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//! Checkers is a simple allocation sanitizer for Rust. It plugs in through the //! [global allocator] and can sanity check your unsafe Rust during integration //! testing. Since it plugs in through the global allocator it doesn't require any //! additional dependencies and works for all platforms - but it is more limited in //! what it can verify. //! //! [global allocator]: https://doc.rust-lang.org/std/alloc/trait.GlobalAlloc.html //! //! It can check for the following things: //! * Double-frees. //! * Memory leaks. //! * Freeing regions which are not allocated. //! * Freeing only part of regions which are allocated. //! * Freeing a region with a [mismatched layout]. //! * That the underlying allocator produces regions adhering to the requested //! layout. Namely size and alignment. //! * Detailed information on memory usage. //! * Other user-defined conditions ([see test]). //! //! What it can't do: //! * Test multithreaded code. Since the allocator is global, it is difficult to //! scope the state for each test case. //! * Detect out-of-bounds accesses. //! //! [mismatched layout]: https://doc.rust-lang.org/std/alloc/trait.GlobalAlloc.html#safety //! [see test]: https://github.com/udoprog/checkers/blob/master/tests/leaky_tests.rs //! //! # Features //! //! The following are features available, that changes how checkers work. //! //! * `realloc` - Enabling this feature causes checker to verify //! that a `realloc` operation is correct. That bytes from the old region were //! faithfully transferred to the new, resized one. //! Since this can have a rather significant performance impact, it can be //! disabled. //! * `macros` - Enables dependencies and re-exports of macros, like //! [`#[checkers::test]`](attr.test.html). //! //! # Examples //! //! It is recommended that you use checkers for [integration tests], which by //! default lives in the `./tests` directory. Each file in this directory will be //! compiled as a separate program, so the use of the global allocator can be more //! isolated. //! //! [integration tests]: https://doc.rust-lang.org/book/ch11-03-test-organization.html#integration-tests //! //! We then use checkers by installing [`checkers::Allocator`] as the global //! allocator, after this we can make use of [`#[checkers::test]`](attr.test.html) attribute macro or //! the [`checkers::with`] function in our tests. //! //! [`checkers::Allocator`]: crate::Allocator //! [`checkers::with`]: crate::with //! //! ```rust //! #[global_allocator] //! static ALLOCATOR: checkers::Allocator = checkers::Allocator::system(); //! //! #[checkers::test] //! fn test_allocations() { //! let _ = Box::into_raw(Box::new(42)); //! } //! ``` //! //! The above would result in the following test output: //! //! ```text //! dangling region: 0x226e5784f30-0x226e5784f40 (size: 16, align: 8). //! thread 'test_leak_box' panicked at 'allocation checks failed', tests\leaky_tests.rs:4:1 //! ``` //! //! With `checkers::with`, we can perform more detailed diagnostics: //! //! ```rust //! #[global_allocator] //! static ALLOCATOR: checkers::Allocator = checkers::Allocator::system(); //! //! #[test] //! fn test_event_inspection() { //! let snapshot = checkers::with(|| { //! let _ = vec![1, 2, 3, 4]; //! }); //! //! assert_eq!(2, snapshot.events.len()); //! assert!(snapshot.events[0].is_alloc_with(|r| r.size >= 16)); //! assert!(snapshot.events[1].is_free_with(|a| a.size >= 16)); //! assert_eq!(1, snapshot.events.allocs()); //! assert_eq!(1, snapshot.events.frees()); //! assert!(snapshot.events.max_memory_used().unwrap() >= 16); //! } //! ``` use std::{ cell::{Cell, RefCell}, fmt, }; mod allocator; mod events; mod machine; mod utils; pub use self::allocator::Allocator; pub use self::events::Events; pub use self::machine::{Machine, Region, Violation}; #[cfg(feature = "macros")] pub use checkers_macros::test; thread_local! { /// Thread-local state required by the allocator. /// /// Feel free to interact with this directly, but it's primarily used /// through the [`test`](crate::test) macro. static STATE: RefCell<State> = RefCell::new(State::new()); static MUTED: Cell<bool> = Cell::new(true); } /// Perform an operation, while having access to the thread-local state. pub fn with_state<F, R>(f: F) -> R where F: FnOnce(&RefCell<State>) -> R, { crate::STATE.with(f) } /// Test if the crate is currently muted. The allocator is muted by default. /// /// We mute the allocator for allocations we don't want to be tracked. This is /// useful to avoid tracing internal allocations. /// /// # Examples /// /// ```rust /// assert!(checkers::is_muted()); /// /// { /// let _g = checkers::mute_guard(false); /// assert!(!checkers::is_muted()); /// } /// /// assert!(checkers::is_muted()); /// /// checkers::with_unmuted(|| { /// assert!(!checkers::is_muted()); /// }); /// /// assert!(checkers::is_muted()); /// /// let result = std::panic::catch_unwind(|| { /// let _g = checkers::mute_guard(false); /// assert!(!checkers::is_muted()); /// panic!("uh oh"); /// }); /// assert!(result.is_err()); /// assert!(checkers::is_muted()); /// ``` pub fn is_muted() -> bool { MUTED.with(Cell::get) } /// Enable muting for the duration of the guard. A guard ensures that the muted /// state is restored to its original value even if we are unwinding due to a /// panic. You should prefer to use [with_unmuted] when possible. /// /// See [is_muted] for details on what this means. pub fn mute_guard(muted: bool) -> MuteGuard { MuteGuard(MUTED.with(|s| s.replace(muted))) } /// Run the given closure while the allocator is muted. /// /// See [is_muted] for details on what this means. pub fn with_unmuted<F, R>(f: F) -> R where F: FnOnce() -> R, { let _g = crate::mute_guard(false); f() } /// A helper guard to make sure the state is de-allocated on drop. pub struct MuteGuard(bool); impl Drop for MuteGuard { fn drop(&mut self) { MUTED.with(|s| s.set(self.0)); } } /// Verify the state of the allocator. /// /// Note: this macro is used by default if the `verify` parameter is not /// specified in [`#[checkers::test]`](attr.test.html). /// /// Currently performs the following tests: /// * Checks that each allocation has an exact corresponding deallocation, /// and that it happened _after_ the allocation it relates to. /// * That there are no overlapping frees / allocations. /// * That the thread-local timeline matches. /// /// # Examples /// /// ```rust /// #[global_allocator] /// static ALLOCATOR: checkers::Allocator = checkers::Allocator::system(); /// /// fn verify_test_custom_verify(state: &mut checkers::State) { /// assert_eq!(1, state.events.allocs()); /// checkers::verify!(state); /// } /// /// #[checkers::test(verify = "verify_test_custom_verify")] /// fn test_custom_verify() { /// let _ = Box::into_raw(vec![1, 2, 3, 4, 5].into_boxed_slice()); /// } /// ``` #[macro_export] macro_rules! verify { ($state:expr) => { let mut validations = Vec::new(); $state.validate(&mut validations); for e in &validations { eprintln!("{}", e); } if !validations.is_empty() { panic!("allocation checks failed"); } }; } #[derive(Debug)] pub struct Snapshot { pub events: Events, } /// Run the specified closure and return a snapshot of the memory state /// afterwards. /// /// This can be useful to programmatically test for allocation invariants, /// while the default behavior is to simply panic on invariant errors. /// /// # Examples /// /// ```rust /// #[global_allocator] /// static ALLOCATOR: checkers::Allocator = checkers::Allocator::system(); /// /// let snapshot = checkers::with(|| { /// let _ = vec![1, 2, 3, 4]; /// }); /// /// assert_eq!(2, snapshot.events.len()); /// assert!(snapshot.events[0].is_alloc_with(|a| a.size >= 16)); /// assert!(snapshot.events[1].is_free_with(|a| a.size >= 16)); /// assert_eq!(1, snapshot.events.allocs()); /// assert_eq!(1, snapshot.events.frees()); /// assert!(snapshot.events.max_memory_used().unwrap() >= 16); /// ``` pub fn with<F>(f: F) -> Snapshot where F: FnOnce(), { crate::with_state(|s| { s.borrow_mut().events.clear(); crate::with_unmuted(f); let snapshot = Snapshot { events: s.borrow().events.clone(), }; snapshot }) } /// Structure containing all thread-local state required to use the /// single-threaded allocation checker. pub struct State { pub events: Events, } impl State { /// Construct new local state. pub const fn new() -> Self { Self { events: Events::new(), } } /// Reserve the specified number of events. /// /// See [Events::reserve] for more documentation. pub fn reserve(&mut self, cap: usize) { self.events.reserve(cap); } /// Clear the current collection of events. /// /// See [Events::clear] for more documentation. pub fn clear(&mut self) { self.events.clear(); } /// Validate the current state. /// /// See [Events::validate] for more documentation. pub fn validate(&self, errors: &mut Vec<Violation>) { self.events.validate(errors); } } /// A type-erased pointer. /// The inner representation is specifically _not_ a raw pointer to avoid /// aliasing the pointers handled by the allocator. #[derive(Debug, Clone, Copy, Default, PartialEq, Eq, PartialOrd, Ord, Hash)] pub struct Pointer(usize); impl Pointer { /// Construct a new default poitner. pub const fn new() -> Self { Self(0) } /// Add the given offset to the current pointer. pub fn saturating_add(self, n: usize) -> Self { Self(self.0.saturating_add(n)) } /// Test if pointer is aligned with the given argument. pub fn is_aligned_with(self, n: usize) -> bool { self.0 % n == 0 } } impl fmt::Display for Pointer { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { write!(fmt, "{:?}", &(self.0 as *const ())) } } impl From<*mut u8> for Pointer { fn from(value: *mut u8) -> Self { Self(value as usize) } } impl From<usize> for Pointer { fn from(value: usize) -> Self { Self(value) } } /// Description of a zero-allocation. #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] #[non_exhaustive] pub struct AllocZeroed { pub is_zeroed: Option<bool>, pub alloc: Region, } impl AllocZeroed { /// Construct a new reallocation. pub fn new(is_zeroed: Option<bool>, alloc: Region) -> Self { Self { is_zeroed, alloc } } } /// Description of a reallocation. #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] #[non_exhaustive] pub struct Realloc { /// Indicates if the subset of the old region was faithfully copied over /// to the new region. pub is_relocated: Option<bool>, pub free: Region, pub alloc: Region, } impl Realloc { /// Construct a new reallocation. pub fn new(is_relocated: Option<bool>, free: Region, alloc: Region) -> Self { Self { is_relocated, free, alloc, } } } /// Metadata for a single allocation or deallocation. #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] pub enum Event { /// An allocation. Alloc(Region), /// A deallocation. Free(Region), /// A zerod allocation, with an optional boolean indicates if it is actually /// zeroed or not. AllocZeroed(AllocZeroed), Realloc(Realloc), } impl Event { /// Test if this event is an allocation which matches the specified /// predicate. /// /// # Examples /// /// ```rust /// let event = checkers::Event::Alloc(checkers::Region::new(100.into(), 100, 4)); /// /// assert!(event.is_alloc_with(|r| r.size == 100 && r.align == 4)); /// assert!(!event.is_free_with(|r| r.size == 100 && r.align == 4)); /// ``` pub fn is_alloc_with<F>(self, f: F) -> bool where F: FnOnce(Region) -> bool, { match self { Self::Alloc(region) | Self::AllocZeroed(AllocZeroed { alloc: region, .. }) => f(region), _ => false, } } /// Test if this event is a deallocation which matches the specified /// predicate. /// /// # Examples /// /// ```rust /// let event = checkers::Event::Free(checkers::Region::new(100.into(), 100, 4)); /// /// assert!(!event.is_alloc_with(|r| r.size == 100 && r.align == 4)); /// assert!(event.is_free_with(|r| r.size == 100 && r.align == 4)); /// ``` pub fn is_free_with<F>(self, f: F) -> bool where F: FnOnce(Region) -> bool, { match self { Self::Free(region) => f(region), _ => false, } } /// Test if this event is an allocation which matches the specified /// predicate. /// /// # Examples /// /// ```rust /// use checkers::{Event, Region, AllocZeroed}; /// let event = Event::AllocZeroed(AllocZeroed::new(Some(true), Region::new(100.into(), 100, 4))); /// /// assert!(event.is_alloc_zeroed_with(|r| r.alloc.size == 100 && r.alloc.align == 4)); /// assert!(!event.is_free_with(|r| r.size == 100 && r.align == 4)); /// ``` pub fn is_alloc_zeroed_with<F>(self, f: F) -> bool where F: FnOnce(AllocZeroed) -> bool, { match self { Self::AllocZeroed(alloc_zeroed) => f(alloc_zeroed), _ => false, } } /// Test if this event is an allocation which matches the specified /// predicate. /// /// # Examples /// /// ```rust /// use checkers::{Event, Region, Realloc}; /// /// let event = Event::Realloc(Realloc::new( /// Some(true), /// Region::new(10.into(), 10, 1), /// Region::new(20.into(), 20, 1) /// )); /// /// assert!(event.is_realloc_with(|r| r.free.size == 10 && r.alloc.size == 20)); /// ``` pub fn is_realloc_with<F>(self, f: F) -> bool where F: FnOnce(Realloc) -> bool, { match self { Self::Realloc(realloc) => f(realloc), _ => false, } } }