Genesis: add an option to load account code from a file

[axic]

e.g.

  "accounts": {
    "0000000000000000000000000000000000000001": { "codeFromFile": "/path/to/ecrecover.wasm" }
  }

[axic]

@chfast @gumb0 what do you think?

[winsvega]

so the "code" : "0x0001" should work directly from json file.
I guess we could just add a syntax to parse the code if it contains link to a file.

but speaking of wasm first there should be a support for wasm code
#4754

[axic]

This only cares about filling the account code with raw data, whatever that data is. Nothing in the genesis should be processed or compiled afterwards.

The above feature isn't good only for ewasm, but for example the blockhash EVM bytecode could be placed there too.

[chfast]

The .wasm files in the example contain a bytecode already. No compilation is needed here.

I'm just worried about using relative paths in the JSON file...

[gumb0]

Maybe just require all code files to be in the same dir as json? and codeFromFile will have only the name

[winsvega]

hm. yes this sounds like a nice feauture.

in the same dir might become with too many files. a subdir would be reasonable

[chfast]

I can make the relative paths to work relatively to the config.json file. But we also use string literals for config :)

[axic]

I think another decision to be made is whether the file referenced should have:

• binary code
• hex string
• hex string prefixed 0x

[winsvega]

the function importCode deals with hex and prefixed hex.

[axic]

I don't think importCode from testeth is relevant here?

I would personally prefer to take the file as binary but considering all tools output EVM bytecode as hexadecimal (without the 0x prefix) probably that is the most sane choice.