LuaJIT FFI cdata introspection
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- Subject: LuaJIT FFI cdata introspection
- From: Michal Kottman <k0mpjut0r@...>
- Date: 2011年2月18日 21:41:13 +0100
I'm trying to add some kind of introspection to LuaJIT FFI, that will
allow to determine not only the type of a cdata object, but also list
it's fields. My goal is to recursively print/dump various complex data
structures in true Lua fashion (I'm trying it out on the ffmpeg
libraries using preprocessed headers). Currently I have this (warning,
bad code, it's my first attempt at modifying LuaJIT):
LJLIB_CF(ffi_fields)
{
CTState *cts = ctype_cts(L);
CTypeID id = ffi_checkctype(L, cts);
CType *ct = lj_ctype_rawref(cts, id);
if (ctype_isstruct(ct->info) && ct->size != CTSIZE_INVALID) {
int i=0;
lua_createtable(L,0,0);
while (ct->sib) {
ct = ctype_get(cts, ct->sib);
setstrV(L, L->top++, gcrefp(ct->name, GCstr));
lua_rawseti(L, -2, ++i);
}
return 1;
} else {
lj_err_argtype(L, 1, "struct type");
}
return 0;
}
When ffi.fields() is passed a struct type, or a name of such type, it
returns a table of strings, which are the names of fields in the
struct. However, it fails when I pass an instance/cdata object of such
type. When looking at ct->info, it is CT_PTR. How can I get to the
structure this pointer refers to? I've tried using ct =
ctype_child(cts, ct), but it fails later on setstrV() with assertion
error. I have a feeling I am abusing things I should not be touching
:).