Serializing to a specific endianess

[felinira]

As far as I can see the types are currently serialized to the platform endianness (they get encoded as-is). However, in some cases (for example GVDB) the endianess of the serialized data is specified, and needs to be uniform.

Would it be possible to add a way to serialize any generic SerializeTo to a target endianess?

That would make it much easier for me to add support for this crate in https://crates.io/crates/gvdb

[wmanley]

I wouldn't object to this, but I don't think I have the bandwidth to review such a change, let alone implement it.

To make this work you'd have to extend the gvariant type format, perhaps using <, > and = to indicate endianness (much like Python's struct package does. You'd map <u to type LittleEndian<u32> which would be a #[repr(transparent)] wrapper around u32 with getters and setters doing byte swaps (or not as the case may be).

Serialisation is a little bit of an afterthought in this crate. For the deserialisation case endianness is less relevant as it's easier to implement on top. It's primarily designed for lazy in-place zero-copy deserialisation of gvariants - serving the mmap use case where you want to mmap a large file and access parts of it without paying the cost of reading any data you don't need.

If you wanted to achieve the same end without modifying this crate you could store your data in big endian, and convert to/from when writing to that data store, rather than converting when serialising.

I notice that you're already using the zvariant crate in gvdb. Why do you want to switch?

[felinira]

Thanks for the pointers.

The rationale for switching is that zvariant considered dropping gvariant support completely.

I'll take another deep look at this when / if this happens.