create_obj.rs

//! Create a compiled standalone object file for a given Wasm file.

use super::ObjectFormat;
use crate::{commands::PrefixerFn, store::CompilerOptions};
use anyhow::{Context, Result};
use clap::Parser;
use std::env;
use std::fs;
use std::fs::File;
use std::io::prelude::*;
use std::io::BufWriter;
use std::path::PathBuf;
use wasmer::*;
use wasmer_object::{emit_serialized, get_object_for_target};

const WASMER_SERIALIZED_HEADER: &[u8] = include_bytes!("wasmer_deserialize_module.h");

#[derive(Debug, Parser)]
/// The options for the `wasmer create-exe` subcommand
pub struct CreateObj {
    /// Input file
    #[clap(name = "FILE", parse(from_os_str))]
    path: PathBuf,

    /// Output file
    #[clap(name = "OUTPUT_PATH", short = 'o', parse(from_os_str))]
    output: PathBuf,

    /// Header output file
    #[clap(
        name = "OUTPUT_HEADER_PATH",
        long = "output-header-path",
        parse(from_os_str)
    )]
    header_output: Option<PathBuf>,

    /// Compilation Target triple
    ///
    /// Accepted target triple values must follow the
    /// ['target_lexicon'](https://crates.io/crates/target-lexicon) crate format.
    ///
    /// The recommended targets we try to support are:
    ///
    /// - "x86_64-linux-gnu"
    /// - "aarch64-linux-gnu"
    /// - "x86_64-apple-darwin"
    /// - "arm64-apple-darwin"
    #[clap(long = "target")]
    target_triple: Option<Triple>,

    /// Object format options
    ///
    /// This flag accepts two options: `symbols` or `serialized`.
    /// - (default) `symbols` creates an object where all functions and metadata of the module are regular object symbols
    /// - `serialized` creates an object where the module is zero-copy serialized as raw data
    #[clap(name = "OBJECT_FORMAT", long = "object-format", verbatim_doc_comment)]
    object_format: Option<ObjectFormat>,

    #[clap(short = 'm', multiple = true, number_of_values = 1)]
    cpu_features: Vec<CpuFeature>,

    #[clap(flatten)]
    compiler: CompilerOptions,
}

impl CreateObj {
    /// Runs logic for the `create-obj` subcommand
    pub fn execute(&self) -> Result<()> {
        let target = self
            .target_triple
            .as_ref()
            .map(|target_triple| {
                let mut features = self
                    .cpu_features
                    .clone()
                    .into_iter()
                    .fold(CpuFeature::set(), |a, b| a | b);
                // Cranelift requires SSE2, so we have this "hack" for now to facilitate
                // usage
                if target_triple.architecture == Architecture::X86_64 {
                    features |= CpuFeature::SSE2;
                }
                Target::new(target_triple.clone(), features)
            })
            .unwrap_or_default();
        let (store, compiler_type) = self.compiler.get_store_for_target(target.clone())?;
        let object_format = self.object_format.unwrap_or(ObjectFormat::Symbols);

        println!("Compiler: {}", compiler_type.to_string());
        println!("Target: {}", target.triple());
        println!("Format: {:?}", object_format);

        let starting_cd = env::current_dir()?;

        let output_path = starting_cd.join(&self.output);
        let header_output = self.header_output.clone().unwrap_or_else(|| {
            let mut retval = self.output.clone();
            retval.set_extension("h");
            retval
        });

        let header_output_path = starting_cd.join(&header_output);
        let wasm_module_path = starting_cd.join(&self.path);

        match object_format {
            ObjectFormat::Serialized => {
                let module = Module::from_file(&store, &wasm_module_path)
                    .context("failed to compile Wasm")?;
                let bytes = module.serialize()?;
                let mut obj = get_object_for_target(target.triple())?;
                emit_serialized(&mut obj, &bytes, target.triple())?;
                let mut writer = BufWriter::new(File::create(&output_path)?);
                obj.write_stream(&mut writer)
                    .map_err(|err| anyhow::anyhow!(err.to_string()))?;
                writer.flush()?;
                let mut writer = BufWriter::new(File::create(&header_output_path)?);
                writer.write_all(WASMER_SERIALIZED_HEADER)?;
                writer.flush()?;
            }
            ObjectFormat::Symbols => {
                let engine = store.engine();
                let engine_inner = engine.inner();
                let compiler = engine_inner.compiler()?;
                let features = engine_inner.features();
                let tunables = store.tunables();
                let data: Vec<u8> = fs::read(wasm_module_path)?;
                let prefixer: Option<PrefixerFn> = None;
                let (module_info, obj, metadata_length, symbol_registry) =
                    Artifact::generate_object(
                        compiler, &data, prefixer, &target, tunables, features,
                    )?;

                let header_file_src = crate::c_gen::staticlib_header::generate_header_file(
                    &module_info,
                    &*symbol_registry,
                    metadata_length,
                );
                let mut writer = BufWriter::new(File::create(&output_path)?);
                obj.write_stream(&mut writer)
                    .map_err(|err| anyhow::anyhow!(err.to_string()))?;
                writer.flush()?;
                let mut writer = BufWriter::new(File::create(&header_output_path)?);
                writer.write_all(header_file_src.as_bytes())?;
                writer.flush()?;
            }
        }

        eprintln!(
            "✔ Object compiled successfully to `{}` and the header file was generated at `{}`.",
            self.output.display(),
            header_output.display(),
        );
        eprintln!("\n---\n");
        eprintln!(
            r#"To use, link the object file to your executable and call the `wasmer_object_module_new` function defined in the header file. For example, in the C language:

	#include "{}"
	
	wasm_module_t *module = wasmer_object_module_new(store, "my_module_name");
            "#,
            header_output.display(),
        );

        Ok(())
    }
}