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refactor is_borrowed/unborrow into shared/mut variants

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This commit is contained in:
Pat Hickey
2020-11-19 15:29:12 -08:00
parent 224e8b0e88
commit f5f180a8fe
5 changed files with 120 additions and 64 deletions
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4
crates/wiggle/src/guest_type.rs
View File

@@ -85,7 +85,7 @@ macro_rules! primitives {
start: offset,
len: size,
};
if ptr.mem().is_borrowed(region) {
if ptr.mem().is_mut_borrowed(region) {
return Err(GuestError::PtrBorrowed(region));
}
Ok(unsafe { <$i>::from_le_bytes(*host_ptr.cast::<[u8; mem::size_of::<Self>()]>()) })
@@ -104,7 +104,7 @@ macro_rules! primitives {
start: offset,
len: size,
};
if ptr.mem().is_borrowed(region) {
if ptr.mem().is_shared_borrowed(region) || ptr.mem().is_mut_borrowed(region) {
return Err(GuestError::PtrBorrowed(region));
}
unsafe {

112
crates/wiggle/src/lib.rs
View File

@@ -153,28 +153,36 @@ pub unsafe trait GuestMemory {
/// safe to recursively call into a WebAssembly module, or to manipulate
/// the WebAssembly memory by any other means.
fn has_outstanding_borrows(&self) -> bool;
/// Check if a region of linear memory is borrowed. This is called during
/// any `GuestPtr::read` or `GuestPtr::write` operation to ensure that
/// wiggle is not reading or writing a region of memory which Rust believes
/// it has exclusive access to.
fn is_borrowed(&self, r: Region) -> bool;
/// Borrow a region of linear memory. This is used when constructing a
/// `GuestSlice` or `GuestStr`. Those types will give Rust `&mut` access
/// Check if a region of linear memory is exclusively borrowed. This is called during any
/// `GuestPtr::read` or `GuestPtr::write` operation to ensure that wiggle is not reading or
/// writing a region of memory which Rust believes it has exclusive access to.
fn is_mut_borrowed(&self, r: Region) -> bool;
/// Check if a region of linear memory has any shared borrows.
fn is_shared_borrowed(&self, r: Region) -> bool;
/// Exclusively borrow a region of linear memory. This is used when constructing a
/// `GuestSliceMut` or `GuestStrMut`. Those types will give Rust `&mut` access
/// to the region of linear memory, therefore, the `GuestMemory` impl must
/// guarantee that at most one `BorrowHandle` is issued to a given region,
/// `GuestMemory::has_outstanding_borrows` is true for the duration of the
/// borrow, and that `GuestMemory::is_borrowed` of any overlapping region
/// borrow, and that `GuestMemory::is_mut_borrowed` of any overlapping region
/// is false for the duration of the borrow.
fn mut_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError>;
/// Shared borrow a region of linear memory. This is used when constructing a
/// `GuestSlice` or `GuestStr`. Those types will give Rust `&` (shared reference) access
/// to the region of linear memory.
fn shared_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError>;
/// Unborrow a previously borrowed region. As long as `GuestSlice` and
/// `GuestStr` are implemented correctly, a `BorrowHandle` should only be
/// Unborrow a previously borrowed mutable region. As long as `GuestSliceMut` and
/// `GuestStrMut` are implemented correctly, a mut `BorrowHandle` should only be
/// unborrowed once.
fn unborrow(&self, h: BorrowHandle);
fn mut_unborrow(&self, h: BorrowHandle);
/// Unborrow a previously borrowed shared region. As long as `GuestSlice` and
/// `GuestStr` are implemented correctly, a shared `BorrowHandle` should only be
/// unborrowed once.
fn shared_unborrow(&self, h: BorrowHandle);
}
/// A handle to a borrow on linear memory. It is produced by `borrow` and
/// consumed by `unborrow`. Only the `GuestMemory` impl should ever construct
/// A handle to a borrow on linear memory. It is produced by `{mut, shared}_borrow` and
/// consumed by `{mut, shared}_unborrow`. Only the `GuestMemory` impl should ever construct
/// a `BorrowHandle` or inspect its contents.
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub struct BorrowHandle(pub usize);
@@ -187,8 +195,11 @@ unsafe impl<'a, T: ?Sized + GuestMemory> GuestMemory for &'a T {
fn has_outstanding_borrows(&self) -> bool {
T::has_outstanding_borrows(self)
}
fn is_borrowed(&self, r: Region) -> bool {
T::is_borrowed(self, r)
fn is_mut_borrowed(&self, r: Region) -> bool {
T::is_mut_borrowed(self, r)
}
fn is_shared_borrowed(&self, r: Region) -> bool {
T::is_shared_borrowed(self, r)
}
fn mut_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::mut_borrow(self, r)
@@ -196,8 +207,11 @@ unsafe impl<'a, T: ?Sized + GuestMemory> GuestMemory for &'a T {
fn shared_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::shared_borrow(self, r)
}
fn unborrow(&self, h: BorrowHandle) {
T::unborrow(self, h)
fn mut_unborrow(&self, h: BorrowHandle) {
T::mut_unborrow(self, h)
}
fn shared_unborrow(&self, h: BorrowHandle) {
T::shared_unborrow(self, h)
}
}
@@ -208,8 +222,11 @@ unsafe impl<'a, T: ?Sized + GuestMemory> GuestMemory for &'a mut T {
fn has_outstanding_borrows(&self) -> bool {
T::has_outstanding_borrows(self)
}
fn is_borrowed(&self, r: Region) -> bool {
T::is_borrowed(self, r)
fn is_mut_borrowed(&self, r: Region) -> bool {
T::is_mut_borrowed(self, r)
}
fn is_shared_borrowed(&self, r: Region) -> bool {
T::is_shared_borrowed(self, r)
}
fn mut_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::mut_borrow(self, r)
@@ -217,8 +234,11 @@ unsafe impl<'a, T: ?Sized + GuestMemory> GuestMemory for &'a mut T {
fn shared_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::shared_borrow(self, r)
}
fn unborrow(&self, h: BorrowHandle) {
T::unborrow(self, h)
fn mut_unborrow(&self, h: BorrowHandle) {
T::mut_unborrow(self, h)
}
fn shared_unborrow(&self, h: BorrowHandle) {
T::shared_unborrow(self, h)
}
}
@@ -229,8 +249,11 @@ unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Box<T> {
fn has_outstanding_borrows(&self) -> bool {
T::has_outstanding_borrows(self)
}
fn is_borrowed(&self, r: Region) -> bool {
T::is_borrowed(self, r)
fn is_mut_borrowed(&self, r: Region) -> bool {
T::is_mut_borrowed(self, r)
}
fn is_shared_borrowed(&self, r: Region) -> bool {
T::is_shared_borrowed(self, r)
}
fn mut_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::mut_borrow(self, r)
@@ -238,8 +261,11 @@ unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Box<T> {
fn shared_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::shared_borrow(self, r)
}
fn unborrow(&self, h: BorrowHandle) {
T::unborrow(self, h)
fn mut_unborrow(&self, h: BorrowHandle) {
T::mut_unborrow(self, h)
}
fn shared_unborrow(&self, h: BorrowHandle) {
T::shared_unborrow(self, h)
}
}
@@ -250,8 +276,11 @@ unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Rc<T> {
fn has_outstanding_borrows(&self) -> bool {
T::has_outstanding_borrows(self)
}
fn is_borrowed(&self, r: Region) -> bool {
T::is_borrowed(self, r)
fn is_mut_borrowed(&self, r: Region) -> bool {
T::is_mut_borrowed(self, r)
}
fn is_shared_borrowed(&self, r: Region) -> bool {
T::is_shared_borrowed(self, r)
}
fn mut_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::mut_borrow(self, r)
@@ -259,8 +288,11 @@ unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Rc<T> {
fn shared_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::shared_borrow(self, r)
}
fn unborrow(&self, h: BorrowHandle) {
T::unborrow(self, h)
fn mut_unborrow(&self, h: BorrowHandle) {
T::mut_unborrow(self, h)
}
fn shared_unborrow(&self, h: BorrowHandle) {
T::shared_unborrow(self, h)
}
}
@@ -271,8 +303,11 @@ unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Arc<T> {
fn has_outstanding_borrows(&self) -> bool {
T::has_outstanding_borrows(self)
}
fn is_borrowed(&self, r: Region) -> bool {
T::is_borrowed(self, r)
fn is_mut_borrowed(&self, r: Region) -> bool {
T::is_mut_borrowed(self, r)
}
fn is_shared_borrowed(&self, r: Region) -> bool {
T::is_shared_borrowed(self, r)
}
fn mut_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::mut_borrow(self, r)
@@ -280,8 +315,11 @@ unsafe impl<T: ?Sized + GuestMemory> GuestMemory for Arc<T> {
fn shared_borrow(&self, r: Region) -> Result<BorrowHandle, GuestError> {
T::shared_borrow(self, r)
}
fn unborrow(&self, h: BorrowHandle) {
T::unborrow(self, h)
fn mut_unborrow(&self, h: BorrowHandle) {
T::mut_unborrow(self, h)
}
fn shared_unborrow(&self, h: BorrowHandle) {
T::shared_unborrow(self, h)
}
}
@@ -771,7 +809,7 @@ impl<'a, T> std::ops::Deref for GuestSlice<'a, T> {
impl<'a, T> Drop for GuestSlice<'a, T> {
fn drop(&mut self) {
self.mem.unborrow(self.borrow)
self.mem.shared_unborrow(self.borrow)
}
}
@@ -799,7 +837,7 @@ impl<'a, T> std::ops::DerefMut for GuestSliceMut<'a, T> {
impl<'a, T> Drop for GuestSliceMut<'a, T> {
fn drop(&mut self) {
self.mem.unborrow(self.borrow)
self.mem.mut_unborrow(self.borrow)
}
}
@@ -820,7 +858,7 @@ impl<'a> std::ops::Deref for GuestStr<'a> {
impl<'a> Drop for GuestStr<'a> {
fn drop(&mut self) {
self.mem.unborrow(self.borrow)
self.mem.shared_unborrow(self.borrow)
}
}
@@ -848,7 +886,7 @@ impl<'a> std::ops::DerefMut for GuestStrMut<'a> {
impl<'a> Drop for GuestStrMut<'a> {
fn drop(&mut self) {
self.mem.unborrow(self.borrow)
self.mem.mut_unborrow(self.borrow)
}
}