/* LSB wrapper helpers

The header file contains helpers for LSB wrappers generation.
*/

#ifndef __LSB_HELPERS_H
#define __LSB_HELPERS_H

#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>

/* Library dlopen helpers.  lib_id is an identifier to refer to this library
   and lib_soname is a string with sonema to dlopen.
*/
#define LSB_LIB_LOAD(lib_id, lib_soname) \
void * lib_id##_h; \
int lib_id##_h_tried = 0; \
char lib_id##_name[] = lib_soname; \
int lib_id##_available() \
{ \
    if (!lib_id##_h_tried){ \
        lib_id##_h = dlopen(lib_soname,RTLD_LAZY | RTLD_GLOBAL); \
        lib_id##_h_tried = 1; \
        return (int)(lib_id##_h); \
    }else{ \
        return (int)(lib_id##_h); \
    } \
} \
void* lib_id##_handle() \
{ \
    if (! lib_id##_available()){ \
        fprintf(stderr,"Required library %s is absent in your system.  LSB does not require it to present, but the program can't run without it.  Sorry.\n",lib_soname); \
        exit(-1); \
    } \
    return lib_id##_h; \
} \

// availablilty declaration for lsb_config.h
#define LSB_AVAIL_RUNTIME(something) extern int something##_available();

// f - name of funciton defined in some other place
// lib - id of library as supplied in LSB_LIB_LOAD
#define LSB_CHECKER(lib,f) \
__typeof__(f) * f##_a;  \
char const* f##_lib_name = lib##_name;  \
int f##_a_tried = 0;  \
int f##_available() \
{ \
    if (f##_a_tried){ \
        return (int)f##_a; \
    }else{ \
        if (!lib##_available()){ \
            return 0; \
        } \
        *(void **) (&f##_a)=dlsym(lib##_handle(), #f); \
        f##_a_tried = 1; \
        return (int)f##_a; \
    } \
}

/* Unfortunately, there is no way to predefine a macro for automatic wrapper 
   generation.  So you're just to copy it from the header file and use the
   LSB_WRAPPER_CALL macro, like that:

        int function(int arg1, void* arg2)
        {
            LSB_WRAPPER_CALL(library_id,function,arg1,arg2);
        }

*/
#define LSB_WRAPPER_CALL(f, ...) \
    if (!f##_available()) \
    { \
        fprintf(stderr,"Required interface %s is absent in your system's library %s.  LSB does not require it to present, but the program can't run without it.  Sorry.\n",#f,f##_lib_name); \
        exit(-1); \
    } \
    return (*f##_a)(__VA_ARGS__)

/* Special handle for symbols that are dlsym'ed from RTLD_DEFAULT.
   Such symbols should be assigned to DEFAULT library */
extern char DEFAULT_name[];
extern int DEFAULT_available();
extern void* DEFAULT_handle();

#endif //include sentry