[libgda] GdaStatement: fix memory leak at statement execution

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 2bc8767b37f2fa17d6bdb29e16cc19b7863e1f29
Author: Daniel Espinosa <esodan gmail com>
Date:   Fri Apr 19 15:05:41 2019 -0500

    GdaStatement: fix memory leak at statement execution

 libgda/gda-statement.c              |  4 ++--
 libgda/gda-util.c                   | 14 ++++++--------
 libgda/sqlite/gda-sqlite-provider.c | 10 +++++-----
 3 files changed, 13 insertions(+), 15 deletions(-)
---
diff --git a/libgda/gda-statement.c b/libgda/gda-statement.c
index 63d289138..40e8868c1 100644
--- a/libgda/gda-statement.c
+++ b/libgda/gda-statement.c
@@ -205,11 +205,11 @@ gda_statement_dispose (GObject *object)
        stmt = GDA_STATEMENT (object);
        GdaStatementPrivate *priv = gda_statement_get_instance_private (stmt);
 
-       if (priv->requested_types) {
+       if (priv->requested_types != NULL) {
                g_free (priv->requested_types);
                priv->requested_types = NULL;
        }
-       if (priv->internal_struct) {
+       if (priv->internal_struct != NULL) {
                gda_sql_statement_free (priv->internal_struct);
                priv->internal_struct = NULL;
        }
diff --git a/libgda/gda-util.c b/libgda/gda-util.c
index b22f96d24..436bb52b1 100644
--- a/libgda/gda-util.c
+++ b/libgda/gda-util.c
@@ -1628,7 +1628,8 @@ gda_rewrite_statement_for_null_parameters (GdaStatement *stmt, GdaSet *params,
                                           GdaStatement **out_stmt, GError **error)
 {
        GdaSqlStatement *sqlst;
-       gboolean mod;
+       gboolean mod = FALSE;
+       gboolean ret = FALSE;
        g_return_val_if_fail (GDA_IS_STATEMENT (stmt), FALSE);
        g_return_val_if_fail (!params || GDA_IS_SET (params), FALSE);
 
@@ -1642,16 +1643,13 @@ gda_rewrite_statement_for_null_parameters (GdaStatement *stmt, GdaSet *params,
                if (out_stmt) {
                        if (mod) {
                                *out_stmt = g_object_new (GDA_TYPE_STATEMENT, "structure", sqlst, NULL);
-                               gda_sql_statement_free (sqlst);
+        ret = mod;
                        }
                }
-               return mod;
-       }
-       else {
-               gda_sql_statement_free (sqlst);
-               /* error => leave *out_stmt to %NULL */
-               return TRUE;
        }
+       gda_sql_statement_free (sqlst);
+       /* error => leave *out_stmt to %NULL */
+       return ret;
 }
 
 
diff --git a/libgda/sqlite/gda-sqlite-provider.c b/libgda/sqlite/gda-sqlite-provider.c
index 7b3747b4b..6edf91e2d 100644
--- a/libgda/sqlite/gda-sqlite-provider.c
+++ b/libgda/sqlite/gda-sqlite-provider.c
@@ -3493,7 +3493,7 @@ gda_sqlite_provider_statement_execute (GdaServerProvider *provider, GdaConnectio
                }
                else if (gda_holder_value_is_default (h) && !gda_holder_get_value (h)) {
                        /* create a new GdaStatement to handle all default values and execute it instead */
-                       GdaSqlStatement *sqlst;
+                       GdaSqlStatement *sqlst = NULL;
                        GError *lerror = NULL;
                        sqlst = gda_statement_rewrite_for_default_values (stmt, params, TRUE, &lerror);
                        if (!sqlst) {
@@ -3506,7 +3506,7 @@ gda_sqlite_provider_statement_execute (GdaServerProvider *provider, GdaConnectio
                                break;
                        }
 
-                       GdaStatement *rstmt;
+                       GdaStatement *rstmt = NULL;
                        GObject *res;
                        rstmt = g_object_new (GDA_TYPE_STATEMENT, "structure", sqlst, NULL);
                        gda_sql_statement_free (sqlst);
@@ -3524,12 +3524,12 @@ gda_sqlite_provider_statement_execute (GdaServerProvider *provider, GdaConnectio
                const GValue *value = gda_holder_get_value (h);
                /*g_print ("BINDING param '%s' to GdaHolder %p, valued to [%s]\n", pname, h, 
gda_value_stringify (value));*/
                if (!value || gda_value_is_null (value)) {
-                       GdaStatement *rstmt;
+                       GdaStatement *rstmt = NULL;
                        if (! gda_rewrite_statement_for_null_parameters (stmt, params, &rstmt, error))
                                SQLITE3_CALL (prov, sqlite3_bind_null) (_gda_sqlite_pstmt_get_stmt (ps), i);
-                       else if (!rstmt)
+                       else if (rstmt == NULL) {
                                return NULL;
-                       else {
+      } else {
                                /* The strategy here is to execute @rstmt using its prepared
                                 * statement, but with common data from @ps. Beware that
                                 * the @param_ids attribute needs to be retained (i.e. it must not