Fix to bug #673, http://bugs.skysql.com/show_bug.cgi?id=673

dcb.c:dcb_hashtable_stats:division by zero
hashtable.c:hashtable_get_stats: NULL-pointer reference
service.c:serviceStartPort:set service->users NULL to avoid referring to freed memory
users.c:dcb_usersPrintf: NULL-pointer reference
debugcmd.c:convert_arg: changed return value to 1 in case of error, 0 (==NULL) is valid but it indicates that there are no users loaded.
	execute_cmd: fixed command handling

server/core/dcb.c

@@ -1610,7 +1610,9 @@ void dcb_hashtable_stats(
                    hashsize);
         
 	dcb_printf(dcb, "\tNo. of entries:     	%d\n", total);
-	dcb_printf(dcb, "\tAverage chain length:	%.1f\n", (float)total / hashsize);
+	dcb_printf(dcb, 
+		"\tAverage chain length:	%.1f\n", 
+		(hashsize == 0 ? (float)hashsize : (float)total / hashsize));
 	dcb_printf(dcb, "\tLongest chain length:	%d\n", longest);
 }
 

server/core/hashtable.c

@@ -449,28 +449,33 @@ void hashtable_get_stats(
         int          i;
         int          j;
 
-        ht = (HASHTABLE *)table;
+	*nelems = 0;
-        CHK_HASHTABLE(ht);
+	*longest = 0;
-        *nelems = 0;
+	*hashsize = 0;
-        *longest = 0;
-	hashtable_read_lock(ht);
 	
-	for (i = 0; i < ht->hashsize; i++)
+	if (table != NULL)
 	{
-		j = 0;
+		ht = (HASHTABLE *)table;
-		entries = ht->entries[i];
+		CHK_HASHTABLE(ht);
-		while (entries)
+		hashtable_read_lock(ht);
+		
+		for (i = 0; i < ht->hashsize; i++)
 		{
-			j++;
+			j = 0;
-			entries = entries->next;
+			entries = ht->entries[i];
+			while (entries)
+			{
+				j++;
+				entries = entries->next;
+			}
+			*nelems += j;
+			if (j > *longest) {
+				*longest = j;
+			}
 		}
-		*nelems += j;
+		*hashsize = ht->hashsize;
-		if (j > *longest) {
+		hashtable_read_unlock(ht);
-			*longest = j;
-                }
 	}
-        *hashsize = ht->hashsize;
-	hashtable_read_unlock(ht);
 }
 
 

server/core/service.c

@@ -217,6 +217,7 @@ GWPROTOCOL	*funcs;
 					service->name)));
 				hashtable_free(service->users->data);
 				free(service->users);
+				service->users = NULL;
 				dcb_free(port->listener);
 				port->listener = NULL;
 				goto retblock;

server/core/users.c

@@ -183,32 +183,41 @@ char		*sep;
 void		*user;
 
 	dcb_printf(dcb, "Users table data\n");
-	dcb_hashtable_stats(dcb, users->data);
-	if ((iter = hashtable_iterator(users->data)) != NULL)
-	{
-		dcb_printf(dcb, "User names: ");
-		sep = "";
 	
-		if (users->usersCustomUserFormat != NULL) {
+	if (users == NULL || users->data == NULL)
-			while ((user = hashtable_next(iter)) != NULL)
+	{
-			{
+		dcb_printf(dcb, "Users table is empty\n");
-				char *custom_user;
+	}
-				custom_user = users->usersCustomUserFormat(user);
+	else 
-				if (custom_user) {
+	{
-					dcb_printf(dcb, "%s%s", sep, custom_user);
+		dcb_hashtable_stats(dcb, users->data);
-					free(custom_user);
+		
+		if ((iter = hashtable_iterator(users->data)) != NULL)
+		{
+			dcb_printf(dcb, "User names: ");
+			sep = "";
+
+			if (users->usersCustomUserFormat != NULL) {
+				while ((user = hashtable_next(iter)) != NULL)
+				{
+					char *custom_user;
+					custom_user = users->usersCustomUserFormat(user);
+					if (custom_user) {
+						dcb_printf(dcb, "%s%s", sep, custom_user);
+						free(custom_user);
+						sep = ", ";
+					}
+				}
+			} else {
+				while ((user = hashtable_next(iter)) != NULL)
+				{
+					dcb_printf(dcb, "%s%s", sep, (char *)user);
 					sep = ", ";
 				}
 			}
-		} else {
-			while ((user = hashtable_next(iter)) != NULL)
-			{
-				dcb_printf(dcb, "%s%s", sep, (char *)user);
-				sep = ", ";
-			}
-		}
 
-		dcb_printf(dcb, "\n");
+			hashtable_iterator_free(iter);
-                hashtable_iterator_free(iter);
+		}
 	}
+	dcb_printf(dcb, "\n");
 }

server/modules/routing/debugcmd.c

@@ -678,7 +678,7 @@ SERVICE		*service;
 			if (service)
 				return (unsigned long)(service->users);
 			else
-				return 0;
+				return 1; /*< invalid argument */
 		}
 		return rval;
 	case ARG_TYPE_DCB:
@@ -886,11 +886,15 @@ bool in_space = false;
 								break;
 							case 1:
 								arg1 = convert_arg(cli->mode, args[2],cmds[i].options[j].arg_types[0]);
-								if (arg1)
+								if (arg1 == 0x1)
-									cmds[i].options[j].fn(dcb, arg1);
+								{
-								else
 									dcb_printf(dcb, "Invalid argument: %s\n",
-										args[2]);
+										   args[2]);
+								}
+								else
+								{
+									cmds[i].options[j].fn(dcb, arg1);
+								}
 								break;
 							case 2:
 								arg1 = convert_arg(cli->mode, args[2],cmds[i].options[j].arg_types[0]);