happens.
Good Luck.
Helmut
Use ORG directive.
For example, for a function to start at location 2000H
ORG 2000H
MY_FUNC:
: YOUR CODE HERE
RET
I have a DLL file that I purchased (Without the Source Code) and I'm linking it to my application, simply by using "LoadLibrary("file.dll")", then it imports a function that gets an unique ID of the computer. Now let's say that our hacker detected the name of this function and now he's creating a new dll file, with the same name and the same function's name in it.
His new DLL file will be replaced (simply by grabbing his dll to the directory and replacing with mine) and the function of the unique ID is available but returns nothing. So now my application gets a blank unique ID and the hacker got out of my hands.
Any ideas how to prevent it? my project is programmed on C++.
Thanks in advance.
You could ask the company from which you get the DLL to provide a LIB of this DLL. Then you could statically link to this LIB. When doing this, the code of the library would be part of your code and thus transparent to hooking!.
Another possibility (in the case of an external DLL is really necessary): you could try to convince your DLL provider to export the function NOT by NAME but by Ordinal. This leads to security by obscurity. This would not prevent hooking or replacement, but at least this would not make the exported function evident to understand. Like 73 (exported function by number) instead of CreateMyFile (exported function by name).
I need to include a .h file to my project which will be supplied at the runtime. Since .h files are linked at linking time i am unable to include .h file. So i decided to write a dummy program which would create .h file and then i would call my actual program. Is there anyway to do this. Or any other solution is possible. I basically need to create a .h file before my program starts execution and need to link it up to my program.
i actually should take a file which is created by user, parse the file and then create a structure with the fields present in that file.for example if the file contains the following data:-
fno:int:4,fname:char:30,ftype:int:4
then i should create a structure like
struct somename
{
int fno;
char fname[30];
int ftype
};
Then i should be able to create instances of the structure created. This is what i like to do
dlopen is a solution. It allows to load dynamic library at runtime.
Compile your dummy program as a dynamic library.
Make use of dlopen on your .so
Call any function you need as if it has been linked by gcc (see dlsym).
What you can do is:
create .h file
fork
if in child: execve
if in father: wait (or not, depends on what you want to do)
I would use a Makefile; your program would receive the header file at runtime, (perhaps check it?) then execve() the make command passing the name of the file.
However, this sounds very cumbersome; perhaps you are trying to achieve something with the wrong tool. Maybe you want to use some scripting first? Or write two separate programs..? What are you trying to do?