[PDO] Bound-check column index in getColumnMeta()

[iliaal]

PDOStatement::getColumnMeta() indexed columns as soon as the driver hook succeeded, without checking that columns had been described or that the index was in range, so a driver that reports success unconditionally (pdo_odbc) segfaulted on an unexecuted statement. Both cases now raise ValueError, matching the fetch paths. Drivers that report failure themselves still return false.

[NickSdot]

Suggested change

	} catch (ValueError $e) {
	echo get_class($e), ': ', $e->getMessage(), "\n";
	}
	$stmt->execute();
	var_dump($stmt->getColumnMeta(0));
	try {
	var_dump($stmt->getColumnMeta(5));
	} catch (ValueError $e) {
	echo get_class($e), ': ', $e->getMessage(), "\n";
	}
	} catch (Throwable $e) {
	echo $e::class, ': ', $e->getMessage(), "\n";
	}
	$stmt->execute();
	var_dump($stmt->getColumnMeta(0));
	try {
	var_dump($stmt->getColumnMeta(5));
	} catch (Throwable $e) {
	echo $e::class, ': ', $e->getMessage(), "\n";
	}

[iliaal]

Took the $e::class part. The thrown type changed to PDOException in the meantime, and ext/pdo tests catch that rather than Throwable.

[SakiTakamachi]

Would this make sense?

Suggested change

	if (stmt->columns == NULL || colno >= stmt->column_count) {
	zend_value_error("Invalid column index");
	RETURN_THROWS();
	}
	if (stmt->columns == NULL || colno >= stmt->column_count) {
	pdo_raise_impl_error(stmt->dbh, stmt, "07009", "invalid column index");
	RETURN_FALSE;
	}

07009 (Invalid descriptor index) seems like a good fit for this case.

[iliaal]

Adopted. Added a zval_ptr_dtor(return_value) with it, since the hook has already built the array and RETURN_FALSE would otherwise drop it.

The guard sits after the hook though, so it does not cover pdo_firebird, which indexes out_sqlda.sqlvar[colno] unchecked and then returns 1. I would fix that driver-side like GH-17837 rather than move the guard ahead of the hook, since that would change what the bound-checking drivers return. Sound right?