sqlx_core/io/
read_buf.rs

1use bytes::{BufMut, BytesMut};
2
3/// An extension for [`BufMut`] for getting a writeable buffer in safe code.
4pub trait ReadBuf: BufMut {
5    /// Get the full capacity of this buffer as a safely initialized slice.
6    fn init_mut(&mut self) -> &mut [u8];
7}
8
9impl ReadBuf for &'_ mut [u8] {
10    #[inline(always)]
11    fn init_mut(&mut self) -> &mut [u8] {
12        self
13    }
14}
15
16impl ReadBuf for BytesMut {
17    #[inline(always)]
18    fn init_mut(&mut self) -> &mut [u8] {
19        // `self.remaining_mut()` returns `usize::MAX - self.len()`
20        let remaining = self.capacity() - self.len();
21
22        // I'm hoping for most uses that this operation is elided by the optimizer.
23        self.put_bytes(0, remaining);
24
25        self
26    }
27}
28
29#[test]
30fn test_read_buf_bytes_mut() {
31    let mut buf = BytesMut::with_capacity(8);
32    buf.put_u32(0x12345678);
33
34    assert_eq!(buf.init_mut(), [0x12, 0x34, 0x56, 0x78, 0, 0, 0, 0]);
35}
sqlx_core/io/read_buf.rs

sqlx_core/io/
read_buf.rs
