Export host C functions to luajit FFI without export
- From: Domingo Alvarez Duarte <mingodad@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Tue, 20 Jan 2015 21:44:23 -0800
After some thought I found a solution that is clean and sugest it to be
added to luajit.
On the header "lj_clib.h"
typedef void *(*clib_getsym_func_ptr)(CLibrary *cl, const char *name);
LUA_API clib_getsym_func_ptr set_lj_clib_get_sym(clib_getsym_func_ptr
funcPtr);
On the "lj_clib.c" just after the following comment line:
/* -- C library indexing --------------------------------------------------
*/
static clib_getsym_func_ptr clib_getsym_funcPtr = clib_getsym;
clib_getsym_func_ptr set_lj_clib_get_sym(clib_getsym_func_ptr funcPtr)
{
clib_getsym_func_ptr oldPtr = clib_getsym_funcPtr;
clib_getsym_funcPtr = funcPtr;
return oldPtr;
}
/* Index a C library by name. */
TValue *lj_clib_index(lua_State *L, CLibrary *cl, GCstr *name)
{
...
//void *p = clib_getsym(cl, sym); //// change this line by the
following
void *p = (*clib_getsym_funcPtr)(cl, sym);
...
}
On the lua host file:
//if we have this definition on "luajit.h" we do not need to add it here
manually
typedef void *(*clib_getsym_func_ptr)(void *cl, const char *name);
extern clib_getsym_func_ptr set_lj_clib_get_sym(clib_getsym_func_ptr
funcPtr);
static clib_getsym_func_ptr old_clib_getsym_func_ptr;
void *my_clib_getsym_func(void *cl, const char *name)
{
void *funcPtr= NULL ;
printf("my_clib_getsym_func => %s\n", name);
if(strcmp(name, "myprintf") == 0)
{
funcPtr = printf;
}
else
{
funcPtr = (*old_clib_getsym_func_ptr)(cl, name);
}
return funcPtr;
}
Before using luajit:
old_clib_getsym_func_ptr = set_lj_clib_get_sym(my_clib_getsym_func);
That's it a clean way to expose host functions to luajit without make then
external linkable.
Again I hope this will be useful to other people also and propose to add to
luajit !
Cheers !
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