1 files changed, 41 insertions, 43 deletions

diff --git a/src/tools.c b/src/tools.c
index 2fc7b58..e89b340 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -202,19 +202,19 @@ static lua_CFunction luaG_tocfunction( lua_State *L, int _i, FuncSubType *_out)
 
 
 // inspired from tconcat() in ltablib.c
-static char const * luaG_pushFQN(lua_State *L, int t, int last)
+static char const* luaG_pushFQN(lua_State *L, int t, int last)
 {
         int i = 1;
         luaL_Buffer b;
         STACK_CHECK( L)
         luaL_buffinit(L, &b);
-        for( ; i < last; i++)
+        for( ; i < last; ++ i)
         {
                 lua_rawgeti( L, t, i);
                 luaL_addvalue( &b);
                 luaL_addlstring(&b, ".", 1);
         }
-        if (i == last)  /* add last value (if interval was not empty) */
+        if( i == last)  // add last value (if interval was not empty)
         {
                 lua_rawgeti( L, t, i);
                 luaL_addvalue( &b);
@@ -225,7 +225,7 @@ static char const * luaG_pushFQN(lua_State *L, int t, int last)
 }
 
 
-static void populate_func_lookup_table_recur( lua_State *L, int _ctx_base, int _i, int _depth)
+static void populate_func_lookup_table_recur( lua_State* L, int _ctx_base, int _i, int _depth)
 {
         lua_Integer visit_count;
         // slot 1 in the stack contains the table that receives everything we found
@@ -282,49 +282,47 @@ static void populate_func_lookup_table_recur( lua_State *L, int _ctx_base, int _
                         lua_pushvalue( L, -2);                                                                // ... {_i} {bfc} k {} k
                         lua_insert( L, -2);                                                                   // ... {_i} {bfc} k k {}
                         lua_rawset( L, breadth_first_cache);                                                  // ... {_i} {bfc} k
-                        STACK_MID( L, 2)
                 }
-                else if( lua_isfunction( L, -1))                                                        // ... {_i} {bfc} k func
+                else if( lua_isfunction( L, -1) && (luaG_getfuncsubtype( L, -1) != FST_Bytecode))       // ... {_i} {bfc} k func
                 {
-                        if( luaG_getfuncsubtype( L, -1) != FST_Bytecode)
+                        char const* prevName, * newName;
+                        // first, raise an error if the function is already known
+                        lua_pushvalue( L, -1);                                                                // ... {_i} {bfc} k func func
+                        lua_rawget( L, dest);                                                                 // ... {_i} {bfc} k func name?
+                        prevName = lua_tostring( L, -1); // NULL if we got nil (first encounter of this function)
+                        // push function name in fqn stack (note that concatenation will crash if name is a not string or a number)
+                        lua_pushvalue( L, -3);                                                                // ... {_i} {bfc} k func name? k
+                        ++ _depth;
+                        lua_rawseti( L, fqn, _depth);                                                         // ... {_i} {bfc} k func name?
+                        // generate name
+                        newName = luaG_pushFQN( L, fqn, _depth);                                              // ... {_i} {bfc} k func name? "f.q.n"
+                        // Lua 5.2 introduced a hash randomizer seed which causes table iteration to yield a different key order
+                        // on different VMs even when the tables are populated the exact same way.
+                        // When Lua is built with compatibility options (such as LUA_COMPAT_ALL),
+                        // this causes several base libraries to register functions under multiple names.
+                        // This, with the randomizer, can cause the first name of a function to be different on different VMs,
+                        // which breaks function transfer.
+                        // This means that Lua 5.2 must be built with compatibility off to be able to use Lanes.
+                        // Even under Lua 5.1, this may cause trouble (even if this would be much less frequent)
+                        // Unfortunately, this fails with string.gfind/string.gmatch when Lua 5.1 is built with LUA_COMPAT_GFIND (which is the case of LuaBinaries),
+                        // so for the time being, fail only for Lua 5.2 as the randomizer is the real show breaker here.
+                        if( (LUA_VERSION_NUM > 501) && (prevName != NULL))
                         {
-                                //char const *fqnString; for debugging
-                                bool_t not_registered;
-                                // first, skip everything if the function is already known
-                                lua_pushvalue( L, -1);                                                              // ... {_i} {bfc} k func func
-                                lua_rawget( L, dest);                                                               // ... {_i} {bfc} k func name?
-                                not_registered = lua_isnil( L, -1);
-                                lua_pop( L, 1);                                                                     // ... {_i} {bfc} k func
-                                if( not_registered)
-                                {
-                                        ++ _depth;
-                                        // push function name in fqn stack (note that concatenation will crash if name is a not string!)
-                                        lua_pushvalue( L, -2);                                                            // ... {_i} {bfc} k func k
-                                        lua_rawseti( L, fqn, _depth);                                                     // ... {_i} {bfc} k func
-                                        // generate name
-                                        /*fqnString =*/ (void) luaG_pushFQN( L, fqn, _depth);                             // ... {_i} {bfc} k func "f.q.n"
-                                        //puts( fqnString);
-                                        // prepare the stack for database feed
-                                        lua_pushvalue( L, -1);                                                            // ... {_i} {bfc} k func "f.q.n" "f.q.n"
-                                        lua_pushvalue( L, -3);                                                            // ... {_i} {bfc} k func "f.q.n" "f.q.n" func
-                                        // t["f.q.n"] = func
-                                        lua_rawset( L, dest);                                                             // ... {_i} {bfc} k func "f.q.n"
-                                        // t[func] = "f.q.n"
-                                        lua_rawset( L, dest);                                                             // ... {_i} {bfc} k
-                                        // remove table name from fqn stack
-                                        lua_pushnil( L);                                                                  // ... {_i} {bfc} k nil
-                                        lua_rawseti( L, fqn, _depth);                                                     // ... {_i} {bfc} k
-                                        -- _depth;
-                                }
-                                else
-                                {
-                                        lua_pop( L, 1);                                                                   // ... {_i} {bfc} k
-                                }
-                        }
-                        else
-                        {
-                                lua_pop( L, 1);                                                                     // ... {_i} {bfc} k
+                                (void) luaL_error( L, "multiple names detected (%s and %s)", prevName, newName);
+                                return;
                         }
+                        // prepare the stack for database feed
+                        lua_remove( L, -2);                                                                   // ... {_i} {bfc} k func "f.q.n"
+                        lua_pushvalue( L, -1);                                                                // ... {_i} {bfc} k func "f.q.n" "f.q.n"
+                        lua_pushvalue( L, -3);                                                                // ... {_i} {bfc} k func "f.q.n" "f.q.n" func
+                        // t["f.q.n"] = func 
+                        lua_rawset( L, dest);                                                                 // ... {_i} {bfc} k func "f.q.n"
+                        // t[func] = "f.q.n"
+                        lua_rawset( L, dest);                                                                 // ... {_i} {bfc} k
+                        // remove table name from fqn stack
+                        lua_pushnil( L);                                                                      // ... {_i} {bfc} k nil
+                        lua_rawseti( L, fqn, _depth);                                                         // ... {_i} {bfc} k
+                        -- _depth;
                 }
                 else
                 {