Unable to use SQLite3 in Rust via FFI due to a misused prepared statement -
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i porting code rust reads database path stdin, opens database , loops queries. have done similar in c pretty sure problem non-understanding of rust ffi.
i using sqlite3 binding provided libsqlite3-sys, 1 rusqlite. the whole code here.
open_connection initializes pointer , passes sqlite3_open_v2 , checks if went well.
// line 54 of complete code fn open_connection(s: string) -> result<rawconnection, sqlite3error> { unsafe { let mut db: *mut sqlite3::sqlite3 = mem::uninitialized(); let r = sqlite3::sqlite3_open_v2(cstring::new(s).unwrap().as_ptr(), &mut db, sqlite3::sqlite_open_create | sqlite3::sqlite_open_readwrite, ptr::null()); match r { sqlite3::sqlite_ok => ok(rawconnection { db: db }), _ => return err(sqlite3error::openerror), } } } i create sql statement converting query rust string c string, creating pointer location of statement , go on creating statement , checking output:
// line 35 of complete code fn create_statement(conn: &rawconnection, query: string) -> result<statement, sqlite3error> { let len = query.len(); let raw_query = cstring::new(query).unwrap().as_ptr(); unsafe { let mut stmt: *mut sqlite3::sqlite3_stmt = mem::uninitialized(); if stmt.is_null() { println!("now null!"); } match sqlite3::sqlite3_prepare_v2(conn.db, raw_query, len i32, &mut stmt, ptr::null_mut()) { sqlite3::sqlite_ok => ok(statement { stmt: stmt }), _ => err(sqlite3error::statementerror), } } } i try execute statement
// line 81 of complete code fn execute_statement(conn: &rawconnection, stmt: statement) -> result<cursor, sqlite3error> { match unsafe { sqlite3::sqlite3_step(stmt.stmt) } { sqlite3::sqlite_ok => ok(cursor::okcursor), sqlite3::sqlite_done => ok(cursor::donecursor), sqlite3::sqlite_row => { let n_columns = unsafe { sqlite3::sqlite3_column_count(stmt.stmt) } i32; let mut types: vec<entitytype> = vec::new(); in 0..n_columns { types.push(match unsafe { sqlite3::sqlite3_column_type(stmt.stmt, i) } { sqlite3::sqlite_integer => entitytype::integer, sqlite3::sqlite_float => entitytype::float, sqlite3::sqlite_text => entitytype::text, sqlite3::sqlite_blob => entitytype::blob, sqlite3::sqlite_null => entitytype::null, _ => entitytype::null, }) } ok(cursor::rowscursor { stmt: stmt, num_columns: n_columns, types: types, previous_status: sqlite3::sqlite_row, }) } x => { println!("{}", x); return err(sqlite3error::executeerror); } } } this fails error code 21 misuse. usually, error happens when try execute null statement have no idea how figure out.
do see other problem may cause code 21 misuse?
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