FFI: Handle __pairs/__ipairs metamethods for cdata objects.

4 files changed, 37 insertions, 6 deletions

diff --git a/src/lib_base.c b/src/lib_base.c
index 9702c5b4..824fc0e7 100644
--- a/src/lib_base.c
+++ b/src/lib_base.c
@@ -278,12 +278,16 @@ LJLIB_ASM(next)
   return FFH_UNREACHABLE;
 }
 
-#ifdef LUAJIT_ENABLE_LUA52COMPAT
+#if defined(LUAJIT_ENABLE_LUA52COMPAT) || LJ_HASFFI
 static int ffh_pairs(lua_State *L, MMS mm)
 {
   TValue *o = lj_lib_checkany(L, 1);
   cTValue *mo = lj_meta_lookup(L, o, mm);
-  if (!tvisnil(mo)) {
+  if (
+#if !defined(LUAJIT_ENABLE_LUA52COMPAT)
+      tviscdata(o) &&
+#endif
+      !tvisnil(mo)) {
     L->top = o+1;  /* Only keep one argument. */
     copyTV(L, L->base-1, mo);  /* Replace callable. */
     return FFH_TAILCALL;
diff --git a/src/lib_ffi.c b/src/lib_ffi.c
index 24a6625c..69bebefc 100644
--- a/src/lib_ffi.c
+++ b/src/lib_ffi.c
@@ -323,6 +323,30 @@ checkgc:
   return 1;
 }
 
+static int ffi_pairs(lua_State *L, MMS mm)
+{
+  CTState *cts = ctype_cts(L);
+  CTypeID id = ffi_checkcdata(L, 1)->ctypeid;
+  CType *ct = ctype_raw(cts, id);
+  cTValue *tv;
+  if (ctype_isptr(ct->info)) id = ctype_cid(ct->info);
+  tv = lj_ctype_meta(cts, id, mm);
+  if (!tv)
+    lj_err_callerv(L, LJ_ERR_FFI_BADMM, strdata(lj_ctype_repr(L, id, NULL)),
+                   strdata(mmname_str(G(L), mm)));
+  return lj_meta_tailcall(L, tv);
+}
+
+LJLIB_CF(ffi_meta___pairs)
+{
+  return ffi_pairs(L, MM_pairs);
+}
+
+LJLIB_CF(ffi_meta___ipairs)
+{
+  return ffi_pairs(L, MM_ipairs);
+}
+
 LJLIB_PUSH("ffi") LJLIB_SET(__metatable)
 
 #include "lj_libdef.h"
diff --git a/src/lj_errmsg.h b/src/lj_errmsg.h
index 5b10dea8..dd3eefa8 100644
--- a/src/lj_errmsg.h
+++ b/src/lj_errmsg.h
@@ -162,6 +162,7 @@ ERRDEF(FFI_NUMARG,	"wrong number of arguments for function call")
 ERRDEF(FFI_BADMEMBER,   LUA_QS " has no member named " LUA_QS)
 ERRDEF(FFI_BADIDX,      LUA_QS " cannot be indexed")
 ERRDEF(FFI_BADIDXW,     LUA_QS " cannot be indexed with " LUA_QS)
+ERRDEF(FFI_BADMM,       LUA_QS " has no " LUA_QS " metamethod")
 ERRDEF(FFI_WRCONST,     "attempt to write to constant location")
 ERRDEF(FFI_NODECL,      "missing declaration for symbol " LUA_QS)
 ERRDEF(FFI_BADCBACK,    "bad callback")
diff --git a/src/lj_obj.h b/src/lj_obj.h
index 7890e54b..67fb5ed9 100644
--- a/src/lj_obj.h
+++ b/src/lj_obj.h
@@ -447,10 +447,12 @@ enum {
 #define MMDEF_FFI(_)
 #endif
 
-#ifdef LUAJIT_ENABLE_LUA52COMPAT
-#define MMDEF_52(_) _(pairs) _(ipairs)
+#if defined(LUAJIT_ENABLE_LUA52COMPAT) || LJ_HASFFI
+#define MMDEF_PAIRS(_) _(pairs) _(ipairs)
 #else
-#define MMDEF_52(_)
+#define MMDEF_PAIRS(_)
+#define MM_pairs        255
+#define MM_ipairs       255
 #endif
 
 #define MMDEF(_) \
@@ -460,7 +462,7 @@ enum {
   /* The following must be in ORDER ARITH. */ \
   _(add) _(sub) _(mul) _(div) _(mod) _(pow) _(unm) \
   /* The following are used in the standard libraries. */ \
-  _(metatable) _(tostring) MMDEF_FFI(_) MMDEF_52(_)
+  _(metatable) _(tostring) MMDEF_FFI(_) MMDEF_PAIRS(_)
 
 typedef enum {
 #define MMENUM(name)    MM_##name,