header files - C typedef for function prototype dlsym -

header files - C typedef for function prototype dlsym -

i writing shared library ld_preload , intercept calls existing library (in linux).

i have 50+ different function prototypes , attribute declaration write , want maintain code short possible because function prototypes large.

the issue having following: lets want intercept calls dostuff(int, void*)

i have next code:

header file:

typedef int (*dostuffprototype) (int, void*); extern dostuffprototype dlsym_dostuff; extern int dostuff(int, void*);

c file

dostuffprototype dlsym_dostuff; __attribute__((constructor)) void libsomething() { void* lib_ptr; dlerror(); lib_ptr = dlopen(lib_name, rtld_lazy); ... // loading references real library dlsym_dostuff = (dostuffprototype) dlsym(lib_ptr, "dostuff"); }

ok works fine i'd replace next line in header:

extern int dostuff(int, void*);

with like:

extern dostuffprototype dostuff;

but

'dostuff' redeclared different kind of symbol

since declared in real library...but...it has no problem current syntax...the 1 have write arguments on again... if take dereferencing off typedef:

typedef int (dostuffprototype) (int, void*);

then extern dostuffprototype dostuff; works dlsym_dostuff = (dostuffprototype) dlsym(lib_ptr, "dostuff"); not compile...

i have tried many things: possible?

it's clear

typedef int (*dostuffprototype) (int, void*);

and

typedef int (dostuffprototype) (int, void*);

create different typedefs.

my suggestion create 2 different typedefs , utilize each 1 appropriately.

typedef int (dostuffprototype) (int, void*); typedef dostuffprototype* dostuffprototypeptr

and utilize them like:

extern dostuffprototypeptr dlsym_dostuff; extern dostuffprototype dostuff; ... dlsym_dostuff = (dostuffprototypeptr) dlsym(lib_ptr, "dostuff");

c header-files dlsym