lua-utils: formalized object/userdata conversion, stricter validation.

Added a few macros and inlines to do checked and unchecked/trusted
conversion between objects and userdata. Changed all existing code
to use these. This should also make it easier to switch to a different
association mechanism/model when we move to Lua 5.2 or later.

Also added compile-time selectable stricter checking for valid userdata.
The stricter version stores the self pointer XOR'ed with the data
pointer. This should prevent us from misidentifying an empty linked
list or hook for a valid userdata.

diff --git a/src/core/lua-utils/object.c b/src/core/lua-utils/object.c
index 52aed5c..f98b73d 100644 (file)
--- a/src/core/lua-utils/object.c
+++ b/src/core/lua-utils/object.c
@@ -43,15 +43,19 @@
 #include <murphy/common/mm.h>
 #include <murphy/core/lua-utils/object.h>
 
+#undef  __MURPHY_MANGLE_CLASS_SELF__     /* extra self-mangling if defined */
+#define CHECK    true                    /* do type/self-checking */
+#define NOCHECK (!CHECK)                 /* omit type/self-checking */
+
 typedef struct userdata_s userdata_t;
 
 struct userdata_s {
-    userdata_t *self;
+    userdata_t *selfish;
     mrp_lua_classdef_t *def;
     int  luatbl;
     int  reftbl;                          /* table of private references */
     int  exttbl;                          /* table of object extensions */
-    int  dead : 1;                        /* being cleaed up */
+    int  dead : 1;                        /* being cleaned up */
     int  initializing : 1;                /* being initialized */
 };
 
@@ -91,6 +95,63 @@ static mrp_lua_classdef_t invalid_classdef = {
 }, *invalid_class = &invalid_classdef;
 
 
+#define USER_TO_DATA(u) ((void *)(((userdata_t *)(u)) + 1))
+#define DATA_TO_USER(d) (((userdata_t *)(d)) - 1)
+
+static inline void userdata_setself(userdata_t *u)
+{
+#ifdef __MURPHY_MANGLE_CLASS_SELF__
+    void *data = USER_TO_DATA(u);
+
+    u->selfish = (void *)(((ptrdiff_t)u) ^ ((ptrdiff_t)data));
+#else
+    u->selfish = u;
+#endif
+}
+
+
+static inline void *userdata_getself(userdata_t *u)
+{
+#ifdef __MURPHY_MANGLE_CLASS_SELF__
+    void *data = USER_TO_DATA(u);
+    void *self = (void *)(((ptrdiff_t)u->selfish) ^ ((ptrdiff_t)data));
+#else
+    void *self = u->selfish;
+#endif
+
+    if (u == self)
+        return self;
+    else
+        return NULL;
+}
+
+
+static inline userdata_t *userdata_get(void *data, bool check)
+{
+    userdata_t *u;
+
+    if (data != NULL) {
+        u = DATA_TO_USER(data);
+
+        if (!check || userdata_getself(u) == u)
+            return u;
+    }
+
+    return NULL;
+}
+
+
+static inline void *object_get(userdata_t *u, bool check)
+{
+    if (u != NULL) {
+        if (!check || (userdata_getself(u) == u))
+            return USER_TO_DATA(u);
+    }
+
+    return NULL;
+}
+
+
 int mrp_lua_create_object_class(lua_State *L, mrp_lua_classdef_t *def)
 {
     if (def->constructor == NULL) {
@@ -306,18 +367,6 @@ mrp_lua_type_t mrp_lua_class_type(const char *type_name)
 }
 
 
-static inline userdata_t *get_userdata(void *o)
-{
-    return (o != NULL ? (((userdata_t *)o) - 1) : NULL);
-}
-
-
-static inline void *get_object(userdata_t *u)
-{
-    return (u != NULL ? (void *)(u + 1) : NULL);
-}
-
-
 void *mrp_lua_create_object(lua_State          *L,
                             mrp_lua_classdef_t *def,
                             const char         *name,
@@ -358,7 +407,7 @@ void *mrp_lua_create_object(lua_State          *L,
     lua_rawset(L, -3);
 
     lua_pushvalue(L, -1);
-    userdata->self   = userdata;
+    userdata_setself(userdata);
     userdata->def    = def;
     userdata->luatbl = luaL_ref(L, LUA_REGISTRYINDEX);
 
@@ -380,7 +429,7 @@ void *mrp_lua_create_object(lua_State          *L,
     if (def->flags & MRP_LUA_CLASS_EXTENSIBLE)
         object_create_exttbl(userdata, L);
 
-    return (void *)(userdata + 1);
+    return USER_TO_DATA(userdata);
 }
 
 
@@ -416,10 +465,10 @@ void mrp_lua_set_object_index(lua_State          *L,
 
 void mrp_lua_destroy_object(lua_State *L, const char *name,int idx, void *data)
 {
-    userdata_t *userdata = (userdata_t *)data - 1;
+    userdata_t *userdata = userdata_get(data, CHECK);
     mrp_lua_classdef_t *def;
 
-    if (data && userdata == userdata->self && !userdata->dead) {
+    if (userdata && !userdata->dead) {
         userdata->dead = true;
         def = userdata->def;
 
@@ -496,14 +545,14 @@ void *mrp_lua_check_object(lua_State *L, mrp_lua_classdef_t *def, int idx)
         }
     }
 
-    if (userdata != userdata->self) {
+    if (userdata_getself(userdata) != userdata) {
         luaL_error(L, "invalid userdata");
         userdata = NULL;
     }
 
     lua_pop(L, 2);
 
-    return userdata ? (void *)(userdata + 1) : NULL;
+    return userdata ? USER_TO_DATA(userdata) : NULL;
 }
 
 
@@ -582,7 +631,7 @@ int mrp_lua_pointer_of_type(void *data, mrp_lua_type_t type)
      * We consider NULL to be a valid instance. Might need to be changed.
      */
 
-    if ((u = get_userdata(data)) != NULL)
+    if ((u = userdata_get(data, CHECK)) != NULL)
         return type == u->def->type_id;
     else
         return true;
@@ -611,21 +660,21 @@ void *mrp_lua_to_object(lua_State *L, mrp_lua_classdef_t *def, int idx)
 
     lua_getfield(L, LUA_REGISTRYINDEX, def->userdata_id);
 
-    if (!lua_rawequal(L, -1, -2) || userdata != userdata->self)
+    if (!lua_rawequal(L, -1, -2) || userdata != userdata_getself(userdata))
         userdata = NULL;
 
     lua_settop(L, top);
 
-    return userdata ? (void *)(userdata + 1) : NULL;
+    return userdata ? USER_TO_DATA(userdata) : NULL;
 }
 
 
 
 int mrp_lua_push_object(lua_State *L, void *data)
 {
-    userdata_t *userdata = (userdata_t *)data - 1;
+    userdata_t *userdata = userdata_get(data, CHECK);
 
-    if (!data || userdata != userdata->self || userdata->dead)
+    if (!userdata || userdata->dead)
         lua_pushnil(L);
     else
         lua_rawgeti(L, LUA_REGISTRYINDEX, userdata->luatbl);
@@ -633,12 +682,13 @@ int mrp_lua_push_object(lua_State *L, void *data)
     return 1;
 }
 
+
 mrp_lua_classdef_t *mrp_lua_get_object_classdef(void *data)
 {
-    userdata_t *userdata = (userdata_t *)data - 1;
+    userdata_t *userdata = userdata_get(data, CHECK);
     mrp_lua_classdef_t *def;
 
-    if (!data || userdata != userdata->self || userdata->dead)
+    if (!userdata || userdata->dead)
         def = NULL;
     else
         def = userdata->def;
@@ -676,7 +726,7 @@ static int userdata_destructor(lua_State *L)
         if (!lua_rawequal(L, -1, -2))
             luaL_typerror(L, -2, def->userdata_id);
         else
-            def->destructor((void *)(userdata + 1));
+            def->destructor(USER_TO_DATA(userdata));
     }
 
     return 0;
@@ -686,7 +736,7 @@ static int userdata_destructor(lua_State *L)
 static int default_setter(void *data, lua_State *L, int member,
                           mrp_lua_value_t *v)
 {
-    userdata_t             *u = (userdata_t *)data - 1;
+    userdata_t             *u = DATA_TO_USER(data);
     mrp_lua_class_member_t *m;
     mrp_lua_value_t        *vptr;
     void                  **itemsp;
@@ -807,7 +857,7 @@ static int default_setter(void *data, lua_State *L, int member,
 static int default_getter(void *data, lua_State *L, int member,
                           mrp_lua_value_t *v)
 {
-    userdata_t             *u = (userdata_t *)data - 1;
+    userdata_t             *u = DATA_TO_USER(data);
     mrp_lua_class_member_t *m;
     mrp_lua_value_t        *vptr;
 
@@ -1137,7 +1187,7 @@ static inline int get_reftbl(userdata_t *u)
 
 int mrp_lua_object_ref_value(void *data, lua_State *L, int idx)
 {
-    int tbl = get_reftbl(get_userdata(data));
+    int tbl = get_reftbl(userdata_get(data, CHECK));
     int ref;
 
     if (tbl != LUA_NOREF) {
@@ -1158,7 +1208,7 @@ void mrp_lua_object_unref_value(void *data, lua_State *L, int ref)
     int tbl;
 
     if (ref != LUA_NOREF && ref != LUA_REFNIL) {
-        tbl = get_reftbl(get_userdata(data));
+        tbl = get_reftbl(userdata_get(data, CHECK));
 
         if (tbl != LUA_NOREF) {
             lua_rawgeti(L, LUA_REGISTRYINDEX, tbl);
@@ -1174,7 +1224,7 @@ int mrp_lua_object_deref_value(void *data, lua_State *L, int ref, int pushnil)
     int tbl;
 
     if (ref != LUA_NOREF) {
-        tbl = get_reftbl(get_userdata(data));
+        tbl = get_reftbl(userdata_get(data, CHECK));
 
         if (ref != LUA_REFNIL && tbl != LUA_NOREF) {
             lua_rawgeti(L, LUA_REGISTRYINDEX, tbl);
@@ -1203,8 +1253,8 @@ int mrp_lua_object_getref(void *owner, void *data, lua_State *L, int ref)
     if (ref == LUA_NOREF || ref == LUA_REFNIL)
         return ref;
 
-    if ((otbl = get_reftbl(get_userdata(owner))) == LUA_NOREF ||
-        (dtbl = get_reftbl(get_userdata(data)))  == LUA_NOREF)
+    if ((otbl = get_reftbl(userdata_get(owner, CHECK))) == LUA_NOREF ||
+        (dtbl = get_reftbl(userdata_get(data , CHECK))) == LUA_NOREF)
         return LUA_NOREF;
 
     lua_rawgeti(L, LUA_REGISTRYINDEX, otbl);
@@ -1248,10 +1298,10 @@ static void object_delete_exttbl(userdata_t *u, lua_State *L)
 }
 
 
-int mrp_lua_object_setext(void *data, lua_State *L, const char *name,
-                          int vidx, char *err, size_t esize)
+static int object_setext(void *data, lua_State *L, const char *name,
+                         int vidx, char *err, size_t esize)
 {
-    userdata_t *u = (userdata_t *)data - 1;
+    userdata_t *u = DATA_TO_USER(data);
 
     if (u->exttbl == LUA_NOREF) {
         if (err)
@@ -1273,9 +1323,9 @@ int mrp_lua_object_setext(void *data, lua_State *L, const char *name,
 }
 
 
-void mrp_lua_object_getext(void *data, lua_State *L, const char *name)
+static void object_getext(void *data, lua_State *L, const char *name)
 {
-    userdata_t *u = (userdata_t *)data - 1;
+    userdata_t *u = DATA_TO_USER(data);
 
    if (u->exttbl == LUA_NOREF) {
        lua_pushnil(L);
@@ -1288,9 +1338,9 @@ void mrp_lua_object_getext(void *data, lua_State *L, const char *name)
 }
 
 
-void mrp_lua_object_setiext(void *data, lua_State *L, int idx, int val)
+static void object_setiext(void *data, lua_State *L, int idx, int val)
 {
-    userdata_t *u = (userdata_t *)data - 1;
+    userdata_t *u = DATA_TO_USER(data);
 
     lua_rawgeti(L, LUA_REGISTRYINDEX, u->exttbl);
     lua_pushvalue(L, val > 0 ? val : val - 1);
@@ -1299,9 +1349,9 @@ void mrp_lua_object_setiext(void *data, lua_State *L, int idx, int val)
 }
 
 
-void mrp_lua_object_getiext(void *data, lua_State *L, int idx)
+static void object_getiext(void *data, lua_State *L, int idx)
 {
-    userdata_t *u = (userdata_t *)data - 1;
+    userdata_t *u = DATA_TO_USER(data);
 
     lua_rawgeti(L, LUA_REGISTRYINDEX, u->exttbl);
     lua_rawgeti(L, -1, idx);
@@ -1514,7 +1564,7 @@ int mrp_lua_object_push_array(lua_State *L, int type, void *items, size_t nitem)
 
 int mrp_lua_set_member(void *data, lua_State *L, char *err, size_t esize)
 {
-    userdata_t             *u = (userdata_t *)data - 1;
+    userdata_t             *u = DATA_TO_USER(data);
     int                     midx = class_member(u, L, -2);
     mrp_lua_class_member_t *m;
     mrp_lua_value_t         v;
@@ -1680,7 +1730,7 @@ int mrp_lua_set_member(void *data, lua_State *L, char *err, size_t esize)
         lua_pushliteral(L, "userdata");
         lua_rawget(L, -2);
         if ((v.obj.ptr = lua_touserdata(L, -1)) != NULL)
-            v.obj.ptr = ((userdata_t *)v.obj.ptr) + 1;
+            v.obj.ptr = USER_TO_DATA(v.obj.ptr);
         lua_pop(L, 1);
 
         if (m->setter(data, L, midx, &v) == 1)
@@ -1710,7 +1760,7 @@ int mrp_lua_set_member(void *data, lua_State *L, char *err, size_t esize)
 
 int mrp_lua_get_member(void *data, lua_State *L, char *err, size_t esize)
 {
-    userdata_t             *u = (userdata_t *)data - 1;
+    userdata_t             *u = DATA_TO_USER(data);
     int                     midx = class_member(u, L, -1);
     mrp_lua_class_member_t *m;
     mrp_lua_value_t         v;
@@ -1811,7 +1861,7 @@ int mrp_lua_get_member(void *data, lua_State *L, char *err, size_t esize)
 int mrp_lua_init_members(void *data, lua_State *L, int idx,
                          char *err, size_t esize)
 {
-    userdata_t *u = (userdata_t *)data - 1;
+    userdata_t *u = userdata_get(data, CHECK);
     const char *n;
     size_t      l;
 
@@ -1839,7 +1889,7 @@ int mrp_lua_init_members(void *data, lua_State *L, int idx,
             goto error;
         case 0:
             if (u->def->flags & MRP_LUA_CLASS_EXTENSIBLE) {
-                if (mrp_lua_object_setext(data, L, n, -1, err, esize) < 0)
+                if (object_setext(data, L, n, -1, err, esize) < 0)
                     goto error;
             }
             else {
@@ -1880,8 +1930,8 @@ static inline int is_native(userdata_t *u, const char *name)
 static int override_setfield(lua_State *L)
 {
     void       *data = mrp_lua_check_object(L, NULL, 1);
+    userdata_t *u    = DATA_TO_USER(data);
     char        err[128] = "";
-    userdata_t *u = (userdata_t *)data - 1;
     const char *name;
 
     if (data == NULL)
@@ -1912,10 +1962,10 @@ static int override_setfield(lua_State *L)
         if (is_native(u, name))
             return u->def->setfield(L);
         else
-            mrp_lua_object_setext(data, L, name, 3, NULL, 0);
+            object_setext(data, L, name, 3, NULL, 0);
     }
     else {
-        mrp_lua_object_setiext(data, L, lua_tointeger(L, 2), 3);
+        object_setiext(data, L, lua_tointeger(L, 2), 3);
     }
 
  out:
@@ -1928,8 +1978,8 @@ static int override_setfield(lua_State *L)
 static int override_getfield(lua_State *L)
 {
     void       *data = mrp_lua_check_object(L, NULL, 1);
+    userdata_t *u    = DATA_TO_USER(data);
     char        err[128] = "";
-    userdata_t *u = (userdata_t *)data - 1;
     const char *name;
 
     mrp_debug("getting field for object of type '%s'", u->def->class_name);
@@ -1955,10 +2005,10 @@ static int override_getfield(lua_State *L)
         if (is_native(u, name))
             return u->def->setfield(L);
         else
-            mrp_lua_object_getext(data, L, name);
+            object_getext(data, L, name);
     }
     else {
-        mrp_lua_object_getiext(data, L, 2);
+        object_getiext(data, L, 2);
     }
 
  out:

diff --git a/src/core/lua-utils/object.h b/src/core/lua-utils/object.h
index 56568f6..8e70417 100644 (file)
--- a/src/core/lua-utils/object.h
+++ b/src/core/lua-utils/object.h
@@ -522,15 +522,6 @@ int mrp_lua_object_deref_value(void *object, lua_State *L, int ref,
 int mrp_lua_object_getref(void *owner, void *object, lua_State *L, int ref);
 /** Decreate the reference count of the given object reference. */
 #define mrp_lua_object_putref(o, L, ref) mrp_lua_object_unref_value(o, L, ref)
-/** Set a user-specified field for an extensible object to the value at vidx. */
-int mrp_lua_object_setext(void *object, lua_State *L, const char *name,
-                          int vidx, char *err, size_t esize);
-/** Get and push the user-specified field of an extensible object. */
-void mrp_lua_object_getext(void *data, lua_State *L, const char *name);
-/** Set a user-specified index of an extensible object to the value at vidx. */
-void mrp_lua_object_setiext(void *data, lua_State *L, int idx, int val);
-/** Get and push the user-specified index of an extensible object. */
-void mrp_lua_object_getiext(void *data, lua_State *L, int idx);
 /** Set a pre-declared object member. */
 int mrp_lua_set_member(void *data, lua_State *L, char *err, size_t esize);
 /** Get and push a pre-declared object member. */