cursor.c

/* cursor.c - the cursor type
 *
 * Copyright (C) 2004-2010 Gerhard Häring <gh@ghaering.de>
 *
 * This file is part of pysqlite.
 *
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software
 * in a product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 */

#ifndef Py_BUILD_CORE_BUILTIN
# define Py_BUILD_CORE_MODULE 1
#endif

#include "cursor.h"
#include "microprotocols.h"
#include "module.h"
#include "util.h"

#include "pycore_pyerrors.h" // _PyErr_FormatFromCause()
#include "pycore_weakref.h" // FT_CLEAR_WEAKREFS()

typedef enum {
 TYPE_LONG,
 TYPE_FLOAT,
 TYPE_UNICODE,
 TYPE_BUFFER,
 TYPE_UNKNOWN
} parameter_type;

#define clinic_state() (pysqlite_get_state_by_type(Py_TYPE(self)))
#include "clinic/cursor.c.h"
#undef clinic_state

#define _pysqlite_Cursor_CAST(op) ((pysqlite_Cursor *)(op))

static inline int
check_cursor_locked(pysqlite_Cursor *cur)
{
 if (cur->locked) {
 PyErr_SetString(cur->connection->ProgrammingError,
 "Recursive use of cursors not allowed.");
 return 0;
 }
 return 1;
}

static pysqlite_state *
get_module_state_by_cursor(pysqlite_Cursor *cursor)
{
 if (cursor->connection != NULL && cursor->connection->state != NULL) {
 return cursor->connection->state;
 }
 return pysqlite_get_state_by_type(Py_TYPE(cursor));
}

static void
cursor_sqlite3_internal_error(pysqlite_Cursor *cursor,
 const char *error_message,
 int chain_exceptions)
{
 pysqlite_state *state = get_module_state_by_cursor(cursor);
 if (chain_exceptions) {
 assert(PyErr_Occurred());
 PyObject *exc = PyErr_GetRaisedException();
 PyErr_SetString(state->InternalError, error_message);
 _PyErr_ChainExceptions1(exc);
 }
 else {
 assert(!PyErr_Occurred());
 PyErr_SetString(state->InternalError, error_message);
 }
}

static void
cursor_cannot_reset_stmt_error(pysqlite_Cursor *cursor, int chain_exceptions)
{
 cursor_sqlite3_internal_error(cursor,
 "cannot reset statement",
 chain_exceptions);
}

/*[clinic input]
module _sqlite3
class _sqlite3.Cursor "pysqlite_Cursor *" "clinic_state()->CursorType"
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=3c5b8115c5cf30f1]*/

/*[clinic input]
_sqlite3.Cursor.__init__ as pysqlite_cursor_init

 connection: object(type='pysqlite_Connection *', subclass_of='clinic_state()->ConnectionType')
 /

[clinic start generated code]*/

static int
pysqlite_cursor_init_impl(pysqlite_Cursor *self,
 pysqlite_Connection *connection)
/*[clinic end generated code: output=ac59dce49a809ca8 input=23d4265b534989fb]*/
{
 if (!check_cursor_locked(self)) {
 return -1;
 }

 Py_INCREF(connection);
 Py_XSETREF(self->connection, connection);
 Py_CLEAR(self->statement);
 Py_CLEAR(self->row_cast_map);

 Py_INCREF(Py_None);
 Py_XSETREF(self->description, Py_None);

 Py_INCREF(Py_None);
 Py_XSETREF(self->lastrowid, Py_None);

 self->arraysize = 1;
 self->closed = 0;
 self->rowcount = -1L;

 Py_INCREF(Py_None);
 Py_XSETREF(self->row_factory, Py_None);

 if (!pysqlite_check_thread(self->connection)) {
 return -1;
 }

 self->initialized = 1;

 return 0;
}

static inline int
stmt_reset(pysqlite_Statement *self)
{
 int rc = SQLITE_OK;

 if (self->st != NULL) {
 Py_BEGIN_ALLOW_THREADS
 rc = sqlite3_reset(self->st);
 Py_END_ALLOW_THREADS
 }

 return rc;
}

static int
cursor_traverse(PyObject *op, visitproc visit, void *arg)
{
 pysqlite_Cursor *self = _pysqlite_Cursor_CAST(op);
 Py_VISIT(Py_TYPE(self));
 Py_VISIT(self->connection);
 Py_VISIT(self->description);
 Py_VISIT(self->row_cast_map);
 Py_VISIT(self->lastrowid);
 Py_VISIT(self->row_factory);
 Py_VISIT(self->statement);
 return 0;
}

static int
cursor_clear(PyObject *op)
{
 pysqlite_Cursor *self = _pysqlite_Cursor_CAST(op);
 Py_CLEAR(self->connection);
 Py_CLEAR(self->description);
 Py_CLEAR(self->row_cast_map);
 Py_CLEAR(self->lastrowid);
 Py_CLEAR(self->row_factory);
 if (self->statement) {
 /* Reset the statement if the user has not closed the cursor */
 int rc = stmt_reset(self->statement);
 Py_CLEAR(self->statement);
 if (rc != SQLITE_OK) {
 cursor_cannot_reset_stmt_error(self, 0);
 PyErr_FormatUnraisable("Exception ignored in cursor_clear()");
 }
 }

 return 0;
}

static void
cursor_dealloc(PyObject *op)
{
 pysqlite_Cursor *self = _pysqlite_Cursor_CAST(op);
 PyTypeObject *tp = Py_TYPE(self);
 PyObject_GC_UnTrack(self);
 FT_CLEAR_WEAKREFS(op, self->in_weakreflist);
 (void)tp->tp_clear(op);
 tp->tp_free(self);
 Py_DECREF(tp);
}

static PyObject *
_pysqlite_get_converter(pysqlite_state *state, const char *keystr,
 Py_ssize_t keylen)
{
 PyObject *key;
 PyObject *upcase_key;
 PyObject *retval;

 key = PyUnicode_FromStringAndSize(keystr, keylen);
 if (!key) {
 return NULL;
 }
 upcase_key = PyObject_CallMethodNoArgs(key, state->str_upper);
 Py_DECREF(key);
 if (!upcase_key) {
 return NULL;
 }

 retval = PyDict_GetItemWithError(state->converters, upcase_key);
 Py_DECREF(upcase_key);

 return retval;
}

static int
pysqlite_build_row_cast_map(pysqlite_Cursor* self)
{
 int i;
 const char* pos;
 const char* decltype;
 PyObject* converter;

 if (!self->connection->detect_types) {
 return 0;
 }

 Py_XSETREF(self->row_cast_map, PyList_New(0));
 if (!self->row_cast_map) {
 return -1;
 }

 for (i = 0; i < sqlite3_column_count(self->statement->st); i++) {
 converter = NULL;

 if (self->connection->detect_types & PARSE_COLNAMES) {
 const char *colname = sqlite3_column_name(self->statement->st, i);
 if (colname == NULL) {
 PyErr_NoMemory();
 Py_CLEAR(self->row_cast_map);
 return -1;
 }
 const char *type_start = NULL;
 for (pos = colname; *pos != 0; pos++) {
 if (*pos == '[') {
 type_start = pos + 1;
 }
 else if (*pos == ']' && type_start != NULL) {
 pysqlite_state *state = self->connection->state;
 converter = _pysqlite_get_converter(state, type_start,
 pos - type_start);
 if (!converter && PyErr_Occurred()) {
 Py_CLEAR(self->row_cast_map);
 return -1;
 }
 break;
 }
 }
 }

 if (!converter && self->connection->detect_types & PARSE_DECLTYPES) {
 decltype = sqlite3_column_decltype(self->statement->st, i);
 if (decltype) {
 for (pos = decltype;;pos++) {
 /* Converter names are split at '(' and blanks.
 * This allows 'INTEGER NOT NULL' to be treated as 'INTEGER' and
 * 'NUMBER(10)' to be treated as 'NUMBER', for example.
 * In other words, it will work as people expect it to work.*/
 if (*pos == ' ' || *pos == '(' || *pos == 0) {
 pysqlite_state *state = self->connection->state;
 converter = _pysqlite_get_converter(state, decltype,
 pos - decltype);
 if (!converter && PyErr_Occurred()) {
 Py_CLEAR(self->row_cast_map);
 return -1;
 }
 break;
 }
 }
 }
 }

 if (!converter) {
 converter = Py_None;
 }

 if (PyList_Append(self->row_cast_map, converter) != 0) {
 Py_CLEAR(self->row_cast_map);
 return -1;
 }
 }

 return 0;
}

static PyObject *
_pysqlite_build_column_name(pysqlite_Cursor *self, const char *colname)
{
 const char* pos;
 Py_ssize_t len;

 if (self->connection->detect_types & PARSE_COLNAMES) {
 for (pos = colname; *pos; pos++) {
 if (*pos == '[') {
 if ((pos != colname) && (*(pos-1) == ' ')) {
 pos--;
 }
 break;
 }
 }
 len = pos - colname;
 }
 else {
 len = strlen(colname);
 }
 return PyUnicode_FromStringAndSize(colname, len);
}

/*
 * Returns a row from the currently active SQLite statement
 *
 * Precondidition:
 * - sqlite3_step() has been called before and it returned SQLITE_ROW.
 */
static PyObject *
_pysqlite_fetch_one_row(pysqlite_Cursor* self)
{
 int i, numcols;
 PyObject* row;
 int coltype;
 PyObject* converter;
 PyObject* converted;
 Py_ssize_t nbytes;
 char buf[200];
 const char* colname;
 PyObject* error_msg;

 Py_BEGIN_ALLOW_THREADS
 numcols = sqlite3_data_count(self->statement->st);
 Py_END_ALLOW_THREADS

 row = PyTuple_New(numcols);
 if (!row)
 return NULL;

 sqlite3 *db = self->connection->db;
 for (i = 0; i < numcols; i++) {
 if (self->connection->detect_types
 && self->row_cast_map != NULL
 && i < PyList_GET_SIZE(self->row_cast_map))
 {
 converter = PyList_GET_ITEM(self->row_cast_map, i);
 }
 else {
 converter = Py_None;
 }

 /*
 * Note, sqlite3_column_bytes() must come after sqlite3_column_blob()
 * or sqlite3_column_text().
 *
 * See https://sqlite.org/c3ref/column_blob.html for details.
 */
 if (converter != Py_None) {
 const void *blob = sqlite3_column_blob(self->statement->st, i);
 if (blob == NULL) {
 if (sqlite3_errcode(db) == SQLITE_NOMEM) {
 PyErr_NoMemory();
 goto error;
 }
 converted = Py_NewRef(Py_None);
 }
 else {
 nbytes = sqlite3_column_bytes(self->statement->st, i);
 PyObject *item = PyBytes_FromStringAndSize(blob, nbytes);
 if (item == NULL) {
 goto error;
 }
 converted = PyObject_CallOneArg(converter, item);
 Py_DECREF(item);
 }
 } else {
 Py_BEGIN_ALLOW_THREADS
 coltype = sqlite3_column_type(self->statement->st, i);
 Py_END_ALLOW_THREADS
 if (coltype == SQLITE_NULL) {
 converted = Py_NewRef(Py_None);
 } else if (coltype == SQLITE_INTEGER) {
 converted = PyLong_FromLongLong(sqlite3_column_int64(self->statement->st, i));
 } else if (coltype == SQLITE_FLOAT) {
 converted = PyFloat_FromDouble(sqlite3_column_double(self->statement->st, i));
 } else if (coltype == SQLITE_TEXT) {
 const char *text = (const char*)sqlite3_column_text(self->statement->st, i);
 if (text == NULL && sqlite3_errcode(db) == SQLITE_NOMEM) {
 PyErr_NoMemory();
 goto error;
 }

 nbytes = sqlite3_column_bytes(self->statement->st, i);
 if (self->connection->text_factory == (PyObject*)&PyUnicode_Type) {
 converted = PyUnicode_FromStringAndSize(text, nbytes);
 if (!converted && PyErr_ExceptionMatches(PyExc_UnicodeDecodeError)) {
 PyErr_Clear();
 colname = sqlite3_column_name(self->statement->st, i);
 if (colname == NULL) {
 PyErr_NoMemory();
 goto error;
 }
 PyOS_snprintf(buf, sizeof(buf) - 1, "Could not decode to UTF-8 column '%s' with text '%s'",
 colname , text);
 error_msg = PyUnicode_Decode(buf, strlen(buf), "ascii", "replace");

 PyObject *exc = self->connection->OperationalError;
 if (!error_msg) {
 PyErr_SetString(exc, "Could not decode to UTF-8");
 } else {
 PyErr_SetObject(exc, error_msg);
 Py_DECREF(error_msg);
 }
 }
 } else if (self->connection->text_factory == (PyObject*)&PyBytes_Type) {
 converted = PyBytes_FromStringAndSize(text, nbytes);
 } else if (self->connection->text_factory == (PyObject*)&PyByteArray_Type) {
 converted = PyByteArray_FromStringAndSize(text, nbytes);
 } else {
 converted = PyObject_CallFunction(self->connection->text_factory, "y#", text, nbytes);
 }
 } else {
 /* coltype == SQLITE_BLOB */
 const void *blob = sqlite3_column_blob(self->statement->st, i);
 if (blob == NULL && sqlite3_errcode(db) == SQLITE_NOMEM) {
 PyErr_NoMemory();
 goto error;
 }

 nbytes = sqlite3_column_bytes(self->statement->st, i);
 converted = PyBytes_FromStringAndSize(blob, nbytes);
 }
 }

 if (!converted) {
 goto error;
 }
 PyTuple_SET_ITEM(row, i, converted);
 }

 if (PyErr_Occurred())
 goto error;

 return row;

error:
 Py_DECREF(row);
 return NULL;
}

/*
 * Checks if a cursor object is usable.
 *
 * 0 => error; 1 => ok
 */
static int check_cursor(pysqlite_Cursor* cur)
{
 if (!cur->initialized) {
 pysqlite_state *state = pysqlite_get_state_by_type(Py_TYPE(cur));
 PyErr_SetString(state->ProgrammingError,
 "Base Cursor.__init__ not called.");
 return 0;
 }

 assert(cur->connection != NULL);
 assert(cur->connection->state != NULL);

 if (cur->closed) {
 PyErr_SetString(cur->connection->state->ProgrammingError,
 "Cannot operate on a closed cursor.");
 return 0;
 }

 return (pysqlite_check_thread(cur->connection)
 && pysqlite_check_connection(cur->connection)
 && check_cursor_locked(cur));
}

static int
begin_transaction(pysqlite_Connection *self)
{
 assert(self->isolation_level != NULL);
 int rc;

 Py_BEGIN_ALLOW_THREADS
 sqlite3_stmt *statement;
 char begin_stmt[16] = "BEGIN ";
#ifdef Py_DEBUG
 size_t len = strlen(self->isolation_level);
 assert(len <= 9);
#endif
 (void)strcat(begin_stmt, self->isolation_level);
 rc = sqlite3_prepare_v2(self->db, begin_stmt, -1, &statement, NULL);
 if (rc == SQLITE_OK) {
 (void)sqlite3_step(statement);
 rc = sqlite3_finalize(statement);
 }
 Py_END_ALLOW_THREADS

 if (rc != SQLITE_OK) {
 set_error_from_db(self->state, self->db);
 return -1;
 }

 return 0;
}

static PyObject *
get_statement_from_cache(pysqlite_Cursor *self, PyObject *operation)
{
 PyObject *args[] = { NULL, operation, }; // Borrowed ref.
 PyObject *cache = self->connection->statement_cache;
 size_t nargsf = 1 | PY_VECTORCALL_ARGUMENTS_OFFSET;
 return PyObject_Vectorcall(cache, args + 1, nargsf, NULL);
}

static inline int
stmt_step(sqlite3_stmt *statement)
{
 int rc;

 Py_BEGIN_ALLOW_THREADS
 rc = sqlite3_step(statement);
 Py_END_ALLOW_THREADS

 return rc;
}

static int
bind_param(pysqlite_state *state, pysqlite_Statement *self, int pos,
 PyObject *parameter)
{
 int rc = SQLITE_OK;
 const char *string;
 Py_ssize_t buflen;
 parameter_type paramtype;

 if (parameter == Py_None) {
 rc = sqlite3_bind_null(self->st, pos);
 goto final;
 }

 if (PyLong_CheckExact(parameter)) {
 paramtype = TYPE_LONG;
 } else if (PyFloat_CheckExact(parameter)) {
 paramtype = TYPE_FLOAT;
 } else if (PyUnicode_CheckExact(parameter)) {
 paramtype = TYPE_UNICODE;
 } else if (PyLong_Check(parameter)) {
 paramtype = TYPE_LONG;
 } else if (PyFloat_Check(parameter)) {
 paramtype = TYPE_FLOAT;
 } else if (PyUnicode_Check(parameter)) {
 paramtype = TYPE_UNICODE;
 } else if (PyObject_CheckBuffer(parameter)) {
 paramtype = TYPE_BUFFER;
 } else {
 paramtype = TYPE_UNKNOWN;
 }

 switch (paramtype) {
 case TYPE_LONG: {
 sqlite_int64 value = _pysqlite_long_as_int64(parameter);
 rc = (value == -1 && PyErr_Occurred())
 ? SQLITE_ERROR
 : sqlite3_bind_int64(self->st, pos, value);
 break;
 }
 case TYPE_FLOAT: {
 double value = PyFloat_AsDouble(parameter);
 rc = (value == -1 && PyErr_Occurred())
 ? SQLITE_ERROR
 : sqlite3_bind_double(self->st, pos, value);
 break;
 }
 case TYPE_UNICODE:
 string = PyUnicode_AsUTF8AndSize(parameter, &buflen);
 if (string == NULL) {
 return SQLITE_ERROR;
 }
 if (buflen > INT_MAX) {
 PyErr_SetString(PyExc_OverflowError,
 "string longer than INT_MAX bytes");
 return SQLITE_ERROR;
 }
 rc = sqlite3_bind_text(self->st, pos, string, (int)buflen, SQLITE_TRANSIENT);
 break;
 case TYPE_BUFFER: {
 Py_buffer view;
 if (PyObject_GetBuffer(parameter, &view, PyBUF_SIMPLE) != 0) {
 return SQLITE_ERROR;
 }
 if (view.len > INT_MAX) {
 PyErr_SetString(PyExc_OverflowError,
 "BLOB longer than INT_MAX bytes");
 PyBuffer_Release(&view);
 return SQLITE_ERROR;
 }
 rc = sqlite3_bind_blob(self->st, pos, view.buf, (int)view.len, SQLITE_TRANSIENT);
 PyBuffer_Release(&view);
 break;
 }
 case TYPE_UNKNOWN:
 PyErr_Format(state->ProgrammingError,
 "Error binding parameter %d: type '%s' is not supported",
 pos, Py_TYPE(parameter)->tp_name);
 rc = SQLITE_ERROR;
 }

final:
 return rc;
}

/* returns 0 if the object is one of Python's internal ones that don't need to be adapted */
static inline int
need_adapt(pysqlite_state *state, PyObject *obj)
{
 if (state->BaseTypeAdapted) {
 return 1;
 }

 if (PyLong_CheckExact(obj) || PyFloat_CheckExact(obj)
 || PyUnicode_CheckExact(obj) || PyByteArray_CheckExact(obj)) {
 return 0;
 } else {
 return 1;
 }
}

static void
bind_parameters(pysqlite_state *state, pysqlite_Statement *self,
 PyObject *parameters)
{
 PyObject* current_param;
 PyObject* adapted;
 const char* binding_name;
 int i;
 int rc;
 int num_params_needed;
 Py_ssize_t num_params;

 Py_BEGIN_ALLOW_THREADS
 num_params_needed = sqlite3_bind_parameter_count(self->st);
 Py_END_ALLOW_THREADS

 if (PyTuple_CheckExact(parameters) || PyList_CheckExact(parameters) || (!PyDict_Check(parameters) && PySequence_Check(parameters))) {
 /* parameters passed as sequence */
 if (PyTuple_CheckExact(parameters)) {
 num_params = PyTuple_GET_SIZE(parameters);
 } else if (PyList_CheckExact(parameters)) {
 num_params = PyList_GET_SIZE(parameters);
 } else {
 num_params = PySequence_Size(parameters);
 if (num_params == -1) {
 return;
 }
 }
 if (num_params != num_params_needed) {
 PyErr_Format(state->ProgrammingError,
 "Incorrect number of bindings supplied. The current "
 "statement uses %d, and there are %zd supplied.",
 num_params_needed, num_params);
 return;
 }
 for (i = 0; i < num_params; i++) {
 const char *name = sqlite3_bind_parameter_name(self->st, i+1);
 if (name != NULL && name[0] != '?') {
 PyErr_Format(state->ProgrammingError,
 "Binding %d ('%s') is a named parameter, but you "
 "supplied a sequence which requires nameless (qmark) "
 "placeholders.",
 i+1, name);
 return;
 }

 if (PyTuple_CheckExact(parameters)) {
 PyObject *item = PyTuple_GET_ITEM(parameters, i);
 current_param = Py_NewRef(item);
 } else if (PyList_CheckExact(parameters)) {
 PyObject *item = PyList_GetItem(parameters, i);
 current_param = Py_XNewRef(item);
 } else {
 current_param = PySequence_GetItem(parameters, i);
 }
 if (!current_param) {
 return;
 }

 if (!need_adapt(state, current_param)) {
 adapted = current_param;
 } else {
 PyObject *protocol = (PyObject *)state->PrepareProtocolType;
 adapted = pysqlite_microprotocols_adapt(state, current_param,
 protocol,
 current_param);
 Py_DECREF(current_param);
 if (!adapted) {
 return;
 }
 }

 rc = bind_param(state, self, i + 1, adapted);
 Py_DECREF(adapted);

 if (rc != SQLITE_OK) {
 PyObject *exc = PyErr_GetRaisedException();
 sqlite3 *db = sqlite3_db_handle(self->st);
 set_error_from_db(state, db);
 _PyErr_ChainExceptions1(exc);
 return;
 }
 }
 } else if (PyDict_Check(parameters)) {
 /* parameters passed as dictionary */
 for (i = 1; i <= num_params_needed; i++) {
 Py_BEGIN_ALLOW_THREADS
 binding_name = sqlite3_bind_parameter_name(self->st, i);
 Py_END_ALLOW_THREADS
 if (!binding_name) {
 PyErr_Format(state->ProgrammingError,
 "Binding %d has no name, but you supplied a "
 "dictionary (which has only names).", i);
 return;
 }

 binding_name++; /* skip first char (the colon) */
 PyObject *current_param = NULL;
 int found = PyMapping_GetOptionalItemString(parameters,
 binding_name,
 &current_param);
 if (found == -1) {
 return;
 }
 else if (found == 0) {
 PyErr_Format(state->ProgrammingError,
 "You did not supply a value for binding "
 "parameter :%s.", binding_name);
 return;
 }

 if (!need_adapt(state, current_param)) {
 adapted = current_param;
 } else {
 PyObject *protocol = (PyObject *)state->PrepareProtocolType;
 adapted = pysqlite_microprotocols_adapt(state, current_param,
 protocol,
 current_param);
 Py_DECREF(current_param);
 if (!adapted) {
 return;
 }
 }

 rc = bind_param(state, self, i, adapted);
 Py_DECREF(adapted);

 if (rc != SQLITE_OK) {
 PyObject *exc = PyErr_GetRaisedException();
 sqlite3 *db = sqlite3_db_handle(self->st);
 set_error_from_db(state, db);
 _PyErr_ChainExceptions1(exc);
 return;
 }
 }
 } else {
 PyErr_SetString(state->ProgrammingError,
 "parameters are of unsupported type");
 }
}

PyObject *
_pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* operation, PyObject* second_argument)
{
 PyObject* parameters_list = NULL;
 PyObject* parameters_iter = NULL;
 PyObject* parameters = NULL;
 int i;
 int rc;
 int numcols;
 PyObject* column_name;

 if (!check_cursor(self)) {
 goto error;
 }

 self->locked = 1;

 if (multiple) {
 if (PyIter_Check(second_argument)) {
 /* iterator */
 parameters_iter = Py_NewRef(second_argument);
 } else {
 /* sequence */
 parameters_iter = PyObject_GetIter(second_argument);
 if (!parameters_iter) {
 goto error;
 }
 }
 } else {
 parameters_list = PyList_New(0);
 if (!parameters_list) {
 goto error;
 }

 if (second_argument == NULL) {
 second_argument = PyTuple_New(0);
 if (!second_argument) {
 goto error;
 }
 } else {
 Py_INCREF(second_argument);
 }
 if (PyList_Append(parameters_list, second_argument) != 0) {
 Py_DECREF(second_argument);
 goto error;
 }
 Py_DECREF(second_argument);

 parameters_iter = PyObject_GetIter(parameters_list);
 if (!parameters_iter) {
 goto error;
 }
 }

 /* reset description */
 Py_INCREF(Py_None);
 Py_SETREF(self->description, Py_None);

 if (self->statement) {
 // Reset pending statements on this cursor.
 if (stmt_reset(self->statement) != SQLITE_OK) {
 goto reset_failure;
 }
 }

 PyObject *stmt = get_statement_from_cache(self, operation);
 Py_XSETREF(self->statement, (pysqlite_Statement *)stmt);
 if (!self->statement) {
 goto error;
 }

 pysqlite_state *state = self->connection->state;
 if (multiple && sqlite3_stmt_readonly(self->statement->st)) {
 PyErr_SetString(state->ProgrammingError,
 "executemany() can only execute DML statements.");
 goto error;
 }

 if (sqlite3_stmt_busy(self->statement->st)) {
 Py_SETREF(self->statement,
 pysqlite_statement_create(self->connection, operation));
 if (self->statement == NULL) {
 goto error;
 }
 }

 if (stmt_reset(self->statement) != SQLITE_OK) {
 goto reset_failure;
 }
 self->rowcount = self->statement->is_dml ? 0L : -1L;

 /* We start a transaction implicitly before a DML statement.
 SELECT is the only exception. See #9924. */
 if (self->connection->autocommit == AUTOCOMMIT_LEGACY
 && self->connection->isolation_level
 && self->statement->is_dml
 && sqlite3_get_autocommit(self->connection->db))
 {
 if (begin_transaction(self->connection) < 0) {
 goto error;
 }
 }

 assert(!sqlite3_stmt_busy(self->statement->st));
 while (1) {
 parameters = PyIter_Next(parameters_iter);
 if (!parameters) {
 break;
 }

 bind_parameters(state, self->statement, parameters);
 if (PyErr_Occurred()) {
 goto error;
 }

 rc = stmt_step(self->statement->st);
 if (rc != SQLITE_DONE && rc != SQLITE_ROW) {
 if (PyErr_Occurred()) {
 /* there was an error that occurred in a user-defined callback */
 if (state->enable_callback_tracebacks) {
 PyErr_Print();
 } else {
 PyErr_Clear();
 }
 }
 set_error_from_db(state, self->connection->db);
 goto error;
 }

 if (pysqlite_build_row_cast_map(self) != 0) {
 _PyErr_FormatFromCause(state->OperationalError,
 "Error while building row_cast_map");
 goto error;
 }

 assert(rc == SQLITE_ROW || rc == SQLITE_DONE);
 Py_BEGIN_ALLOW_THREADS
 numcols = sqlite3_column_count(self->statement->st);
 Py_END_ALLOW_THREADS
 if (self->description == Py_None && numcols > 0) {
 Py_SETREF(self->description, PyTuple_New(numcols));
 if (!self->description) {
 goto error;
 }
 for (i = 0; i < numcols; i++) {
 const char *colname;
 colname = sqlite3_column_name(self->statement->st, i);
 if (colname == NULL) {
 PyErr_NoMemory();
 goto error;
 }
 column_name = _pysqlite_build_column_name(self, colname);
 if (column_name == NULL) {
 goto error;
 }
 PyObject *descriptor = PyTuple_Pack(7, column_name,
 Py_None, Py_None, Py_None,
 Py_None, Py_None, Py_None);
 Py_DECREF(column_name);
 if (descriptor == NULL) {
 goto error;
 }
 PyTuple_SET_ITEM(self->description, i, descriptor);
 }
 }

 if (rc == SQLITE_DONE) {
 if (self->statement->is_dml) {
 self->rowcount += (long)sqlite3_changes(self->connection->db);
 }
 if (stmt_reset(self->statement) != SQLITE_OK) {
 goto reset_failure;
 }
 }
 Py_XDECREF(parameters);
 }

 if (!multiple) {
 sqlite_int64 lastrowid;

 Py_BEGIN_ALLOW_THREADS
 lastrowid = sqlite3_last_insert_rowid(self->connection->db);
 Py_END_ALLOW_THREADS

 Py_SETREF(self->lastrowid, PyLong_FromLongLong(lastrowid));
 // Fall through on error.
 }

error:
 Py_XDECREF(parameters);
 Py_XDECREF(parameters_iter);
 Py_XDECREF(parameters_list);

 self->locked = 0;

 if (PyErr_Occurred()) {
 if (self->statement) {
 sqlite3 *db = sqlite3_db_handle(self->statement->st);
 int sqlite3_state = sqlite3_errcode(db);
 // stmt_reset() may return a previously set exception,
 // either triggered because of Python or sqlite3.
 rc = stmt_reset(self->statement);
 Py_CLEAR(self->statement);
 if (sqlite3_state == SQLITE_OK && rc != SQLITE_OK) {
 cursor_cannot_reset_stmt_error(self, 1);
 }
 }
 self->rowcount = -1L;
 return NULL;
 }
 if (self->statement && !sqlite3_stmt_busy(self->statement->st)) {
 Py_CLEAR(self->statement);
 }
 return Py_NewRef((PyObject *)self);

reset_failure:
 /* suite to execute when stmt_reset() failed and no exception is set */
 assert(!PyErr_Occurred());

 Py_XDECREF(parameters);
 Py_XDECREF(parameters_iter);
 Py_XDECREF(parameters_list);

 self->locked = 0;
 self->rowcount = -1L;
 Py_CLEAR(self->statement);
 cursor_cannot_reset_stmt_error(self, 0);
 return NULL;
}

/*[clinic input]
_sqlite3.Cursor.execute as pysqlite_cursor_execute

 sql: unicode
 parameters: object(c_default = 'NULL') = ()
 /

Executes an SQL statement.
[clinic start generated code]*/

static PyObject *
pysqlite_cursor_execute_impl(pysqlite_Cursor *self, PyObject *sql,
 PyObject *parameters)
/*[clinic end generated code: output=d81b4655c7c0bbad input=a8e0200a11627f94]*/
{
 return _pysqlite_query_execute(self, 0, sql, parameters);
}

/*[clinic input]
_sqlite3.Cursor.executemany as pysqlite_cursor_executemany

 sql: unicode
 seq_of_parameters: object
 /

Repeatedly executes an SQL statement.
[clinic start generated code]*/

static PyObject *
pysqlite_cursor_executemany_impl(pysqlite_Cursor *self, PyObject *sql,
 PyObject *seq_of_parameters)
/*[clinic end generated code: output=2c65a3c4733fb5d8 input=0d0a52e5eb7ccd35]*/
{
 return _pysqlite_query_execute(self, 1, sql, seq_of_parameters);
}

/*[clinic input]
_sqlite3.Cursor.executescript as pysqlite_cursor_executescript

 sql_script: str
 /

Executes multiple SQL statements at once.
[clinic start generated code]*/

static PyObject *
pysqlite_cursor_executescript_impl(pysqlite_Cursor *self,
 const char *sql_script)
/*[clinic end generated code: output=8fd726dde1c65164 input=78f093be415a8a2c]*/
{
 if (!check_cursor(self)) {
 return NULL;
 }

 size_t sql_len = strlen(sql_script);
 int max_length = sqlite3_limit(self->connection->db,
 SQLITE_LIMIT_SQL_LENGTH, -1);
 if (sql_len > (unsigned)max_length) {
 PyErr_SetString(self->connection->DataError,
 "query string is too large");
 return NULL;
 }

 // Commit if needed
 sqlite3 *db = self->connection->db;
 if (self->connection->autocommit == AUTOCOMMIT_LEGACY
 && !sqlite3_get_autocommit(db))
 {
 int rc = SQLITE_OK;

 Py_BEGIN_ALLOW_THREADS
 rc = sqlite3_exec(db, "COMMIT", NULL, NULL, NULL);
 Py_END_ALLOW_THREADS

 if (rc != SQLITE_OK) {
 goto error;
 }
 }

 while (1) {
 int rc;
 const char *tail;

 Py_BEGIN_ALLOW_THREADS
 sqlite3_stmt *stmt;
 rc = sqlite3_prepare_v2(db, sql_script, (int)sql_len + 1, &stmt,
 &tail);
 if (rc == SQLITE_OK) {
 do {
 rc = sqlite3_step(stmt);
 } while (rc == SQLITE_ROW);
 rc = sqlite3_finalize(stmt);
 }
 Py_END_ALLOW_THREADS

 if (rc != SQLITE_OK) {
 goto error;
 }

 if (*tail == (char)0) {
 break;
 }
 sql_len -= (tail - sql_script);
 sql_script = tail;
 }

 return Py_NewRef((PyObject *)self);

error:
 set_error_from_db(self->connection->state, db);
 return NULL;
}

static PyObject *
pysqlite_cursor_iternext(PyObject *op)
{
 pysqlite_Cursor *self = _pysqlite_Cursor_CAST(op);
 if (!check_cursor(self)) {
 return NULL;
 }

 if (self->statement == NULL) {
 return NULL;
 }

 sqlite3_stmt *stmt = self->statement->st;
 assert(stmt != NULL);
 assert(sqlite3_data_count(stmt) != 0);

 self->locked = 1; // GH-80254: Prevent recursive use of cursors.
 PyObject *row = _pysqlite_fetch_one_row(self);
 self->locked = 0;
 if (row == NULL) {
 return NULL;
 }
 int rc = stmt_step(stmt);
 if (rc == SQLITE_DONE) {
 if (self->statement->is_dml) {
 self->rowcount = (long)sqlite3_changes(self->connection->db);
 }
 rc = stmt_reset(self->statement);
 Py_CLEAR(self->statement);
 if (rc != SQLITE_OK) {
 goto reset_failure;
 }
 }
 else if (rc != SQLITE_ROW) {
 rc = set_error_from_db(self->connection->state, self->connection->db);
 int reset_rc = stmt_reset(self->statement);
 Py_CLEAR(self->statement);
 Py_DECREF(row);
 if (rc == SQLITE_OK && reset_rc != SQLITE_OK) {
 goto reset_failure;
 }
 return NULL;
 }
 if (!Py_IsNone(self->row_factory)) {
 PyObject *factory = self->row_factory;
 PyObject *args[] = { op, row, };
 PyObject *new_row = PyObject_Vectorcall(factory, args, 2, NULL);
 Py_SETREF(row, new_row);
 }
 return row;

reset_failure:
 cursor_cannot_reset_stmt_error(self, 0);
 return NULL;
}

/*[clinic input]
_sqlite3.Cursor.fetchone as pysqlite_cursor_fetchone

Fetches one row from the resultset.
[clinic start generated code]*/

static PyObject *
pysqlite_cursor_fetchone_impl(pysqlite_Cursor *self)
/*[clinic end generated code: output=4bd2eabf5baaddb0 input=e78294ec5980fdba]*/
{
 PyObject* row;

 row = pysqlite_cursor_iternext((PyObject *)self);
 if (!row && !PyErr_Occurred()) {
 Py_RETURN_NONE;
 }

 return row;
}

/*[clinic input]
_sqlite3.Cursor.fetchmany as pysqlite_cursor_fetchmany

 size as maxrows: uint32(c_default='((pysqlite_Cursor *)self)->arraysize') = 1
 The default value is set by the Cursor.arraysize attribute.

Fetches several rows from the resultset.
[clinic start generated code]*/

static PyObject *
pysqlite_cursor_fetchmany_impl(pysqlite_Cursor *self, uint32_t maxrows)
/*[clinic end generated code: output=3325f2b477c71baf input=a509c412aa70b27e]*/
{
 PyObject* row;
 PyObject* list;

 list = PyList_New(0);
 if (!list) {
 return NULL;
 }

 while (maxrows > 0 && (row = pysqlite_cursor_iternext((PyObject *)self))) {
 int rc = PyList_Append(list, row);
 Py_DECREF(row);
 if (rc < 0) {
 break;
 }
 maxrows--;
 }

 if (PyErr_Occurred()) {
 Py_DECREF(list);
 return NULL;
 } else {
 return list;
 }
}

/*[clinic input]
_sqlite3.Cursor.fetchall as pysqlite_cursor_fetchall

Fetches all rows from the resultset.
[clinic start generated code]*/

static PyObject *
pysqlite_cursor_fetchall_impl(pysqlite_Cursor *self)
/*[clinic end generated code: output=d5da12aca2da4b27 input=f5d401086a8df25a]*/
{
 PyObject* row;
 PyObject* list;

 list = PyList_New(0);
 if (!list) {
 return NULL;
 }

 while ((row = pysqlite_cursor_iternext((PyObject *)self))) {
 if (PyList_Append(list, row) < 0) {
 Py_DECREF(row);
 break;
 }
 Py_DECREF(row);
 }

 if (PyErr_Occurred()) {
 Py_DECREF(list);
 return NULL;
 } else {
 return list;
 }
}

/*[clinic input]
_sqlite3.Cursor.setinputsizes as pysqlite_cursor_setinputsizes

 sizes: object
 /

Required by DB-API. Does nothing in sqlite3.
[clinic start generated code]*/

static PyObject *
pysqlite_cursor_setinputsizes_impl(pysqlite_Cursor *self, PyObject *sizes)
/*[clinic end generated code: output=a06c12790bd05f2e input=de7950a3aec79bdf]*/
{
 Py_RETURN_NONE;
}

/*[clinic input]
_sqlite3.Cursor.setoutputsize as pysqlite_cursor_setoutputsize

 size: object
 column: object = None
 /

Required by DB-API. Does nothing in sqlite3.
[clinic start generated code]*/

static PyObject *
pysqlite_cursor_setoutputsize_impl(pysqlite_Cursor *self, PyObject *size,
 PyObject *column)
/*[clinic end generated code: output=018d7e9129d45efe input=607a6bece8bbb273]*/
{
 Py_RETURN_NONE;
}

/*[clinic input]
_sqlite3.Cursor.close as pysqlite_cursor_close

Closes the cursor.
[clinic start generated code]*/

static PyObject *
pysqlite_cursor_close_impl(pysqlite_Cursor *self)
/*[clinic end generated code: output=b6055e4ec6fe63b6 input=08b36552dbb9a986]*/
{
 if (!check_cursor_locked(self)) {
 return NULL;
 }

 if (!self->connection) {
 PyTypeObject *tp = Py_TYPE(self);
 pysqlite_state *state = pysqlite_get_state_by_type(tp);
 PyErr_SetString(state->ProgrammingError,
 "Base Cursor.__init__ not called.");
 return NULL;
 }
 if (!pysqlite_check_thread(self->connection) || !pysqlite_check_connection(self->connection)) {
 return NULL;
 }

 if (self->statement) {
 int rc = stmt_reset(self->statement);
 // Force self->statement to be NULL even if stmt_reset() may have
 // failed to avoid a possible double-free if someone calls close()
 // twice as a leak here would be better than a double-free.
 Py_CLEAR(self->statement);
 if (rc != SQLITE_OK) {
 cursor_cannot_reset_stmt_error(self, 0);
 return NULL;
 }
 }

 self->closed = 1;

 Py_RETURN_NONE;
}

/*[clinic input]
@getter
_sqlite3.Cursor.arraysize
[clinic start generated code]*/

static PyObject *
_sqlite3_Cursor_arraysize_get_impl(pysqlite_Cursor *self)
/*[clinic end generated code: output=e0919d97175e6c50 input=3278f8d3ecbd90e3]*/
{
 return PyLong_FromUInt32(self->arraysize);
}

/*[clinic input]
@setter
_sqlite3.Cursor.arraysize
[clinic start generated code]*/

static int
_sqlite3_Cursor_arraysize_set_impl(pysqlite_Cursor *self, PyObject *value)
/*[clinic end generated code: output=af59a6b09f8cce6e input=ace48cb114e26060]*/
{
 return PyLong_AsUInt32(value, &self->arraysize);
}

static PyMethodDef cursor_methods[] = {
 PYSQLITE_CURSOR_CLOSE_METHODDEF
 PYSQLITE_CURSOR_EXECUTEMANY_METHODDEF
 PYSQLITE_CURSOR_EXECUTESCRIPT_METHODDEF
 PYSQLITE_CURSOR_EXECUTE_METHODDEF
 PYSQLITE_CURSOR_FETCHALL_METHODDEF
 PYSQLITE_CURSOR_FETCHMANY_METHODDEF
 PYSQLITE_CURSOR_FETCHONE_METHODDEF
 PYSQLITE_CURSOR_SETINPUTSIZES_METHODDEF
 PYSQLITE_CURSOR_SETOUTPUTSIZE_METHODDEF
 {NULL, NULL}
};

static struct PyMemberDef cursor_members[] =
{
 {"connection", _Py_T_OBJECT, offsetof(pysqlite_Cursor, connection), Py_READONLY},
 {"description", _Py_T_OBJECT, offsetof(pysqlite_Cursor, description), Py_READONLY},
 {"lastrowid", _Py_T_OBJECT, offsetof(pysqlite_Cursor, lastrowid), Py_READONLY},
 {"rowcount", Py_T_LONG, offsetof(pysqlite_Cursor, rowcount), Py_READONLY},
 {"row_factory", _Py_T_OBJECT, offsetof(pysqlite_Cursor, row_factory), 0},
 {"__weaklistoffset__", Py_T_PYSSIZET, offsetof(pysqlite_Cursor, in_weakreflist), Py_READONLY},
 {NULL}
};

static struct PyGetSetDef cursor_getsets[] = {
 _SQLITE3_CURSOR_ARRAYSIZE_GETSETDEF
 {NULL},
};

static const char cursor_doc[] =
PyDoc_STR("SQLite database cursor class.");

static PyType_Slot cursor_slots[] = {
 {Py_tp_dealloc, cursor_dealloc},
 {Py_tp_doc, (void *)cursor_doc},
 {Py_tp_iter, PyObject_SelfIter},
 {Py_tp_iternext, pysqlite_cursor_iternext},
 {Py_tp_methods, cursor_methods},
 {Py_tp_members, cursor_members},
 {Py_tp_getset, cursor_getsets},
 {Py_tp_init, pysqlite_cursor_init},
 {Py_tp_traverse, cursor_traverse},
 {Py_tp_clear, cursor_clear},
 {0, NULL},
};

static PyType_Spec cursor_spec = {
 .name = MODULE_NAME ".Cursor",
 .basicsize = sizeof(pysqlite_Cursor),
 .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
 Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_IMMUTABLETYPE),
 .slots = cursor_slots,
};

int
pysqlite_cursor_setup_types(PyObject *module)
{
 PyObject *type = PyType_FromModuleAndSpec(module, &cursor_spec, NULL);
 if (type == NULL) {
 return -1;
 }
 pysqlite_state *state = pysqlite_get_state(module);
 state->CursorType = (PyTypeObject *)type;
 return 0;
}