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// This file contains code from external sources.
// Attributions: https://github.com/wasmerio/wasmer/blob/main/docs/ATTRIBUTIONS.md
//! Memory management for linear memories.
//!
//! `Memory` is to WebAssembly linear memories what `Table` is to WebAssembly tables.
use crate::mmap::MmapType;
use crate::threadconditions::ThreadConditions;
pub use crate::threadconditions::{NotifyLocation, WaiterError};
use crate::trap::Trap;
use crate::{mmap::Mmap, store::MaybeInstanceOwned, vmcontext::VMMemoryDefinition};
use more_asserts::assert_ge;
use std::cell::UnsafeCell;
use std::convert::TryInto;
use std::ptr::NonNull;
use std::rc::Rc;
use std::slice;
use std::sync::RwLock;
use std::time::Duration;
use wasmer_types::{Bytes, MemoryError, MemoryStyle, MemoryType, Pages, WASM_PAGE_SIZE};
// The memory mapped area
#[derive(Debug)]
struct WasmMmap {
// Our OS allocation of mmap'd memory.
alloc: Mmap,
// The current logical size in wasm pages of this linear memory.
size: Pages,
/// The owned memory definition used by the generated code
vm_memory_definition: MaybeInstanceOwned<VMMemoryDefinition>,
}
impl WasmMmap {
fn get_vm_memory_definition(&self) -> NonNull<VMMemoryDefinition> {
self.vm_memory_definition.as_ptr()
}
fn size(&self) -> Pages {
unsafe {
let md_ptr = self.get_vm_memory_definition();
let md = md_ptr.as_ref();
Bytes::from(md.current_length).try_into().unwrap()
}
}
fn grow(&mut self, delta: Pages, conf: VMMemoryConfig) -> Result<Pages, MemoryError> {
// Optimization of memory.grow 0 calls.
if delta.0 == 0 {
return Ok(self.size);
}
let new_pages = self
.size
.checked_add(delta)
.ok_or(MemoryError::CouldNotGrow {
current: self.size,
attempted_delta: delta,
})?;
let prev_pages = self.size;
if let Some(maximum) = conf.maximum {
if new_pages > maximum {
return Err(MemoryError::CouldNotGrow {
current: self.size,
attempted_delta: delta,
});
}
}
// Wasm linear memories are never allowed to grow beyond what is
// indexable. If the memory has no maximum, enforce the greatest
// limit here.
if new_pages >= Pages::max_value() {
// Linear memory size would exceed the index range.
return Err(MemoryError::CouldNotGrow {
current: self.size,
attempted_delta: delta,
});
}
let delta_bytes = delta.bytes().0;
let prev_bytes = prev_pages.bytes().0;
let new_bytes = new_pages.bytes().0;
if new_bytes > self.alloc.len() - conf.offset_guard_size {
// If the new size is within the declared maximum, but needs more memory than we
// have on hand, it's a dynamic heap and it can move.
let guard_bytes = conf.offset_guard_size;
let request_bytes =
new_bytes
.checked_add(guard_bytes)
.ok_or_else(|| MemoryError::CouldNotGrow {
current: new_pages,
attempted_delta: Bytes(guard_bytes).try_into().unwrap(),
})?;
let mut new_mmap =
Mmap::accessible_reserved(new_bytes, request_bytes, None, MmapType::Private)
.map_err(MemoryError::Region)?;
let copy_len = self.alloc.len() - conf.offset_guard_size;
new_mmap.as_mut_slice()[..copy_len].copy_from_slice(&self.alloc.as_slice()[..copy_len]);
self.alloc = new_mmap;
} else if delta_bytes > 0 {
// Make the newly allocated pages accessible.
self.alloc
.make_accessible(prev_bytes, delta_bytes)
.map_err(MemoryError::Region)?;
}
self.size = new_pages;
// update memory definition
unsafe {
let mut md_ptr = self.vm_memory_definition.as_ptr();
let md = md_ptr.as_mut();
md.current_length = new_pages.bytes().0;
md.base = self.alloc.as_mut_ptr() as _;
}
Ok(prev_pages)
}
/// Grows the memory to at least a minimum size. If the memory is already big enough
/// for the min size then this function does nothing
fn grow_at_least(&mut self, min_size: u64, conf: VMMemoryConfig) -> Result<(), MemoryError> {
let cur_size = self.size.bytes().0 as u64;
if cur_size < min_size {
let growth = min_size - cur_size;
let growth_pages = ((growth - 1) / WASM_PAGE_SIZE as u64) + 1;
self.grow(Pages(growth_pages as u32), conf)?;
}
Ok(())
}
/// Resets the memory down to a zero size
fn reset(&mut self) -> Result<(), MemoryError> {
self.size.0 = 0;
Ok(())
}
/// Copies the memory
/// (in this case it performs a copy-on-write to save memory)
pub fn copy(&mut self) -> Result<Self, MemoryError> {
let mem_length = self.size.bytes().0;
let mut alloc = self
.alloc
.copy(Some(mem_length))
.map_err(MemoryError::Generic)?;
let base_ptr = alloc.as_mut_ptr();
Ok(Self {
vm_memory_definition: MaybeInstanceOwned::Host(Box::new(UnsafeCell::new(
VMMemoryDefinition {
base: base_ptr,
current_length: mem_length,
},
))),
alloc,
size: self.size,
})
}
}
/// A linear memory instance.
#[derive(Debug, Clone)]
struct VMMemoryConfig {
// The optional maximum size in wasm pages of this linear memory.
maximum: Option<Pages>,
/// The WebAssembly linear memory description.
memory: MemoryType,
/// Our chosen implementation style.
style: MemoryStyle,
// Size in bytes of extra guard pages after the end to optimize loads and stores with
// constant offsets.
offset_guard_size: usize,
}
impl VMMemoryConfig {
fn ty(&self, minimum: Pages) -> MemoryType {
let mut out = self.memory;
out.minimum = minimum;
out
}
fn style(&self) -> MemoryStyle {
self.style
}
}
/// A linear memory instance.
#[derive(Debug)]
pub struct VMOwnedMemory {
// The underlying allocation.
mmap: WasmMmap,
// Configuration of this memory
config: VMMemoryConfig,
}
unsafe impl Send for VMOwnedMemory {}
unsafe impl Sync for VMOwnedMemory {}
impl VMOwnedMemory {
/// Create a new linear memory instance with specified minimum and maximum number of wasm pages.
///
/// This creates a `Memory` with owned metadata: this can be used to create a memory
/// that will be imported into Wasm modules.
pub fn new(memory: &MemoryType, style: &MemoryStyle) -> Result<Self, MemoryError> {
unsafe { Self::new_internal(memory, style, None, None, MmapType::Private) }
}
/// Create a new linear memory instance with specified minimum and maximum number of wasm pages
/// that is backed by a memory file. When set to private the file will be remaing in memory and
/// never flush to disk, when set to shared the memory will be flushed to disk.
///
/// This creates a `Memory` with owned metadata: this can be used to create a memory
/// that will be imported into Wasm modules.
pub fn new_with_file(
memory: &MemoryType,
style: &MemoryStyle,
backing_file: std::path::PathBuf,
memory_type: MmapType,
) -> Result<Self, MemoryError> {
unsafe { Self::new_internal(memory, style, None, Some(backing_file), memory_type) }
}
/// Create a new linear memory instance with specified minimum and maximum number of wasm pages.
///
/// This creates a `Memory` with metadata owned by a VM, pointed to by
/// `vm_memory_location`: this can be used to create a local memory.
///
/// # Safety
/// - `vm_memory_location` must point to a valid location in VM memory.
pub unsafe fn from_definition(
memory: &MemoryType,
style: &MemoryStyle,
vm_memory_location: NonNull<VMMemoryDefinition>,
) -> Result<Self, MemoryError> {
Self::new_internal(
memory,
style,
Some(vm_memory_location),
None,
MmapType::Private,
)
}
/// Create a new linear memory instance with specified minimum and maximum number of wasm pages
/// that is backed by a file. When set to private the file will be remaing in memory and
/// never flush to disk, when set to shared the memory will be flushed to disk.
///
/// This creates a `Memory` with metadata owned by a VM, pointed to by
/// `vm_memory_location`: this can be used to create a local memory.
///
/// # Safety
/// - `vm_memory_location` must point to a valid location in VM memory.
pub unsafe fn from_definition_with_file(
memory: &MemoryType,
style: &MemoryStyle,
vm_memory_location: NonNull<VMMemoryDefinition>,
backing_file: Option<std::path::PathBuf>,
memory_type: MmapType,
) -> Result<Self, MemoryError> {
Self::new_internal(
memory,
style,
Some(vm_memory_location),
backing_file,
memory_type,
)
}
/// Build a `Memory` with either self-owned or VM owned metadata.
unsafe fn new_internal(
memory: &MemoryType,
style: &MemoryStyle,
vm_memory_location: Option<NonNull<VMMemoryDefinition>>,
backing_file: Option<std::path::PathBuf>,
memory_type: MmapType,
) -> Result<Self, MemoryError> {
if memory.minimum > Pages::max_value() {
return Err(MemoryError::MinimumMemoryTooLarge {
min_requested: memory.minimum,
max_allowed: Pages::max_value(),
});
}
// `maximum` cannot be set to more than `65536` pages.
if let Some(max) = memory.maximum {
if max > Pages::max_value() {
return Err(MemoryError::MaximumMemoryTooLarge {
max_requested: max,
max_allowed: Pages::max_value(),
});
}
if max < memory.minimum {
return Err(MemoryError::InvalidMemory {
reason: format!(
"the maximum ({} pages) is less than the minimum ({} pages)",
max.0, memory.minimum.0
),
});
}
}
let offset_guard_bytes = style.offset_guard_size() as usize;
let minimum_pages = match style {
MemoryStyle::Dynamic { .. } => memory.minimum,
MemoryStyle::Static { bound, .. } => {
assert_ge!(*bound, memory.minimum);
*bound
}
};
let minimum_bytes = minimum_pages.bytes().0;
let request_bytes = minimum_bytes.checked_add(offset_guard_bytes).unwrap();
let mapped_pages = memory.minimum;
let mapped_bytes = mapped_pages.bytes();
let mut alloc =
Mmap::accessible_reserved(mapped_bytes.0, request_bytes, backing_file, memory_type)
.map_err(MemoryError::Region)?;
let base_ptr = alloc.as_mut_ptr();
let mem_length = memory
.minimum
.bytes()
.0
.max(alloc.as_slice_accessible().len());
let mmap = WasmMmap {
vm_memory_definition: if let Some(mem_loc) = vm_memory_location {
{
let mut ptr = mem_loc;
let md = ptr.as_mut();
md.base = base_ptr;
md.current_length = mem_length;
}
MaybeInstanceOwned::Instance(mem_loc)
} else {
MaybeInstanceOwned::Host(Box::new(UnsafeCell::new(VMMemoryDefinition {
base: base_ptr,
current_length: mem_length,
})))
},
alloc,
size: Bytes::from(mem_length).try_into().unwrap(),
};
Ok(Self {
mmap,
config: VMMemoryConfig {
maximum: memory.maximum,
offset_guard_size: offset_guard_bytes,
memory: *memory,
style: *style,
},
})
}
/// Converts this owned memory into shared memory
pub fn to_shared(self) -> VMSharedMemory {
VMSharedMemory {
mmap: Rc::new(RwLock::new(self.mmap)),
config: self.config,
conditions: ThreadConditions::new(),
}
}
/// Copies this memory to a new memory
pub fn copy(&mut self) -> Result<Self, MemoryError> {
Ok(Self {
mmap: self.mmap.copy()?,
config: self.config.clone(),
})
}
}
impl LinearMemory for VMOwnedMemory {
/// Returns the type for this memory.
fn ty(&self) -> MemoryType {
let minimum = self.mmap.size();
self.config.ty(minimum)
}
/// Returns the size of hte memory in pages
fn size(&self) -> Pages {
self.mmap.size()
}
/// Returns the memory style for this memory.
fn style(&self) -> MemoryStyle {
self.config.style()
}
/// Grow memory by the specified amount of wasm pages.
///
/// Returns `None` if memory can't be grown by the specified amount
/// of wasm pages.
fn grow(&mut self, delta: Pages) -> Result<Pages, MemoryError> {
self.mmap.grow(delta, self.config.clone())
}
/// Grows the memory to at least a minimum size. If the memory is already big enough
/// for the min size then this function does nothing
fn grow_at_least(&mut self, min_size: u64) -> Result<(), MemoryError> {
self.mmap.grow_at_least(min_size, self.config.clone())
}
/// Resets the memory down to a zero size
fn reset(&mut self) -> Result<(), MemoryError> {
self.mmap.reset()?;
Ok(())
}
/// Return a `VMMemoryDefinition` for exposing the memory to compiled wasm code.
fn vmmemory(&self) -> NonNull<VMMemoryDefinition> {
self.mmap.vm_memory_definition.as_ptr()
}
/// Owned memory can not be cloned (this will always return None)
fn try_clone(&self) -> Result<Box<dyn LinearMemory + 'static>, MemoryError> {
Err(MemoryError::MemoryNotShared)
}
/// Copies this memory to a new memory
fn copy(&mut self) -> Result<Box<dyn LinearMemory + 'static>, MemoryError> {
let forked = Self::copy(self)?;
Ok(Box::new(forked))
}
}
/// A shared linear memory instance.
#[derive(Debug, Clone)]
pub struct VMSharedMemory {
// The underlying allocation.
mmap: Rc<RwLock<WasmMmap>>,
// Configuration of this memory
config: VMMemoryConfig,
// waiters list for this memory
conditions: ThreadConditions,
}
unsafe impl Send for VMSharedMemory {}
unsafe impl Sync for VMSharedMemory {}
impl VMSharedMemory {
/// Create a new linear memory instance with specified minimum and maximum number of wasm pages.
///
/// This creates a `Memory` with owned metadata: this can be used to create a memory
/// that will be imported into Wasm modules.
pub fn new(memory: &MemoryType, style: &MemoryStyle) -> Result<Self, MemoryError> {
Ok(VMOwnedMemory::new(memory, style)?.to_shared())
}
/// Create a new linear memory instance with specified minimum and maximum number of wasm pages
/// that is backed by a file. When set to private the file will be remaing in memory and
/// never flush to disk, when set to shared the memory will be flushed to disk.
///
/// This creates a `Memory` with owned metadata: this can be used to create a memory
/// that will be imported into Wasm modules.
pub fn new_with_file(
memory: &MemoryType,
style: &MemoryStyle,
backing_file: std::path::PathBuf,
memory_type: MmapType,
) -> Result<Self, MemoryError> {
Ok(VMOwnedMemory::new_with_file(memory, style, backing_file, memory_type)?.to_shared())
}
/// Create a new linear memory instance with specified minimum and maximum number of wasm pages.
///
/// This creates a `Memory` with metadata owned by a VM, pointed to by
/// `vm_memory_location`: this can be used to create a local memory.
///
/// # Safety
/// - `vm_memory_location` must point to a valid location in VM memory.
pub unsafe fn from_definition(
memory: &MemoryType,
style: &MemoryStyle,
vm_memory_location: NonNull<VMMemoryDefinition>,
) -> Result<Self, MemoryError> {
Ok(VMOwnedMemory::from_definition(memory, style, vm_memory_location)?.to_shared())
}
/// Create a new linear memory instance with specified minimum and maximum number of wasm pages
/// that is backed by a file. When set to private the file will be remaing in memory and
/// never flush to disk, when set to shared the memory will be flushed to disk.
///
/// This creates a `Memory` with metadata owned by a VM, pointed to by
/// `vm_memory_location`: this can be used to create a local memory.
///
/// # Safety
/// - `vm_memory_location` must point to a valid location in VM memory.
pub unsafe fn from_definition_with_file(
memory: &MemoryType,
style: &MemoryStyle,
vm_memory_location: NonNull<VMMemoryDefinition>,
backing_file: Option<std::path::PathBuf>,
memory_type: MmapType,
) -> Result<Self, MemoryError> {
Ok(VMOwnedMemory::from_definition_with_file(
memory,
style,
vm_memory_location,
backing_file,
memory_type,
)?
.to_shared())
}
/// Copies this memory to a new memory
pub fn copy(&mut self) -> Result<Self, MemoryError> {
let mut guard = self.mmap.write().unwrap();
Ok(Self {
mmap: Rc::new(RwLock::new(guard.copy()?)),
config: self.config.clone(),
conditions: ThreadConditions::new(),
})
}
}
impl LinearMemory for VMSharedMemory {
/// Returns the type for this memory.
fn ty(&self) -> MemoryType {
let minimum = {
let guard = self.mmap.read().unwrap();
guard.size()
};
self.config.ty(minimum)
}
/// Returns the size of hte memory in pages
fn size(&self) -> Pages {
let guard = self.mmap.read().unwrap();
guard.size()
}
/// Returns the memory style for this memory.
fn style(&self) -> MemoryStyle {
self.config.style()
}
/// Grow memory by the specified amount of wasm pages.
///
/// Returns `None` if memory can't be grown by the specified amount
/// of wasm pages.
fn grow(&mut self, delta: Pages) -> Result<Pages, MemoryError> {
let mut guard = self.mmap.write().unwrap();
guard.grow(delta, self.config.clone())
}
/// Grows the memory to at least a minimum size. If the memory is already big enough
/// for the min size then this function does nothing
fn grow_at_least(&mut self, min_size: u64) -> Result<(), MemoryError> {
let mut guard = self.mmap.write().unwrap();
guard.grow_at_least(min_size, self.config.clone())
}
/// Resets the memory down to a zero size
fn reset(&mut self) -> Result<(), MemoryError> {
let mut guard = self.mmap.write().unwrap();
guard.reset()?;
Ok(())
}
/// Return a `VMMemoryDefinition` for exposing the memory to compiled wasm code.
fn vmmemory(&self) -> NonNull<VMMemoryDefinition> {
let guard = self.mmap.read().unwrap();
guard.vm_memory_definition.as_ptr()
}
/// Shared memory can always be cloned
fn try_clone(&self) -> Result<Box<dyn LinearMemory + 'static>, MemoryError> {
Ok(Box::new(self.clone()))
}
/// Copies this memory to a new memory
fn copy(&mut self) -> Result<Box<dyn LinearMemory + 'static>, MemoryError> {
let forked = Self::copy(self)?;
Ok(Box::new(forked))
}
// Add current thread to waiter list
fn do_wait(
&mut self,
dst: NotifyLocation,
timeout: Option<Duration>,
) -> Result<u32, WaiterError> {
self.conditions.do_wait(dst, timeout)
}
/// Notify waiters from the wait list. Return the number of waiters notified
fn do_notify(&mut self, dst: NotifyLocation, count: u32) -> u32 {
self.conditions.do_notify(dst, count)
}
fn thread_conditions(&self) -> Option<&ThreadConditions> {
Some(&self.conditions)
}
}
impl From<VMOwnedMemory> for VMMemory {
fn from(mem: VMOwnedMemory) -> Self {
Self(Box::new(mem))
}
}
impl From<VMSharedMemory> for VMMemory {
fn from(mem: VMSharedMemory) -> Self {
Self(Box::new(mem))
}
}
/// Represents linear memory that can be either owned or shared
#[derive(Debug)]
pub struct VMMemory(pub Box<dyn LinearMemory + 'static>);
impl From<Box<dyn LinearMemory + 'static>> for VMMemory {
fn from(mem: Box<dyn LinearMemory + 'static>) -> Self {
Self(mem)
}
}
impl LinearMemory for VMMemory {
/// Returns the type for this memory.
fn ty(&self) -> MemoryType {
self.0.ty()
}
/// Returns the size of hte memory in pages
fn size(&self) -> Pages {
self.0.size()
}
/// Grow memory by the specified amount of wasm pages.
///
/// Returns `None` if memory can't be grown by the specified amount
/// of wasm pages.
fn grow(&mut self, delta: Pages) -> Result<Pages, MemoryError> {
self.0.grow(delta)
}
/// Grows the memory to at least a minimum size. If the memory is already big enough
/// for the min size then this function does nothing
fn grow_at_least(&mut self, min_size: u64) -> Result<(), MemoryError> {
self.0.grow_at_least(min_size)
}
/// Resets the memory down to a zero size
fn reset(&mut self) -> Result<(), MemoryError> {
self.0.reset()?;
Ok(())
}
/// Returns the memory style for this memory.
fn style(&self) -> MemoryStyle {
self.0.style()
}
/// Return a `VMMemoryDefinition` for exposing the memory to compiled wasm code.
fn vmmemory(&self) -> NonNull<VMMemoryDefinition> {
self.0.vmmemory()
}
/// Attempts to clone this memory (if its clonable)
fn try_clone(&self) -> Result<Box<dyn LinearMemory + 'static>, MemoryError> {
self.0.try_clone()
}
/// Initialize memory with data
unsafe fn initialize_with_data(&self, start: usize, data: &[u8]) -> Result<(), Trap> {
self.0.initialize_with_data(start, data)
}
/// Copies this memory to a new memory
fn copy(&mut self) -> Result<Box<dyn LinearMemory + 'static>, MemoryError> {
self.0.copy()
}
// Add current thread to waiter list
fn do_wait(
&mut self,
dst: NotifyLocation,
timeout: Option<Duration>,
) -> Result<u32, WaiterError> {
self.0.do_wait(dst, timeout)
}
/// Notify waiters from the wait list. Return the number of waiters notified
fn do_notify(&mut self, dst: NotifyLocation, count: u32) -> u32 {
self.0.do_notify(dst, count)
}
fn thread_conditions(&self) -> Option<&ThreadConditions> {
self.0.thread_conditions()
}
}
impl VMMemory {
/// Creates a new linear memory instance of the correct type with specified
/// minimum and maximum number of wasm pages.
///
/// This creates a `Memory` with owned metadata: this can be used to create a memory
/// that will be imported into Wasm modules.
pub fn new(memory: &MemoryType, style: &MemoryStyle) -> Result<Self, MemoryError> {
Ok(if memory.shared {
Self(Box::new(VMSharedMemory::new(memory, style)?))
} else {
Self(Box::new(VMOwnedMemory::new(memory, style)?))
})
}
/// Returns the number of pages in the allocated memory block
pub fn get_runtime_size(&self) -> u32 {
self.0.size().0
}
/// Create a new linear memory instance with specified minimum and maximum number of wasm pages.
///
/// This creates a `Memory` with metadata owned by a VM, pointed to by
/// `vm_memory_location`: this can be used to create a local memory.
///
/// # Safety
/// - `vm_memory_location` must point to a valid location in VM memory.
pub unsafe fn from_definition(
memory: &MemoryType,
style: &MemoryStyle,
vm_memory_location: NonNull<VMMemoryDefinition>,
) -> Result<Self, MemoryError> {
Ok(if memory.shared {
Self(Box::new(VMSharedMemory::from_definition(
memory,
style,
vm_memory_location,
)?))
} else {
Self(Box::new(VMOwnedMemory::from_definition(
memory,
style,
vm_memory_location,
)?))
})
}
/// Creates VMMemory from a custom implementation - the following into implementations
/// are natively supported
/// - VMOwnedMemory -> VMMemory
/// - Box<dyn LinearMemory + 'static> -> VMMemory
pub fn from_custom<IntoVMMemory>(memory: IntoVMMemory) -> Self
where
IntoVMMemory: Into<Self>,
{
memory.into()
}
/// Copies this memory to a new memory
pub fn copy(&mut self) -> Result<Box<dyn LinearMemory + 'static>, MemoryError> {
LinearMemory::copy(self)
}
}
#[doc(hidden)]
/// Default implementation to initialize memory with data
pub unsafe fn initialize_memory_with_data(
memory: &VMMemoryDefinition,
start: usize,
data: &[u8],
) -> Result<(), Trap> {
let mem_slice = slice::from_raw_parts_mut(memory.base, memory.current_length);
let end = start + data.len();
let to_init = &mut mem_slice[start..end];
to_init.copy_from_slice(data);
Ok(())
}
/// Represents memory that is used by the WebAsssembly module
pub trait LinearMemory
where
Self: std::fmt::Debug + Send,
{
/// Returns the type for this memory.
fn ty(&self) -> MemoryType;
/// Returns the size of hte memory in pages
fn size(&self) -> Pages;
/// Returns the memory style for this memory.
fn style(&self) -> MemoryStyle;
/// Grow memory by the specified amount of wasm pages.
///
/// Returns `None` if memory can't be grown by the specified amount
/// of wasm pages.
fn grow(&mut self, delta: Pages) -> Result<Pages, MemoryError>;
/// Grows the memory to at least a minimum size. If the memory is already big enough
/// for the min size then this function does nothing
fn grow_at_least(&mut self, _min_size: u64) -> Result<(), MemoryError> {
Err(MemoryError::UnsupportedOperation {
message: "grow_at_least() is not supported".to_string(),
})
}
/// Resets the memory back to zero length
fn reset(&mut self) -> Result<(), MemoryError> {
Err(MemoryError::UnsupportedOperation {
message: "reset() is not supported".to_string(),
})
}
/// Return a `VMMemoryDefinition` for exposing the memory to compiled wasm code.
fn vmmemory(&self) -> NonNull<VMMemoryDefinition>;
/// Attempts to clone this memory (if its clonable)
fn try_clone(&self) -> Result<Box<dyn LinearMemory + 'static>, MemoryError>;
#[doc(hidden)]
/// # Safety
/// This function is unsafe because WebAssembly specification requires that data is always set at initialization time.
/// It should be the implementors responsibility to make sure this respects the spec
unsafe fn initialize_with_data(&self, start: usize, data: &[u8]) -> Result<(), Trap> {
let memory = self.vmmemory().as_ref();
initialize_memory_with_data(memory, start, data)
}
/// Copies this memory to a new memory
fn copy(&mut self) -> Result<Box<dyn LinearMemory + 'static>, MemoryError>;
/// Add current thread to the waiter hash, and wait until notified or timout.
/// Return 0 if the waiter has been notified, 2 if the timeout occured, or None if en error happened
fn do_wait(
&mut self,
_dst: NotifyLocation,
_timeout: Option<Duration>,
) -> Result<u32, WaiterError> {
Err(WaiterError::Unimplemented)
}
/// Notify waiters from the wait list. Return the number of waiters notified
fn do_notify(&mut self, _dst: NotifyLocation, _count: u32) -> u32 {
0
}
/// Access the internal atomics handler.
///
/// Will be [`None`] if the memory does not support atomics.
fn thread_conditions(&self) -> Option<&ThreadConditions> {
None
}
}