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