krishvishal opened a new issue, #2878:
URL: https://github.com/apache/iggy/issues/2878
### Bug description
`bytemuck::Pod` requires that every possible bit pattern is a valid instance
of the type.
- `Command2` defines discriminants `0..=12` only (13 of 256 possible u8
values)
- `Operation` defines discriminants `0, 128..=147, 160..=161, 200` (23 of
256 possible u8 values)
When `bytemuck::from_bytes::<PrepareHeader>(&buf)` is called on a network
buffer containing e.g. command = `0xFF`, Rust materializes a Command2 with an
invalid discriminant. This is UB and the compiler is free to assume enum fields
always hold valid discriminants.
### Deployment
Not applicable
### Versions
_No response_
### Hardware / environment
_No response_
### Sample code
```rust
use bytemuck::{Pod, Zeroable};
/// Only discriminants 0, 1, 2 are valid.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
enum Command {
Ping = 0,
Pong = 1,
Request = 2,
}
#[derive(Debug, Clone, Copy)]
#[repr(C)]
struct Header {
command: Command,
}
unsafe impl Zeroable for Header {}
unsafe impl Pod for Header {}
fn main() {
let buf: [u8; 1] = [255];
let header: &Header = bytemuck::from_bytes(&buf);
match header.command {
Command::Ping => println!("ping"),
Command::Pong => println!("pong"),
Command::Request => println!("request"),
}
println!("command == Ping? {}", header.command == Command::Ping);
println!("raw byte: 0x{:02X}", header.command as u8);
}
```
### Logs
_No response_
### Iggy server config
_No response_
### Reproduction
Try this MWE on Rust Playground:
https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=2e4f80fe9eb435682b0ede6b7c3c95b8
And run the above example using Miri to see it throw error.
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