Allow malloc from shared heap without module_inst

[calvin2021y]

Feature

Allow host to malloc from shared heap without module_inst, emplace the data into memory, then decide which module to detach.

we also need a public api to tranlate the shared heap memory addr into module_inst uint64_t addr after attached.

Benefit

This is useful to avoid memory copy, and the context is extract after the io task is done. (context decidce which module_inst to call)

In this case, after the io finished and data is copy into shared heap, you has a chance to verify the data, then decide to create a new module_inst or use a exsits one to attach.

[calvin2021y]

A useful feature will bebool wasm_runtime_attach_shared_heap(wasm_module_inst_t module_inst, wasm_shared_heap_t shared_heap, bool readonly);

A readonly shared_heap make sure memory is readonly for wasm_module_inst_t

[TianlongLiang]

Allow host to malloc from shared heap without module_inst, emplace the data into memory, then decide which module to detach.

You can use a preallocated shared heap to do that, it's not fully ready yet(In this dev branch the interpreter support is finished and AOT is WIP)

You can check the example usage here

we also need a public api to tranlate the shared heap memory addr into module_inst uint64_t addr after attached.

I believe that wasm_runtime_addr_native_to_app can do it.

A readonly shared_heap make sure memory is readonly for wasm_module_inst_t

This can also be achieved by a preallocated shared heap, you can mmap a memory, then after finishing writing it use mprotect to make it read-only and create a preallocated shared heap from it.

[yamt]

A readonly shared_heap make sure memory is readonly for wasm_module_inst_t

This can also be achieved by a preallocated shared heap, you can mmap a memory, then after finishing writing it use mprotect to make it read-only and create a preallocated shared heap from it.

assuming hw bound checks?

anyway, it sounds a bit fragile as wasm doesn't have a concept of read-only memory.