Add some missing wrappers (#1139)

* Add some missing wrappers:

sqlite3_value_subtype
sqlite3_result_subtype
sqlite3_changes64
sqlite3_db_readonly
sqlite3_txn_state
sqlite3_stmt_isexplain
sqlite3_vtab_config
sqlite3_index_info.idxFlags
sqlite3_index_info.colUsed
sqlite3_index_info.idxStr
sqlite3_vtab_collation

* Mark series VTab as innocuous and csv as direct only

src/transaction.rs

@@ -375,6 +375,20 @@ impl Drop for Savepoint<'_> {
     }
 }
 
+/// Transaction state of a database
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[non_exhaustive]
+#[cfg(feature = "modern_sqlite")] // 3.37.0
+#[cfg_attr(docsrs, doc(cfg(feature = "modern_sqlite")))]
+pub enum TransactionState {
+    /// Equivalent to SQLITE_TXN_NONE
+    None,
+    /// Equivalent to SQLITE_TXN_READ
+    Read,
+    /// Equivalent to SQLITE_TXN_WRITE
+    Write,
+}
+
 impl Connection {
     /// Begin a new transaction with the default behavior (DEFERRED).
     ///
@@ -499,6 +513,16 @@ impl Connection {
     pub fn savepoint_with_name<T: Into<String>>(&mut self, name: T) -> Result<Savepoint<'_>> {
         Savepoint::with_name(self, name)
     }
+
+    /// Determine the transaction state of a database
+    #[cfg(feature = "modern_sqlite")] // 3.37.0
+    #[cfg_attr(docsrs, doc(cfg(feature = "modern_sqlite")))]
+    pub fn transaction_state(
+        &self,
+        db_name: Option<crate::DatabaseName<'_>>,
+    ) -> Result<TransactionState> {
+        self.db.borrow().txn_state(db_name)
+    }
 }
 
 #[cfg(test)]
@@ -710,4 +734,25 @@ mod test {
         assert_eq!(x, i);
         Ok(())
     }
+
+    #[test]
+    #[cfg(feature = "modern_sqlite")]
+    fn txn_state() -> Result<()> {
+        use super::TransactionState;
+        use crate::DatabaseName;
+        let db = Connection::open_in_memory()?;
+        assert_eq!(
+            TransactionState::None,
+            db.transaction_state(Some(DatabaseName::Main))?
+        );
+        assert_eq!(TransactionState::None, db.transaction_state(None)?);
+        db.execute_batch("BEGIN")?;
+        assert_eq!(TransactionState::None, db.transaction_state(None)?);
+        let _: i32 = db.pragma_query_value(None, "user_version", |row| row.get(0))?;
+        assert_eq!(TransactionState::Read, db.transaction_state(None)?);
+        db.pragma_update(None, "user_version", 1)?;
+        assert_eq!(TransactionState::Write, db.transaction_state(None)?);
+        db.execute_batch("ROLLBACK")?;
+        Ok(())
+    }
 }