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use crate::prelude::*;
use crate::Engine;
use anyhow::{anyhow, bail, Context, Result};
use std::borrow::Cow;
use std::path::Path;
/// Builder-style structure used to create a [`Module`](crate::module::Module) or
/// pre-compile a module to a serialized list of bytes.
///
/// This structure can be used for more advanced configuration when compiling a
/// WebAssembly module. Most configuration can use simpler constructors such as:
///
/// * [`Module::new`](crate::Module::new)
/// * [`Module::from_file`](crate::Module::from_file)
/// * [`Module::from_binary`](crate::Module::from_binary)
///
/// Note that a [`CodeBuilder`] always involves compiling WebAssembly bytes
/// to machine code. To deserialize a list of bytes use
/// [`Module::deserialize`](crate::Module::deserialize) instead.
///
/// A [`CodeBuilder`] requires a source of WebAssembly bytes to be configured
/// before calling [`compile_module_serialized`] or [`compile_module`]. This can be
/// provided with either the [`wasm`] or [`wasm_file`] method. Note that only
/// a single source of bytes can be provided.
///
/// # WebAssembly Text Format
///
/// This builder supports the WebAssembly Text Format (`*.wat` files).
/// WebAssembly text files are automatically converted to a WebAssembly binary
/// and then the binary is compiled. This requires the `wat` feature of the
/// `wasmtime` crate to be enabled, and the feature is enabled by default.
///
/// If the text format is not desired then the [`CodeBuilder::wat`] method
/// can be used to disable this conversion.
///
/// [`compile_module_serialized`]: CodeBuilder::compile_module_serialized
/// [`compile_module`]: CodeBuilder::compile_module
/// [`wasm`]: CodeBuilder::wasm
/// [`wasm_file`]: CodeBuilder::wasm_file
pub struct CodeBuilder<'a> {
pub(super) engine: &'a Engine,
wasm: Option<Cow<'a, [u8]>>,
wasm_path: Option<Cow<'a, Path>>,
dwarf_package: Option<Cow<'a, [u8]>>,
dwarf_package_path: Option<Cow<'a, Path>>,
wat: bool,
}
impl<'a> CodeBuilder<'a> {
/// Creates a new builder which will insert modules into the specified
/// [`Engine`].
pub fn new(engine: &'a Engine) -> CodeBuilder<'a> {
CodeBuilder {
engine,
wasm: None,
wasm_path: None,
dwarf_package: None,
dwarf_package_path: None,
wat: cfg!(feature = "wat"),
}
}
/// Configures the WebAssembly binary or text that is being compiled.
///
/// The `wasm_bytes` parameter is either a binary WebAssembly file or a
/// WebAssembly module in its text format. This will be stored within the
/// [`CodeBuilder`] for processing later when compilation is finalized.
///
/// The optional `wasm_path` parameter is the path to the `wasm_bytes` on
/// disk, if any. This may be used for diagnostics and other
/// debugging-related purposes, but this method will not read the path
/// specified.
///
/// # Errors
///
/// If wasm bytes have already been configured via a call to this method or
/// [`CodeBuilder::wasm_file`] then an error will be returned.
pub fn wasm(&mut self, wasm_bytes: &'a [u8], wasm_path: Option<&'a Path>) -> Result<&mut Self> {
if self.wasm.is_some() {
bail!("cannot call `wasm` or `wasm_file` twice");
}
self.wasm = Some(wasm_bytes.into());
self.wasm_path = wasm_path.map(|p| p.into());
if self.wasm_path.is_some() {
self.dwarf_package_from_wasm_path()?;
}
Ok(self)
}
/// Configures whether the WebAssembly text format is supported in this
/// builder.
///
/// This support is enabled by default if the `wat` crate feature is also
/// enabled.
///
/// # Errors
///
/// If this feature is explicitly enabled here via this method and the
/// `wat` crate feature is disabled then an error will be returned.
pub fn wat(&mut self, enable: bool) -> Result<&mut Self> {
if !cfg!(feature = "wat") && enable {
bail!("support for `wat` was disabled at compile time");
}
self.wat = enable;
Ok(self)
}
/// Reads the `file` specified for the WebAssembly bytes that are going to
/// be compiled.
///
/// This method will read `file` from the filesystem and interpret it
/// either as a WebAssembly binary or as a WebAssembly text file. The
/// contents are inspected to do this, the file extension is not consulted.
///
/// A DWARF package file will be probed using the root of `file` and with a
/// `.dwp` extension. If found, it will be loaded and DWARF fusion
/// performed.
///
/// # Errors
///
/// If wasm bytes have already been configured via a call to this method or
/// [`CodeBuilder::wasm`] then an error will be returned.
///
/// If `file` can't be read or an error happens reading it then that will
/// also be returned.
///
/// If DWARF fusion is performed and the DWARF packaged file cannot be read
/// then an error will be returned.
pub fn wasm_file(&mut self, file: &'a Path) -> Result<&mut Self> {
if self.wasm.is_some() {
bail!("cannot call `wasm` or `wasm_file` twice");
}
let wasm = std::fs::read(file)
.with_context(|| format!("failed to read input file: {}", file.display()))?;
self.wasm = Some(wasm.into());
self.wasm_path = Some(file.into());
self.dwarf_package_from_wasm_path()?;
Ok(self)
}
pub(super) fn wasm_binary(&self) -> Result<Cow<'_, [u8]>> {
let wasm = self
.wasm
.as_ref()
.ok_or_else(|| anyhow!("no wasm bytes have been configured"))?;
if self.wat {
#[cfg(feature = "wat")]
return wat::parse_bytes(wasm).map_err(|mut e| {
if let Some(path) = &self.wasm_path {
e.set_path(path);
}
e.into()
});
}
Ok((&wasm[..]).into())
}
/// Explicitly specify DWARF `.dwp` path.
///
/// # Errors
///
/// This method will return an error if the `.dwp` file has already been set
/// through [`CodeBuilder::dwarf_package`] or auto-detection in
/// [`CodeBuilder::wasm_file`].
///
/// This method will also return an error if `file` cannot be read.
pub fn dwarf_package_file(&mut self, file: &Path) -> Result<&mut Self> {
if self.dwarf_package.is_some() {
bail!("cannot call `dwarf_package` or `dwarf_package_file` twice");
}
let dwarf_package = std::fs::read(file)
.with_context(|| format!("failed to read dwarf input file: {}", file.display()))?;
self.dwarf_package_path = Some(Cow::Owned(file.to_owned()));
self.dwarf_package = Some(dwarf_package.into());
Ok(self)
}
fn dwarf_package_from_wasm_path(&mut self) -> Result<&mut Self> {
let dwarf_package_path_buf = self.wasm_path.as_ref().unwrap().with_extension("dwp");
if dwarf_package_path_buf.exists() {
return self.dwarf_package_file(dwarf_package_path_buf.as_path());
}
Ok(self)
}
/// Gets the DWARF package.
pub(super) fn dwarf_package_binary(&self) -> Option<&[u8]> {
return self.dwarf_package.as_deref();
}
/// Set the DWARF package binary.
///
/// Initializes `dwarf_package` from `dwp_bytes` in preparation for
/// DWARF fusion. Allows the DWARF package to be supplied as a byte array
/// when the file probing performed in `wasm_file` is not appropriate.
///
/// # Errors
///
/// Returns an error if the `*.dwp` file is already set via auto-probing in
/// [`CodeBuilder::wasm_file`] or explicitly via
/// [`CodeBuilder::dwarf_package_file`].
pub fn dwarf_package(&mut self, dwp_bytes: &'a [u8]) -> Result<&mut Self> {
if self.dwarf_package.is_some() {
bail!("cannot call `dwarf_package` or `dwarf_package_file` twice");
}
self.dwarf_package = Some(dwp_bytes.into());
Ok(self)
}
/// Finishes this compilation and produces a serialized list of bytes.
///
/// This method requires that either [`CodeBuilder::wasm`] or
/// [`CodeBuilder::wasm_file`] was invoked prior to indicate what is
/// being compiled.
///
/// This method will block the current thread until compilation has
/// finished, and when done the serialized artifact will be returned.
///
/// Note that this method will never cache compilations, even if the
/// `cache` feature is enabled.
///
/// # Errors
///
/// This can fail if the input wasm module was not valid or if another
/// compilation-related error is encountered.
pub fn compile_module_serialized(&self) -> Result<Vec<u8>> {
let wasm = self.wasm_binary()?;
let dwarf_package = self.dwarf_package_binary();
let (v, _) = super::build_artifacts(self.engine, &wasm, dwarf_package.as_deref())?;
Ok(v)
}
/// Same as [`CodeBuilder::compile_module_serialized`] except that it
/// compiles a serialized [`Component`](crate::component::Component)
/// instead of a module.
#[cfg(feature = "component-model")]
pub fn compile_component_serialized(&self) -> Result<Vec<u8>> {
let bytes = self.wasm_binary()?;
let (v, _) = super::build_component_artifacts(self.engine, &bytes, None)?;
Ok(v)
}
}
/// This is a helper struct used when caching to hash the state of an `Engine`
/// used for module compilation.
///
/// The hash computed for this structure is used to key the global wasmtime
/// cache and dictates whether artifacts are reused. Consequently the contents
/// of this hash dictate when artifacts are or aren't re-used.
pub struct HashedEngineCompileEnv<'a>(pub &'a Engine);
impl std::hash::Hash for HashedEngineCompileEnv<'_> {
fn hash<H: std::hash::Hasher>(&self, hasher: &mut H) {
// Hash the compiler's state based on its target and configuration.
let compiler = self.0.compiler();
compiler.triple().hash(hasher);
compiler.flags().hash(hasher);
compiler.isa_flags().hash(hasher);
// Hash configuration state read for compilation
let config = self.0.config();
self.0.tunables().hash(hasher);
config.features.hash(hasher);
config.wmemcheck.hash(hasher);
// Catch accidental bugs of reusing across crate versions.
config.module_version.hash(hasher);
}
}