Incompatible pointer types assigning to 'int (*)(int, int, int, int, int)' from 'int-CodePudding

I have this pointer to an orgFunction takes 5 int as input and returns int, and orgfunctionhook takes the same args and return:

int (*orgFunction)(int a1, int a2 , int a3 , int a4, int a5);

int orgFunctionHook(int a1, int a2 , int a3 , int a4, int a5)
{
  // do something..
  return orgFunction(a1,a2,a3,a4,a5);
}

void Load(){
    orgFunction = (int*)HookFunction((char*)"something", 0x50000, (void*)orgFunctionHook);
}

And the HookFunction takes 3 args, const char, an address for my original function, and some hook

for ease this is the definition for it:

void* HookFunction(char* path, uint64_t vaddr, void* replace);

it returns a void*, my function i want to use it return int, once i use it in the Load()

I get this error:

" Incompatible pointer types assigning to 'int (*)(int, int, int, int, int)' from 'int *' "

My attempt to solve it was to declare it like this:

void Load(){
    void * orgFunction = (int*)HookFunction((char*)"something", 0x50000, (void*)orgFunctionHook);
}

but this makes a problem in the run time it when it runs the orgFunctionHook, the pointer address to the function orgFunction will be assinged as 0x0 ( EMPTY )

Is there could be another solution to pass this without losing the pointer to the origin function?

EDIT: Forgot to mention, that I can't change anything related to the HookFunction, its return or paramters remain the same.

CodePudding user response：

You're casting to the wrong type. As mentioned in the error message, the function pointer has type int (*)(int,int,int,int,int) but you're attempting to assign an expression of type int * to it. These types are incompatible.

The proper way to do this would be to create a typedef for the function pointer type:

typedef int (*ftype)(int, int, int, int, int);

Then you declare your function pointer with this type:

ftype orgFunction;

And similarly with HookFunction:

ftype HookFunction(char* path, uint64_t vaddr, ftype replace);

Then your Load function would look like this:

void Load(){
    orgFunction = HookFunction((char*)"something", 0x50000, orgFunctionHook);
}

If you can't modify HookFunction, then just use the typedef in the call:

void Load(){
    orgFunction = (ftype)HookFunction((char*)"something", 0x50000, (void *)orgFunctionHook);
}