Does this structure packing size and alignment of WasiAddrinfo match the c++ host code's __wasi_addrinfo_t

[danielblignaut]

Hi,

I'm comparing the sockets client code here:

wasmedge_wasi_socket/src/socket.rs

Line 61 in 7685fa0

pub enum AiFlags {

with the host functions in the engine here:
https://github.com/WasmEdge/WasmEdge/blob/0bbc4f7d28f8bdbd37175a174f15d4f9a61953f7/thirdparty/wasi/api.hpp#L1759

It looks like this mapping from the rust enum to the c++ bitflag is not correct?

The Rust enum AiFlags does not map directly to any specific C++ enum value because Rust's AiFlags::AiPassive has an explicit discriminant of 0, while in the C++ code, __WASI_AIFLAGS_AI_PASSIVE has an implicit discriminant of 1 (since it's defined as 1ULL << 0). In other words, the Rust enum AiFlags is zero-based, while the C++ enum __wasi_aiflags_t is one-based. Therefore, there is no direct mapping between them.

However, I'm guessing "this just works" for AiPassive because in the context of getaddrinfo, the AI_PASSIVE flag is defined to have a value of 0 in POSIX, so it's possible that AiFlags::AiPassive could be used to represent __WASI_AIFLAGS_AI_PASSIVE with a value of 0 in C++.

However, the other enum values will therefore map incorrectly as it currently stands... I'm not very good at either C++ or Rust, but can anyone validate that this is correct?
and in fact either the rust enum needs to change to be indexed starting from 1, not 0 or the bit flags should change to:
__WASI_AIFLAGS_AI_PASSIVE = 0 << 0
__WASI_AIFLAGS_AI_CANONNAME = 1 << 0

and so on.

If I look at the WasiAddrInfo struct overall, it has the following information: size = 40, align = 4 but the __wasi_addrinfo_t struct in C++ has size = 28, align = 4.

I would expect these to be the same? Should the rust code or host code be treated as correct?