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wiggle: get BorrowChecker from GuestMemory method

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This commit is contained in:
Pat Hickey
2020-05-21 12:37:14 -07:00
parent 3920d8c1f3
commit 96d6884d33
13 changed files with 112 additions and 128 deletions
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54
crates/wiggle/src/lib.rs
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@@ -65,7 +65,7 @@ pub use region::Region;
/// into the memory region given by a `GuestMemory`.
///
/// These smart pointers are dynamically borrow-checked by the `BorrowChecker`
/// passed to the wiggle-generated ABI-level functions. While a `GuestSlice`
/// given by [`GuestMemory::borrow_checker()`]. While a `GuestSlice`
/// or a `GuestStr` are live, the [`BorrowChecker::has_outstanding_borrows()`]
/// method will always return `true`. If you need to re-enter the guest or
/// otherwise read or write to the contents of a WebAssembly memory, all
@@ -84,6 +84,11 @@ pub unsafe trait GuestMemory {
/// [`GuestMemory`] documentation.
fn base(&self) -> (*mut u8, u32);
/// Gives a reference to the [`BorrowChecker`] used to keep track of each
/// outstanding borrow of the memory region. [`BorrowChecker::new`] safety
/// rules require that exactly one checker exist for each memory region.
fn borrow_checker(&self) -> &BorrowChecker;
/// Validates a guest-relative pointer given various attributes, and returns
/// the corresponding host pointer.
///
@@ -138,12 +143,12 @@ pub unsafe trait GuestMemory {
/// Note that `T` can be almost any type, and typically `offset` is a `u32`.
/// The exception is slices and strings, in which case `offset` is a `(u32,
/// u32)` of `(offset, length)`.
fn ptr<'a, T>(&'a self, bc: &'a BorrowChecker, offset: T::Pointer) -> GuestPtr<'a, T>
fn ptr<'a, T>(&'a self, offset: T::Pointer) -> GuestPtr<'a, T>
where
Self: Sized,
T: ?Sized + Pointee,
{
GuestPtr::new(self, bc, offset)
GuestPtr::new(self, offset)
}
}
@@ -153,30 +158,45 @@ unsafe impl<'a, T: ?Sized + GuestMemory> GuestMemory for &'a T {
fn base(&self) -> (*mut u8, u32) {
T::base(self)
}
fn borrow_checker(&self) -> &BorrowChecker {
T::borrow_checker(self)
}
}
unsafe impl<'a, T: ?Sized + GuestMemory> GuestMemory for &'a mut T {
fn base(&self) -> (*mut u8, u32) {
T::base(self)
}
fn borrow_checker(&self) -> &BorrowChecker {
T::borrow_checker(self)
}
}
unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Box<T> {
fn base(&self) -> (*mut u8, u32) {
T::base(self)
}
fn borrow_checker(&self) -> &BorrowChecker {
T::borrow_checker(self)
}
}
unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Rc<T> {
fn base(&self) -> (*mut u8, u32) {
T::base(self)
}
fn borrow_checker(&self) -> &BorrowChecker {
T::borrow_checker(self)
}
}
unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Arc<T> {
fn base(&self) -> (*mut u8, u32) {
T::base(self)
}
fn borrow_checker(&self) -> &BorrowChecker {
T::borrow_checker(self)
}
}
/// A *guest* pointer into host memory.
@@ -229,7 +249,6 @@ unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Arc<T> {
/// already-attached helper methods.
pub struct GuestPtr<'a, T: ?Sized + Pointee> {
mem: &'a (dyn GuestMemory + 'a),
bc: &'a BorrowChecker,
pointer: T::Pointer,
_marker: marker::PhantomData<&'a Cell<T>>,
}
@@ -240,14 +259,9 @@ impl<'a, T: ?Sized + Pointee> GuestPtr<'a, T> {
/// Note that for sized types like `u32`, `GuestPtr<T>`, etc, the `pointer`
/// vlue is a `u32` offset into guest memory. For slices and strings,
/// `pointer` is a `(u32, u32)` offset/length pair.
pub fn new(
mem: &'a (dyn GuestMemory + 'a),
bc: &'a BorrowChecker,
pointer: T::Pointer,
) -> GuestPtr<'a, T> {
pub fn new(mem: &'a (dyn GuestMemory + 'a), pointer: T::Pointer) -> GuestPtr<'a, T> {
GuestPtr {
mem,
bc,
pointer,
_marker: marker::PhantomData,
}
@@ -268,7 +282,7 @@ impl<'a, T: ?Sized + Pointee> GuestPtr<'a, T> {
/// Returns the borrow checker that this pointer uses
pub fn borrow_checker(&self) -> &'a BorrowChecker {
self.bc
self.mem.borrow_checker()
}
/// Casts this `GuestPtr` type to a different type.
@@ -281,7 +295,7 @@ impl<'a, T: ?Sized + Pointee> GuestPtr<'a, T> {
where
T: Pointee<Pointer = u32>,
{
GuestPtr::new(self.mem, self.bc, self.pointer)
GuestPtr::new(self.mem, self.pointer)
}
/// Safely read a value from this pointer.
@@ -348,7 +362,7 @@ impl<'a, T: ?Sized + Pointee> GuestPtr<'a, T> {
Some(o) => o,
None => return Err(GuestError::PtrOverflow),
};
Ok(GuestPtr::new(self.mem, self.bc, offset))
Ok(GuestPtr::new(self.mem, offset))
}
/// Returns a `GuestPtr` for an array of `T`s using this pointer as the
@@ -357,7 +371,7 @@ impl<'a, T: ?Sized + Pointee> GuestPtr<'a, T> {
where
T: GuestType<'a> + Pointee<Pointer = u32>,
{
GuestPtr::new(self.mem, self.bc, (self.pointer, elems))
GuestPtr::new(self.mem, (self.pointer, elems))
}
}
@@ -410,7 +424,7 @@ impl<'a, T> GuestPtr<'a, [T]> {
self.mem
.validate_size_align(self.pointer.0, T::guest_align(), len)? as *mut T;
let borrow = self.bc.borrow(Region {
let borrow = self.mem.borrow_checker().borrow(Region {
start: self.pointer.0,
len,
})?;
@@ -426,7 +440,7 @@ impl<'a, T> GuestPtr<'a, [T]> {
Ok(GuestSlice {
ptr,
bc: self.bc,
bc: self.mem.borrow_checker(),
borrow,
})
}
@@ -461,7 +475,7 @@ impl<'a, T> GuestPtr<'a, [T]> {
/// Returns a `GuestPtr` pointing to the base of the array for the interior
/// type `T`.
pub fn as_ptr(&self) -> GuestPtr<'a, T> {
GuestPtr::new(self.mem, self.bc, self.offset_base())
GuestPtr::new(self.mem, self.offset_base())
}
}
@@ -480,7 +494,7 @@ impl<'a> GuestPtr<'a, str> {
/// Returns a raw pointer for the underlying slice of bytes that this
/// pointer points to.
pub fn as_bytes(&self) -> GuestPtr<'a, [u8]> {
GuestPtr::new(self.mem, self.bc, self.pointer)
GuestPtr::new(self.mem, self.pointer)
}
/// Attempts to create a [`GuestStr<'_>`] from this pointer, performing
@@ -497,7 +511,7 @@ impl<'a> GuestPtr<'a, str> {
.mem
.validate_size_align(self.pointer.0, 1, self.pointer.1)?;
let borrow = self.bc.borrow(Region {
let borrow = self.mem.borrow_checker().borrow(Region {
start: self.pointer.0,
len: self.pointer.1,
})?;
@@ -509,7 +523,7 @@ impl<'a> GuestPtr<'a, str> {
match str::from_utf8_mut(ptr) {
Ok(ptr) => Ok(GuestStr {
ptr,
bc: self.bc,
bc: self.mem.borrow_checker(),
borrow,
}),
Err(e) => Err(GuestError::InvalidUtf8(e)),