1 use std::convert::TryFrom;
7 use rustc_middle::ty::{
9 layout::{self, LayoutOf, Size, TyAndLayout},
12 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
13 use rustc_span::source_map::DUMMY_SP;
19 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
21 /// Gets an instance for a path.
22 fn try_resolve_did<'mir, 'tcx>(tcx: TyCtxt<'tcx>, path: &[&str]) -> Option<DefId> {
25 .find(|&&krate| tcx.original_crate_name(krate).as_str() == path[0])
27 let krate = DefId { krate: *krate, index: CRATE_DEF_INDEX };
28 let mut items = tcx.item_children(krate);
29 let mut path_it = path.iter().skip(1).peekable();
31 while let Some(segment) = path_it.next() {
32 for item in mem::replace(&mut items, Default::default()).iter() {
33 if item.ident.name.as_str() == *segment {
34 if path_it.peek().is_none() {
35 return Some(item.res.def_id());
38 items = tcx.item_children(item.res.def_id());
47 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
48 /// Gets an instance for a path.
49 fn resolve_path(&self, path: &[&str]) -> ty::Instance<'tcx> {
50 let did = try_resolve_did(self.eval_context_ref().tcx.tcx, path)
51 .unwrap_or_else(|| panic!("failed to find required Rust item: {:?}", path));
52 ty::Instance::mono(self.eval_context_ref().tcx.tcx, did)
55 /// Evaluates the scalar at the specified path. Returns Some(val)
56 /// if the path could be resolved, and None otherwise
60 ) -> InterpResult<'tcx, ScalarMaybeUndef<Tag>> {
61 let this = self.eval_context_mut();
62 let instance = this.resolve_path(path);
63 let cid = GlobalId { instance, promoted: None };
64 let const_val = this.const_eval_raw(cid)?;
65 let const_val = this.read_scalar(const_val.into())?;
69 /// Helper function to get a `libc` constant as a `Scalar`.
70 fn eval_libc(&mut self, name: &str) -> InterpResult<'tcx, Scalar<Tag>> {
71 self.eval_context_mut()
72 .eval_path_scalar(&["libc", name])?
76 /// Helper function to get a `libc` constant as an `i32`.
77 fn eval_libc_i32(&mut self, name: &str) -> InterpResult<'tcx, i32> {
78 // TODO: Cache the result.
79 self.eval_libc(name)?.to_i32()
82 /// Helper function to get a `windows` constant as a `Scalar`.
83 fn eval_windows(&mut self, module: &str, name: &str) -> InterpResult<'tcx, Scalar<Tag>> {
84 self.eval_context_mut()
85 .eval_path_scalar(&["std", "sys", "windows", module, name])?
89 /// Helper function to get a `windows` constant as an `u64`.
90 fn eval_windows_u64(&mut self, module: &str, name: &str) -> InterpResult<'tcx, u64> {
91 // TODO: Cache the result.
92 self.eval_windows(module, name)?.to_u64()
95 /// Helper function to get the `TyAndLayout` of a `libc` type
96 fn libc_ty_layout(&mut self, name: &str) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
97 let this = self.eval_context_mut();
98 let ty = this.resolve_path(&["libc", name]).monomorphic_ty(*this.tcx);
102 /// Helper function to get the `TyAndLayout` of a `windows` type
103 fn windows_ty_layout(&mut self, name: &str) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
104 let this = self.eval_context_mut();
105 let ty = this.resolve_path(&["std", "sys", "windows", "c", name]).monomorphic_ty(*this.tcx);
109 /// Write a 0 of the appropriate size to `dest`.
110 fn write_null(&mut self, dest: PlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
111 self.eval_context_mut().write_scalar(Scalar::from_int(0, dest.layout.size), dest)
114 /// Test if this immediate equals 0.
115 fn is_null(&self, val: Scalar<Tag>) -> InterpResult<'tcx, bool> {
116 let this = self.eval_context_ref();
117 let null = Scalar::null_ptr(this);
118 this.ptr_eq(val, null)
121 /// Turn a Scalar into an Option<NonNullScalar>
122 fn test_null(&self, val: Scalar<Tag>) -> InterpResult<'tcx, Option<Scalar<Tag>>> {
123 let this = self.eval_context_ref();
124 Ok(if this.is_null(val)? { None } else { Some(val) })
127 /// Get the `Place` for a local
128 fn local_place(&mut self, local: mir::Local) -> InterpResult<'tcx, PlaceTy<'tcx, Tag>> {
129 let this = self.eval_context_mut();
130 let place = mir::Place { local: local, projection: List::empty() };
131 this.eval_place(&place)
134 /// Generate some random bytes, and write them to `dest`.
135 fn gen_random(&mut self, ptr: Scalar<Tag>, len: u64) -> InterpResult<'tcx> {
136 // Some programs pass in a null pointer and a length of 0
137 // to their platform's random-generation function (e.g. getrandom())
138 // on Linux. For compatibility with these programs, we don't perform
139 // any additional checks - it's okay if the pointer is invalid,
140 // since we wouldn't actually be writing to it.
144 let this = self.eval_context_mut();
146 let mut data = vec![0; usize::try_from(len).unwrap()];
148 if this.machine.communicate {
149 // Fill the buffer using the host's rng.
150 getrandom::getrandom(&mut data)
151 .map_err(|err| err_unsup_format!("host getrandom failed: {}", err))?;
153 let rng = this.memory.extra.rng.get_mut();
154 rng.fill_bytes(&mut data);
157 this.memory.write_bytes(ptr, data.iter().copied())
160 /// Call a function: Push the stack frame and pass the arguments.
161 /// For now, arguments must be scalars (so that the caller does not have to know the layout).
164 f: ty::Instance<'tcx>,
165 args: &[Immediate<Tag>],
166 dest: Option<PlaceTy<'tcx, Tag>>,
167 stack_pop: StackPopCleanup,
168 ) -> InterpResult<'tcx> {
169 let this = self.eval_context_mut();
172 let mir = &*this.load_mir(f.def, None)?;
176 .and_then(Frame::current_source_info)
178 .unwrap_or(DUMMY_SP);
179 this.push_stack_frame(f, span, mir, dest, stack_pop)?;
181 // Initialize arguments.
182 let mut callee_args = this.frame().body.args_iter();
184 let callee_arg = this.local_place(
185 callee_args.next().expect("callee has fewer arguments than expected"),
187 this.write_immediate(*arg, callee_arg)?;
189 callee_args.next().expect_none("callee has more arguments than expected");
194 /// Visits the memory covered by `place`, sensitive to freezing: the 3rd parameter
195 /// will be true if this is frozen, false if this is in an `UnsafeCell`.
196 fn visit_freeze_sensitive(
198 place: MPlaceTy<'tcx, Tag>,
200 mut action: impl FnMut(Pointer<Tag>, Size, bool) -> InterpResult<'tcx>,
201 ) -> InterpResult<'tcx> {
202 let this = self.eval_context_ref();
203 trace!("visit_frozen(place={:?}, size={:?})", *place, size);
206 this.size_and_align_of_mplace(place)?
207 .map(|(size, _)| size)
208 .unwrap_or_else(|| place.layout.size)
210 // Store how far we proceeded into the place so far. Everything to the left of
211 // this offset has already been handled, in the sense that the frozen parts
212 // have had `action` called on them.
213 let mut end_ptr = place.ptr.assert_ptr();
214 // Called when we detected an `UnsafeCell` at the given offset and size.
215 // Calls `action` and advances `end_ptr`.
216 let mut unsafe_cell_action = |unsafe_cell_ptr: Scalar<Tag>, unsafe_cell_size: Size| {
217 let unsafe_cell_ptr = unsafe_cell_ptr.assert_ptr();
218 debug_assert_eq!(unsafe_cell_ptr.alloc_id, end_ptr.alloc_id);
219 debug_assert_eq!(unsafe_cell_ptr.tag, end_ptr.tag);
220 // We assume that we are given the fields in increasing offset order,
221 // and nothing else changes.
222 let unsafe_cell_offset = unsafe_cell_ptr.offset;
223 let end_offset = end_ptr.offset;
224 assert!(unsafe_cell_offset >= end_offset);
225 let frozen_size = unsafe_cell_offset - end_offset;
226 // Everything between the end_ptr and this `UnsafeCell` is frozen.
227 if frozen_size != Size::ZERO {
228 action(end_ptr, frozen_size, /*frozen*/ true)?;
230 // This `UnsafeCell` is NOT frozen.
231 if unsafe_cell_size != Size::ZERO {
232 action(unsafe_cell_ptr, unsafe_cell_size, /*frozen*/ false)?;
234 // Update end end_ptr.
235 end_ptr = unsafe_cell_ptr.wrapping_offset(unsafe_cell_size, this);
241 let mut visitor = UnsafeCellVisitor {
243 unsafe_cell_action: |place| {
244 trace!("unsafe_cell_action on {:?}", place.ptr);
245 // We need a size to go on.
246 let unsafe_cell_size = this
247 .size_and_align_of_mplace(place)?
248 .map(|(size, _)| size)
249 // for extern types, just cover what we can
250 .unwrap_or_else(|| place.layout.size);
251 // Now handle this `UnsafeCell`, unless it is empty.
252 if unsafe_cell_size != Size::ZERO {
253 unsafe_cell_action(place.ptr, unsafe_cell_size)
259 visitor.visit_value(place)?;
261 // The part between the end_ptr and the end of the place is also frozen.
262 // So pretend there is a 0-sized `UnsafeCell` at the end.
263 unsafe_cell_action(place.ptr.ptr_wrapping_offset(size, this), Size::ZERO)?;
267 /// Visiting the memory covered by a `MemPlace`, being aware of
268 /// whether we are inside an `UnsafeCell` or not.
269 struct UnsafeCellVisitor<'ecx, 'mir, 'tcx, F>
271 F: FnMut(MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx>,
273 ecx: &'ecx MiriEvalContext<'mir, 'tcx>,
274 unsafe_cell_action: F,
277 impl<'ecx, 'mir, 'tcx, F> ValueVisitor<'mir, 'tcx, Evaluator<'tcx>>
278 for UnsafeCellVisitor<'ecx, 'mir, 'tcx, F>
280 F: FnMut(MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx>,
282 type V = MPlaceTy<'tcx, Tag>;
285 fn ecx(&self) -> &MiriEvalContext<'mir, 'tcx> {
289 // Hook to detect `UnsafeCell`.
290 fn visit_value(&mut self, v: MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
291 trace!("UnsafeCellVisitor: {:?} {:?}", *v, v.layout.ty);
292 let is_unsafe_cell = match v.layout.ty.kind {
294 Some(adt.did) == self.ecx.tcx.lang_items().unsafe_cell_type(),
298 // We do not have to recurse further, this is an `UnsafeCell`.
299 (self.unsafe_cell_action)(v)
300 } else if self.ecx.type_is_freeze(v.layout.ty) {
301 // This is `Freeze`, there cannot be an `UnsafeCell`
304 // We want to not actually read from memory for this visit. So, before
305 // walking this value, we have to make sure it is not a
306 // `Variants::Multiple`.
307 match v.layout.variants {
308 layout::Variants::Multiple { .. } => {
309 // A multi-variant enum, or generator, or so.
310 // Treat this like a union: without reading from memory,
311 // we cannot determine the variant we are in. Reading from
312 // memory would be subject to Stacked Borrows rules, leading
313 // to all sorts of "funny" recursion.
314 // We only end up here if the type is *not* freeze, so we just call the
315 // `UnsafeCell` action.
316 (self.unsafe_cell_action)(v)
318 layout::Variants::Single { .. } => {
319 // Proceed further, try to find where exactly that `UnsafeCell`
327 // Make sure we visit aggregrates in increasing offset order.
330 place: MPlaceTy<'tcx, Tag>,
331 fields: impl Iterator<Item = InterpResult<'tcx, MPlaceTy<'tcx, Tag>>>,
332 ) -> InterpResult<'tcx> {
333 match place.layout.fields {
334 layout::FieldPlacement::Array { .. } => {
335 // For the array layout, we know the iterator will yield sorted elements so
336 // we can avoid the allocation.
337 self.walk_aggregate(place, fields)
339 layout::FieldPlacement::Arbitrary { .. } => {
340 // Gather the subplaces and sort them before visiting.
342 fields.collect::<InterpResult<'tcx, Vec<MPlaceTy<'tcx, Tag>>>>()?;
343 places.sort_by_key(|place| place.ptr.assert_ptr().offset);
344 self.walk_aggregate(place, places.into_iter().map(Ok))
346 layout::FieldPlacement::Union { .. } => {
348 bug!("a union is not an aggregate we should ever visit")
353 // We have to do *something* for unions.
354 fn visit_union(&mut self, v: MPlaceTy<'tcx, Tag>, fields: usize) -> InterpResult<'tcx> {
355 assert!(fields > 0); // we should never reach "pseudo-unions" with 0 fields, like primitives
357 // With unions, we fall back to whatever the type says, to hopefully be consistent
359 // FIXME: are we consistent, and is this really the behavior we want?
360 let frozen = self.ecx.type_is_freeze(v.layout.ty);
361 if frozen { Ok(()) } else { (self.unsafe_cell_action)(v) }
366 // Writes several `ImmTy`s contiguously into memory. This is useful when you have to pack
367 // different values into a struct.
368 fn write_packed_immediates(
370 place: MPlaceTy<'tcx, Tag>,
371 imms: &[ImmTy<'tcx, Tag>],
372 ) -> InterpResult<'tcx> {
373 let this = self.eval_context_mut();
375 let mut offset = Size::from_bytes(0);
378 this.write_immediate_to_mplace(
380 place.offset(offset, MemPlaceMeta::None, imm.layout, &*this.tcx)?,
382 offset += imm.layout.size;
387 /// Helper function used inside the shims of foreign functions to check that isolation is
388 /// disabled. It returns an error using the `name` of the foreign function if this is not the
390 fn check_no_isolation(&self, name: &str) -> InterpResult<'tcx> {
391 if !self.eval_context_ref().machine.communicate {
392 throw_machine_stop!(TerminationInfo::UnsupportedInIsolation(format!(
393 "`{}` not available when isolation is enabled",
399 /// Helper function used inside the shims of foreign functions to assert that the target OS
400 /// is `target_os`. It panics showing a message with the `name` of the foreign function
401 /// if this is not the case.
402 fn assert_target_os(&self, target_os: &str, name: &str) {
404 self.eval_context_ref().tcx.sess.target.target.target_os,
406 "`{}` is only available on the `{}` target OS",
412 /// Sets the last error variable.
413 fn set_last_error(&mut self, scalar: Scalar<Tag>) -> InterpResult<'tcx> {
414 let this = self.eval_context_mut();
415 let errno_place = this.machine.last_error.unwrap();
416 this.write_scalar(scalar, errno_place.into())
419 /// Gets the last error variable.
420 fn get_last_error(&self) -> InterpResult<'tcx, Scalar<Tag>> {
421 let this = self.eval_context_ref();
422 let errno_place = this.machine.last_error.unwrap();
423 this.read_scalar(errno_place.into())?.not_undef()
426 /// Sets the last OS error using a `std::io::Error`. This function tries to produce the most
427 /// similar OS error from the `std::io::ErrorKind` and sets it as the last OS error.
428 fn set_last_error_from_io_error(&mut self, e: std::io::Error) -> InterpResult<'tcx> {
429 use std::io::ErrorKind::*;
430 let this = self.eval_context_mut();
431 let target = &this.tcx.sess.target.target;
432 let target_os = &target.target_os;
433 let last_error = if target.options.target_family == Some("unix".to_owned()) {
434 this.eval_libc(match e.kind() {
435 ConnectionRefused => "ECONNREFUSED",
436 ConnectionReset => "ECONNRESET",
437 PermissionDenied => "EPERM",
438 BrokenPipe => "EPIPE",
439 NotConnected => "ENOTCONN",
440 ConnectionAborted => "ECONNABORTED",
441 AddrNotAvailable => "EADDRNOTAVAIL",
442 AddrInUse => "EADDRINUSE",
443 NotFound => "ENOENT",
444 Interrupted => "EINTR",
445 InvalidInput => "EINVAL",
446 TimedOut => "ETIMEDOUT",
447 AlreadyExists => "EEXIST",
448 WouldBlock => "EWOULDBLOCK",
450 throw_unsup_format!("io error {} cannot be transformed into a raw os error", e)
453 } else if target_os == "windows" {
454 // FIXME: we have to finish implementing the Windows equivalent of this.
455 this.eval_windows("c", match e.kind() {
456 NotFound => "ERROR_FILE_NOT_FOUND",
457 _ => throw_unsup_format!("io error {} cannot be transformed into a raw os error", e)
460 throw_unsup_format!("setting the last OS error from an io::Error is unsupported for {}.", target_os)
462 this.set_last_error(last_error)
465 /// Helper function that consumes an `std::io::Result<T>` and returns an
466 /// `InterpResult<'tcx,T>::Ok` instead. In case the result is an error, this function returns
467 /// `Ok(-1)` and sets the last OS error accordingly.
469 /// This function uses `T: From<i32>` instead of `i32` directly because some IO related
470 /// functions return different integer types (like `read`, that returns an `i64`).
471 fn try_unwrap_io_result<T: From<i32>>(
473 result: std::io::Result<T>,
474 ) -> InterpResult<'tcx, T> {
478 self.eval_context_mut().set_last_error_from_io_error(e)?;
485 pub fn immty_from_int_checked<'tcx>(
486 int: impl Into<i128>,
487 layout: TyAndLayout<'tcx>,
488 ) -> InterpResult<'tcx, ImmTy<'tcx, Tag>> {
489 let int = int.into();
490 Ok(ImmTy::try_from_int(int, layout).ok_or_else(|| {
491 err_unsup_format!("signed value {:#x} does not fit in {} bits", int, layout.size.bits())
495 pub fn immty_from_uint_checked<'tcx>(
496 int: impl Into<u128>,
497 layout: TyAndLayout<'tcx>,
498 ) -> InterpResult<'tcx, ImmTy<'tcx, Tag>> {
499 let int = int.into();
500 Ok(ImmTy::try_from_uint(int, layout).ok_or_else(|| {
501 err_unsup_format!("unsigned value {:#x} does not fit in {} bits", int, layout.size.bits())