rusqlite/src/limits.rs

//! Run-Time Limits

use crate::{ffi, Connection, Error, Result};
use std::os::raw::c_int;

/// Run-Time limit categories, for use with [`Connection::limit`] and
/// [`Connection::set_limit`].
///
/// See the official documentation for more information:
/// - <https://www.sqlite.org/c3ref/c_limit_attached.html>
/// - <https://www.sqlite.org/limits.html>
#[derive(Copy, Clone, Debug)]
#[repr(i32)]
#[non_exhaustive]
#[expect(non_camel_case_types)]
#[cfg_attr(docsrs, doc(cfg(feature = "limits")))]
pub enum Limit {
    /// The maximum size of any string or BLOB or table row, in bytes.
    SQLITE_LIMIT_LENGTH = ffi::SQLITE_LIMIT_LENGTH,
    /// The maximum length of an SQL statement, in bytes.
    SQLITE_LIMIT_SQL_LENGTH = ffi::SQLITE_LIMIT_SQL_LENGTH,
    /// The maximum number of columns in a table definition or in the result set
    /// of a SELECT or the maximum number of columns in an index or in an
    /// ORDER BY or GROUP BY clause.
    SQLITE_LIMIT_COLUMN = ffi::SQLITE_LIMIT_COLUMN,
    /// The maximum depth of the parse tree on any expression.
    SQLITE_LIMIT_EXPR_DEPTH = ffi::SQLITE_LIMIT_EXPR_DEPTH,
    /// The maximum number of terms in a compound SELECT statement.
    SQLITE_LIMIT_COMPOUND_SELECT = ffi::SQLITE_LIMIT_COMPOUND_SELECT,
    /// The maximum number of instructions in a virtual machine program used to
    /// implement an SQL statement.
    SQLITE_LIMIT_VDBE_OP = ffi::SQLITE_LIMIT_VDBE_OP,
    /// The maximum number of arguments on a function.
    SQLITE_LIMIT_FUNCTION_ARG = ffi::SQLITE_LIMIT_FUNCTION_ARG,
    /// The maximum number of attached databases.
    SQLITE_LIMIT_ATTACHED = ffi::SQLITE_LIMIT_ATTACHED,
    /// The maximum length of the pattern argument to the LIKE or GLOB
    /// operators.
    SQLITE_LIMIT_LIKE_PATTERN_LENGTH = ffi::SQLITE_LIMIT_LIKE_PATTERN_LENGTH,
    /// The maximum index number of any parameter in an SQL statement.
    SQLITE_LIMIT_VARIABLE_NUMBER = ffi::SQLITE_LIMIT_VARIABLE_NUMBER,
    /// The maximum depth of recursion for triggers.
    SQLITE_LIMIT_TRIGGER_DEPTH = ffi::SQLITE_LIMIT_TRIGGER_DEPTH,
    /// The maximum number of auxiliary worker threads that a single prepared
    /// statement may start.
    SQLITE_LIMIT_WORKER_THREADS = ffi::SQLITE_LIMIT_WORKER_THREADS,
    /// Only used for testing
    #[cfg(test)]
    INVALID = -1,
}

impl Connection {
    /// Returns the current value of a [`Limit`].
    #[inline]
    #[cfg_attr(docsrs, doc(cfg(feature = "limits")))]
    pub fn limit(&self, limit: Limit) -> Result<i32> {
        let c = self.db.borrow();
        let rc = unsafe { ffi::sqlite3_limit(c.db(), limit as c_int, -1) };
        if rc < 0 {
            return Err(Error::SqliteFailure(
                ffi::Error::new(ffi::SQLITE_RANGE),
                Some(format!("{limit:?} is invalid")),
            ));
        }
        Ok(rc)
    }

    /// Changes the [`Limit`] to `new_val`, returning the prior
    /// value of the limit.
    #[inline]
    #[cfg_attr(docsrs, doc(cfg(feature = "limits")))]
    pub fn set_limit(&self, limit: Limit, new_val: i32) -> Result<i32> {
        if new_val < 0 {
            return Err(Error::SqliteFailure(
                ffi::Error::new(ffi::SQLITE_RANGE),
                Some(format!("{new_val} is invalid")),
            ));
        }
        let c = self.db.borrow_mut();
        let rc = unsafe { ffi::sqlite3_limit(c.db(), limit as c_int, new_val) };
        if rc < 0 {
            return Err(Error::SqliteFailure(
                ffi::Error::new(ffi::SQLITE_RANGE),
                Some(format!("{limit:?} is invalid")),
            ));
        }
        Ok(rc)
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::Result;

    #[test]
    fn test_limit_values() {
        assert_eq!(Limit::SQLITE_LIMIT_LENGTH as i32, ffi::SQLITE_LIMIT_LENGTH,);
        assert_eq!(
            Limit::SQLITE_LIMIT_SQL_LENGTH as i32,
            ffi::SQLITE_LIMIT_SQL_LENGTH,
        );
        assert_eq!(Limit::SQLITE_LIMIT_COLUMN as i32, ffi::SQLITE_LIMIT_COLUMN,);
        assert_eq!(
            Limit::SQLITE_LIMIT_EXPR_DEPTH as i32,
            ffi::SQLITE_LIMIT_EXPR_DEPTH,
        );
        assert_eq!(
            Limit::SQLITE_LIMIT_COMPOUND_SELECT as i32,
            ffi::SQLITE_LIMIT_COMPOUND_SELECT,
        );
        assert_eq!(
            Limit::SQLITE_LIMIT_VDBE_OP as i32,
            ffi::SQLITE_LIMIT_VDBE_OP,
        );
        assert_eq!(
            Limit::SQLITE_LIMIT_FUNCTION_ARG as i32,
            ffi::SQLITE_LIMIT_FUNCTION_ARG,
        );
        assert_eq!(
            Limit::SQLITE_LIMIT_ATTACHED as i32,
            ffi::SQLITE_LIMIT_ATTACHED,
        );
        assert_eq!(
            Limit::SQLITE_LIMIT_LIKE_PATTERN_LENGTH as i32,
            ffi::SQLITE_LIMIT_LIKE_PATTERN_LENGTH,
        );
        assert_eq!(
            Limit::SQLITE_LIMIT_VARIABLE_NUMBER as i32,
            ffi::SQLITE_LIMIT_VARIABLE_NUMBER,
        );
        assert_eq!(
            Limit::SQLITE_LIMIT_TRIGGER_DEPTH as i32,
            ffi::SQLITE_LIMIT_TRIGGER_DEPTH,
        );
        assert_eq!(
            Limit::SQLITE_LIMIT_WORKER_THREADS as i32,
            ffi::SQLITE_LIMIT_WORKER_THREADS,
        );
    }

    #[test]
    fn test_limit() -> Result<()> {
        let db = Connection::open_in_memory()?;
        db.set_limit(Limit::SQLITE_LIMIT_LENGTH, 1024)?;
        assert_eq!(1024, db.limit(Limit::SQLITE_LIMIT_LENGTH)?);

        db.set_limit(Limit::SQLITE_LIMIT_SQL_LENGTH, 1024)?;
        assert_eq!(1024, db.limit(Limit::SQLITE_LIMIT_SQL_LENGTH)?);

        db.set_limit(Limit::SQLITE_LIMIT_COLUMN, 64)?;
        assert_eq!(64, db.limit(Limit::SQLITE_LIMIT_COLUMN)?);

        db.set_limit(Limit::SQLITE_LIMIT_EXPR_DEPTH, 256)?;
        assert_eq!(256, db.limit(Limit::SQLITE_LIMIT_EXPR_DEPTH)?);

        db.set_limit(Limit::SQLITE_LIMIT_COMPOUND_SELECT, 32)?;
        assert_eq!(32, db.limit(Limit::SQLITE_LIMIT_COMPOUND_SELECT)?);

        db.set_limit(Limit::SQLITE_LIMIT_FUNCTION_ARG, 32)?;
        assert_eq!(32, db.limit(Limit::SQLITE_LIMIT_FUNCTION_ARG)?);

        db.set_limit(Limit::SQLITE_LIMIT_ATTACHED, 2)?;
        assert_eq!(2, db.limit(Limit::SQLITE_LIMIT_ATTACHED)?);

        db.set_limit(Limit::SQLITE_LIMIT_LIKE_PATTERN_LENGTH, 128)?;
        assert_eq!(128, db.limit(Limit::SQLITE_LIMIT_LIKE_PATTERN_LENGTH)?);

        db.set_limit(Limit::SQLITE_LIMIT_VARIABLE_NUMBER, 99)?;
        assert_eq!(99, db.limit(Limit::SQLITE_LIMIT_VARIABLE_NUMBER)?);

        db.set_limit(Limit::SQLITE_LIMIT_TRIGGER_DEPTH, 32)?;
        assert_eq!(32, db.limit(Limit::SQLITE_LIMIT_TRIGGER_DEPTH)?);

        db.set_limit(Limit::SQLITE_LIMIT_WORKER_THREADS, 2)?;
        assert_eq!(2, db.limit(Limit::SQLITE_LIMIT_WORKER_THREADS)?);

        assert!(db
            .set_limit(Limit::SQLITE_LIMIT_WORKER_THREADS, -1)
            .is_err());
        assert!(db.set_limit(Limit::INVALID, 0).is_err());
        assert!(db.limit(Limit::INVALID).is_err());
        Ok(())
    }
}