Struct wasmer_vm::instance::VMInstance

pub struct VMInstance {
    instance_layout: Layout,
    instance: NonNull<Instance>,
}

A handle holding an Instance of a WebAssembly module.

This is more or less a public facade of the private Instance, providing useful higher-level API.

Fields

instance_layout: Layout

The layout of Instance (which can vary).

instance: NonNull<Instance>

The Instance itself.

Instance must not be dropped manually by Rust, because it’s allocated manually with alloc and a specific layout (Rust would be able to drop Instance itself but it will imply a memory leak because of alloc).

No one in the code has a copy of the Instance’s pointer. Self is the only one.

Implementations

impl VMInstance

pub unsafe fn new( allocator: InstanceAllocator, module: Arc<ModuleInfo>, context: &mut StoreObjects, finished_functions: BoxedSlice<LocalFunctionIndex, FunctionBodyPtr>, finished_function_call_trampolines: BoxedSlice<SignatureIndex, VMTrampoline>, finished_memories: BoxedSlice<LocalMemoryIndex, InternalStoreHandle<VMMemory>>, finished_tables: BoxedSlice<LocalTableIndex, InternalStoreHandle<VMTable>>, finished_globals: BoxedSlice<LocalGlobalIndex, InternalStoreHandle<VMGlobal>>, imports: Imports, vmshared_signatures: BoxedSlice<SignatureIndex, VMSharedSignatureIndex>, ) -> Result<Self, Trap>

Create a new VMInstance pointing at a new Instance.

Safety

This method is not necessarily inherently unsafe to call, but in general the APIs of an Instance are quite unsafe and have not been really audited for safety that much. As a result the unsafety here on this method is a low-overhead way of saying “this is an extremely unsafe type to work with”.

Extreme care must be taken when working with VMInstance and it’s recommended to have relatively intimate knowledge of how it works internally if you’d like to do so. If possible it’s recommended to use the wasmer crate API rather than this type since that is vetted for safety.

However the following must be taken care of before calling this function:

• The memory at instance.tables_ptr() must be initialized with data for all the local tables.
• The memory at instance.memories_ptr() must be initialized with data for all the local memories.

pub(crate) fn instance(&self) -> &Instance

Return a reference to the contained Instance.

pub(crate) fn instance_mut(&mut self) -> &mut Instance

Return a mutable reference to the contained Instance.

pub unsafe fn finish_instantiation( &mut self, config: &VMConfig, trap_handler: Option<*const TrapHandlerFn<'static>>, data_initializers: &[DataInitializer<'_>], ) -> Result<(), Trap>

Finishes the instantiation process started by Instance::new.

Safety

Only safe to call immediately after instantiation.

pub fn vmctx(&self) -> &VMContext

Return a reference to the vmctx used by compiled wasm code.

pub fn vmctx_ptr(&self) -> *mut VMContext

Return a raw pointer to the vmctx used by compiled wasm code.

pub fn vmoffsets(&self) -> &VMOffsets

Return a reference to the VMOffsets to get offsets in the Self::vmctx_ptr region. Be careful when doing pointer arithmetic!

pub fn module(&self) -> &Arc<ModuleInfo>

Return a reference-counting pointer to a module.

pub fn module_ref(&self) -> &ModuleInfo

Return a reference to a module.

pub fn lookup(&mut self, field: &str) -> Option<VMExtern>

Lookup an export with the given name.

pub fn lookup_by_declaration(&mut self, export: ExportIndex) -> VMExtern

Lookup an export with the given export declaration.

pub fn exports(&self) -> Iter<'_, String, ExportIndex>

Return an iterator over the exports of this instance.

Specifically, it provides access to the key-value pairs, where the keys are export names, and the values are export declarations which can be resolved lookup_by_declaration.

pub fn memory_index(&self, memory: &VMMemoryDefinition) -> LocalMemoryIndex

Return the memory index for the given VMMemoryDefinition in this instance.

pub fn memory_grow<IntoPages>( &mut self, memory_index: LocalMemoryIndex, delta: IntoPages, ) -> Result<Pages, MemoryError>

where IntoPages: Into<Pages>,

Grow memory in this instance by the specified amount of pages.

Returns None if memory can’t be grown by the specified amount of pages.

pub fn table_index(&self, table: &VMTableDefinition) -> LocalTableIndex

Return the table index for the given VMTableDefinition in this instance.

pub fn table_grow( &mut self, table_index: LocalTableIndex, delta: u32, init_value: TableElement, ) -> Option<u32>

Grow table in this instance by the specified amount of pages.

Returns None if memory can’t be grown by the specified amount of pages.

pub fn table_get( &self, table_index: LocalTableIndex, index: u32, ) -> Option<TableElement>

Get table element reference.

Returns None if index is out of bounds.

pub fn table_set( &mut self, table_index: LocalTableIndex, index: u32, val: TableElement, ) -> Result<(), Trap>

Set table element reference.

Returns an error if the index is out of bounds

pub fn get_local_table(&mut self, index: LocalTableIndex) -> &mut VMTable

Get a table defined locally within this module.

Trait Implementations

impl Debug for VMInstance

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Drop for VMInstance

VMInstance are created with an InstanceAllocator and it will “consume” the memory So the Drop here actualy free it (else it would be leaked)

fn drop(&mut self)

Executes the destructor for this type.

impl PartialEq for VMInstance

fn eq(&self, other: &VMInstance) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StoreObject for VMInstance

fn list(ctx: &StoreObjects) -> &Vec<Self>

fn list_mut(ctx: &mut StoreObjects) -> &mut Vec<Self>

impl Eq for VMInstance

impl StructuralPartialEq for VMInstance