Function read_u32_advance

nodedb-query/src/msgpack_scan/reader.rs:308–332

Read an unsigned integer that fits in a `u32` at `*off`, advancing `*off` past it. Accepts positive fixint, uint8, uint16, uint32. Returns `None` for negative, signed-typed, oversized (uint64), or non-integer values.

(buf: &[u8], off: &mut usize)

/// past it. Accepts positive fixint, uint8, uint16, uint32. Returns `None`
/// for negative, signed-typed, oversized (uint64), or non-integer values.
pub fn read_u32_advance(buf: &[u8], off: &mut usize) -> Option<u32> {
    let tag = get(buf, *off)?;
    match tag {
        0x00..=0x7f => {
            *off += 1;
            Some(tag as u32)
        }
        UINT8 => {
            let v = get(buf, *off + 1)? as u32;
            *off += 2;
            Some(v)
        }
        UINT16 => {
            let v = read_u16_be(buf, *off + 1)? as u32;
            *off += 3;
            Some(v)
        }
        UINT32 => {
            let v = read_u32_be(buf, *off + 1)?;
            *off += 5;
            Some(v)
        }
        _ => None,
    }
}

/// Return `(data_start, byte_len)` for the string at `offset` without
/// validating UTF-8. Used internally for key comparison.