bun_sql 0.1.0

A Rust-native programmable browser runtime built on Servo and SpiderMonkey
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use core::cell::Cell;

use bun_core::strings;

use super::any_mysql_error::Error as AnyMySQLError;
use super::new_reader::{NewReader, ReaderContext};
use crate::shared::data::Data;

// TODO(port): lifetime — `offset`/`message_start` are caller-owned `usize` on the
// stack (LIFETIMES.tsv has no entry; classified BORROW_PARAM). Zig passes `@This()`
// by value (Copy) and mutates through `*usize`; modeled here as `&'a Cell<usize>`
// to keep `Copy` + interior mutability without `unsafe`.
#[derive(Clone, Copy)]
pub struct StackReader<'a> {
    pub buffer: &'a [u8],
    pub offset: &'a Cell<usize>,
    pub message_start: &'a Cell<usize>,
}

impl<'a> StackReader<'a> {
    pub fn mark_message_start(&self) {
        self.message_start.set(self.offset.get());
    }

    pub fn set_offset_from_start(&self, offset: usize) {
        self.offset.set(self.message_start.get() + offset);
    }

    pub fn ensure_capacity(&self, length: usize) -> bool {
        self.offset
            .get()
            .checked_add(length)
            .is_some_and(|end| self.buffer.len() >= end)
    }

    pub fn init(
        buffer: &'a [u8],
        offset: &'a Cell<usize>,
        message_start: &'a Cell<usize>,
    ) -> NewReader<StackReader<'a>> {
        // TODO(port): NewReader field name assumed `wrapped` per Zig struct literal
        NewReader {
            wrapped: StackReader {
                buffer,
                offset,
                message_start,
            },
        }
    }

    pub fn peek(&self) -> &'a [u8] {
        &self.buffer[self.offset.get()..]
    }

    pub fn skip(&self, count: isize) {
        if count < 0 {
            let abs_count = count.unsigned_abs();
            if abs_count > self.offset.get() {
                self.offset.set(0);
                return;
            }
            self.offset.set(self.offset.get() - abs_count);
            return;
        }

        let ucount: usize = usize::try_from(count).expect("int cast");
        if self.offset.get() + ucount > self.buffer.len() {
            self.offset.set(self.buffer.len());
            return;
        }

        self.offset.set(self.offset.get() + ucount);
    }

    pub fn read(&self, count: usize) -> Result<Data, AnyMySQLError> {
        let offset = self.offset.get();
        if !self.ensure_capacity(count) {
            return Err(AnyMySQLError::ShortRead);
        }

        self.skip(isize::try_from(count).expect("int cast"));
        Ok(Data::Temporary(bun_ptr::RawSlice::new(
            &self.buffer[offset..self.offset.get()],
        )))
    }

    pub fn read_z(&self) -> Result<Data, AnyMySQLError> {
        let remaining = self.peek();
        if let Some(zero) = strings::index_of_char(remaining, 0) {
            let zero = zero as usize;
            self.skip(isize::try_from(zero + 1).expect("int cast"));
            return Ok(Data::Temporary(bun_ptr::RawSlice::new(&remaining[0..zero])));
        }

        Err(AnyMySQLError::ShortRead)
    }
}

impl<'a> ReaderContext for StackReader<'a> {
    fn mark_message_start(self) {
        Self::mark_message_start(&self)
    }
    fn peek(&self) -> &[u8] {
        Self::peek(self)
    }
    fn skip(self, count: isize) {
        Self::skip(&self, count)
    }
    fn ensure_capacity(self, count: usize) -> bool {
        Self::ensure_capacity(&self, count)
    }
    fn read(self, count: usize) -> Result<Data, AnyMySQLError> {
        Self::read(&self, count)
    }
    fn read_z(self) -> Result<Data, AnyMySQLError> {
        Self::read_z(&self)
    }
    fn set_offset_from_start(self, offset: usize) {
        Self::set_offset_from_start(&self, offset)
    }
}

// ported from: src/sql/mysql/protocol/StackReader.zig