luajit: implement read-only tables

Author: RaphaelIT7

LuaJIT-2.1/src/lib_table.c

@@ -286,6 +286,24 @@ LJLIB_CF(table_pack)
 }
 #endif
 
+LJLIB_CF(table_setreadonly)
+{
+  GCtab *t = lj_lib_checktab(L, 1);
+  int readOnly = lj_lib_checkint(L, 2) != 0;
+  
+  lj_tab_setreadonly(t, readOnly);
+  return 0;
+}
+
+LJLIB_CF(table_isreadonly)
+{
+  GCtab *t = lj_lib_checktab(L, 1);
+  int readOnly = lj_lib_checkint(L, 2) != 0;
+  
+  lua_pushboolean(L, lj_tab_isreadonly(t));
+  return 1;
+}
+
 LJLIB_NOREG LJLIB_CF(table_new)		LJLIB_REC(.)
 {
   int32_t a = lj_lib_checkint(L, 1);
@@ -296,7 +314,7 @@ LJLIB_NOREG LJLIB_CF(table_new)		LJLIB_REC(.)
 
 LJLIB_NOREG LJLIB_CF(table_clear)	LJLIB_REC(.)
 {
-  lj_tab_clear(lj_lib_checktab(L, 1));
+  lj_tab_clear(L, lj_lib_checktab(L, 1));
   return 0;
 }
 

LuaJIT-2.1/src/lj_errmsg.h

@@ -21,6 +21,7 @@ ERRDEF(TABOV,	"table overflow")
 ERRDEF(NANIDX,	"table index is NaN")
 ERRDEF(NILIDX,	"table index is nil")
 ERRDEF(NEXTIDX,	"invalid key to " LUA_QL("next"))
+ERRDEF(READONLY, "table is in read only")
 
 /* Metamethod resolving. */
 ERRDEF(BADCALL,	"attempt to call a %s value")

LuaJIT-2.1/src/lj_gc.h

@@ -23,6 +23,7 @@ enum {
 #define LJ_GC_CDATA_FIN	0x10
 #define LJ_GC_FIXED	0x20
 #define LJ_GC_SFIXED	0x40
+#define LJ_GC_READONLY	0x80
 
 #define LJ_GC_WHITES	(LJ_GC_WHITE0 | LJ_GC_WHITE1)
 #define LJ_GC_COLORS	(LJ_GC_WHITES | LJ_GC_BLACK)
@@ -45,6 +46,10 @@ enum {
 #define fixstring(s)	((s)->marked |= LJ_GC_FIXED)
 #define markfinalized(x)	((x)->gch.marked |= LJ_GC_FINALIZED)
 
+#define isreadonly(x)	((x)->marked & LJ_GC_READONLY)
+#define markreadonly(x) ((x)->marked |= LJ_GC_READONLY)
+#define unmarkreadonly(x) ((x)->marked &= ~LJ_GC_READONLY)
+
 /* Collector. */
 LJ_FUNC size_t lj_gc_separateudata(global_State *g, int all);
 LJ_FUNC void lj_gc_finalize_udata(lua_State *L);

LuaJIT-2.1/src/lj_meta.c

@@ -166,6 +166,12 @@ TValue *lj_meta_tset(lua_State *L, cTValue *o, cTValue *k)
     cTValue *mo;
     if (LJ_LIKELY(tvistab(o))) {
       GCtab *t = tabV(o);
+      if (isreadonly(t))
+      {
+        lj_err_msg(L, LJ_ERR_READONLY);
+        return NULL;
+      }
+
       cTValue *tv = lj_tab_get(L, t, k);
       if (LJ_LIKELY(!tvisnil(tv))) {
 	t->nomm = 0;  /* Invalidate negative metamethod cache. */

LuaJIT-2.1/src/lj_tab.c

@@ -13,6 +13,7 @@
 #include "lj_gc.h"
 #include "lj_err.h"
 #include "lj_tab.h"
+#include "lj_lib.h"
 
 /* -- Object hashing ------------------------------------------------------ */
 
@@ -201,8 +202,13 @@ GCtab * LJ_FASTCALL lj_tab_dup(lua_State *L, const GCtab *kt)
 }
 
 /* Clear a table. */
-void LJ_FASTCALL lj_tab_clear(GCtab *t)
+void LJ_FASTCALL lj_tab_clear(lua_State* L, GCtab *t)
 {
+  if (isreadonly(t))
+  {
+  	lj_err_msg(L, LJ_ERR_READONLY);
+  }
+
   clearapart(t);
   if (t->hmask > 0) {
     Node *node = noderef(t->node);
@@ -229,6 +235,11 @@ void LJ_FASTCALL lj_tab_free(global_State *g, GCtab *t)
 /* Resize a table to fit the new array/hash part sizes. */
 void lj_tab_resize(lua_State *L, GCtab *t, uint32_t asize, uint32_t hbits)
 {
+  if (isreadonly(t))
+  {
+  	lj_err_msg(L, LJ_ERR_READONLY);
+  }
+
   Node *oldnode = noderef(t->node);
   uint32_t oldasize = t->asize;
   uint32_t oldhmask = t->hmask;
@@ -434,6 +445,11 @@ cTValue *lj_tab_get(lua_State *L, GCtab *t, cTValue *key)
 /* Insert new key. Use Brent's variation to optimize the chain length. */
 TValue *lj_tab_newkey(lua_State *L, GCtab *t, cTValue *key)
 {
+  if (isreadonly(t))
+  {
+  	lj_err_msg(L, LJ_ERR_READONLY);
+  }
+
   Node *n = hashkey(t, key);
   if (!tvisnil(&n->val) || t->hmask == 0) {
     Node *nodebase = noderef(t->node);
@@ -509,6 +525,11 @@ TValue *lj_tab_newkey(lua_State *L, GCtab *t, cTValue *key)
 
 TValue *lj_tab_setinth(lua_State *L, GCtab *t, int32_t key)
 {
+  if (isreadonly(t))
+  {
+  	lj_err_msg(L, LJ_ERR_READONLY);
+  }
+
   TValue k;
   Node *n;
   k.n = (lua_Number)key;
@@ -522,6 +543,11 @@ TValue *lj_tab_setinth(lua_State *L, GCtab *t, int32_t key)
 
 TValue *lj_tab_setstr(lua_State *L, GCtab *t, const GCstr *key)
 {
+  if (isreadonly(t))
+  {
+  	lj_err_msg(L, LJ_ERR_READONLY);
+  }
+
   TValue k;
   Node *n = hashstr(t, key);
   do {
@@ -534,6 +560,11 @@ TValue *lj_tab_setstr(lua_State *L, GCtab *t, const GCstr *key)
 
 TValue *lj_tab_set(lua_State *L, GCtab *t, cTValue *key)
 {
+  if (isreadonly(t))
+  {
+  	lj_err_msg(L, LJ_ERR_READONLY);
+  }
+
   Node *n;
   t->nomm = 0;  /* Invalidate negative metamethod cache. */
   if (tvisstr(key)) {
@@ -684,3 +715,17 @@ MSize LJ_FASTCALL lj_tab_len_hint(GCtab *t, size_t hint)
 }
 #endif
 
+void LJ_FASTCALL lj_tab_setreadonly(GCtab *t, int readOnly)
+{
+  if (readOnly != 0)
+  {
+  	markreadonly(t);
+  } else {
+  	unmarkreadonly(t);
+  }
+}
+
+int LJ_FASTCALL lj_tab_isreadonly(GCtab *t)
+{
+  return isreadonly(t);
+}

LuaJIT-2.1/src/lj_tab.h

@@ -58,7 +58,7 @@ LJ_FUNC GCtab *lj_tab_new_ah(lua_State *L, int32_t a, int32_t h);
 LJ_FUNC GCtab * LJ_FASTCALL lj_tab_new1(lua_State *L, uint32_t ahsize);
 #endif
 LJ_FUNCA GCtab * LJ_FASTCALL lj_tab_dup(lua_State *L, const GCtab *kt);
-LJ_FUNC void LJ_FASTCALL lj_tab_clear(GCtab *t);
+LJ_FUNC void LJ_FASTCALL lj_tab_clear(lua_State* L, GCtab *t);
 LJ_FUNC void LJ_FASTCALL lj_tab_free(global_State *g, GCtab *t);
 LJ_FUNC void lj_tab_resize(lua_State *L, GCtab *t, uint32_t asize, uint32_t hbits);
 LJ_FUNCA void lj_tab_reasize(lua_State *L, GCtab *t, uint32_t nasize);
@@ -75,6 +75,8 @@ LJ_FUNCA TValue *lj_tab_newkey(lua_State *L, GCtab *t, cTValue *key);
 LJ_FUNCA TValue *lj_tab_setinth(lua_State *L, GCtab *t, int32_t key);
 LJ_FUNC TValue *lj_tab_setstr(lua_State *L, GCtab *t, const GCstr *key);
 LJ_FUNC TValue *lj_tab_set(lua_State *L, GCtab *t, cTValue *key);
+LJ_FUNC void LJ_FASTCALL lj_tab_setreadonly(GCtab *t, int readOnly);
+LJ_FUNC int LJ_FASTCALL lj_tab_isreadonly(GCtab *t);
 
 #define inarray(t, key)		((MSize)(key) < (MSize)(t)->asize)
 #define arrayslot(t, i)		(&tvref((t)->array)[(i)])