Fix loading of RDB files lua AUX fields when the script is defined.

In the case of slaves loading the RDB from master, or in other similar
cases, the script is already defined, and the function registering the
script should not fail in the assert() call.

src/rdb.c

@@ -1679,7 +1679,7 @@ int rdbLoadRio(rio *rdb, rdbSaveInfo *rsi) {
                 if (rsi) rsi->repl_offset = strtoll(auxval->ptr,NULL,10);
             } else if (!strcasecmp(auxkey->ptr,"lua")) {
                 /* Load the script back in memory. */
-                if (luaCreateFunction(NULL,server.lua,NULL,auxval) == C_ERR) {
+                if (luaCreateFunction(NULL,server.lua,NULL,auxval,1) == C_ERR) {
                     rdbExitReportCorruptRDB(
                         "Can't load Lua script from RDB file! "
                         "BODY: %s", auxval->ptr);

src/scripting.c

@@ -1151,13 +1151,16 @@ int redis_math_randomseed (lua_State *L) {
  * on the fly doing the SHA1 of the body, this means that passing the funcname
  * is just an optimization in case it's already at hand.
  *
+ * if 'allow_dup' is true, the function can be called with a script already
+ * in memory without crashing in assert(). In this case C_OK is returned.
+ *
  * The function increments the reference count of the 'body' object as a
  * side effect of a successful call.
  *
  * On success C_OK is returned, and nothing is left on the Lua stack.
  * On error C_ERR is returned and an appropriate error is set in the
  * client context. */
-int luaCreateFunction(client *c, lua_State *lua, char *funcname, robj *body) {
+int luaCreateFunction(client *c, lua_State *lua, char *funcname, robj *body, int allow_dup) {
     sds funcdef = sdsempty();
     char fname[43];
 
@@ -1168,6 +1171,9 @@ int luaCreateFunction(client *c, lua_State *lua, char *funcname, robj *body) {
         funcname = fname;
     }
 
+    if (allow_dup && dictFind(server.lua_scripts,funcname+2) != NULL)
+        return C_OK;
+
     funcdef = sdscat(funcdef,"function ");
     funcdef = sdscatlen(funcdef,funcname,42);
     funcdef = sdscatlen(funcdef,"() ",3);
@@ -1302,7 +1308,7 @@ void evalGenericCommand(client *c, int evalsha) {
             addReply(c, shared.noscripterr);
             return;
         }
-        if (luaCreateFunction(c,lua,funcname,c->argv[1]) == C_ERR) {
+        if (luaCreateFunction(c,lua,funcname,c->argv[1],0) == C_ERR) {
             lua_pop(lua,1); /* remove the error handler from the stack. */
             /* The error is sent to the client by luaCreateFunction()
              * itself when it returns C_ERR. */
@@ -1474,7 +1480,7 @@ void scriptCommand(client *c) {
         sha1hex(funcname+2,c->argv[2]->ptr,sdslen(c->argv[2]->ptr));
         sha = sdsnewlen(funcname+2,40);
         if (dictFind(server.lua_scripts,sha) == NULL) {
-            if (luaCreateFunction(c,server.lua,funcname,c->argv[2])
+            if (luaCreateFunction(c,server.lua,funcname,c->argv[2],0)
                     == C_ERR) {
                 sdsfree(sha);
                 return;

src/server.h

@@ -1794,7 +1794,7 @@ void scriptingInit(int setup);
 int ldbRemoveChild(pid_t pid);
 void ldbKillForkedSessions(void);
 int ldbPendingChildren(void);
-int luaCreateFunction(client *c, lua_State *lua, char *funcname, robj *body);
+int luaCreateFunction(client *c, lua_State *lua, char *funcname, robj *body, int allow_dup);
 
 /* Blocked clients */
 void processUnblockedClients(void);