Fix memory leaks in maxinfo (modified for develop-branch)

MXS-1009. This commit adds a gwbuf_free after maxinfo_execute() to
free a buffer with an sql-query after it has been processed. Also,
the parse tree in maxinfo_execute_query() is now freed. The tree_free-
function was renamed to maxinfo_tree_free, since it is now globally
available.

This commit has additional changes (in relation to the 1.4.4 branch)
to remove errors caused by differences in the html and sql-sides of
MaxInfo.

server/modules/routing/maxinfo/maxinfo.c

@@ -359,29 +359,35 @@ execute(ROUTER *rinstance, void *router_session, GWBUF *queue)
         return 1;
     }
 
-    // We have a complete request in a signle buffer
+    int rc = 1;
+    // We have a complete request in a single buffer
     if (modutil_MySQL_Query(queue, &sql, &len, &residual))
     {
         sql = strndup(sql, len);
-        int rc = maxinfo_execute_query(instance, session, sql);
+        rc = maxinfo_execute_query(instance, session, sql);
         MXS_FREE(sql);
-        return rc;
     }
     else
     {
         switch (MYSQL_COMMAND(queue))
         {
             case COM_PING:
-                return maxinfo_ping(instance, session, queue);
+                rc = maxinfo_ping(instance, session, queue);
+                break;
             case COM_STATISTICS:
-                return maxinfo_statistics(instance, session, queue);
+                rc = maxinfo_statistics(instance, session, queue);
+                break;
+            case COM_QUIT:
+                break;
             default:
                 MXS_ERROR("maxinfo: Unexpected MySQL command 0x%x",
                           MYSQL_COMMAND(queue));
+                break;
         }
     }
-
+    // MaxInfo doesn't route the data forward so it should be freed.
-    return 1;
+    gwbuf_free(queue);
+    return rc;
 }
 
 /**
@@ -652,6 +658,7 @@ maxinfo_execute_query(INFO_INSTANCE *instance, INFO_SESSION *session, char *sql)
     else
     {
         maxinfo_execute(session->dcb, tree);
+        maxinfo_free_tree(tree);
     }
     return 1;
 }

server/modules/routing/maxinfo/maxinfo.h

@@ -138,6 +138,7 @@ typedef enum
 
 
 extern MAXINFO_TREE *maxinfo_parse(char *, PARSE_ERROR *);
+extern void     maxinfo_free_tree(MAXINFO_TREE *);
 extern void     maxinfo_execute(DCB *, MAXINFO_TREE *);
 extern void         maxinfo_send_error(DCB *, int, char  *);
 extern void         maxinfo_send_parse_error(DCB *, char *, PARSE_ERROR);

server/modules/routing/maxinfo/maxinfo_exec.c

@@ -880,21 +880,27 @@ static void
 exec_show_variables(DCB *dcb, MAXINFO_TREE *filter)
 {
     RESULTSET *result;
-    VARCONTEXT context;
+    VARCONTEXT *context;
+
+    if ((context = MXS_MALLOC(sizeof(VARCONTEXT))) == NULL)
+    {
+        return;
+    }
 
     if (filter)
     {
-        context.like = filter->value;
+        context->like = filter->value;
     }
     else
     {
-        context.like = NULL;
+        context->like = NULL;
     }
-    context.index = 0;
+    context->index = 0;
 
-    if ((result = resultset_create(variable_row, &context)) == NULL)
+    if ((result = resultset_create(variable_row, context)) == NULL)
     {
         maxinfo_send_error(dcb, 0, "No resources available");
+        MXS_FREE(context);
         return;
     }
     resultset_add_column(result, "Variable_name", 40, COL_TYPE_VARCHAR);
@@ -1166,21 +1172,27 @@ static void
 exec_show_status(DCB *dcb, MAXINFO_TREE *filter)
 {
     RESULTSET *result;
-    VARCONTEXT context;
+    VARCONTEXT *context;
+
+    if ((context = MXS_MALLOC(sizeof(VARCONTEXT))) == NULL)
+    {
+        return;
+    }
 
     if (filter)
     {
-        context.like = filter->value;
+        context->like = filter->value;
     }
     else
     {
-        context.like = NULL;
+        context->like = NULL;
     }
-    context.index = 0;
+    context->index = 0;
 
-    if ((result = resultset_create(status_row, &context)) == NULL)
+    if ((result = resultset_create(status_row, context)) == NULL)
     {
         maxinfo_send_error(dcb, 0, "No resources available");
+        MXS_FREE(context);
         return;
     }
     resultset_add_column(result, "Variable_name", 40, COL_TYPE_VARCHAR);

server/modules/routing/maxinfo/maxinfo_parse.c

@@ -43,7 +43,7 @@
 #include <maxscale/log_manager.h>
 
 static MAXINFO_TREE *make_tree_node(MAXINFO_OPERATOR, char *, MAXINFO_TREE *, MAXINFO_TREE *);
-static void free_tree(MAXINFO_TREE *);
+void maxinfo_free_tree(MAXINFO_TREE *); // This function is needed by maxinfo.c
 static char *fetch_token(char *, int *, char **);
 static MAXINFO_TREE *parse_column_list(char **sql);
 static MAXINFO_TREE *parse_table_name(char **sql);
@@ -95,13 +95,13 @@ maxinfo_parse(char *sql, PARSE_ERROR *parse_error)
                     {
                         // Expected expression
                         *parse_error = PARSE_EXPECTED_LIKE;
-                        free_tree(tree);
+                        maxinfo_free_tree(tree);
                         return NULL;
                     }
                 }
                 // Malformed show
                 MXS_FREE(text);
-                free_tree(tree);
+                maxinfo_free_tree(tree);
                 *parse_error = PARSE_MALFORMED_SHOW;
                 return NULL;
 #if 0
@@ -132,7 +132,7 @@ maxinfo_parse(char *sql, PARSE_ERROR *parse_error)
                 {
                     /** Unknown token after SHUTDOWN MONITOR|SERVICE */
                     *parse_error = PARSE_SYNTAX_ERROR;
-                    free_tree(tree);
+                    maxinfo_free_tree(tree);
                     return NULL;
                 }
                 return tree;
@@ -146,7 +146,7 @@ maxinfo_parse(char *sql, PARSE_ERROR *parse_error)
                 {
                     /** Missing token for RESTART MONITOR|SERVICE */
                     *parse_error = PARSE_SYNTAX_ERROR;
-                    free_tree(tree);
+                    maxinfo_free_tree(tree);
                     return NULL;
                 }
                 tree->right = make_tree_node(MAXOP_LITERAL, text, NULL, NULL);
@@ -156,7 +156,7 @@ maxinfo_parse(char *sql, PARSE_ERROR *parse_error)
                     /** Unknown token after RESTART MONITOR|SERVICE */
                     *parse_error = PARSE_SYNTAX_ERROR;
                     MXS_FREE(text);
-                    free_tree(tree);
+                    maxinfo_free_tree(tree);
                     return NULL;
                 }
                 return tree;
@@ -278,20 +278,20 @@ make_tree_node(MAXINFO_OPERATOR op, char *value, MAXINFO_TREE *left, MAXINFO_TRE
 }
 
 /**
- * Recusrsively free the storage associated with a parse tree
+ * Recursively free the storage associated with a parse tree
  *
  * @param tree  The parse tree to free
  */
-static void
+void
-free_tree(MAXINFO_TREE *tree)
+maxinfo_free_tree(MAXINFO_TREE *tree)
 {
     if (tree->left)
     {
-        free_tree(tree->left);
+        maxinfo_free_tree(tree->left);
     }
     if (tree->right)
     {
-        free_tree(tree->right);
+        maxinfo_free_tree(tree->right);
     }
     if (tree->value)
     {
@@ -431,7 +431,7 @@ MAXINFO_TREE* maxinfo_parse_literals(MAXINFO_TREE *tree, int min_args, char *ptr
             (node->right = make_tree_node(MAXOP_LITERAL, text, NULL, NULL)) == NULL)
         {
             *parse_error = PARSE_SYNTAX_ERROR;
-            free_tree(tree);
+            maxinfo_free_tree(tree);
             if (ptr)
             {
                 MXS_FREE(text);