How do I write to the memory in wasmer-go?

Question

According to this issue on the wasmer-go github, it used to be that you could use instance.Memory but this appears to be missing from newer versions. I can do instance.Exports.GetMemory("mem") but this does not allow me to write to it. My question is: how do I write to this memory?

Thank you for any help!

Just so you know: this is to pass strings to a wasm function

Answer 1

The way I have made this work is with an exported allocate function (__alloc in AssemblyScript or malloc in WASM compiled from Go), use this exported function to allocate the memory and it returns the starting address. Use instance.Exports.GetMemory("mem").Data() to get the byte array of the memory, start at the address returned from the allocate function, and just manually overwrite the bytes in the array with the bytes from the string. I know this is not the best way but it is the way that works without needing changes to wasmer-go. Keep in mind different modules may use different utf standards (Go uses 8, AssemblyScript 16), I handle this with an export that is read on instance creation.