segfault when disconnecting from db with server side prepare
От | Scot Loach |
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Тема | segfault when disconnecting from db with server side prepare |
Дата | |
Msg-id | A8535F8D62F3644997E91F4F66E341FC1BB2F1@exchange.sandvine.com обсуждение исходный текст |
Список | pgsql-odbc |
If I enable server side prepare (UseServerSidePrepare=1 in my DSN) and connect to the database, execute a query, then disconnect,the following code path is taken: SQL_Disconnect calls PGAPI_Disconnect PGAPI_Disconnect calls CC_Cleanup CC_Cleanup iterates through its statements: /* Free all the stmts on this connection */ for (i = 0; i < self->num_stmts; i++) { stmt = self->stmts[i]; if (stmt) { stmt->hdbc = NULL; /* prevent any more dbase interactions */ SC_Destructor(stmt); self->stmts[i] = NULL; } } SC_Destructor calls SC_initialize_stmts(self, TRUE) SC_Initialize_stmts calls SC_set_prepared(self, FALSE), which dereferences the hdbc pointer, which was set to null in thecode block above: void SC_set_prepared(StatementClass *stmt, BOOL prepared) { if (prepared == stmt->prepared) return; if (!prepared) { ConnectionClass *conn = SC_get_conn(stmt); *** CRASH *** if (CONN_CONNECTED == conn->status) { QResultClass *res; char dealloc_stmt[128]; sprintf(dealloc_stmt, "DEALLOCATE _PLAN%0x", stmt); res = CC_send_query(conn, dealloc_stmt, NULL, 0); if (res) QR_Destructor(res); } } stmt->prepared = prepared; } The SC_set_prepared function is trying to deallocate the query plan on the server side - is this necessary if we're shuttingdown the connection? (anyway, the socket has already been closed before the statements are deallocated.) I think the proper way to fix this is to simply add a check for a null pointer in the SC_set_prepared function, but I wantedto ask here first since I don't know if this will have any unforseen consequences.
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