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fixes

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This commit is contained in:
Pat Hickey
2020-11-20 11:42:42 -08:00
parent f7a0d86c64
commit 2a937f06db
1 changed files with 17 additions and 13 deletions
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30
crates/wiggle/borrow/src/lib.rs
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@@ -9,19 +9,23 @@ pub struct BorrowChecker {
} }
impl BorrowChecker { impl BorrowChecker {
/// A `BorrowChecker` manages run-time validation of borrows from a `GuestMemory`. It keeps /// A `BorrowChecker` manages run-time validation of borrows from a
/// track of regions of guest memory which are possible to alias with Rust references (via the /// `GuestMemory`. It keeps track of regions of guest memory which are
/// `GuestSlice` and `GuestStr` structs, which implement `std::ops::Deref` and /// possible to alias with Rust references (via the `GuestSlice` and
/// `std::ops::DerefMut`. It also enforces that `GuestPtr::read` and `GuestPtr::write` do not /// `GuestStr` structs, which implement `std::ops::Deref` and
/// access memory with an outstanding borrow. /// `std::ops::DerefMut`. It also enforces that `GuestPtr::read`
/// does not access memory with an outstanding mutable borrow, and
/// `GuestPtr::write` does not access memory with an outstanding
/// shared or mutable borrow.
pub fn new() -> Self { pub fn new() -> Self {
BorrowChecker { BorrowChecker {
bc: RefCell::new(InnerBorrowChecker::new()), bc: RefCell::new(InnerBorrowChecker::new()),
} }
} }
/// Indicates whether any outstanding borrows are known to the `BorrowChecker`. This function /// Indicates whether any outstanding shared or mutable borrows are known
/// must be `false` in order for it to be safe to recursively call into a WebAssembly module, /// to the `BorrowChecker`. This function must be `false` in order for it
/// or to manipulate the WebAssembly memory by any other means. /// to be safe to recursively call into a WebAssembly module, or to
/// manipulate the WebAssembly memory by any other means.
pub fn has_outstanding_borrows(&self) -> bool { pub fn has_outstanding_borrows(&self) -> bool {
self.bc.borrow().has_outstanding_borrows() self.bc.borrow().has_outstanding_borrows()
} }
@@ -207,13 +211,13 @@ mod test {
let h2 = bs.mut_borrow(r2).expect("can borrow r2"); let h2 = bs.mut_borrow(r2).expect("can borrow r2");
assert!(bs.mut_borrow(r2).is_err(), "can't borrow r2 twice"); assert!(bs.mut_borrow(r2).is_err(), "can't borrow r2 twice");
bs.unborrow(h2); bs.mut_unborrow(h2);
assert_eq!( assert_eq!(
bs.has_outstanding_borrows(), bs.has_outstanding_borrows(),
true, true,
"h1 is still outstanding" "h1 is still outstanding"
); );
bs.unborrow(h1); bs.mut_unborrow(h1);
assert_eq!(bs.has_outstanding_borrows(), false, "no remaining borrows"); assert_eq!(bs.has_outstanding_borrows(), false, "no remaining borrows");
let _h3 = bs let _h3 = bs
@@ -232,14 +236,14 @@ mod test {
let h2 = bs.shared_borrow(r2).expect("can borrow r2"); let h2 = bs.shared_borrow(r2).expect("can borrow r2");
let h3 = bs.shared_borrow(r2).expect("can shared borrow r2 twice"); let h3 = bs.shared_borrow(r2).expect("can shared borrow r2 twice");
bs.unborrow(h2); bs.shared_unborrow(h2);
assert_eq!( assert_eq!(
bs.has_outstanding_borrows(), bs.has_outstanding_borrows(),
true, true,
"h1, h3 still outstanding" "h1, h3 still outstanding"
); );
bs.unborrow(h1); bs.shared_unborrow(h1);
bs.unborrow(h3); bs.shared_unborrow(h3);
assert_eq!(bs.has_outstanding_borrows(), false, "no remaining borrows"); assert_eq!(bs.has_outstanding_borrows(), false, "no remaining borrows");
} }
} }