3 use std::convert::TryFrom;
8 layout::{self, LayoutOf, Size, TyLayout},
11 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
12 use rustc_span::source_map::DUMMY_SP;
18 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
20 /// Gets an instance for a path.
21 fn resolve_did<'mir, 'tcx>(tcx: TyCtxt<'tcx>, path: &[&str]) -> InterpResult<'tcx, DefId> {
24 .find(|&&krate| tcx.original_crate_name(krate).as_str() == path[0])
26 let krate = DefId { krate: *krate, index: CRATE_DEF_INDEX };
27 let mut items = tcx.item_children(krate);
28 let mut path_it = path.iter().skip(1).peekable();
30 while let Some(segment) = path_it.next() {
31 for item in mem::replace(&mut items, Default::default()).iter() {
32 if item.ident.name.as_str() == *segment {
33 if path_it.peek().is_none() {
34 return Some(item.res.def_id());
37 items = tcx.item_children(item.res.def_id());
45 let path = path.iter().map(|&s| s.to_owned()).collect();
46 err_unsup!(PathNotFound(path)).into()
50 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
51 /// Gets an instance for a path.
52 fn resolve_path(&self, path: &[&str]) -> InterpResult<'tcx, ty::Instance<'tcx>> {
53 Ok(ty::Instance::mono(
54 self.eval_context_ref().tcx.tcx,
55 resolve_did(self.eval_context_ref().tcx.tcx, path)?,
59 /// Write a 0 of the appropriate size to `dest`.
60 fn write_null(&mut self, dest: PlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
61 self.eval_context_mut().write_scalar(Scalar::from_int(0, dest.layout.size), dest)
64 /// Test if this immediate equals 0.
65 fn is_null(&self, val: Scalar<Tag>) -> InterpResult<'tcx, bool> {
66 let this = self.eval_context_ref();
67 let null = Scalar::from_int(0, this.memory.pointer_size());
68 this.ptr_eq(val, null)
71 /// Turn a Scalar into an Option<NonNullScalar>
72 fn test_null(&self, val: Scalar<Tag>) -> InterpResult<'tcx, Option<Scalar<Tag>>> {
73 let this = self.eval_context_ref();
74 Ok(if this.is_null(val)? { None } else { Some(val) })
77 /// Get the `Place` for a local
78 fn local_place(&mut self, local: mir::Local) -> InterpResult<'tcx, PlaceTy<'tcx, Tag>> {
79 let this = self.eval_context_mut();
80 let place = mir::Place { local: local, projection: List::empty() };
81 this.eval_place(&place)
84 /// Generate some random bytes, and write them to `dest`.
85 fn gen_random(&mut self, ptr: Scalar<Tag>, len: u64) -> InterpResult<'tcx> {
86 // Some programs pass in a null pointer and a length of 0
87 // to their platform's random-generation function (e.g. getrandom())
88 // on Linux. For compatibility with these programs, we don't perform
89 // any additional checks - it's okay if the pointer is invalid,
90 // since we wouldn't actually be writing to it.
94 let this = self.eval_context_mut();
96 let mut data = vec![0; usize::try_from(len).unwrap()];
98 if this.machine.communicate {
99 // Fill the buffer using the host's rng.
100 getrandom::getrandom(&mut data)
101 .map_err(|err| err_unsup_format!("getrandom failed: {}", err))?;
103 let rng = this.memory.extra.rng.get_mut();
104 rng.fill_bytes(&mut data);
107 this.memory.write_bytes(ptr, data.iter().copied())
110 /// Call a function: Push the stack frame and pass the arguments.
111 /// For now, arguments must be scalars (so that the caller does not have to know the layout).
114 f: ty::Instance<'tcx>,
115 args: &[Immediate<Tag>],
116 dest: Option<PlaceTy<'tcx, Tag>>,
117 stack_pop: StackPopCleanup,
118 ) -> InterpResult<'tcx> {
119 let this = self.eval_context_mut();
122 let mir = &*this.load_mir(f.def, None)?;
126 .and_then(Frame::current_source_info)
128 .unwrap_or(DUMMY_SP);
129 this.push_stack_frame(f, span, mir, dest, stack_pop)?;
131 // Initialize arguments.
132 let mut callee_args = this.frame().body.args_iter();
134 let callee_arg = this.local_place(
135 callee_args.next().expect("callee has fewer arguments than expected"),
137 this.write_immediate(*arg, callee_arg)?;
139 callee_args.next().expect_none("callee has more arguments than expected");
144 /// Visits the memory covered by `place`, sensitive to freezing: the 3rd parameter
145 /// will be true if this is frozen, false if this is in an `UnsafeCell`.
146 fn visit_freeze_sensitive(
148 place: MPlaceTy<'tcx, Tag>,
150 mut action: impl FnMut(Pointer<Tag>, Size, bool) -> InterpResult<'tcx>,
151 ) -> InterpResult<'tcx> {
152 let this = self.eval_context_ref();
153 trace!("visit_frozen(place={:?}, size={:?})", *place, size);
156 this.size_and_align_of_mplace(place)?
157 .map(|(size, _)| size)
158 .unwrap_or_else(|| place.layout.size)
160 // Store how far we proceeded into the place so far. Everything to the left of
161 // this offset has already been handled, in the sense that the frozen parts
162 // have had `action` called on them.
163 let mut end_ptr = place.ptr.assert_ptr();
164 // Called when we detected an `UnsafeCell` at the given offset and size.
165 // Calls `action` and advances `end_ptr`.
166 let mut unsafe_cell_action = |unsafe_cell_ptr: Scalar<Tag>, unsafe_cell_size: Size| {
167 let unsafe_cell_ptr = unsafe_cell_ptr.assert_ptr();
168 debug_assert_eq!(unsafe_cell_ptr.alloc_id, end_ptr.alloc_id);
169 debug_assert_eq!(unsafe_cell_ptr.tag, end_ptr.tag);
170 // We assume that we are given the fields in increasing offset order,
171 // and nothing else changes.
172 let unsafe_cell_offset = unsafe_cell_ptr.offset;
173 let end_offset = end_ptr.offset;
174 assert!(unsafe_cell_offset >= end_offset);
175 let frozen_size = unsafe_cell_offset - end_offset;
176 // Everything between the end_ptr and this `UnsafeCell` is frozen.
177 if frozen_size != Size::ZERO {
178 action(end_ptr, frozen_size, /*frozen*/ true)?;
180 // This `UnsafeCell` is NOT frozen.
181 if unsafe_cell_size != Size::ZERO {
182 action(unsafe_cell_ptr, unsafe_cell_size, /*frozen*/ false)?;
184 // Update end end_ptr.
185 end_ptr = unsafe_cell_ptr.wrapping_offset(unsafe_cell_size, this);
191 let mut visitor = UnsafeCellVisitor {
193 unsafe_cell_action: |place| {
194 trace!("unsafe_cell_action on {:?}", place.ptr);
195 // We need a size to go on.
196 let unsafe_cell_size = this
197 .size_and_align_of_mplace(place)?
198 .map(|(size, _)| size)
199 // for extern types, just cover what we can
200 .unwrap_or_else(|| place.layout.size);
201 // Now handle this `UnsafeCell`, unless it is empty.
202 if unsafe_cell_size != Size::ZERO {
203 unsafe_cell_action(place.ptr, unsafe_cell_size)
209 visitor.visit_value(place)?;
211 // The part between the end_ptr and the end of the place is also frozen.
212 // So pretend there is a 0-sized `UnsafeCell` at the end.
213 unsafe_cell_action(place.ptr.ptr_wrapping_offset(size, this), Size::ZERO)?;
217 /// Visiting the memory covered by a `MemPlace`, being aware of
218 /// whether we are inside an `UnsafeCell` or not.
219 struct UnsafeCellVisitor<'ecx, 'mir, 'tcx, F>
221 F: FnMut(MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx>,
223 ecx: &'ecx MiriEvalContext<'mir, 'tcx>,
224 unsafe_cell_action: F,
227 impl<'ecx, 'mir, 'tcx, F> ValueVisitor<'mir, 'tcx, Evaluator<'tcx>>
228 for UnsafeCellVisitor<'ecx, 'mir, 'tcx, F>
230 F: FnMut(MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx>,
232 type V = MPlaceTy<'tcx, Tag>;
235 fn ecx(&self) -> &MiriEvalContext<'mir, 'tcx> {
239 // Hook to detect `UnsafeCell`.
240 fn visit_value(&mut self, v: MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
241 trace!("UnsafeCellVisitor: {:?} {:?}", *v, v.layout.ty);
242 let is_unsafe_cell = match v.layout.ty.kind {
244 Some(adt.did) == self.ecx.tcx.lang_items().unsafe_cell_type(),
248 // We do not have to recurse further, this is an `UnsafeCell`.
249 (self.unsafe_cell_action)(v)
250 } else if self.ecx.type_is_freeze(v.layout.ty) {
251 // This is `Freeze`, there cannot be an `UnsafeCell`
254 // We want to not actually read from memory for this visit. So, before
255 // walking this value, we have to make sure it is not a
256 // `Variants::Multiple`.
257 match v.layout.variants {
258 layout::Variants::Multiple { .. } => {
259 // A multi-variant enum, or generator, or so.
260 // Treat this like a union: without reading from memory,
261 // we cannot determine the variant we are in. Reading from
262 // memory would be subject to Stacked Borrows rules, leading
263 // to all sorts of "funny" recursion.
264 // We only end up here if the type is *not* freeze, so we just call the
265 // `UnsafeCell` action.
266 (self.unsafe_cell_action)(v)
268 layout::Variants::Single { .. } => {
269 // Proceed further, try to find where exactly that `UnsafeCell`
277 // Make sure we visit aggregrates in increasing offset order.
280 place: MPlaceTy<'tcx, Tag>,
281 fields: impl Iterator<Item = InterpResult<'tcx, MPlaceTy<'tcx, Tag>>>,
282 ) -> InterpResult<'tcx> {
283 match place.layout.fields {
284 layout::FieldPlacement::Array { .. } => {
285 // For the array layout, we know the iterator will yield sorted elements so
286 // we can avoid the allocation.
287 self.walk_aggregate(place, fields)
289 layout::FieldPlacement::Arbitrary { .. } => {
290 // Gather the subplaces and sort them before visiting.
292 fields.collect::<InterpResult<'tcx, Vec<MPlaceTy<'tcx, Tag>>>>()?;
293 places.sort_by_key(|place| place.ptr.assert_ptr().offset);
294 self.walk_aggregate(place, places.into_iter().map(Ok))
296 layout::FieldPlacement::Union { .. } => {
298 bug!("a union is not an aggregate we should ever visit")
303 // We have to do *something* for unions.
304 fn visit_union(&mut self, v: MPlaceTy<'tcx, Tag>, fields: usize) -> InterpResult<'tcx> {
305 assert!(fields > 0); // we should never reach "pseudo-unions" with 0 fields, like primitives
307 // With unions, we fall back to whatever the type says, to hopefully be consistent
309 // FIXME: are we consistent, and is this really the behavior we want?
310 let frozen = self.ecx.type_is_freeze(v.layout.ty);
311 if frozen { Ok(()) } else { (self.unsafe_cell_action)(v) }
316 /// Helper function to get a `libc` constant as a `Scalar`.
317 fn eval_libc(&mut self, name: &str) -> InterpResult<'tcx, Scalar<Tag>> {
318 self.eval_context_mut()
319 .eval_path_scalar(&["libc", name])?
320 .ok_or_else(|| err_unsup_format!("Path libc::{} cannot be resolved.", name))?
324 /// Helper function to get a `libc` constant as an `i32`.
325 fn eval_libc_i32(&mut self, name: &str) -> InterpResult<'tcx, i32> {
326 self.eval_libc(name)?.to_i32()
329 /// Helper function to get the `TyLayout` of a `libc` type
330 fn libc_ty_layout(&mut self, name: &str) -> InterpResult<'tcx, TyLayout<'tcx>> {
331 let this = self.eval_context_mut();
332 let ty = this.resolve_path(&["libc", name])?.monomorphic_ty(*this.tcx);
336 // Writes several `ImmTy`s contiguosly into memory. This is useful when you have to pack
337 // different values into a struct.
338 fn write_packed_immediates(
340 place: MPlaceTy<'tcx, Tag>,
341 imms: &[ImmTy<'tcx, Tag>],
342 ) -> InterpResult<'tcx> {
343 let this = self.eval_context_mut();
345 let mut offset = Size::from_bytes(0);
348 this.write_immediate_to_mplace(
350 place.offset(offset, MemPlaceMeta::None, imm.layout, &*this.tcx)?,
352 offset += imm.layout.size;
357 /// Helper function used inside the shims of foreign functions to check that isolation is
358 /// disabled. It returns an error using the `name` of the foreign function if this is not the
360 fn check_no_isolation(&self, name: &str) -> InterpResult<'tcx> {
361 if !self.eval_context_ref().machine.communicate {
363 "`{}` not available when isolation is enabled. Pass the flag `-Zmiri-disable-isolation` to disable it.",
369 /// Helper function used inside the shims of foreign functions to assert that the target
370 /// platform is `platform`. It panics showing a message with the `name` of the foreign function
371 /// if this is not the case.
372 fn assert_platform(&self, platform: &str, name: &str) {
374 self.eval_context_ref().tcx.sess.target.target.target_os,
376 "`{}` is only available on the `{}` platform",
382 /// Sets the last error variable.
383 fn set_last_error(&mut self, scalar: Scalar<Tag>) -> InterpResult<'tcx> {
384 let this = self.eval_context_mut();
385 let errno_place = this.machine.last_error.unwrap();
386 this.write_scalar(scalar, errno_place.into())
389 /// Gets the last error variable.
390 fn get_last_error(&self) -> InterpResult<'tcx, Scalar<Tag>> {
391 let this = self.eval_context_ref();
392 let errno_place = this.machine.last_error.unwrap();
393 this.read_scalar(errno_place.into())?.not_undef()
396 /// Sets the last OS error using a `std::io::Error`. This function tries to produce the most
397 /// similar OS error from the `std::io::ErrorKind` and sets it as the last OS error.
398 fn set_last_error_from_io_error(&mut self, e: std::io::Error) -> InterpResult<'tcx> {
399 use std::io::ErrorKind::*;
400 let this = self.eval_context_mut();
401 let target = &this.tcx.tcx.sess.target.target;
402 let last_error = if target.options.target_family == Some("unix".to_owned()) {
403 this.eval_libc(match e.kind() {
404 ConnectionRefused => "ECONNREFUSED",
405 ConnectionReset => "ECONNRESET",
406 PermissionDenied => "EPERM",
407 BrokenPipe => "EPIPE",
408 NotConnected => "ENOTCONN",
409 ConnectionAborted => "ECONNABORTED",
410 AddrNotAvailable => "EADDRNOTAVAIL",
411 AddrInUse => "EADDRINUSE",
412 NotFound => "ENOENT",
413 Interrupted => "EINTR",
414 InvalidInput => "EINVAL",
415 TimedOut => "ETIMEDOUT",
416 AlreadyExists => "EEXIST",
417 WouldBlock => "EWOULDBLOCK",
419 throw_unsup_format!("The {} error cannot be transformed into a raw os error", e)
423 // FIXME: we have to implement the Windows equivalent of this.
425 "Setting the last OS error from an io::Error is unsupported for {}.",
429 this.set_last_error(last_error)
432 /// Helper function that consumes an `std::io::Result<T>` and returns an
433 /// `InterpResult<'tcx,T>::Ok` instead. In case the result is an error, this function returns
434 /// `Ok(-1)` and sets the last OS error accordingly.
436 /// This function uses `T: From<i32>` instead of `i32` directly because some IO related
437 /// functions return different integer types (like `read`, that returns an `i64`).
438 fn try_unwrap_io_result<T: From<i32>>(
440 result: std::io::Result<T>,
441 ) -> InterpResult<'tcx, T> {
445 self.eval_context_mut().set_last_error_from_io_error(e)?;
451 /// Helper function to read an OsString from a null-terminated sequence of bytes, which is what
452 /// the Unix APIs usually handle.
453 fn read_os_str_from_c_str<'a>(&'a self, scalar: Scalar<Tag>) -> InterpResult<'tcx, &'a OsStr>
458 #[cfg(target_os = "unix")]
459 fn bytes_to_os_str<'tcx, 'a>(bytes: &'a [u8]) -> InterpResult<'tcx, &'a OsStr> {
460 Ok(std::os::unix::ffi::OsStringExt::from_bytes(bytes))
462 #[cfg(not(target_os = "unix"))]
463 fn bytes_to_os_str<'tcx, 'a>(bytes: &'a [u8]) -> InterpResult<'tcx, &'a OsStr> {
464 let s = std::str::from_utf8(bytes)
465 .map_err(|_| err_unsup_format!("{:?} is not a valid utf-8 string", bytes))?;
469 let this = self.eval_context_ref();
470 let bytes = this.memory.read_c_str(scalar)?;
471 bytes_to_os_str(bytes)
474 /// Helper function to write an OsStr as a null-terminated sequence of bytes, which is what
475 /// the Unix APIs usually handle. This function returns `Ok((false, length))` without trying
476 /// to write if `size` is not large enough to fit the contents of `os_string` plus a null
477 /// terminator. It returns `Ok((true, length))` if the writing process was successful. The
478 /// string length returned does not include the null terminator.
479 fn write_os_str_to_c_str(
484 ) -> InterpResult<'tcx, (bool, u64)> {
485 #[cfg(target_os = "unix")]
486 fn os_str_to_bytes<'tcx, 'a>(os_str: &'a OsStr) -> InterpResult<'tcx, &'a [u8]> {
487 std::os::unix::ffi::OsStringExt::into_bytes(os_str)
489 #[cfg(not(target_os = "unix"))]
490 fn os_str_to_bytes<'tcx, 'a>(os_str: &'a OsStr) -> InterpResult<'tcx, &'a [u8]> {
491 // On non-unix platforms the best we can do to transform bytes from/to OS strings is to do the
492 // intermediate transformation into strings. Which invalidates non-utf8 paths that are actually
496 .map(|s| s.as_bytes())
497 .ok_or_else(|| err_unsup_format!("{:?} is not a valid utf-8 string", os_str).into())
500 let bytes = os_str_to_bytes(os_str)?;
501 // If `size` is smaller or equal than `bytes.len()`, writing `bytes` plus the required null
502 // terminator to memory using the `ptr` pointer would cause an out-of-bounds access.
503 let string_length = u64::try_from(bytes.len()).unwrap();
504 if size <= string_length {
505 return Ok((false, string_length));
507 self.eval_context_mut()
509 .write_bytes(scalar, bytes.iter().copied().chain(iter::once(0u8)))?;
510 Ok((true, string_length))
513 fn alloc_os_str_as_c_str(
516 memkind: MemoryKind<MiriMemoryKind>,
518 let size = u64::try_from(os_str.len()).unwrap().checked_add(1).unwrap(); // Make space for `0` terminator.
519 let this = self.eval_context_mut();
521 let arg_type = this.tcx.mk_array(this.tcx.types.u8, size);
522 let arg_place = this.allocate(this.layout_of(arg_type).unwrap(), memkind);
523 self.write_os_str_to_c_str(os_str, arg_place.ptr, size).unwrap();
524 arg_place.ptr.assert_ptr()
528 pub fn immty_from_int_checked<'tcx>(
529 int: impl Into<i128>,
530 layout: TyLayout<'tcx>,
531 ) -> InterpResult<'tcx, ImmTy<'tcx, Tag>> {
532 let int = int.into();
533 Ok(ImmTy::try_from_int(int, layout).ok_or_else(|| {
534 err_unsup_format!("Signed value {:#x} does not fit in {} bits", int, layout.size.bits())
538 pub fn immty_from_uint_checked<'tcx>(
539 int: impl Into<u128>,
540 layout: TyLayout<'tcx>,
541 ) -> InterpResult<'tcx, ImmTy<'tcx, Tag>> {
542 let int = int.into();
543 Ok(ImmTy::try_from_uint(int, layout).ok_or_else(|| {
544 err_unsup_format!("Signed value {:#x} does not fit in {} bits", int, layout.size.bits())