1 use std::convert::TryFrom;
7 use rustc_middle::ty::{self, List, TyCtxt, layout::TyAndLayout};
8 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
9 use rustc_target::abi::{LayoutOf, Size, FieldsShape, Variants};
15 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
17 /// Gets an instance for a path.
18 fn try_resolve_did<'mir, 'tcx>(tcx: TyCtxt<'tcx>, path: &[&str]) -> Option<DefId> {
21 .find(|&&krate| tcx.original_crate_name(krate).as_str() == path[0])
23 let krate = DefId { krate: *krate, index: CRATE_DEF_INDEX };
24 let mut items = tcx.item_children(krate);
25 let mut path_it = path.iter().skip(1).peekable();
27 while let Some(segment) = path_it.next() {
28 for item in mem::replace(&mut items, Default::default()).iter() {
29 if item.ident.name.as_str() == *segment {
30 if path_it.peek().is_none() {
31 return Some(item.res.def_id());
34 items = tcx.item_children(item.res.def_id());
43 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
44 /// Gets an instance for a path.
45 fn resolve_path(&self, path: &[&str]) -> ty::Instance<'tcx> {
46 let did = try_resolve_did(self.eval_context_ref().tcx.tcx, path)
47 .unwrap_or_else(|| panic!("failed to find required Rust item: {:?}", path));
48 ty::Instance::mono(self.eval_context_ref().tcx.tcx, did)
51 /// Evaluates the scalar at the specified path. Returns Some(val)
52 /// if the path could be resolved, and None otherwise
56 ) -> InterpResult<'tcx, ScalarMaybeUndef<Tag>> {
57 let this = self.eval_context_mut();
58 let instance = this.resolve_path(path);
59 let cid = GlobalId { instance, promoted: None };
60 let const_val = this.const_eval_raw(cid)?;
61 let const_val = this.read_scalar(const_val.into())?;
65 /// Helper function to get a `libc` constant as a `Scalar`.
66 fn eval_libc(&mut self, name: &str) -> InterpResult<'tcx, Scalar<Tag>> {
67 self.eval_context_mut()
68 .eval_path_scalar(&["libc", name])?
72 /// Helper function to get a `libc` constant as an `i32`.
73 fn eval_libc_i32(&mut self, name: &str) -> InterpResult<'tcx, i32> {
74 // TODO: Cache the result.
75 self.eval_libc(name)?.to_i32()
78 /// Helper function to get a `windows` constant as a `Scalar`.
79 fn eval_windows(&mut self, module: &str, name: &str) -> InterpResult<'tcx, Scalar<Tag>> {
80 self.eval_context_mut()
81 .eval_path_scalar(&["std", "sys", "windows", module, name])?
85 /// Helper function to get a `windows` constant as an `u64`.
86 fn eval_windows_u64(&mut self, module: &str, name: &str) -> InterpResult<'tcx, u64> {
87 // TODO: Cache the result.
88 self.eval_windows(module, name)?.to_u64()
91 /// Helper function to get the `TyAndLayout` of a `libc` type
92 fn libc_ty_layout(&mut self, name: &str) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
93 let this = self.eval_context_mut();
94 let ty = this.resolve_path(&["libc", name]).monomorphic_ty(*this.tcx);
98 /// Helper function to get the `TyAndLayout` of a `windows` type
99 fn windows_ty_layout(&mut self, name: &str) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
100 let this = self.eval_context_mut();
101 let ty = this.resolve_path(&["std", "sys", "windows", "c", name]).monomorphic_ty(*this.tcx);
105 /// Write a 0 of the appropriate size to `dest`.
106 fn write_null(&mut self, dest: PlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
107 self.eval_context_mut().write_scalar(Scalar::from_int(0, dest.layout.size), dest)
110 /// Test if this immediate equals 0.
111 fn is_null(&self, val: Scalar<Tag>) -> InterpResult<'tcx, bool> {
112 let this = self.eval_context_ref();
113 let null = Scalar::null_ptr(this);
114 this.ptr_eq(val, null)
117 /// Turn a Scalar into an Option<NonNullScalar>
118 fn test_null(&self, val: Scalar<Tag>) -> InterpResult<'tcx, Option<Scalar<Tag>>> {
119 let this = self.eval_context_ref();
120 Ok(if this.is_null(val)? { None } else { Some(val) })
123 /// Get the `Place` for a local
124 fn local_place(&mut self, local: mir::Local) -> InterpResult<'tcx, PlaceTy<'tcx, Tag>> {
125 let this = self.eval_context_mut();
126 let place = mir::Place { local: local, projection: List::empty() };
127 this.eval_place(place)
130 /// Generate some random bytes, and write them to `dest`.
131 fn gen_random(&mut self, ptr: Scalar<Tag>, len: u64) -> InterpResult<'tcx> {
132 // Some programs pass in a null pointer and a length of 0
133 // to their platform's random-generation function (e.g. getrandom())
134 // on Linux. For compatibility with these programs, we don't perform
135 // any additional checks - it's okay if the pointer is invalid,
136 // since we wouldn't actually be writing to it.
140 let this = self.eval_context_mut();
142 let mut data = vec![0; usize::try_from(len).unwrap()];
144 if this.machine.communicate {
145 // Fill the buffer using the host's rng.
146 getrandom::getrandom(&mut data)
147 .map_err(|err| err_unsup_format!("host getrandom failed: {}", err))?;
149 let rng = this.memory.extra.rng.get_mut();
150 rng.fill_bytes(&mut data);
153 this.memory.write_bytes(ptr, data.iter().copied())
156 /// Call a function: Push the stack frame and pass the arguments.
157 /// For now, arguments must be scalars (so that the caller does not have to know the layout).
160 f: ty::Instance<'tcx>,
161 args: &[Immediate<Tag>],
162 dest: Option<PlaceTy<'tcx, Tag>>,
163 stack_pop: StackPopCleanup,
164 ) -> InterpResult<'tcx> {
165 let this = self.eval_context_mut();
168 let mir = &*this.load_mir(f.def, None)?;
169 this.push_stack_frame(f, mir, dest, stack_pop)?;
171 // Initialize arguments.
172 let mut callee_args = this.frame().body.args_iter();
174 let callee_arg = this.local_place(
175 callee_args.next().expect("callee has fewer arguments than expected"),
177 this.write_immediate(*arg, callee_arg)?;
179 callee_args.next().expect_none("callee has more arguments than expected");
184 /// Visits the memory covered by `place`, sensitive to freezing: the 3rd parameter
185 /// will be true if this is frozen, false if this is in an `UnsafeCell`.
186 fn visit_freeze_sensitive(
188 place: MPlaceTy<'tcx, Tag>,
190 mut action: impl FnMut(Pointer<Tag>, Size, bool) -> InterpResult<'tcx>,
191 ) -> InterpResult<'tcx> {
192 let this = self.eval_context_ref();
193 trace!("visit_frozen(place={:?}, size={:?})", *place, size);
196 this.size_and_align_of_mplace(place)?
197 .map(|(size, _)| size)
198 .unwrap_or_else(|| place.layout.size)
200 // Store how far we proceeded into the place so far. Everything to the left of
201 // this offset has already been handled, in the sense that the frozen parts
202 // have had `action` called on them.
203 let mut end_ptr = place.ptr.assert_ptr();
204 // Called when we detected an `UnsafeCell` at the given offset and size.
205 // Calls `action` and advances `end_ptr`.
206 let mut unsafe_cell_action = |unsafe_cell_ptr: Scalar<Tag>, unsafe_cell_size: Size| {
207 let unsafe_cell_ptr = unsafe_cell_ptr.assert_ptr();
208 debug_assert_eq!(unsafe_cell_ptr.alloc_id, end_ptr.alloc_id);
209 debug_assert_eq!(unsafe_cell_ptr.tag, end_ptr.tag);
210 // We assume that we are given the fields in increasing offset order,
211 // and nothing else changes.
212 let unsafe_cell_offset = unsafe_cell_ptr.offset;
213 let end_offset = end_ptr.offset;
214 assert!(unsafe_cell_offset >= end_offset);
215 let frozen_size = unsafe_cell_offset - end_offset;
216 // Everything between the end_ptr and this `UnsafeCell` is frozen.
217 if frozen_size != Size::ZERO {
218 action(end_ptr, frozen_size, /*frozen*/ true)?;
220 // This `UnsafeCell` is NOT frozen.
221 if unsafe_cell_size != Size::ZERO {
222 action(unsafe_cell_ptr, unsafe_cell_size, /*frozen*/ false)?;
224 // Update end end_ptr.
225 end_ptr = unsafe_cell_ptr.wrapping_offset(unsafe_cell_size, this);
231 let mut visitor = UnsafeCellVisitor {
233 unsafe_cell_action: |place| {
234 trace!("unsafe_cell_action on {:?}", place.ptr);
235 // We need a size to go on.
236 let unsafe_cell_size = this
237 .size_and_align_of_mplace(place)?
238 .map(|(size, _)| size)
239 // for extern types, just cover what we can
240 .unwrap_or_else(|| place.layout.size);
241 // Now handle this `UnsafeCell`, unless it is empty.
242 if unsafe_cell_size != Size::ZERO {
243 unsafe_cell_action(place.ptr, unsafe_cell_size)
249 visitor.visit_value(place)?;
251 // The part between the end_ptr and the end of the place is also frozen.
252 // So pretend there is a 0-sized `UnsafeCell` at the end.
253 unsafe_cell_action(place.ptr.ptr_wrapping_offset(size, this), Size::ZERO)?;
257 /// Visiting the memory covered by a `MemPlace`, being aware of
258 /// whether we are inside an `UnsafeCell` or not.
259 struct UnsafeCellVisitor<'ecx, 'mir, 'tcx, F>
261 F: FnMut(MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx>,
263 ecx: &'ecx MiriEvalContext<'mir, 'tcx>,
264 unsafe_cell_action: F,
267 impl<'ecx, 'mir, 'tcx, F> ValueVisitor<'mir, 'tcx, Evaluator<'tcx>>
268 for UnsafeCellVisitor<'ecx, 'mir, 'tcx, F>
270 F: FnMut(MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx>,
272 type V = MPlaceTy<'tcx, Tag>;
275 fn ecx(&self) -> &MiriEvalContext<'mir, 'tcx> {
279 // Hook to detect `UnsafeCell`.
280 fn visit_value(&mut self, v: MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
281 trace!("UnsafeCellVisitor: {:?} {:?}", *v, v.layout.ty);
282 let is_unsafe_cell = match v.layout.ty.kind {
284 Some(adt.did) == self.ecx.tcx.lang_items().unsafe_cell_type(),
288 // We do not have to recurse further, this is an `UnsafeCell`.
289 (self.unsafe_cell_action)(v)
290 } else if self.ecx.type_is_freeze(v.layout.ty) {
291 // This is `Freeze`, there cannot be an `UnsafeCell`
294 // We want to not actually read from memory for this visit. So, before
295 // walking this value, we have to make sure it is not a
296 // `Variants::Multiple`.
297 match v.layout.variants {
298 Variants::Multiple { .. } => {
299 // A multi-variant enum, or generator, or so.
300 // Treat this like a union: without reading from memory,
301 // we cannot determine the variant we are in. Reading from
302 // memory would be subject to Stacked Borrows rules, leading
303 // to all sorts of "funny" recursion.
304 // We only end up here if the type is *not* freeze, so we just call the
305 // `UnsafeCell` action.
306 (self.unsafe_cell_action)(v)
308 Variants::Single { .. } => {
309 // Proceed further, try to find where exactly that `UnsafeCell`
317 // Make sure we visit aggregrates in increasing offset order.
320 place: MPlaceTy<'tcx, Tag>,
321 fields: impl Iterator<Item = InterpResult<'tcx, MPlaceTy<'tcx, Tag>>>,
322 ) -> InterpResult<'tcx> {
323 match place.layout.fields {
324 FieldsShape::Array { .. } => {
325 // For the array layout, we know the iterator will yield sorted elements so
326 // we can avoid the allocation.
327 self.walk_aggregate(place, fields)
329 FieldsShape::Arbitrary { .. } => {
330 // Gather the subplaces and sort them before visiting.
332 fields.collect::<InterpResult<'tcx, Vec<MPlaceTy<'tcx, Tag>>>>()?;
333 places.sort_by_key(|place| place.ptr.assert_ptr().offset);
334 self.walk_aggregate(place, places.into_iter().map(Ok))
336 FieldsShape::Union { .. } => {
338 bug!("a union is not an aggregate we should ever visit")
343 // We have to do *something* for unions.
344 fn visit_union(&mut self, v: MPlaceTy<'tcx, Tag>, fields: usize) -> InterpResult<'tcx> {
345 assert!(fields > 0); // we should never reach "pseudo-unions" with 0 fields, like primitives
347 // With unions, we fall back to whatever the type says, to hopefully be consistent
349 // FIXME: are we consistent, and is this really the behavior we want?
350 let frozen = self.ecx.type_is_freeze(v.layout.ty);
351 if frozen { Ok(()) } else { (self.unsafe_cell_action)(v) }
356 // Writes several `ImmTy`s contiguously into memory. This is useful when you have to pack
357 // different values into a struct.
358 fn write_packed_immediates(
360 place: MPlaceTy<'tcx, Tag>,
361 imms: &[ImmTy<'tcx, Tag>],
362 ) -> InterpResult<'tcx> {
363 let this = self.eval_context_mut();
365 let mut offset = Size::from_bytes(0);
368 this.write_immediate_to_mplace(
370 place.offset(offset, MemPlaceMeta::None, imm.layout, &*this.tcx)?,
372 offset += imm.layout.size;
377 /// Helper function used inside the shims of foreign functions to check that isolation is
378 /// disabled. It returns an error using the `name` of the foreign function if this is not the
380 fn check_no_isolation(&self, name: &str) -> InterpResult<'tcx> {
381 if !self.eval_context_ref().machine.communicate {
382 throw_machine_stop!(TerminationInfo::UnsupportedInIsolation(format!(
383 "`{}` not available when isolation is enabled",
389 /// Helper function used inside the shims of foreign functions to assert that the target OS
390 /// is `target_os`. It panics showing a message with the `name` of the foreign function
391 /// if this is not the case.
392 fn assert_target_os(&self, target_os: &str, name: &str) {
394 self.eval_context_ref().tcx.sess.target.target.target_os,
396 "`{}` is only available on the `{}` target OS",
402 /// Sets the last error variable.
403 fn set_last_error(&mut self, scalar: Scalar<Tag>) -> InterpResult<'tcx> {
404 let this = self.eval_context_mut();
405 let errno_place = this.machine.last_error.unwrap();
406 this.write_scalar(scalar, errno_place.into())
409 /// Gets the last error variable.
410 fn get_last_error(&self) -> InterpResult<'tcx, Scalar<Tag>> {
411 let this = self.eval_context_ref();
412 let errno_place = this.machine.last_error.unwrap();
413 this.read_scalar(errno_place.into())?.not_undef()
416 /// Sets the last OS error using a `std::io::Error`. This function tries to produce the most
417 /// similar OS error from the `std::io::ErrorKind` and sets it as the last OS error.
418 fn set_last_error_from_io_error(&mut self, e: std::io::Error) -> InterpResult<'tcx> {
419 use std::io::ErrorKind::*;
420 let this = self.eval_context_mut();
421 let target = &this.tcx.sess.target.target;
422 let target_os = &target.target_os;
423 let last_error = if target.options.target_family == Some("unix".to_owned()) {
424 this.eval_libc(match e.kind() {
425 ConnectionRefused => "ECONNREFUSED",
426 ConnectionReset => "ECONNRESET",
427 PermissionDenied => "EPERM",
428 BrokenPipe => "EPIPE",
429 NotConnected => "ENOTCONN",
430 ConnectionAborted => "ECONNABORTED",
431 AddrNotAvailable => "EADDRNOTAVAIL",
432 AddrInUse => "EADDRINUSE",
433 NotFound => "ENOENT",
434 Interrupted => "EINTR",
435 InvalidInput => "EINVAL",
436 TimedOut => "ETIMEDOUT",
437 AlreadyExists => "EEXIST",
438 WouldBlock => "EWOULDBLOCK",
440 throw_unsup_format!("io error {} cannot be transformed into a raw os error", e)
443 } else if target_os == "windows" {
444 // FIXME: we have to finish implementing the Windows equivalent of this.
445 this.eval_windows("c", match e.kind() {
446 NotFound => "ERROR_FILE_NOT_FOUND",
447 _ => throw_unsup_format!("io error {} cannot be transformed into a raw os error", e)
450 throw_unsup_format!("setting the last OS error from an io::Error is unsupported for {}.", target_os)
452 this.set_last_error(last_error)
455 /// Helper function that consumes an `std::io::Result<T>` and returns an
456 /// `InterpResult<'tcx,T>::Ok` instead. In case the result is an error, this function returns
457 /// `Ok(-1)` and sets the last OS error accordingly.
459 /// This function uses `T: From<i32>` instead of `i32` directly because some IO related
460 /// functions return different integer types (like `read`, that returns an `i64`).
461 fn try_unwrap_io_result<T: From<i32>>(
463 result: std::io::Result<T>,
464 ) -> InterpResult<'tcx, T> {
468 self.eval_context_mut().set_last_error_from_io_error(e)?;
475 pub fn immty_from_int_checked<'tcx>(
476 int: impl Into<i128>,
477 layout: TyAndLayout<'tcx>,
478 ) -> InterpResult<'tcx, ImmTy<'tcx, Tag>> {
479 let int = int.into();
480 Ok(ImmTy::try_from_int(int, layout).ok_or_else(|| {
481 err_unsup_format!("signed value {:#x} does not fit in {} bits", int, layout.size.bits())
485 pub fn immty_from_uint_checked<'tcx>(
486 int: impl Into<u128>,
487 layout: TyAndLayout<'tcx>,
488 ) -> InterpResult<'tcx, ImmTy<'tcx, Tag>> {
489 let int = int.into();
490 Ok(ImmTy::try_from_uint(int, layout).ok_or_else(|| {
491 err_unsup_format!("unsigned value {:#x} does not fit in {} bits", int, layout.size.bits())