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wasm-chisel

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Some useful utilities to transform WebAssembly binaries, most importantly for WebAssembly used in a deterministic / blockchain context, such as with ewasm.

Library

remapimports

Provide a list of imports (with namespace and name) and replace them with a new set of namespace and name pairs.

This can be very useful together with compilers, which do not support the specification of a namespace in imports yet. As of writing mid-2018, that includes pretty much every compiler (one exception is AssemblyScript).

It supports the same presets as verifyimports.

trimexports

Removes all exports, but the ones specified.

This comes with some presets:

trimstartfunc

Remove start function.

This comes with the following preset:

verifyimports

Verifies that the module's imports are compliant with the provided import interface. Can be set to require the existence of the entire import set, or just the validity of existing imports with matching identifiers. Can be set to allow or prohibit unlisted additional imports.

The following presets are provided:

verifyexports

Verifies that the module's exports are compliant with the provided export interface. Can be set to allow or prohibit unlisted additional exports.

The following presets are provided:

dropsection

Removes selected sections from the module.

deployer

Wraps module into an ewasm-compatible constructor. It has two presets:

repack

Re-serializes the module. It will drop any unknown (custom) sections.

remapstart

If there is a start section, export it as main (replacing any pre-existing main export) and remove the start section

snip

Wraps wasm-snip and turns on removing Rust formatting and debugging from wasm.

dropnames

Drops the NamesSection if present.

CLI

chisel is available as a command line tool. It supports two usage patterns, config-driven and unix-style, also known as oneliner.

It uses features implemented in the library as well in wasm-gc and wasm-utils. It comes with a configuration file chisel.yml.

chisel run: searches for chisel.yml in the current directory, if not specified otherwise using the flag -c. Runs the modules specified in the configuration, outputs a new file if any changes were made by translator or creator modules, and prints a brief report of each module's results.

chisel: Invokes unix-style mode. It requires the flags --modules and --config.

Configuration file

The configuration file starts with a ruleset entry, where the name can be anything. Inside the ruleset are its options.

The only required field is file, which specifies the path to the Wasm binary to be chiseled.

Optionally, one may also specified an output file through the output option.

It is important to note that the configuration parsing will not work if all the rules are prepended with a hyphen. Please avoid this until the configuration parser is generalized.

ewasm:
  file: "target/wasm32-unknown-unknown/release/sentinel.wasm"
  output: "out.wasm"
  remapimports:
    preset: "ewasm"

sentinel.rs

TBA

Changelog

A changelog is available.

Maintainers

License

Apache 2.0.