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use crate::prelude::*;
use crate::runtime::vm::{CompiledModuleId, MmapVec, ModuleMemoryImages, VMWasmCallFunction};
use crate::sync::OnceLock;
use crate::{
code::CodeObject,
code_memory::CodeMemory,
instantiate::CompiledModule,
resources::ResourcesRequired,
type_registry::TypeCollection,
types::{ExportType, ExternType, ImportType},
Engine,
};
use alloc::sync::Arc;
use core::fmt;
use core::ops::Range;
use core::ptr::NonNull;
#[cfg(feature = "std")]
use std::path::Path;
use wasmparser::{Parser, ValidPayload, Validator};
use wasmtime_environ::{
CompiledModuleInfo, EntityIndex, HostPtr, ModuleTypes, ObjectKind, TypeTrace, VMOffsets,
VMSharedTypeIndex,
};
mod registry;
pub use registry::{
lookup_code, register_code, unregister_code, ModuleRegistry, RegisteredModuleId,
};
/// A compiled WebAssembly module, ready to be instantiated.
///
/// A `Module` is a compiled in-memory representation of an input WebAssembly
/// binary. A `Module` is then used to create an [`Instance`](crate::Instance)
/// through an instantiation process. You cannot call functions or fetch
/// globals, for example, on a `Module` because it's purely a code
/// representation. Instead you'll need to create an
/// [`Instance`](crate::Instance) to interact with the wasm module.
///
/// A `Module` can be created by compiling WebAssembly code through APIs such as
/// [`Module::new`]. This would be a JIT-style use case where code is compiled
/// just before it's used. Alternatively a `Module` can be compiled in one
/// process and [`Module::serialize`] can be used to save it to storage. A later
/// call to [`Module::deserialize`] will quickly load the module to execute and
/// does not need to compile any code, representing a more AOT-style use case.
///
/// Currently a `Module` does not implement any form of tiering or dynamic
/// optimization of compiled code. Creation of a `Module` via [`Module::new`] or
/// related APIs will perform the entire compilation step synchronously. When
/// finished no further compilation will happen at runtime or later during
/// execution of WebAssembly instances for example.
///
/// Compilation of WebAssembly by default goes through Cranelift and is
/// recommended to be done once-per-module. The same WebAssembly binary need not
/// be compiled multiple times and can instead used an embedder-cached result of
/// the first call.
///
/// `Module` is thread-safe and safe to share across threads.
///
/// ## Modules and `Clone`
///
/// Using `clone` on a `Module` is a cheap operation. It will not create an
/// entirely new module, but rather just a new reference to the existing module.
/// In other words it's a shallow copy, not a deep copy.
///
/// ## Examples
///
/// There are a number of ways you can create a `Module`, for example pulling
/// the bytes from a number of locations. One example is loading a module from
/// the filesystem:
///
/// ```no_run
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// let engine = Engine::default();
/// let module = Module::from_file(&engine, "path/to/foo.wasm")?;
/// # Ok(())
/// # }
/// ```
///
/// You can also load the wasm text format if more convenient too:
///
/// ```no_run
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// let engine = Engine::default();
/// // Now we're using the WebAssembly text extension: `.wat`!
/// let module = Module::from_file(&engine, "path/to/foo.wat")?;
/// # Ok(())
/// # }
/// ```
///
/// And if you've already got the bytes in-memory you can use the
/// [`Module::new`] constructor:
///
/// ```no_run
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// let engine = Engine::default();
/// # let wasm_bytes: Vec<u8> = Vec::new();
/// let module = Module::new(&engine, &wasm_bytes)?;
///
/// // It also works with the text format!
/// let module = Module::new(&engine, "(module (func))")?;
/// # Ok(())
/// # }
/// ```
///
/// Serializing and deserializing a module looks like:
///
/// ```no_run
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// let engine = Engine::default();
/// # let wasm_bytes: Vec<u8> = Vec::new();
/// let module = Module::new(&engine, &wasm_bytes)?;
/// let module_bytes = module.serialize()?;
///
/// // ... can save `module_bytes` to disk or other storage ...
///
/// // recreate the module from the serialized bytes. For the `unsafe` bits
/// // see the documentation of `deserialize`.
/// let module = unsafe { Module::deserialize(&engine, &module_bytes)? };
/// # Ok(())
/// # }
/// ```
///
/// [`Config`]: crate::Config
#[derive(Clone)]
pub struct Module {
inner: Arc<ModuleInner>,
}
struct ModuleInner {
engine: Engine,
/// The compiled artifacts for this module that will be instantiated and
/// executed.
module: CompiledModule,
/// Runtime information such as the underlying mmap, type information, etc.
///
/// Note that this `Arc` is used to share information between compiled
/// modules within a component. For bare core wasm modules created with
/// `Module::new`, for example, this is a uniquely owned `Arc`.
code: Arc<CodeObject>,
/// A set of initialization images for memories, if any.
///
/// Note that this is behind a `OnceCell` to lazily create this image. On
/// Linux where `memfd_create` may be used to create the backing memory
/// image this is a pretty expensive operation, so by deferring it this
/// improves memory usage for modules that are created but may not ever be
/// instantiated.
memory_images: OnceLock<Option<ModuleMemoryImages>>,
/// Flag indicating whether this module can be serialized or not.
serializable: bool,
/// Runtime offset information for `VMContext`.
offsets: VMOffsets<HostPtr>,
}
impl fmt::Debug for Module {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Module")
.field("name", &self.name())
.finish_non_exhaustive()
}
}
impl fmt::Debug for ModuleInner {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("ModuleInner")
.field("name", &self.module.module().name.as_ref())
.finish_non_exhaustive()
}
}
impl Module {
/// Creates a new WebAssembly `Module` from the given in-memory `bytes`.
///
/// The `bytes` provided must be in one of the following formats:
///
/// * A [binary-encoded][binary] WebAssembly module. This is always supported.
/// * A [text-encoded][text] instance of the WebAssembly text format.
/// This is only supported when the `wat` feature of this crate is enabled.
/// If this is supplied then the text format will be parsed before validation.
/// Note that the `wat` feature is enabled by default.
///
/// The data for the wasm module must be loaded in-memory if it's present
/// elsewhere, for example on disk. This requires that the entire binary is
/// loaded into memory all at once, this API does not support streaming
/// compilation of a module.
///
/// The WebAssembly binary will be decoded and validated. It will also be
/// compiled according to the configuration of the provided `engine`.
///
/// # Errors
///
/// This function may fail and return an error. Errors may include
/// situations such as:
///
/// * The binary provided could not be decoded because it's not a valid
/// WebAssembly binary
/// * The WebAssembly binary may not validate (e.g. contains type errors)
/// * Implementation-specific limits were exceeded with a valid binary (for
/// example too many locals)
/// * The wasm binary may use features that are not enabled in the
/// configuration of `engine`
/// * If the `wat` feature is enabled and the input is text, then it may be
/// rejected if it fails to parse.
///
/// The error returned should contain full information about why module
/// creation failed if one is returned.
///
/// [binary]: https://webassembly.github.io/spec/core/binary/index.html
/// [text]: https://webassembly.github.io/spec/core/text/index.html
///
/// # Examples
///
/// The `new` function can be invoked with a in-memory array of bytes:
///
/// ```no_run
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// # let wasm_bytes: Vec<u8> = Vec::new();
/// let module = Module::new(&engine, &wasm_bytes)?;
/// # Ok(())
/// # }
/// ```
///
/// Or you can also pass in a string to be parsed as the wasm text
/// format:
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let module = Module::new(&engine, "(module (func))")?;
/// # Ok(())
/// # }
/// ```
#[cfg(any(feature = "cranelift", feature = "winch"))]
pub fn new(engine: &Engine, bytes: impl AsRef<[u8]>) -> Result<Module> {
crate::CodeBuilder::new(engine)
.wasm_binary_or_text(bytes.as_ref(), None)?
.compile_module()
}
/// Creates a new WebAssembly `Module` from the contents of the given
/// `file` on disk.
///
/// This is a convenience function that will read the `file` provided and
/// pass the bytes to the [`Module::new`] function. For more information
/// see [`Module::new`]
///
/// # Examples
///
/// ```no_run
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// let engine = Engine::default();
/// let module = Module::from_file(&engine, "./path/to/foo.wasm")?;
/// # Ok(())
/// # }
/// ```
///
/// The `.wat` text format is also supported:
///
/// ```no_run
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let module = Module::from_file(&engine, "./path/to/foo.wat")?;
/// # Ok(())
/// # }
/// ```
#[cfg(all(feature = "std", any(feature = "cranelift", feature = "winch")))]
pub fn from_file(engine: &Engine, file: impl AsRef<Path>) -> Result<Module> {
crate::CodeBuilder::new(engine)
.wasm_binary_or_text_file(file.as_ref())?
.compile_module()
}
/// Creates a new WebAssembly `Module` from the given in-memory `binary`
/// data.
///
/// This is similar to [`Module::new`] except that it requires that the
/// `binary` input is a WebAssembly binary, the text format is not supported
/// by this function. It's generally recommended to use [`Module::new`], but
/// if it's required to not support the text format this function can be
/// used instead.
///
/// # Examples
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let wasm = b"\0asm\x01\0\0\0";
/// let module = Module::from_binary(&engine, wasm)?;
/// # Ok(())
/// # }
/// ```
///
/// Note that the text format is **not** accepted by this function:
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// assert!(Module::from_binary(&engine, b"(module)").is_err());
/// # Ok(())
/// # }
/// ```
#[cfg(any(feature = "cranelift", feature = "winch"))]
pub fn from_binary(engine: &Engine, binary: &[u8]) -> Result<Module> {
crate::CodeBuilder::new(engine)
.wasm_binary(binary, None)?
.compile_module()
}
/// Creates a new WebAssembly `Module` from the contents of the given `file`
/// on disk, but with assumptions that the file is from a trusted source.
/// The file should be a binary- or text-format WebAssembly module, or a
/// precompiled artifact generated by the same version of Wasmtime.
///
/// # Unsafety
///
/// All of the reasons that [`deserialize`] is `unsafe` apply to this
/// function as well. Arbitrary data loaded from a file may trick Wasmtime
/// into arbitrary code execution since the contents of the file are not
/// validated to be a valid precompiled module.
///
/// [`deserialize`]: Module::deserialize
///
/// Additionally though this function is also `unsafe` because the file
/// referenced must remain unchanged and a valid precompiled module for the
/// entire lifetime of the [`Module`] returned. Any changes to the file on
/// disk may change future instantiations of the module to be incorrect.
/// This is because the file is mapped into memory and lazily loaded pages
/// reflect the current state of the file, not necessarily the original
/// state of the file.
#[cfg(all(feature = "std", any(feature = "cranelift", feature = "winch")))]
pub unsafe fn from_trusted_file(engine: &Engine, file: impl AsRef<Path>) -> Result<Module> {
let mmap = MmapVec::from_file(file.as_ref())?;
if &mmap[0..4] == b"\x7fELF" {
let code = engine.load_code(mmap, ObjectKind::Module)?;
return Module::from_parts(engine, code, None);
}
crate::CodeBuilder::new(engine)
.wasm_binary_or_text(&mmap[..], Some(file.as_ref()))?
.compile_module()
}
/// Deserializes an in-memory compiled module previously created with
/// [`Module::serialize`] or [`Engine::precompile_module`].
///
/// This function will deserialize the binary blobs emitted by
/// [`Module::serialize`] and [`Engine::precompile_module`] back into an
/// in-memory [`Module`] that's ready to be instantiated.
///
/// Note that the [`Module::deserialize_file`] method is more optimized than
/// this function, so if the serialized module is already present in a file
/// it's recommended to use that method instead.
///
/// # Unsafety
///
/// This function is marked as `unsafe` because if fed invalid input or used
/// improperly this could lead to memory safety vulnerabilities. This method
/// should not, for example, be exposed to arbitrary user input.
///
/// The structure of the binary blob read here is only lightly validated
/// internally in `wasmtime`. This is intended to be an efficient
/// "rehydration" for a [`Module`] which has very few runtime checks beyond
/// deserialization. Arbitrary input could, for example, replace valid
/// compiled code with any other valid compiled code, meaning that this can
/// trivially be used to execute arbitrary code otherwise.
///
/// For these reasons this function is `unsafe`. This function is only
/// designed to receive the previous input from [`Module::serialize`] and
/// [`Engine::precompile_module`]. If the exact output of those functions
/// (unmodified) is passed to this function then calls to this function can
/// be considered safe. It is the caller's responsibility to provide the
/// guarantee that only previously-serialized bytes are being passed in
/// here.
///
/// Note that this function is designed to be safe receiving output from
/// *any* compiled version of `wasmtime` itself. This means that it is safe
/// to feed output from older versions of Wasmtime into this function, in
/// addition to newer versions of wasmtime (from the future!). These inputs
/// will deterministically and safely produce an `Err`. This function only
/// successfully accepts inputs from the same version of `wasmtime`, but the
/// safety guarantee only applies to externally-defined blobs of bytes, not
/// those defined by any version of wasmtime. (this means that if you cache
/// blobs across versions of wasmtime you can be safely guaranteed that
/// future versions of wasmtime will reject old cache entries).
pub unsafe fn deserialize(engine: &Engine, bytes: impl AsRef<[u8]>) -> Result<Module> {
let code = engine.load_code_bytes(bytes.as_ref(), ObjectKind::Module)?;
Module::from_parts(engine, code, None)
}
/// Same as [`deserialize`], except that the contents of `path` are read to
/// deserialize into a [`Module`].
///
/// This method is provided because it can be faster than [`deserialize`]
/// since the data doesn't need to be copied around, but rather the module
/// can be used directly from an mmap'd view of the file provided.
///
/// [`deserialize`]: Module::deserialize
///
/// # Unsafety
///
/// All of the reasons that [`deserialize`] is `unsafe` applies to this
/// function as well. Arbitrary data loaded from a file may trick Wasmtime
/// into arbitrary code execution since the contents of the file are not
/// validated to be a valid precompiled module.
///
/// Additionally though this function is also `unsafe` because the file
/// referenced must remain unchanged and a valid precompiled module for the
/// entire lifetime of the [`Module`] returned. Any changes to the file on
/// disk may change future instantiations of the module to be incorrect.
/// This is because the file is mapped into memory and lazily loaded pages
/// reflect the current state of the file, not necessarily the original
/// state of the file.
#[cfg(feature = "std")]
pub unsafe fn deserialize_file(engine: &Engine, path: impl AsRef<Path>) -> Result<Module> {
let code = engine.load_code_file(path.as_ref(), ObjectKind::Module)?;
Module::from_parts(engine, code, None)
}
/// Entrypoint for creating a `Module` for all above functions, both
/// of the AOT and jit-compiled categories.
///
/// In all cases the compilation artifact, `code_memory`, is provided here.
/// The `info_and_types` argument is `None` when a module is being
/// deserialized from a precompiled artifact or it's `Some` if it was just
/// compiled and the values are already available.
pub(crate) fn from_parts(
engine: &Engine,
code_memory: Arc<CodeMemory>,
info_and_types: Option<(CompiledModuleInfo, ModuleTypes)>,
) -> Result<Self> {
// Acquire this module's metadata and type information, deserializing
// it from the provided artifact if it wasn't otherwise provided
// already.
let (info, types) = match info_and_types {
Some((info, types)) => (info, types),
None => postcard::from_bytes(code_memory.wasmtime_info()).err2anyhow()?,
};
// Register function type signatures into the engine for the lifetime
// of the `Module` that will be returned. This notably also builds up
// maps for trampolines to be used for this module when inserted into
// stores.
//
// Note that the unsafety here should be ok since the `trampolines`
// field should only point to valid trampoline function pointers
// within the text section.
let signatures = TypeCollection::new_for_module(engine, &types);
// Package up all our data into a `CodeObject` and delegate to the final
// step of module compilation.
let code = Arc::new(CodeObject::new(code_memory, signatures, types.into()));
Module::from_parts_raw(engine, code, info, true)
}
pub(crate) fn from_parts_raw(
engine: &Engine,
code: Arc<CodeObject>,
info: CompiledModuleInfo,
serializable: bool,
) -> Result<Self> {
let module =
CompiledModule::from_artifacts(code.code_memory().clone(), info, engine.profiler())?;
// Validate the module can be used with the current instance allocator.
let offsets = VMOffsets::new(HostPtr, module.module());
engine
.allocator()
.validate_module(module.module(), &offsets)?;
Ok(Self {
inner: Arc::new(ModuleInner {
engine: engine.clone(),
code,
memory_images: OnceLock::new(),
module,
serializable,
offsets,
}),
})
}
/// Validates `binary` input data as a WebAssembly binary given the
/// configuration in `engine`.
///
/// This function will perform a speedy validation of the `binary` input
/// WebAssembly module (which is in [binary form][binary], the text format
/// is not accepted by this function) and return either `Ok` or `Err`
/// depending on the results of validation. The `engine` argument indicates
/// configuration for WebAssembly features, for example, which are used to
/// indicate what should be valid and what shouldn't be.
///
/// Validation automatically happens as part of [`Module::new`].
///
/// # Errors
///
/// If validation fails for any reason (type check error, usage of a feature
/// that wasn't enabled, etc) then an error with a description of the
/// validation issue will be returned.
///
/// [binary]: https://webassembly.github.io/spec/core/binary/index.html
pub fn validate(engine: &Engine, binary: &[u8]) -> Result<()> {
let mut validator = Validator::new_with_features(engine.features());
let mut functions = Vec::new();
for payload in Parser::new(0).parse_all(binary) {
let payload = payload.err2anyhow()?;
if let ValidPayload::Func(a, b) = validator.payload(&payload).err2anyhow()? {
functions.push((a, b));
}
if let wasmparser::Payload::Version { encoding, .. } = &payload {
if let wasmparser::Encoding::Component = encoding {
bail!("component passed to module validation");
}
}
}
engine
.run_maybe_parallel(functions, |(validator, body)| {
// FIXME: it would be best here to use a rayon-specific parallel
// iterator that maintains state-per-thread to share the function
// validator allocations (`Default::default` here) across multiple
// functions.
validator.into_validator(Default::default()).validate(&body)
})
.err2anyhow()?;
Ok(())
}
/// Serializes this module to a vector of bytes.
///
/// This function is similar to the [`Engine::precompile_module`] method
/// where it produces an artifact of Wasmtime which is suitable to later
/// pass into [`Module::deserialize`]. If a module is never instantiated
/// then it's recommended to use [`Engine::precompile_module`] instead of
/// this method, but if a module is both instantiated and serialized then
/// this method can be useful to get the serialized version without
/// compiling twice.
#[cfg(any(feature = "cranelift", feature = "winch"))]
pub fn serialize(&self) -> Result<Vec<u8>> {
// The current representation of compiled modules within a compiled
// component means that it cannot be serialized. The mmap returned here
// is the mmap for the entire component and while it contains all
// necessary data to deserialize this particular module it's all
// embedded within component-specific information.
//
// It's not the hardest thing in the world to support this but it's
// expected that there's not much of a use case at this time. In theory
// all that needs to be done is to edit the `.wasmtime.info` section
// to contains this module's metadata instead of the metadata for the
// whole component. The metadata itself is fairly trivially
// recreateable here it's more that there's no easy one-off API for
// editing the sections of an ELF object to use here.
//
// Overall for now this simply always returns an error in this
// situation. If you're reading this and feel that the situation should
// be different please feel free to open an issue.
if !self.inner.serializable {
bail!("cannot serialize a module exported from a component");
}
Ok(self.compiled_module().mmap().to_vec())
}
pub(crate) fn compiled_module(&self) -> &CompiledModule {
&self.inner.module
}
pub(crate) fn code_object(&self) -> &Arc<CodeObject> {
&self.inner.code
}
pub(crate) fn env_module(&self) -> &Arc<wasmtime_environ::Module> {
self.compiled_module().module()
}
pub(crate) fn types(&self) -> &ModuleTypes {
self.inner.code.module_types()
}
pub(crate) fn signatures(&self) -> &TypeCollection {
self.inner.code.signatures()
}
/// Returns identifier/name that this [`Module`] has. This name
/// is used in traps/backtrace details.
///
/// Note that most LLVM/clang/Rust-produced modules do not have a name
/// associated with them, but other wasm tooling can be used to inject or
/// add a name.
///
/// # Examples
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let module = Module::new(&engine, "(module $foo)")?;
/// assert_eq!(module.name(), Some("foo"));
///
/// let module = Module::new(&engine, "(module)")?;
/// assert_eq!(module.name(), None);
///
/// # Ok(())
/// # }
/// ```
pub fn name(&self) -> Option<&str> {
self.compiled_module().module().name.as_deref()
}
/// Returns the list of imports that this [`Module`] has and must be
/// satisfied.
///
/// This function returns the list of imports that the wasm module has, but
/// only the types of each import. The type of each import is used to
/// typecheck the [`Instance::new`](crate::Instance::new) method's `imports`
/// argument. The arguments to that function must match up 1-to-1 with the
/// entries in the array returned here.
///
/// The imports returned reflect the order of the imports in the wasm module
/// itself, and note that no form of deduplication happens.
///
/// # Examples
///
/// Modules with no imports return an empty list here:
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let module = Module::new(&engine, "(module)")?;
/// assert_eq!(module.imports().len(), 0);
/// # Ok(())
/// # }
/// ```
///
/// and modules with imports will have a non-empty list:
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let wat = r#"
/// (module
/// (import "host" "foo" (func))
/// )
/// "#;
/// let module = Module::new(&engine, wat)?;
/// assert_eq!(module.imports().len(), 1);
/// let import = module.imports().next().unwrap();
/// assert_eq!(import.module(), "host");
/// assert_eq!(import.name(), "foo");
/// match import.ty() {
/// ExternType::Func(_) => { /* ... */ }
/// _ => panic!("unexpected import type!"),
/// }
/// # Ok(())
/// # }
/// ```
pub fn imports<'module>(
&'module self,
) -> impl ExactSizeIterator<Item = ImportType<'module>> + 'module {
let module = self.compiled_module().module();
let types = self.types();
let engine = self.engine();
module
.imports()
.map(move |(imp_mod, imp_field, mut ty)| {
ty.canonicalize_for_runtime_usage(&mut |i| {
self.signatures().shared_type(i).unwrap()
});
ImportType::new(imp_mod, imp_field, ty, types, engine)
})
.collect::<Vec<_>>()
.into_iter()
}
/// Returns the list of exports that this [`Module`] has and will be
/// available after instantiation.
///
/// This function will return the type of each item that will be returned
/// from [`Instance::exports`](crate::Instance::exports). Each entry in this
/// list corresponds 1-to-1 with that list, and the entries here will
/// indicate the name of the export along with the type of the export.
///
/// # Examples
///
/// Modules might not have any exports:
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let module = Module::new(&engine, "(module)")?;
/// assert!(module.exports().next().is_none());
/// # Ok(())
/// # }
/// ```
///
/// When the exports are not empty, you can inspect each export:
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let wat = r#"
/// (module
/// (func (export "foo"))
/// (memory (export "memory") 1)
/// )
/// "#;
/// let module = Module::new(&engine, wat)?;
/// assert_eq!(module.exports().len(), 2);
///
/// let mut exports = module.exports();
/// let foo = exports.next().unwrap();
/// assert_eq!(foo.name(), "foo");
/// match foo.ty() {
/// ExternType::Func(_) => { /* ... */ }
/// _ => panic!("unexpected export type!"),
/// }
///
/// let memory = exports.next().unwrap();
/// assert_eq!(memory.name(), "memory");
/// match memory.ty() {
/// ExternType::Memory(_) => { /* ... */ }
/// _ => panic!("unexpected export type!"),
/// }
/// # Ok(())
/// # }
/// ```
pub fn exports<'module>(
&'module self,
) -> impl ExactSizeIterator<Item = ExportType<'module>> + 'module {
let module = self.compiled_module().module();
let types = self.types();
let engine = self.engine();
module.exports.iter().map(move |(name, entity_index)| {
ExportType::new(name, module.type_of(*entity_index), types, engine)
})
}
/// Looks up an export in this [`Module`] by name.
///
/// This function will return the type of an export with the given name.
///
/// # Examples
///
/// There may be no export with that name:
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let module = Module::new(&engine, "(module)")?;
/// assert!(module.get_export("foo").is_none());
/// # Ok(())
/// # }
/// ```
///
/// When there is an export with that name, it is returned:
///
/// ```
/// # use wasmtime::*;
/// # fn main() -> anyhow::Result<()> {
/// # let engine = Engine::default();
/// let wat = r#"
/// (module
/// (func (export "foo"))
/// (memory (export "memory") 1)
/// )
/// "#;
/// let module = Module::new(&engine, wat)?;
/// let foo = module.get_export("foo");
/// assert!(foo.is_some());
///
/// let foo = foo.unwrap();
/// match foo {
/// ExternType::Func(_) => { /* ... */ }
/// _ => panic!("unexpected export type!"),
/// }
///
/// # Ok(())
/// # }
/// ```
pub fn get_export(&self, name: &str) -> Option<ExternType> {
let module = self.compiled_module().module();
let entity_index = module.exports.get(name)?;
Some(ExternType::from_wasmtime(
self.engine(),
self.types(),
&module.type_of(*entity_index),
))
}
/// Looks up an export in this [`Module`] by name to get its index.
///
/// This function will return the index of an export with the given name. This can be useful
/// to avoid the cost of looking up the export by name multiple times. Instead the
/// [`ModuleExport`] can be stored and used to look up the export on the
/// [`Instance`](crate::Instance) later.
pub fn get_export_index(&self, name: &str) -> Option<ModuleExport> {
let compiled_module = self.compiled_module();
let module = compiled_module.module();
module
.exports
.get_full(name)
.map(|(export_name_index, _, &entity)| ModuleExport {
module: self.id(),
entity,
export_name_index,
})
}
/// Returns the [`Engine`] that this [`Module`] was compiled by.
pub fn engine(&self) -> &Engine {
&self.inner.engine
}
/// Returns a summary of the resources required to instantiate this
/// [`Module`].
///
/// Potential uses of the returned information:
///
/// * Determining whether your pooling allocator configuration supports
/// instantiating this module.
///
/// * Deciding how many of which `Module` you want to instantiate within a
/// fixed amount of resources, e.g. determining whether to create 5
/// instances of module X or 10 instances of module Y.
///
/// # Example
///
/// ```
/// # fn main() -> wasmtime::Result<()> {
/// use wasmtime::{Config, Engine, Module};
///
/// let mut config = Config::new();
/// config.wasm_multi_memory(true);
/// let engine = Engine::new(&config)?;
///
/// let module = Module::new(&engine, r#"
/// (module
/// ;; Import a memory. Doesn't count towards required resources.
/// (import "a" "b" (memory 10))
/// ;; Define two local memories. These count towards the required
/// ;; resources.
/// (memory 1)
/// (memory 6)
/// )
/// "#)?;
///
/// let resources = module.resources_required();
///
/// // Instantiating the module will require allocating two memories, and
/// // the maximum initial memory size is six Wasm pages.
/// assert_eq!(resources.num_memories, 2);
/// assert_eq!(resources.max_initial_memory_size, Some(6));
///
/// // The module doesn't need any tables.
/// assert_eq!(resources.num_tables, 0);
/// assert_eq!(resources.max_initial_table_size, None);
/// # Ok(()) }
/// ```
pub fn resources_required(&self) -> ResourcesRequired {
let em = self.env_module();
let num_memories = u32::try_from(em.memory_plans.len() - em.num_imported_memories).unwrap();
let max_initial_memory_size = em
.memory_plans
.values()
.skip(em.num_imported_memories)
.map(|plan| plan.memory.limits.min)
.max();
let num_tables = u32::try_from(em.table_plans.len() - em.num_imported_tables).unwrap();
let max_initial_table_size = em
.table_plans
.values()
.skip(em.num_imported_tables)
.map(|plan| plan.table.limits.min)
.max();
ResourcesRequired {
num_memories,
max_initial_memory_size,
num_tables,
max_initial_table_size,
}
}
/// Returns the range of bytes in memory where this module's compilation
/// image resides.
///
/// The compilation image for a module contains executable code, data, debug
/// information, etc. This is roughly the same as the `Module::serialize`
/// but not the exact same.
///
/// The range of memory reported here is exposed to allow low-level
/// manipulation of the memory in platform-specific manners such as using
/// `mlock` to force the contents to be paged in immediately or keep them
/// paged in after they're loaded.
///
/// It is not safe to modify the memory in this range, nor is it safe to
/// modify the protections of memory in this range.
pub fn image_range(&self) -> Range<*const u8> {
self.compiled_module().mmap().image_range()
}
/// Force initialization of copy-on-write images to happen here-and-now
/// instead of when they're requested during first instantiation.
///
/// When [copy-on-write memory
/// initialization](crate::Config::memory_init_cow) is enabled then Wasmtime
/// will lazily create the initialization image for a module. This method
/// can be used to explicitly dictate when this initialization happens.
///
/// Note that this largely only matters on Linux when memfd is used.
/// Otherwise the copy-on-write image typically comes from disk and in that
/// situation the creation of the image is trivial as the image is always
/// sourced from disk. On Linux, though, when memfd is used a memfd is
/// created and the initialization image is written to it.
///
/// Also note that this method is not required to be called, it's available
/// as a performance optimization if required but is otherwise handled
/// automatically.
pub fn initialize_copy_on_write_image(&self) -> Result<()> {
self.memory_images()?;
Ok(())
}
/// Get the map from `.text` section offsets to Wasm binary offsets for this
/// module.
///
/// Each entry is a (`.text` section offset, Wasm binary offset) pair.
///
/// Entries are yielded in order of `.text` section offset.
///
/// Some entries are missing a Wasm binary offset. This is for code that is
/// not associated with any single location in the Wasm binary, or for when
/// source information was optimized away.
///
/// Not every module has an address map, since address map generation can be
/// turned off on `Config`.
///
/// There is not an entry for every `.text` section offset. Every offset
/// after an entry's offset, but before the next entry's offset, is
/// considered to map to the same Wasm binary offset as the original
/// entry. For example, the address map will not contain the following
/// sequence of entries:
///
/// ```ignore
/// [
/// // ...
/// (10, Some(42)),
/// (11, Some(42)),
/// (12, Some(42)),
/// (13, Some(43)),
/// // ...
/// ]
/// ```
///
/// Instead, it will drop the entries for offsets `11` and `12` since they
/// are the same as the entry for offset `10`:
///
/// ```ignore
/// [
/// // ...
/// (10, Some(42)),
/// (13, Some(43)),
/// // ...
/// ]
/// ```
pub fn address_map<'a>(&'a self) -> Option<impl Iterator<Item = (usize, Option<u32>)> + 'a> {
Some(
wasmtime_environ::iterate_address_map(
self.code_object().code_memory().address_map_data(),
)?
.map(|(offset, file_pos)| (offset as usize, file_pos.file_offset())),
)
}
/// Get this module's code object's `.text` section, containing its compiled
/// executable code.
pub fn text(&self) -> &[u8] {
self.code_object().code_memory().text()
}
/// Get information about functions in this module's `.text` section: their
/// index, name, and offset+length.
///
/// Results are yielded in a ModuleFunction struct.
pub fn functions<'a>(&'a self) -> impl ExactSizeIterator<Item = ModuleFunction> + 'a {
let module = self.compiled_module();
module.finished_functions().map(|(idx, _)| {
let loc = module.func_loc(idx);
let idx = module.module().func_index(idx);
ModuleFunction {
index: idx,
name: module.func_name(idx).map(|n| n.to_string()),
offset: loc.start as usize,
len: loc.length as usize,
}
})
}
pub(crate) fn id(&self) -> CompiledModuleId {
self.inner.module.unique_id()
}
pub(crate) fn offsets(&self) -> &VMOffsets<HostPtr> {
&self.inner.offsets
}
/// Return the address, in memory, of the trampoline that allows Wasm to
/// call a array function of the given signature.
pub(crate) fn wasm_to_array_trampoline(
&self,
signature: VMSharedTypeIndex,
) -> Option<NonNull<VMWasmCallFunction>> {
log::trace!("Looking up trampoline for {signature:?}");
let trampoline_shared_ty = self.inner.engine.signatures().trampoline_type(signature);
let trampoline_module_ty = self
.inner
.code
.signatures()
.trampoline_type(trampoline_shared_ty)?;
debug_assert!(self
.inner
.engine
.signatures()
.borrow(
self.inner
.code
.signatures()
.shared_type(trampoline_module_ty)
.unwrap()
)
.unwrap()
.unwrap_func()
.is_trampoline_type());
let ptr = self
.compiled_module()
.wasm_to_array_trampoline(trampoline_module_ty)
.as_ptr()
.cast::<VMWasmCallFunction>()
.cast_mut();
Some(NonNull::new(ptr).unwrap())
}
pub(crate) fn memory_images(&self) -> Result<Option<&ModuleMemoryImages>> {
let images = self
.inner
.memory_images
.get_or_try_init(|| memory_images(&self.inner.engine, &self.inner.module))?
.as_ref();
Ok(images)
}
/// Lookup the stack map at a program counter value.
pub(crate) fn lookup_stack_map(&self, pc: usize) -> Option<&wasmtime_environ::StackMap> {
let text_offset = pc - self.inner.module.text().as_ptr() as usize;
let (index, func_offset) = self.inner.module.func_by_text_offset(text_offset)?;
let info = self.inner.module.wasm_func_info(index);
// Do a binary search to find the stack map for the given offset.
let index = match info
.stack_maps
.binary_search_by_key(&func_offset, |i| i.code_offset)
{
// Found it.
Ok(i) => i,
// No stack map associated with this PC.
//
// Because we know we are in Wasm code, and we must be at some kind
// of call/safepoint, then the Cranelift backend must have avoided
// emitting a stack map for this location because no refs were live.
Err(_) => return None,
};
Some(&info.stack_maps[index].stack_map)
}
}
/// Describes a function for a given module.
pub struct ModuleFunction {
pub index: wasmtime_environ::FuncIndex,
pub name: Option<String>,
pub offset: usize,
pub len: usize,
}
impl Drop for ModuleInner {
fn drop(&mut self) {
// When a `Module` is being dropped that means that it's no longer
// present in any `Store` and it's additionally not longer held by any
// embedder. Take this opportunity to purge any lingering instantiations
// within a pooling instance allocator, if applicable.
self.engine
.allocator()
.purge_module(self.module.unique_id());
}
}
/// Describes the location of an export in a module.
#[derive(Copy, Clone)]
pub struct ModuleExport {
/// The module that this export is defined in.
pub(crate) module: CompiledModuleId,
/// A raw index into the wasm module.
pub(crate) entity: EntityIndex,
/// The index of the export name.
pub(crate) export_name_index: usize,
}
fn _assert_send_sync() {
fn _assert<T: Send + Sync>() {}
_assert::<Module>();
}
/// Helper method to construct a `ModuleMemoryImages` for an associated
/// `CompiledModule`.
fn memory_images(engine: &Engine, module: &CompiledModule) -> Result<Option<ModuleMemoryImages>> {
// If initialization via copy-on-write is explicitly disabled in
// configuration then this path is skipped entirely.
if !engine.config().memory_init_cow {
return Ok(None);
}
// ... otherwise logic is delegated to the `ModuleMemoryImages::new`
// constructor.
let mmap = if engine.config().force_memory_init_memfd {
None
} else {
Some(module.mmap())
};
ModuleMemoryImages::new(module.module(), module.code_memory().wasm_data(), mmap)
}
#[cfg(test)]
mod tests {
use crate::{Engine, Module};
use wasmtime_environ::MemoryInitialization;
#[test]
fn cow_on_by_default() {
let engine = Engine::default();
let module = Module::new(
&engine,
r#"
(module
(memory 1)
(data (i32.const 100) "abcd")
)
"#,
)
.unwrap();
let init = &module.env_module().memory_initialization;
assert!(matches!(init, MemoryInitialization::Static { .. }));
}
}