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// Copyright 2019-2020 Parity Technologies (UK) Ltd. // This file is part of Tetcore. // Tetcore is free software: you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // Tetcore is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License // along with Tetcore. If not, see <http://www.gnu.org/licenses/>. //! # WASM builder is a utility for building a project as a WASM binary //! //! The WASM builder is a tool that integrates the process of building the WASM binary of your project into the main //! `cargo` build process. //! //! ## Project setup //! //! A project that should be compiled as a WASM binary needs to: //! //! 1. Add a `build.rs` file. //! 2. Add `wasm-builder` as dependency into `build-dependencies`. //! //! The `build.rs` file needs to contain the following code: //! //! ```ignore //! use wasm_builder_runner::{build_current_project, WasmBuilderSource}; //! //! fn main() { //! build_current_project( //! // The name of the file being generated in out-dir. //! "wasm_binary.rs", //! // How to include wasm-builder, in this case from crates.io. //! WasmBuilderSource::Crates("1.0.0"), //! ); //! } //! ``` //! //! As the final step, you need to add the following to your project: //! //! ```ignore //! include!(concat!(env!("OUT_DIR"), "/wasm_binary.rs")); //! ``` //! //! This will include the generated WASM binary as two constants `WASM_BINARY` and `WASM_BINARY_BLOATY`. //! The former is a compact WASM binary and the latter is not compacted. //! //! ## Environment variables //! //! By using environment variables, you can configure which WASM binaries are built and how: //! //! - `SKIP_WASM_BUILD` - Skips building any wasm binary. This is useful when only native should be recompiled. //! - `BUILD_DUMMY_WASM_BINARY` - Builds dummy wasm binaries. These dummy binaries are empty and useful //! for `cargo check` runs. //! - `WASM_BUILD_TYPE` - Sets the build type for building wasm binaries. Supported values are `release` or `debug`. //! By default the build type is equal to the build type used by the main build. //! - `TRIGGER_WASM_BUILD` - Can be set to trigger a wasm build. On subsequent calls the value of the variable //! needs to change. As WASM builder instructs `cargo` to watch for file changes //! this environment variable should only be required in certain circumstances. //! - `WASM_BUILD_RUSTFLAGS` - Extend `RUSTFLAGS` given to `cargo build` while building the wasm binary. //! - `WASM_BUILD_NO_COLOR` - Disable color output of the wasm build. //! - `WASM_TARGET_DIRECTORY` - Will copy any build wasm binary to the given directory. The path needs //! to be absolute. //! - `WASM_BUILD_TOOLCHAIN` - The toolchain that should be used to build the wasm binaries. The //! format needs to be the same as used by cargo, e.g. `nightly-2020-02-20`. //! //! Each project can be skipped individually by using the environment variable `SKIP_PROJECT_NAME_WASM_BUILD`. //! Where `PROJECT_NAME` needs to be replaced by the name of the cargo project, e.g. `node-runtime` will //! be `NODE_RUNTIME`. //! //! ## Prerequisites: //! //! WASM builder requires the following prerequisites for building the WASM binary: //! //! - rust nightly + `wasm32-unknown-unknown` toolchain //! //! If a specific rust nightly is installed with `rustup`, it is important that the wasm target is installed //! as well. For example if installing the rust nightly from 20.02.2020 using `rustup install nightly-2020-02-20`, //! the wasm target needs to be installed as well `rustup target add wasm32-unknown-unknown --toolchain nightly-2020-02-20`. use std::{env, fs, path::PathBuf, process::{Command, self}, io::BufRead}; mod prerequisites; mod wasm_project; /// Environment variable that tells us to skip building the wasm binary. const SKIP_BUILD_ENV: &str = "SKIP_WASM_BUILD"; /// Environment variable to force a certain build type when building the wasm binary. /// Expects "debug" or "release" as value. /// /// By default the WASM binary uses the same build type as the main cargo build. const WASM_BUILD_TYPE_ENV: &str = "WASM_BUILD_TYPE"; /// Environment variable to extend the `RUSTFLAGS` variable given to the wasm build. const WASM_BUILD_RUSTFLAGS_ENV: &str = "WASM_BUILD_RUSTFLAGS"; /// Environment variable to set the target directory to copy the final wasm binary. /// /// The directory needs to be an absolute path. const WASM_TARGET_DIRECTORY: &str = "WASM_TARGET_DIRECTORY"; /// Environment variable to disable color output of the wasm build. const WASM_BUILD_NO_COLOR: &str = "WASM_BUILD_NO_COLOR"; /// Environment variable to set the toolchain used to compile the wasm binary. const WASM_BUILD_TOOLCHAIN: &str = "WASM_BUILD_TOOLCHAIN"; /// Build the currently built project as wasm binary. /// /// The current project is determined by using the `CARGO_MANIFEST_DIR` environment variable. /// /// `file_name` - The name + path of the file being generated. The file contains the /// constant `WASM_BINARY`, which contains the built WASM binary. /// `cargo_manifest` - The path to the `Cargo.toml` of the project that should be built. pub fn build_project(file_name: &str, cargo_manifest: &str) { build_project_with_default_rustflags(file_name, cargo_manifest, ""); } /// Build the currently built project as wasm binary. /// /// The current project is determined by using the `CARGO_MANIFEST_DIR` environment variable. /// /// `file_name` - The name + path of the file being generated. The file contains the /// constant `WASM_BINARY`, which contains the built WASM binary. /// `cargo_manifest` - The path to the `Cargo.toml` of the project that should be built. /// `default_rustflags` - Default `RUSTFLAGS` that will always be set for the build. pub fn build_project_with_default_rustflags( file_name: &str, cargo_manifest: &str, default_rustflags: &str, ) { if check_skip_build() { return; } let cargo_manifest = PathBuf::from(cargo_manifest); if !cargo_manifest.exists() { panic!("'{}' does not exist!", cargo_manifest.display()); } if !cargo_manifest.ends_with("Cargo.toml") { panic!("'{}' no valid path to a `Cargo.toml`!", cargo_manifest.display()); } if let Some(err_msg) = prerequisites::check() { eprintln!("{}", err_msg); process::exit(1); } let (wasm_binary, bloaty) = wasm_project::create_and_compile( &cargo_manifest, default_rustflags, ); write_file_if_changed( file_name.into(), format!( r#" pub const WASM_BINARY: &[u8] = include_bytes!("{wasm_binary}"); pub const WASM_BINARY_BLOATY: &[u8] = include_bytes!("{wasm_binary_bloaty}"); "#, wasm_binary = wasm_binary.wasm_binary_path(), wasm_binary_bloaty = bloaty.wasm_binary_bloaty_path(), ), ); } /// Checks if the build of the WASM binary should be skipped. fn check_skip_build() -> bool { env::var(SKIP_BUILD_ENV).is_ok() } /// Write to the given `file` if the `content` is different. fn write_file_if_changed(file: PathBuf, content: String) { if fs::read_to_string(&file).ok().as_ref() != Some(&content) { fs::write(&file, content).expect(&format!("Writing `{}` can not fail!", file.display())); } } /// Get a cargo command that compiles with nightly fn get_nightly_cargo() -> CargoCommand { let env_cargo = CargoCommand::new( &env::var("CARGO").expect("`CARGO` env variable is always set by cargo"), ); let default_cargo = CargoCommand::new("cargo"); let rustup_run_nightly = CargoCommand::new_with_args("rustup", &["run", "nightly", "cargo"]); let wasm_toolchain = env::var(WASM_BUILD_TOOLCHAIN).ok(); // First check if the user requested a specific toolchain if let Some(cmd) = wasm_toolchain.and_then(|t| get_rustup_nightly(Some(t))) { cmd } else if env_cargo.is_nightly() { env_cargo } else if default_cargo.is_nightly() { default_cargo } else if rustup_run_nightly.is_nightly() { rustup_run_nightly } else { // If no command before provided us with a nightly compiler, we try to search one // with rustup. If that fails as well, we return the default cargo and let the prequisities // check fail. get_rustup_nightly(None).unwrap_or(default_cargo) } } /// Get a nightly from rustup. If `selected` is `Some(_)`, a `CargoCommand` using the given /// nightly is returned. fn get_rustup_nightly(selected: Option<String>) -> Option<CargoCommand> { let host = format!("-{}", env::var("HOST").expect("`HOST` is always set by cargo")); let version = match selected { Some(selected) => selected, None => { let output = Command::new("rustup").args(&["toolchain", "list"]).output().ok()?.stdout; let lines = output.as_slice().lines(); let mut latest_nightly = None; for line in lines.filter_map(|l| l.ok()) { if line.starts_with("nightly-") && line.ends_with(&host) { // Rustup prints them sorted latest_nightly = Some(line.clone()); } } latest_nightly?.trim_end_matches(&host).into() } }; Some(CargoCommand::new_with_args("rustup", &["run", &version, "cargo"])) } /// Builder for cargo commands #[derive(Debug)] struct CargoCommand { program: String, args: Vec<String>, } impl CargoCommand { fn new(program: &str) -> Self { CargoCommand { program: program.into(), args: Vec::new() } } fn new_with_args(program: &str, args: &[&str]) -> Self { CargoCommand { program: program.into(), args: args.iter().map(ToString::to_string).collect(), } } fn command(&self) -> Command { let mut cmd = Command::new(&self.program); cmd.args(&self.args); cmd } /// Check if the supplied cargo command is a nightly version fn is_nightly(&self) -> bool { // `RUSTC_BOOTSTRAP` tells a stable compiler to behave like a nightly. So, when this env // variable is set, we can assume that whatever rust compiler we have, it is a nightly compiler. // For "more" information, see: // https://github.com/rust-lang/rust/blob/fa0f7d0080d8e7e9eb20aa9cbf8013f96c81287f/src/libsyntax/feature_gate/check.rs#L891 env::var("RUSTC_BOOTSTRAP").is_ok() || self.command() .arg("--version") .output() .map_err(|_| ()) .and_then(|o| String::from_utf8(o.stdout).map_err(|_| ())) .unwrap_or_default() .contains("-nightly") } }