wasmtime/runtime/module.rs
1use crate::prelude::*;
2#[cfg(feature = "std")]
3use crate::runtime::vm::open_file_for_mmap;
4use crate::runtime::vm::{CompiledModuleId, MmapVec, ModuleMemoryImages, VMWasmCallFunction};
5use crate::sync::OnceLock;
6use crate::{
7 Engine,
8 code::CodeObject,
9 code_memory::CodeMemory,
10 instantiate::CompiledModule,
11 resources::ResourcesRequired,
12 types::{ExportType, ExternType, ImportType},
13};
14use alloc::sync::Arc;
15use core::fmt;
16use core::ops::Range;
17use core::ptr::NonNull;
18#[cfg(feature = "std")]
19use std::{fs::File, path::Path};
20use wasmparser::{Parser, ValidPayload, Validator};
21#[cfg(feature = "debug")]
22use wasmtime_environ::FrameTable;
23use wasmtime_environ::{
24 CompiledFunctionsTable, CompiledModuleInfo, EntityIndex, HostPtr, ModuleTypes, ObjectKind,
25 TypeTrace, VMOffsets, VMSharedTypeIndex,
26};
27#[cfg(feature = "gc")]
28use wasmtime_unwinder::ExceptionTable;
29mod registry;
30
31pub use registry::*;
32
33/// A compiled WebAssembly module, ready to be instantiated.
34///
35/// A `Module` is a compiled in-memory representation of an input WebAssembly
36/// binary. A `Module` is then used to create an [`Instance`](crate::Instance)
37/// through an instantiation process. You cannot call functions or fetch
38/// globals, for example, on a `Module` because it's purely a code
39/// representation. Instead you'll need to create an
40/// [`Instance`](crate::Instance) to interact with the wasm module.
41///
42/// A `Module` can be created by compiling WebAssembly code through APIs such as
43/// [`Module::new`]. This would be a JIT-style use case where code is compiled
44/// just before it's used. Alternatively a `Module` can be compiled in one
45/// process and [`Module::serialize`] can be used to save it to storage. A later
46/// call to [`Module::deserialize`] will quickly load the module to execute and
47/// does not need to compile any code, representing a more AOT-style use case.
48///
49/// Currently a `Module` does not implement any form of tiering or dynamic
50/// optimization of compiled code. Creation of a `Module` via [`Module::new`] or
51/// related APIs will perform the entire compilation step synchronously. When
52/// finished no further compilation will happen at runtime or later during
53/// execution of WebAssembly instances for example.
54///
55/// Compilation of WebAssembly by default goes through Cranelift and is
56/// recommended to be done once-per-module. The same WebAssembly binary need not
57/// be compiled multiple times and can instead used an embedder-cached result of
58/// the first call.
59///
60/// `Module` is thread-safe and safe to share across threads.
61///
62/// ## Modules and `Clone`
63///
64/// Using `clone` on a `Module` is a cheap operation. It will not create an
65/// entirely new module, but rather just a new reference to the existing module.
66/// In other words it's a shallow copy, not a deep copy.
67///
68/// ## Examples
69///
70/// There are a number of ways you can create a `Module`, for example pulling
71/// the bytes from a number of locations. One example is loading a module from
72/// the filesystem:
73///
74/// ```no_run
75/// # use wasmtime::*;
76/// # fn main() -> anyhow::Result<()> {
77/// let engine = Engine::default();
78/// let module = Module::from_file(&engine, "path/to/foo.wasm")?;
79/// # Ok(())
80/// # }
81/// ```
82///
83/// You can also load the wasm text format if more convenient too:
84///
85/// ```no_run
86/// # use wasmtime::*;
87/// # fn main() -> anyhow::Result<()> {
88/// let engine = Engine::default();
89/// // Now we're using the WebAssembly text extension: `.wat`!
90/// let module = Module::from_file(&engine, "path/to/foo.wat")?;
91/// # Ok(())
92/// # }
93/// ```
94///
95/// And if you've already got the bytes in-memory you can use the
96/// [`Module::new`] constructor:
97///
98/// ```no_run
99/// # use wasmtime::*;
100/// # fn main() -> anyhow::Result<()> {
101/// let engine = Engine::default();
102/// # let wasm_bytes: Vec<u8> = Vec::new();
103/// let module = Module::new(&engine, &wasm_bytes)?;
104///
105/// // It also works with the text format!
106/// let module = Module::new(&engine, "(module (func))")?;
107/// # Ok(())
108/// # }
109/// ```
110///
111/// Serializing and deserializing a module looks like:
112///
113/// ```no_run
114/// # use wasmtime::*;
115/// # fn main() -> anyhow::Result<()> {
116/// let engine = Engine::default();
117/// # let wasm_bytes: Vec<u8> = Vec::new();
118/// let module = Module::new(&engine, &wasm_bytes)?;
119/// let module_bytes = module.serialize()?;
120///
121/// // ... can save `module_bytes` to disk or other storage ...
122///
123/// // recreate the module from the serialized bytes. For the `unsafe` bits
124/// // see the documentation of `deserialize`.
125/// let module = unsafe { Module::deserialize(&engine, &module_bytes)? };
126/// # Ok(())
127/// # }
128/// ```
129///
130/// [`Config`]: crate::Config
131#[derive(Clone)]
132pub struct Module {
133 inner: Arc<ModuleInner>,
134}
135
136struct ModuleInner {
137 engine: Engine,
138 /// The compiled artifacts for this module that will be instantiated and
139 /// executed.
140 module: CompiledModule,
141
142 /// Runtime information such as the underlying mmap, type information, etc.
143 ///
144 /// Note that this `Arc` is used to share information between compiled
145 /// modules within a component. For bare core wasm modules created with
146 /// `Module::new`, for example, this is a uniquely owned `Arc`.
147 code: Arc<CodeObject>,
148
149 /// A set of initialization images for memories, if any.
150 ///
151 /// Note that this is behind a `OnceCell` to lazily create this image. On
152 /// Linux where `memfd_create` may be used to create the backing memory
153 /// image this is a pretty expensive operation, so by deferring it this
154 /// improves memory usage for modules that are created but may not ever be
155 /// instantiated.
156 memory_images: OnceLock<Option<ModuleMemoryImages>>,
157
158 /// Flag indicating whether this module can be serialized or not.
159 #[cfg(any(feature = "cranelift", feature = "winch"))]
160 serializable: bool,
161
162 /// Runtime offset information for `VMContext`.
163 offsets: VMOffsets<HostPtr>,
164}
165
166impl fmt::Debug for Module {
167 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
168 f.debug_struct("Module")
169 .field("name", &self.name())
170 .finish_non_exhaustive()
171 }
172}
173
174impl fmt::Debug for ModuleInner {
175 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
176 f.debug_struct("ModuleInner")
177 .field("name", &self.module.module().name.as_ref())
178 .finish_non_exhaustive()
179 }
180}
181
182impl Module {
183 /// Creates a new WebAssembly `Module` from the given in-memory `bytes`.
184 ///
185 /// The `bytes` provided must be in one of the following formats:
186 ///
187 /// * A [binary-encoded][binary] WebAssembly module. This is always supported.
188 /// * A [text-encoded][text] instance of the WebAssembly text format.
189 /// This is only supported when the `wat` feature of this crate is enabled.
190 /// If this is supplied then the text format will be parsed before validation.
191 /// Note that the `wat` feature is enabled by default.
192 ///
193 /// The data for the wasm module must be loaded in-memory if it's present
194 /// elsewhere, for example on disk. This requires that the entire binary is
195 /// loaded into memory all at once, this API does not support streaming
196 /// compilation of a module.
197 ///
198 /// The WebAssembly binary will be decoded and validated. It will also be
199 /// compiled according to the configuration of the provided `engine`.
200 ///
201 /// # Errors
202 ///
203 /// This function may fail and return an error. Errors may include
204 /// situations such as:
205 ///
206 /// * The binary provided could not be decoded because it's not a valid
207 /// WebAssembly binary
208 /// * The WebAssembly binary may not validate (e.g. contains type errors)
209 /// * Implementation-specific limits were exceeded with a valid binary (for
210 /// example too many locals)
211 /// * The wasm binary may use features that are not enabled in the
212 /// configuration of `engine`
213 /// * If the `wat` feature is enabled and the input is text, then it may be
214 /// rejected if it fails to parse.
215 ///
216 /// The error returned should contain full information about why module
217 /// creation failed if one is returned.
218 ///
219 /// [binary]: https://webassembly.github.io/spec/core/binary/index.html
220 /// [text]: https://webassembly.github.io/spec/core/text/index.html
221 ///
222 /// # Examples
223 ///
224 /// The `new` function can be invoked with a in-memory array of bytes:
225 ///
226 /// ```no_run
227 /// # use wasmtime::*;
228 /// # fn main() -> anyhow::Result<()> {
229 /// # let engine = Engine::default();
230 /// # let wasm_bytes: Vec<u8> = Vec::new();
231 /// let module = Module::new(&engine, &wasm_bytes)?;
232 /// # Ok(())
233 /// # }
234 /// ```
235 ///
236 /// Or you can also pass in a string to be parsed as the wasm text
237 /// format:
238 ///
239 /// ```
240 /// # use wasmtime::*;
241 /// # fn main() -> anyhow::Result<()> {
242 /// # let engine = Engine::default();
243 /// let module = Module::new(&engine, "(module (func))")?;
244 /// # Ok(())
245 /// # }
246 /// ```
247 #[cfg(any(feature = "cranelift", feature = "winch"))]
248 pub fn new(engine: &Engine, bytes: impl AsRef<[u8]>) -> Result<Module> {
249 crate::CodeBuilder::new(engine)
250 .wasm_binary_or_text(bytes.as_ref(), None)?
251 .compile_module()
252 }
253
254 /// Creates a new WebAssembly `Module` from the contents of the given
255 /// `file` on disk.
256 ///
257 /// This is a convenience function that will read the `file` provided and
258 /// pass the bytes to the [`Module::new`] function. For more information
259 /// see [`Module::new`]
260 ///
261 /// # Examples
262 ///
263 /// ```no_run
264 /// # use wasmtime::*;
265 /// # fn main() -> anyhow::Result<()> {
266 /// let engine = Engine::default();
267 /// let module = Module::from_file(&engine, "./path/to/foo.wasm")?;
268 /// # Ok(())
269 /// # }
270 /// ```
271 ///
272 /// The `.wat` text format is also supported:
273 ///
274 /// ```no_run
275 /// # use wasmtime::*;
276 /// # fn main() -> anyhow::Result<()> {
277 /// # let engine = Engine::default();
278 /// let module = Module::from_file(&engine, "./path/to/foo.wat")?;
279 /// # Ok(())
280 /// # }
281 /// ```
282 #[cfg(all(feature = "std", any(feature = "cranelift", feature = "winch")))]
283 pub fn from_file(engine: &Engine, file: impl AsRef<Path>) -> Result<Module> {
284 crate::CodeBuilder::new(engine)
285 .wasm_binary_or_text_file(file.as_ref())?
286 .compile_module()
287 }
288
289 /// Creates a new WebAssembly `Module` from the given in-memory `binary`
290 /// data.
291 ///
292 /// This is similar to [`Module::new`] except that it requires that the
293 /// `binary` input is a WebAssembly binary, the text format is not supported
294 /// by this function. It's generally recommended to use [`Module::new`], but
295 /// if it's required to not support the text format this function can be
296 /// used instead.
297 ///
298 /// # Examples
299 ///
300 /// ```
301 /// # use wasmtime::*;
302 /// # fn main() -> anyhow::Result<()> {
303 /// # let engine = Engine::default();
304 /// let wasm = b"\0asm\x01\0\0\0";
305 /// let module = Module::from_binary(&engine, wasm)?;
306 /// # Ok(())
307 /// # }
308 /// ```
309 ///
310 /// Note that the text format is **not** accepted by this function:
311 ///
312 /// ```
313 /// # use wasmtime::*;
314 /// # fn main() -> anyhow::Result<()> {
315 /// # let engine = Engine::default();
316 /// assert!(Module::from_binary(&engine, b"(module)").is_err());
317 /// # Ok(())
318 /// # }
319 /// ```
320 #[cfg(any(feature = "cranelift", feature = "winch"))]
321 pub fn from_binary(engine: &Engine, binary: &[u8]) -> Result<Module> {
322 crate::CodeBuilder::new(engine)
323 .wasm_binary(binary, None)?
324 .compile_module()
325 }
326
327 /// Creates a new WebAssembly `Module` from the contents of the given `file`
328 /// on disk, but with assumptions that the file is from a trusted source.
329 /// The file should be a binary- or text-format WebAssembly module, or a
330 /// precompiled artifact generated by the same version of Wasmtime.
331 ///
332 /// # Unsafety
333 ///
334 /// All of the reasons that [`deserialize`] is `unsafe` apply to this
335 /// function as well. Arbitrary data loaded from a file may trick Wasmtime
336 /// into arbitrary code execution since the contents of the file are not
337 /// validated to be a valid precompiled module.
338 ///
339 /// [`deserialize`]: Module::deserialize
340 ///
341 /// Additionally though this function is also `unsafe` because the file
342 /// referenced must remain unchanged and a valid precompiled module for the
343 /// entire lifetime of the [`Module`] returned. Any changes to the file on
344 /// disk may change future instantiations of the module to be incorrect.
345 /// This is because the file is mapped into memory and lazily loaded pages
346 /// reflect the current state of the file, not necessarily the original
347 /// state of the file.
348 #[cfg(all(feature = "std", any(feature = "cranelift", feature = "winch")))]
349 pub unsafe fn from_trusted_file(engine: &Engine, file: impl AsRef<Path>) -> Result<Module> {
350 let open_file = open_file_for_mmap(file.as_ref())?;
351 let mmap = crate::runtime::vm::MmapVec::from_file(open_file)?;
352 if &mmap[0..4] == b"\x7fELF" {
353 let code = engine.load_code(mmap, ObjectKind::Module)?;
354 return Module::from_parts(engine, code, None);
355 }
356
357 crate::CodeBuilder::new(engine)
358 .wasm_binary_or_text(&mmap[..], Some(file.as_ref()))?
359 .compile_module()
360 }
361
362 /// Deserializes an in-memory compiled module previously created with
363 /// [`Module::serialize`] or [`Engine::precompile_module`].
364 ///
365 /// This function will deserialize the binary blobs emitted by
366 /// [`Module::serialize`] and [`Engine::precompile_module`] back into an
367 /// in-memory [`Module`] that's ready to be instantiated.
368 ///
369 /// Note that the [`Module::deserialize_file`] method is more optimized than
370 /// this function, so if the serialized module is already present in a file
371 /// it's recommended to use that method instead.
372 ///
373 /// # Unsafety
374 ///
375 /// This function is marked as `unsafe` because if fed invalid input or used
376 /// improperly this could lead to memory safety vulnerabilities. This method
377 /// should not, for example, be exposed to arbitrary user input.
378 ///
379 /// The structure of the binary blob read here is only lightly validated
380 /// internally in `wasmtime`. This is intended to be an efficient
381 /// "rehydration" for a [`Module`] which has very few runtime checks beyond
382 /// deserialization. Arbitrary input could, for example, replace valid
383 /// compiled code with any other valid compiled code, meaning that this can
384 /// trivially be used to execute arbitrary code otherwise.
385 ///
386 /// For these reasons this function is `unsafe`. This function is only
387 /// designed to receive the previous input from [`Module::serialize`] and
388 /// [`Engine::precompile_module`]. If the exact output of those functions
389 /// (unmodified) is passed to this function then calls to this function can
390 /// be considered safe. It is the caller's responsibility to provide the
391 /// guarantee that only previously-serialized bytes are being passed in
392 /// here.
393 ///
394 /// Note that this function is designed to be safe receiving output from
395 /// *any* compiled version of `wasmtime` itself. This means that it is safe
396 /// to feed output from older versions of Wasmtime into this function, in
397 /// addition to newer versions of wasmtime (from the future!). These inputs
398 /// will deterministically and safely produce an `Err`. This function only
399 /// successfully accepts inputs from the same version of `wasmtime`, but the
400 /// safety guarantee only applies to externally-defined blobs of bytes, not
401 /// those defined by any version of wasmtime. (this means that if you cache
402 /// blobs across versions of wasmtime you can be safely guaranteed that
403 /// future versions of wasmtime will reject old cache entries).
404 pub unsafe fn deserialize(engine: &Engine, bytes: impl AsRef<[u8]>) -> Result<Module> {
405 let code = engine.load_code_bytes(bytes.as_ref(), ObjectKind::Module)?;
406 Module::from_parts(engine, code, None)
407 }
408
409 /// In-place deserialization of an in-memory compiled module previously
410 /// created with [`Module::serialize`] or [`Engine::precompile_module`].
411 ///
412 /// See [`Self::deserialize`] for additional information; this method
413 /// works identically except that it will not create a copy of the provided
414 /// memory but will use it directly.
415 ///
416 /// # Unsafety
417 ///
418 /// All of the safety notes from [`Self::deserialize`] apply here as well
419 /// with the additional constraint that the code memory provide by `memory`
420 /// lives for as long as the module and is nevery externally modified for
421 /// the lifetime of the deserialized module.
422 pub unsafe fn deserialize_raw(engine: &Engine, memory: NonNull<[u8]>) -> Result<Module> {
423 // SAFETY: the contract required by `load_code_raw` is the same as this
424 // function.
425 let code = unsafe { engine.load_code_raw(memory, ObjectKind::Module)? };
426 Module::from_parts(engine, code, None)
427 }
428
429 /// Same as [`deserialize`], except that the contents of `path` are read to
430 /// deserialize into a [`Module`].
431 ///
432 /// This method is provided because it can be faster than [`deserialize`]
433 /// since the data doesn't need to be copied around, but rather the module
434 /// can be used directly from an mmap'd view of the file provided.
435 ///
436 /// [`deserialize`]: Module::deserialize
437 ///
438 /// # Unsafety
439 ///
440 /// All of the reasons that [`deserialize`] is `unsafe` applies to this
441 /// function as well. Arbitrary data loaded from a file may trick Wasmtime
442 /// into arbitrary code execution since the contents of the file are not
443 /// validated to be a valid precompiled module.
444 ///
445 /// Additionally though this function is also `unsafe` because the file
446 /// referenced must remain unchanged and a valid precompiled module for the
447 /// entire lifetime of the [`Module`] returned. Any changes to the file on
448 /// disk may change future instantiations of the module to be incorrect.
449 /// This is because the file is mapped into memory and lazily loaded pages
450 /// reflect the current state of the file, not necessarily the original
451 /// state of the file.
452 #[cfg(feature = "std")]
453 pub unsafe fn deserialize_file(engine: &Engine, path: impl AsRef<Path>) -> Result<Module> {
454 let file = open_file_for_mmap(path.as_ref())?;
455 // SAFETY: the contract of `deserialize_open_file` is the samea s this
456 // function.
457 unsafe {
458 Self::deserialize_open_file(engine, file)
459 .with_context(|| format!("failed deserialization for: {}", path.as_ref().display()))
460 }
461 }
462
463 /// Same as [`deserialize_file`], except that it takes an open `File`
464 /// instead of a path.
465 ///
466 /// This method is provided because it can be used instead of
467 /// [`deserialize_file`] in situations where `wasmtime` is running with
468 /// limited file system permissions. In that case a process
469 /// with file system access can pass already opened files to `wasmtime`.
470 ///
471 /// [`deserialize_file`]: Module::deserialize_file
472 ///
473 /// Note that the corresponding will be mapped as private writeable
474 /// (copy-on-write) and executable. For `windows` this means the file needs
475 /// to be opened with at least `FILE_GENERIC_READ | FILE_GENERIC_EXECUTE`
476 /// [`access_mode`].
477 ///
478 /// [`access_mode`]: https://doc.rust-lang.org/std/os/windows/fs/trait.OpenOptionsExt.html#tymethod.access_mode
479 ///
480 /// # Unsafety
481 ///
482 /// All of the reasons that [`deserialize_file`] is `unsafe` applies to this
483 /// function as well.
484 #[cfg(feature = "std")]
485 pub unsafe fn deserialize_open_file(engine: &Engine, file: File) -> Result<Module> {
486 let code = engine.load_code_file(file, ObjectKind::Module)?;
487 Module::from_parts(engine, code, None)
488 }
489
490 /// Entrypoint for creating a `Module` for all above functions, both
491 /// of the AOT and jit-compiled categories.
492 ///
493 /// In all cases the compilation artifact, `code_memory`, is provided here.
494 /// The `info_and_types` argument is `None` when a module is being
495 /// deserialized from a precompiled artifact or it's `Some` if it was just
496 /// compiled and the values are already available.
497 pub(crate) fn from_parts(
498 engine: &Engine,
499 code_memory: Arc<CodeMemory>,
500 info_and_types: Option<(CompiledModuleInfo, CompiledFunctionsTable, ModuleTypes)>,
501 ) -> Result<Self> {
502 // Acquire this module's metadata and type information, deserializing
503 // it from the provided artifact if it wasn't otherwise provided
504 // already.
505 let (mut info, index, mut types) = match info_and_types {
506 Some((info, index, types)) => (info, index, types),
507 None => postcard::from_bytes(code_memory.wasmtime_info())?,
508 };
509
510 // Register function type signatures into the engine for the lifetime
511 // of the `Module` that will be returned. This notably also builds up
512 // maps for trampolines to be used for this module when inserted into
513 // stores.
514 //
515 // Note that the unsafety here should be ok since the `trampolines`
516 // field should only point to valid trampoline function pointers
517 // within the text section.
518 let signatures =
519 engine.register_and_canonicalize_types(&mut types, core::iter::once(&mut info.module));
520
521 // Package up all our data into a `CodeObject` and delegate to the final
522 // step of module compilation.
523 let code = Arc::new(CodeObject::new(code_memory, signatures, types.into()));
524 let index = Arc::new(index);
525 Module::from_parts_raw(engine, code, info, index, true)
526 }
527
528 pub(crate) fn from_parts_raw(
529 engine: &Engine,
530 code: Arc<CodeObject>,
531 info: CompiledModuleInfo,
532 index: Arc<CompiledFunctionsTable>,
533 serializable: bool,
534 ) -> Result<Self> {
535 let module = CompiledModule::from_artifacts(
536 code.code_memory().clone(),
537 info,
538 index,
539 engine.profiler(),
540 )?;
541
542 // Validate the module can be used with the current instance allocator.
543 let offsets = VMOffsets::new(HostPtr, module.module());
544 engine
545 .allocator()
546 .validate_module(module.module(), &offsets)?;
547
548 let _ = serializable;
549
550 Ok(Self {
551 inner: Arc::new(ModuleInner {
552 engine: engine.clone(),
553 code,
554 memory_images: OnceLock::new(),
555 module,
556 #[cfg(any(feature = "cranelift", feature = "winch"))]
557 serializable,
558 offsets,
559 }),
560 })
561 }
562
563 /// Validates `binary` input data as a WebAssembly binary given the
564 /// configuration in `engine`.
565 ///
566 /// This function will perform a speedy validation of the `binary` input
567 /// WebAssembly module (which is in [binary form][binary], the text format
568 /// is not accepted by this function) and return either `Ok` or `Err`
569 /// depending on the results of validation. The `engine` argument indicates
570 /// configuration for WebAssembly features, for example, which are used to
571 /// indicate what should be valid and what shouldn't be.
572 ///
573 /// Validation automatically happens as part of [`Module::new`].
574 ///
575 /// # Errors
576 ///
577 /// If validation fails for any reason (type check error, usage of a feature
578 /// that wasn't enabled, etc) then an error with a description of the
579 /// validation issue will be returned.
580 ///
581 /// [binary]: https://webassembly.github.io/spec/core/binary/index.html
582 pub fn validate(engine: &Engine, binary: &[u8]) -> Result<()> {
583 let mut validator = Validator::new_with_features(engine.features());
584
585 let mut functions = Vec::new();
586 for payload in Parser::new(0).parse_all(binary) {
587 let payload = payload?;
588 if let ValidPayload::Func(a, b) = validator.payload(&payload)? {
589 functions.push((a, b));
590 }
591 if let wasmparser::Payload::Version { encoding, .. } = &payload {
592 if let wasmparser::Encoding::Component = encoding {
593 bail!("component passed to module validation");
594 }
595 }
596 }
597
598 engine.run_maybe_parallel(functions, |(validator, body)| {
599 // FIXME: it would be best here to use a rayon-specific parallel
600 // iterator that maintains state-per-thread to share the function
601 // validator allocations (`Default::default` here) across multiple
602 // functions.
603 validator.into_validator(Default::default()).validate(&body)
604 })?;
605 Ok(())
606 }
607
608 /// Serializes this module to a vector of bytes.
609 ///
610 /// This function is similar to the [`Engine::precompile_module`] method
611 /// where it produces an artifact of Wasmtime which is suitable to later
612 /// pass into [`Module::deserialize`]. If a module is never instantiated
613 /// then it's recommended to use [`Engine::precompile_module`] instead of
614 /// this method, but if a module is both instantiated and serialized then
615 /// this method can be useful to get the serialized version without
616 /// compiling twice.
617 #[cfg(any(feature = "cranelift", feature = "winch"))]
618 pub fn serialize(&self) -> Result<Vec<u8>> {
619 // The current representation of compiled modules within a compiled
620 // component means that it cannot be serialized. The mmap returned here
621 // is the mmap for the entire component and while it contains all
622 // necessary data to deserialize this particular module it's all
623 // embedded within component-specific information.
624 //
625 // It's not the hardest thing in the world to support this but it's
626 // expected that there's not much of a use case at this time. In theory
627 // all that needs to be done is to edit the `.wasmtime.info` section
628 // to contains this module's metadata instead of the metadata for the
629 // whole component. The metadata itself is fairly trivially
630 // recreateable here it's more that there's no easy one-off API for
631 // editing the sections of an ELF object to use here.
632 //
633 // Overall for now this simply always returns an error in this
634 // situation. If you're reading this and feel that the situation should
635 // be different please feel free to open an issue.
636 if !self.inner.serializable {
637 bail!("cannot serialize a module exported from a component");
638 }
639 Ok(self.compiled_module().mmap().to_vec())
640 }
641
642 pub(crate) fn compiled_module(&self) -> &CompiledModule {
643 &self.inner.module
644 }
645
646 pub(crate) fn code_object(&self) -> &Arc<CodeObject> {
647 &self.inner.code
648 }
649
650 pub(crate) fn env_module(&self) -> &Arc<wasmtime_environ::Module> {
651 self.compiled_module().module()
652 }
653
654 pub(crate) fn types(&self) -> &ModuleTypes {
655 self.inner.code.module_types()
656 }
657
658 #[cfg(any(feature = "component-model", feature = "gc-drc"))]
659 pub(crate) fn signatures(&self) -> &crate::type_registry::TypeCollection {
660 self.inner.code.signatures()
661 }
662
663 /// Returns identifier/name that this [`Module`] has. This name
664 /// is used in traps/backtrace details.
665 ///
666 /// Note that most LLVM/clang/Rust-produced modules do not have a name
667 /// associated with them, but other wasm tooling can be used to inject or
668 /// add a name.
669 ///
670 /// # Examples
671 ///
672 /// ```
673 /// # use wasmtime::*;
674 /// # fn main() -> anyhow::Result<()> {
675 /// # let engine = Engine::default();
676 /// let module = Module::new(&engine, "(module $foo)")?;
677 /// assert_eq!(module.name(), Some("foo"));
678 ///
679 /// let module = Module::new(&engine, "(module)")?;
680 /// assert_eq!(module.name(), None);
681 ///
682 /// # Ok(())
683 /// # }
684 /// ```
685 pub fn name(&self) -> Option<&str> {
686 self.compiled_module().module().name.as_deref()
687 }
688
689 /// Returns the list of imports that this [`Module`] has and must be
690 /// satisfied.
691 ///
692 /// This function returns the list of imports that the wasm module has, but
693 /// only the types of each import. The type of each import is used to
694 /// typecheck the [`Instance::new`](crate::Instance::new) method's `imports`
695 /// argument. The arguments to that function must match up 1-to-1 with the
696 /// entries in the array returned here.
697 ///
698 /// The imports returned reflect the order of the imports in the wasm module
699 /// itself, and note that no form of deduplication happens.
700 ///
701 /// # Examples
702 ///
703 /// Modules with no imports return an empty list here:
704 ///
705 /// ```
706 /// # use wasmtime::*;
707 /// # fn main() -> anyhow::Result<()> {
708 /// # let engine = Engine::default();
709 /// let module = Module::new(&engine, "(module)")?;
710 /// assert_eq!(module.imports().len(), 0);
711 /// # Ok(())
712 /// # }
713 /// ```
714 ///
715 /// and modules with imports will have a non-empty list:
716 ///
717 /// ```
718 /// # use wasmtime::*;
719 /// # fn main() -> anyhow::Result<()> {
720 /// # let engine = Engine::default();
721 /// let wat = r#"
722 /// (module
723 /// (import "host" "foo" (func))
724 /// )
725 /// "#;
726 /// let module = Module::new(&engine, wat)?;
727 /// assert_eq!(module.imports().len(), 1);
728 /// let import = module.imports().next().unwrap();
729 /// assert_eq!(import.module(), "host");
730 /// assert_eq!(import.name(), "foo");
731 /// match import.ty() {
732 /// ExternType::Func(_) => { /* ... */ }
733 /// _ => panic!("unexpected import type!"),
734 /// }
735 /// # Ok(())
736 /// # }
737 /// ```
738 pub fn imports<'module>(
739 &'module self,
740 ) -> impl ExactSizeIterator<Item = ImportType<'module>> + 'module {
741 let module = self.compiled_module().module();
742 let types = self.types();
743 let engine = self.engine();
744 module
745 .imports()
746 .map(move |(imp_mod, imp_field, ty)| {
747 debug_assert!(ty.is_canonicalized_for_runtime_usage());
748 ImportType::new(imp_mod, imp_field, ty, types, engine)
749 })
750 .collect::<Vec<_>>()
751 .into_iter()
752 }
753
754 /// Returns the list of exports that this [`Module`] has and will be
755 /// available after instantiation.
756 ///
757 /// This function will return the type of each item that will be returned
758 /// from [`Instance::exports`](crate::Instance::exports). Each entry in this
759 /// list corresponds 1-to-1 with that list, and the entries here will
760 /// indicate the name of the export along with the type of the export.
761 ///
762 /// # Examples
763 ///
764 /// Modules might not have any exports:
765 ///
766 /// ```
767 /// # use wasmtime::*;
768 /// # fn main() -> anyhow::Result<()> {
769 /// # let engine = Engine::default();
770 /// let module = Module::new(&engine, "(module)")?;
771 /// assert!(module.exports().next().is_none());
772 /// # Ok(())
773 /// # }
774 /// ```
775 ///
776 /// When the exports are not empty, you can inspect each export:
777 ///
778 /// ```
779 /// # use wasmtime::*;
780 /// # fn main() -> anyhow::Result<()> {
781 /// # let engine = Engine::default();
782 /// let wat = r#"
783 /// (module
784 /// (func (export "foo"))
785 /// (memory (export "memory") 1)
786 /// )
787 /// "#;
788 /// let module = Module::new(&engine, wat)?;
789 /// assert_eq!(module.exports().len(), 2);
790 ///
791 /// let mut exports = module.exports();
792 /// let foo = exports.next().unwrap();
793 /// assert_eq!(foo.name(), "foo");
794 /// match foo.ty() {
795 /// ExternType::Func(_) => { /* ... */ }
796 /// _ => panic!("unexpected export type!"),
797 /// }
798 ///
799 /// let memory = exports.next().unwrap();
800 /// assert_eq!(memory.name(), "memory");
801 /// match memory.ty() {
802 /// ExternType::Memory(_) => { /* ... */ }
803 /// _ => panic!("unexpected export type!"),
804 /// }
805 /// # Ok(())
806 /// # }
807 /// ```
808 pub fn exports<'module>(
809 &'module self,
810 ) -> impl ExactSizeIterator<Item = ExportType<'module>> + 'module {
811 let module = self.compiled_module().module();
812 let types = self.types();
813 let engine = self.engine();
814 module.exports.iter().map(move |(name, entity_index)| {
815 ExportType::new(name, module.type_of(*entity_index), types, engine)
816 })
817 }
818
819 /// Looks up an export in this [`Module`] by name.
820 ///
821 /// This function will return the type of an export with the given name.
822 ///
823 /// # Examples
824 ///
825 /// There may be no export with that name:
826 ///
827 /// ```
828 /// # use wasmtime::*;
829 /// # fn main() -> anyhow::Result<()> {
830 /// # let engine = Engine::default();
831 /// let module = Module::new(&engine, "(module)")?;
832 /// assert!(module.get_export("foo").is_none());
833 /// # Ok(())
834 /// # }
835 /// ```
836 ///
837 /// When there is an export with that name, it is returned:
838 ///
839 /// ```
840 /// # use wasmtime::*;
841 /// # fn main() -> anyhow::Result<()> {
842 /// # let engine = Engine::default();
843 /// let wat = r#"
844 /// (module
845 /// (func (export "foo"))
846 /// (memory (export "memory") 1)
847 /// )
848 /// "#;
849 /// let module = Module::new(&engine, wat)?;
850 /// let foo = module.get_export("foo");
851 /// assert!(foo.is_some());
852 ///
853 /// let foo = foo.unwrap();
854 /// match foo {
855 /// ExternType::Func(_) => { /* ... */ }
856 /// _ => panic!("unexpected export type!"),
857 /// }
858 ///
859 /// # Ok(())
860 /// # }
861 /// ```
862 pub fn get_export(&self, name: &str) -> Option<ExternType> {
863 let module = self.compiled_module().module();
864 let entity_index = module.exports.get(name)?;
865 Some(ExternType::from_wasmtime(
866 self.engine(),
867 self.types(),
868 &module.type_of(*entity_index),
869 ))
870 }
871
872 /// Looks up an export in this [`Module`] by name to get its index.
873 ///
874 /// This function will return the index of an export with the given name. This can be useful
875 /// to avoid the cost of looking up the export by name multiple times. Instead the
876 /// [`ModuleExport`] can be stored and used to look up the export on the
877 /// [`Instance`](crate::Instance) later.
878 pub fn get_export_index(&self, name: &str) -> Option<ModuleExport> {
879 let compiled_module = self.compiled_module();
880 let module = compiled_module.module();
881 let entity = *module.exports.get(name)?;
882 Some(ModuleExport {
883 module: self.id(),
884 entity,
885 })
886 }
887
888 /// Returns the [`Engine`] that this [`Module`] was compiled by.
889 pub fn engine(&self) -> &Engine {
890 &self.inner.engine
891 }
892
893 /// Returns a summary of the resources required to instantiate this
894 /// [`Module`].
895 ///
896 /// Potential uses of the returned information:
897 ///
898 /// * Determining whether your pooling allocator configuration supports
899 /// instantiating this module.
900 ///
901 /// * Deciding how many of which `Module` you want to instantiate within a
902 /// fixed amount of resources, e.g. determining whether to create 5
903 /// instances of module X or 10 instances of module Y.
904 ///
905 /// # Example
906 ///
907 /// ```
908 /// # fn main() -> wasmtime::Result<()> {
909 /// use wasmtime::{Config, Engine, Module};
910 ///
911 /// let mut config = Config::new();
912 /// config.wasm_multi_memory(true);
913 /// let engine = Engine::new(&config)?;
914 ///
915 /// let module = Module::new(&engine, r#"
916 /// (module
917 /// ;; Import a memory. Doesn't count towards required resources.
918 /// (import "a" "b" (memory 10))
919 /// ;; Define two local memories. These count towards the required
920 /// ;; resources.
921 /// (memory 1)
922 /// (memory 6)
923 /// )
924 /// "#)?;
925 ///
926 /// let resources = module.resources_required();
927 ///
928 /// // Instantiating the module will require allocating two memories, and
929 /// // the maximum initial memory size is six Wasm pages.
930 /// assert_eq!(resources.num_memories, 2);
931 /// assert_eq!(resources.max_initial_memory_size, Some(6));
932 ///
933 /// // The module doesn't need any tables.
934 /// assert_eq!(resources.num_tables, 0);
935 /// assert_eq!(resources.max_initial_table_size, None);
936 /// # Ok(()) }
937 /// ```
938 pub fn resources_required(&self) -> ResourcesRequired {
939 let em = self.env_module();
940 let num_memories = u32::try_from(em.num_defined_memories()).unwrap();
941 let max_initial_memory_size = em
942 .memories
943 .values()
944 .skip(em.num_imported_memories)
945 .map(|memory| memory.limits.min)
946 .max();
947 let num_tables = u32::try_from(em.num_defined_tables()).unwrap();
948 let max_initial_table_size = em
949 .tables
950 .values()
951 .skip(em.num_imported_tables)
952 .map(|table| table.limits.min)
953 .max();
954 ResourcesRequired {
955 num_memories,
956 max_initial_memory_size,
957 num_tables,
958 max_initial_table_size,
959 }
960 }
961
962 /// Returns the range of bytes in memory where this module's compilation
963 /// image resides.
964 ///
965 /// The compilation image for a module contains executable code, data, debug
966 /// information, etc. This is roughly the same as the `Module::serialize`
967 /// but not the exact same.
968 ///
969 /// The range of memory reported here is exposed to allow low-level
970 /// manipulation of the memory in platform-specific manners such as using
971 /// `mlock` to force the contents to be paged in immediately or keep them
972 /// paged in after they're loaded.
973 ///
974 /// It is not safe to modify the memory in this range, nor is it safe to
975 /// modify the protections of memory in this range.
976 pub fn image_range(&self) -> Range<*const u8> {
977 self.compiled_module().mmap().image_range()
978 }
979
980 /// Force initialization of copy-on-write images to happen here-and-now
981 /// instead of when they're requested during first instantiation.
982 ///
983 /// When [copy-on-write memory
984 /// initialization](crate::Config::memory_init_cow) is enabled then Wasmtime
985 /// will lazily create the initialization image for a module. This method
986 /// can be used to explicitly dictate when this initialization happens.
987 ///
988 /// Note that this largely only matters on Linux when memfd is used.
989 /// Otherwise the copy-on-write image typically comes from disk and in that
990 /// situation the creation of the image is trivial as the image is always
991 /// sourced from disk. On Linux, though, when memfd is used a memfd is
992 /// created and the initialization image is written to it.
993 ///
994 /// Also note that this method is not required to be called, it's available
995 /// as a performance optimization if required but is otherwise handled
996 /// automatically.
997 pub fn initialize_copy_on_write_image(&self) -> Result<()> {
998 self.memory_images()?;
999 Ok(())
1000 }
1001
1002 /// Get the map from `.text` section offsets to Wasm binary offsets for this
1003 /// module.
1004 ///
1005 /// Each entry is a (`.text` section offset, Wasm binary offset) pair.
1006 ///
1007 /// Entries are yielded in order of `.text` section offset.
1008 ///
1009 /// Some entries are missing a Wasm binary offset. This is for code that is
1010 /// not associated with any single location in the Wasm binary, or for when
1011 /// source information was optimized away.
1012 ///
1013 /// Not every module has an address map, since address map generation can be
1014 /// turned off on `Config`.
1015 ///
1016 /// There is not an entry for every `.text` section offset. Every offset
1017 /// after an entry's offset, but before the next entry's offset, is
1018 /// considered to map to the same Wasm binary offset as the original
1019 /// entry. For example, the address map will not contain the following
1020 /// sequence of entries:
1021 ///
1022 /// ```ignore
1023 /// [
1024 /// // ...
1025 /// (10, Some(42)),
1026 /// (11, Some(42)),
1027 /// (12, Some(42)),
1028 /// (13, Some(43)),
1029 /// // ...
1030 /// ]
1031 /// ```
1032 ///
1033 /// Instead, it will drop the entries for offsets `11` and `12` since they
1034 /// are the same as the entry for offset `10`:
1035 ///
1036 /// ```ignore
1037 /// [
1038 /// // ...
1039 /// (10, Some(42)),
1040 /// (13, Some(43)),
1041 /// // ...
1042 /// ]
1043 /// ```
1044 pub fn address_map<'a>(&'a self) -> Option<impl Iterator<Item = (usize, Option<u32>)> + 'a> {
1045 Some(
1046 wasmtime_environ::iterate_address_map(
1047 self.code_object().code_memory().address_map_data(),
1048 )?
1049 .map(|(offset, file_pos)| (offset as usize, file_pos.file_offset())),
1050 )
1051 }
1052
1053 /// Get this module's code object's `.text` section, containing its compiled
1054 /// executable code.
1055 pub fn text(&self) -> &[u8] {
1056 self.code_object().code_memory().text()
1057 }
1058
1059 /// Get information about functions in this module's `.text` section: their
1060 /// index, name, and offset+length.
1061 ///
1062 /// Results are yielded in a ModuleFunction struct.
1063 pub fn functions<'a>(&'a self) -> impl ExactSizeIterator<Item = ModuleFunction> + 'a {
1064 let module = self.compiled_module();
1065 module.finished_functions().map(|(idx, _)| {
1066 let loc = module.func_loc(idx);
1067 let idx = module.module().func_index(idx);
1068 ModuleFunction {
1069 index: idx,
1070 name: module.func_name(idx).map(|n| n.to_string()),
1071 offset: loc.start as usize,
1072 len: loc.length as usize,
1073 }
1074 })
1075 }
1076
1077 pub(crate) fn id(&self) -> CompiledModuleId {
1078 self.inner.module.unique_id()
1079 }
1080
1081 pub(crate) fn offsets(&self) -> &VMOffsets<HostPtr> {
1082 &self.inner.offsets
1083 }
1084
1085 /// Return the address, in memory, of the trampoline that allows Wasm to
1086 /// call a array function of the given signature.
1087 pub(crate) fn wasm_to_array_trampoline(
1088 &self,
1089 signature: VMSharedTypeIndex,
1090 ) -> Option<NonNull<VMWasmCallFunction>> {
1091 log::trace!("Looking up trampoline for {signature:?}");
1092 let trampoline_shared_ty = self.inner.engine.signatures().trampoline_type(signature);
1093 let trampoline_module_ty = self
1094 .inner
1095 .code
1096 .signatures()
1097 .trampoline_type(trampoline_shared_ty)?;
1098 debug_assert!(
1099 self.inner
1100 .engine
1101 .signatures()
1102 .borrow(
1103 self.inner
1104 .code
1105 .signatures()
1106 .shared_type(trampoline_module_ty)
1107 .unwrap()
1108 )
1109 .unwrap()
1110 .unwrap_func()
1111 .is_trampoline_type()
1112 );
1113
1114 let ptr = self
1115 .compiled_module()
1116 .wasm_to_array_trampoline(trampoline_module_ty)
1117 .expect("always have a trampoline for the trampoline type")
1118 .as_ptr()
1119 .cast::<VMWasmCallFunction>()
1120 .cast_mut();
1121 Some(NonNull::new(ptr).unwrap())
1122 }
1123
1124 pub(crate) fn memory_images(&self) -> Result<Option<&ModuleMemoryImages>> {
1125 let images = self
1126 .inner
1127 .memory_images
1128 .get_or_try_init(|| memory_images(&self.inner))?
1129 .as_ref();
1130 Ok(images)
1131 }
1132
1133 /// Get the text offset (relative PC) for a given absolute PC in
1134 /// this module.
1135 #[cfg(any(feature = "gc", feature = "debug"))]
1136 pub(crate) fn text_offset(&self, pc: usize) -> u32 {
1137 u32::try_from(pc - self.inner.module.text().as_ptr() as usize).unwrap()
1138 }
1139
1140 /// Lookup the stack map at a program counter value.
1141 #[cfg(feature = "gc")]
1142 pub(crate) fn lookup_stack_map(&self, pc: usize) -> Option<wasmtime_environ::StackMap<'_>> {
1143 let text_offset = self.text_offset(pc);
1144 let info = self.inner.code.code_memory().stack_map_data();
1145 wasmtime_environ::StackMap::lookup(text_offset, info)
1146 }
1147
1148 /// Obtain an exception-table parser on this module's exception metadata.
1149 #[cfg(feature = "gc")]
1150 pub(crate) fn exception_table<'a>(&'a self) -> ExceptionTable<'a> {
1151 ExceptionTable::parse(self.inner.code.code_memory().exception_tables())
1152 .expect("Exception tables were validated on module load")
1153 }
1154
1155 /// Obtain a frame-table parser on this module's frame state slot
1156 /// (debug instrumentation) metadata.
1157 #[cfg(feature = "debug")]
1158 pub(crate) fn frame_table<'a>(&'a self) -> Option<FrameTable<'a>> {
1159 let data = self.inner.code.code_memory().frame_tables();
1160 if data.is_empty() {
1161 None
1162 } else {
1163 Some(FrameTable::parse(data).expect("Frame tables were validated on module load"))
1164 }
1165 }
1166}
1167
1168/// Describes a function for a given module.
1169pub struct ModuleFunction {
1170 pub index: wasmtime_environ::FuncIndex,
1171 pub name: Option<String>,
1172 pub offset: usize,
1173 pub len: usize,
1174}
1175
1176impl Drop for ModuleInner {
1177 fn drop(&mut self) {
1178 // When a `Module` is being dropped that means that it's no longer
1179 // present in any `Store` and it's additionally not longer held by any
1180 // embedder. Take this opportunity to purge any lingering instantiations
1181 // within a pooling instance allocator, if applicable.
1182 self.engine
1183 .allocator()
1184 .purge_module(self.module.unique_id());
1185 }
1186}
1187
1188/// Describes the location of an export in a module.
1189#[derive(Copy, Clone)]
1190pub struct ModuleExport {
1191 /// The module that this export is defined in.
1192 pub(crate) module: CompiledModuleId,
1193 /// A raw index into the wasm module.
1194 pub(crate) entity: EntityIndex,
1195}
1196
1197fn _assert_send_sync() {
1198 fn _assert<T: Send + Sync>() {}
1199 _assert::<Module>();
1200}
1201
1202/// Helper method to construct a `ModuleMemoryImages` for an associated
1203/// `CompiledModule`.
1204fn memory_images(inner: &Arc<ModuleInner>) -> Result<Option<ModuleMemoryImages>> {
1205 // If initialization via copy-on-write is explicitly disabled in
1206 // configuration then this path is skipped entirely.
1207 if !inner.engine.tunables().memory_init_cow {
1208 return Ok(None);
1209 }
1210
1211 // ... otherwise logic is delegated to the `ModuleMemoryImages::new`
1212 // constructor.
1213 ModuleMemoryImages::new(
1214 &inner.engine,
1215 inner.module.module(),
1216 inner.code.code_memory(),
1217 )
1218}
1219
1220impl crate::vm::ModuleMemoryImageSource for CodeMemory {
1221 fn wasm_data(&self) -> &[u8] {
1222 <Self>::wasm_data(self)
1223 }
1224
1225 fn mmap(&self) -> Option<&MmapVec> {
1226 Some(<Self>::mmap(self))
1227 }
1228}
1229
1230#[cfg(test)]
1231mod tests {
1232 use crate::{Engine, Module};
1233 use wasmtime_environ::MemoryInitialization;
1234
1235 #[test]
1236 fn cow_on_by_default() {
1237 let engine = Engine::default();
1238 let module = Module::new(
1239 &engine,
1240 r#"
1241 (module
1242 (memory 1)
1243 (data (i32.const 100) "abcd")
1244 )
1245 "#,
1246 )
1247 .unwrap();
1248
1249 let init = &module.env_module().memory_initialization;
1250 assert!(matches!(init, MemoryInitialization::Static { .. }));
1251 }
1252}