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rust/src/helpers.rs

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pub mod convert;
use std::mem;
use std::num::NonZeroUsize;
use std::time::Duration;
use log::trace;
use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
use rustc_middle::mir;
use rustc_middle::ty::{
self,
layout::{LayoutOf, TyAndLayout},
List, TyCtxt,
};
use rustc_span::{def_id::CrateNum, sym, Span, Symbol};
use rustc_target::abi::{Align, FieldsShape, Size, Variants};
use rustc_target::spec::abi::Abi;
use rand::RngCore;
use crate::*;
impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
// This mapping should match `decode_error_kind` in
// <https://github.com/rust-lang/rust/blob/master/library/std/src/sys/unix/mod.rs>.
const UNIX_IO_ERROR_TABLE: &[(&str, std::io::ErrorKind)] = {
use std::io::ErrorKind::*;
&[
("E2BIG", ArgumentListTooLong),
("EADDRINUSE", AddrInUse),
("EADDRNOTAVAIL", AddrNotAvailable),
("EBUSY", ResourceBusy),
("ECONNABORTED", ConnectionAborted),
("ECONNREFUSED", ConnectionRefused),
("ECONNRESET", ConnectionReset),
("EDEADLK", Deadlock),
("EDQUOT", FilesystemQuotaExceeded),
("EEXIST", AlreadyExists),
("EFBIG", FileTooLarge),
("EHOSTUNREACH", HostUnreachable),
("EINTR", Interrupted),
("EINVAL", InvalidInput),
("EISDIR", IsADirectory),
("ELOOP", FilesystemLoop),
("ENOENT", NotFound),
("ENOMEM", OutOfMemory),
("ENOSPC", StorageFull),
("ENOSYS", Unsupported),
("EMLINK", TooManyLinks),
("ENAMETOOLONG", InvalidFilename),
("ENETDOWN", NetworkDown),
("ENETUNREACH", NetworkUnreachable),
("ENOTCONN", NotConnected),
("ENOTDIR", NotADirectory),
("ENOTEMPTY", DirectoryNotEmpty),
("EPIPE", BrokenPipe),
("EROFS", ReadOnlyFilesystem),
("ESPIPE", NotSeekable),
("ESTALE", StaleNetworkFileHandle),
("ETIMEDOUT", TimedOut),
("ETXTBSY", ExecutableFileBusy),
("EXDEV", CrossesDevices),
// The following have two valid options. We have both for the forwards mapping; only the
// first one will be used for the backwards mapping.
("EPERM", PermissionDenied),
("EACCES", PermissionDenied),
("EWOULDBLOCK", WouldBlock),
("EAGAIN", WouldBlock),
]
};
/// Gets an instance for a path.
fn try_resolve_did<'tcx>(tcx: TyCtxt<'tcx>, path: &[&str]) -> Option<DefId> {
tcx.crates(()).iter().find(|&&krate| tcx.crate_name(krate).as_str() == path[0]).and_then(
|krate| {
let krate = DefId { krate: *krate, index: CRATE_DEF_INDEX };
let mut items = tcx.module_children(krate);
let mut path_it = path.iter().skip(1).peekable();
while let Some(segment) = path_it.next() {
for item in mem::take(&mut items).iter() {
if item.ident.name.as_str() == *segment {
if path_it.peek().is_none() {
return Some(item.res.def_id());
}
items = tcx.module_children(item.res.def_id());
break;
}
}
}
None
},
)
}
pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
/// Gets an instance for a path; fails gracefully if the path does not exist.
fn try_resolve_path(&self, path: &[&str]) -> Option<ty::Instance<'tcx>> {
let did = try_resolve_did(self.eval_context_ref().tcx.tcx, path)?;
Some(ty::Instance::mono(self.eval_context_ref().tcx.tcx, did))
}
/// Gets an instance for a path.
fn resolve_path(&self, path: &[&str]) -> ty::Instance<'tcx> {
self.try_resolve_path(path)
.unwrap_or_else(|| panic!("failed to find required Rust item: {:?}", path))
}
/// Evaluates the scalar at the specified path. Returns Some(val)
/// if the path could be resolved, and None otherwise
fn eval_path_scalar(&self, path: &[&str]) -> InterpResult<'tcx, Scalar<Provenance>> {
let this = self.eval_context_ref();
let instance = this.resolve_path(path);
let cid = GlobalId { instance, promoted: None };
let const_val = this.eval_to_allocation(cid)?;
this.read_scalar(&const_val.into())
}
/// Helper function to get a `libc` constant as a `Scalar`.
fn eval_libc(&self, name: &str) -> InterpResult<'tcx, Scalar<Provenance>> {
self.eval_path_scalar(&["libc", name])
}
/// Helper function to get a `libc` constant as an `i32`.
fn eval_libc_i32(&self, name: &str) -> InterpResult<'tcx, i32> {
// TODO: Cache the result.
self.eval_libc(name)?.to_i32()
}
/// Helper function to get a `windows` constant as a `Scalar`.
fn eval_windows(&self, module: &str, name: &str) -> InterpResult<'tcx, Scalar<Provenance>> {
self.eval_context_ref().eval_path_scalar(&["std", "sys", "windows", module, name])
}
/// Helper function to get a `windows` constant as a `u64`.
fn eval_windows_u64(&self, module: &str, name: &str) -> InterpResult<'tcx, u64> {
// TODO: Cache the result.
self.eval_windows(module, name)?.to_u64()
}
/// Helper function to get the `TyAndLayout` of a `libc` type
fn libc_ty_layout(&self, name: &str) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
let this = self.eval_context_ref();
let ty = this.resolve_path(&["libc", name]).ty(*this.tcx, ty::ParamEnv::reveal_all());
this.layout_of(ty)
}
/// Helper function to get the `TyAndLayout` of a `windows` type
fn windows_ty_layout(&self, name: &str) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
let this = self.eval_context_ref();
let ty = this
.resolve_path(&["std", "sys", "windows", "c", name])
.ty(*this.tcx, ty::ParamEnv::reveal_all());
this.layout_of(ty)
}
/// Project to the given *named* field of the mplace (which must be a struct or union type).
fn mplace_field_named(
&self,
mplace: &MPlaceTy<'tcx, Provenance>,
name: &str,
) -> InterpResult<'tcx, MPlaceTy<'tcx, Provenance>> {
let this = self.eval_context_ref();
let adt = mplace.layout.ty.ty_adt_def().unwrap();
for (idx, field) in adt.non_enum_variant().fields.iter().enumerate() {
if field.name.as_str() == name {
return this.mplace_field(mplace, idx);
}
}
bug!("No field named {} in type {}", name, mplace.layout.ty);
}
/// Write an int of the appropriate size to `dest`. The target type may be signed or unsigned,
/// we try to do the right thing anyway. `i128` can fit all integer types except for `u128` so
/// this method is fine for almost all integer types.
fn write_int(
&mut self,
i: impl Into<i128>,
dest: &PlaceTy<'tcx, Provenance>,
) -> InterpResult<'tcx> {
assert!(dest.layout.abi.is_scalar(), "write_int on non-scalar type {}", dest.layout.ty);
let val = if dest.layout.abi.is_signed() {
Scalar::from_int(i, dest.layout.size)
} else {
Scalar::from_uint(u64::try_from(i.into()).unwrap(), dest.layout.size)
};
self.eval_context_mut().write_scalar(val, dest)
}
/// Write the first N fields of the given place.
fn write_int_fields(
&mut self,
values: &[i128],
dest: &MPlaceTy<'tcx, Provenance>,
) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
for (idx, &val) in values.iter().enumerate() {
let field = this.mplace_field(dest, idx)?;
this.write_int(val, &field.into())?;
}
Ok(())
}
/// Write the given fields of the given place.
fn write_int_fields_named(
&mut self,
values: &[(&str, i128)],
dest: &MPlaceTy<'tcx, Provenance>,
) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
for &(name, val) in values.iter() {
let field = this.mplace_field_named(dest, name)?;
this.write_int(val, &field.into())?;
}
Ok(())
}
/// Write a 0 of the appropriate size to `dest`.
fn write_null(&mut self, dest: &PlaceTy<'tcx, Provenance>) -> InterpResult<'tcx> {
self.write_int(0, dest)
}
/// Test if this pointer equals 0.
fn ptr_is_null(&self, ptr: Pointer<Option<Provenance>>) -> InterpResult<'tcx, bool> {
Ok(ptr.addr().bytes() == 0)
}
/// Get the `Place` for a local
fn local_place(&mut self, local: mir::Local) -> InterpResult<'tcx, PlaceTy<'tcx, Provenance>> {
let this = self.eval_context_mut();
let place = mir::Place { local, projection: List::empty() };
this.eval_place(place)
}
/// Generate some random bytes, and write them to `dest`.
fn gen_random(&mut self, ptr: Pointer<Option<Provenance>>, len: u64) -> InterpResult<'tcx> {
// Some programs pass in a null pointer and a length of 0
// to their platform's random-generation function (e.g. getrandom())
// on Linux. For compatibility with these programs, we don't perform
// any additional checks - it's okay if the pointer is invalid,
// since we wouldn't actually be writing to it.
if len == 0 {
return Ok(());
}
let this = self.eval_context_mut();
let mut data = vec![0; usize::try_from(len).unwrap()];
if this.machine.communicate() {
// Fill the buffer using the host's rng.
getrandom::getrandom(&mut data)
.map_err(|err| err_unsup_format!("host getrandom failed: {}", err))?;
} else {
let rng = this.machine.rng.get_mut();
rng.fill_bytes(&mut data);
}
this.write_bytes_ptr(ptr, data.iter().copied())
}
/// Call a function: Push the stack frame and pass the arguments.
/// For now, arguments must be scalars (so that the caller does not have to know the layout).
///
/// If you do not provie a return place, a dangling zero-sized place will be created
/// for your convenience.
fn call_function(
&mut self,
f: ty::Instance<'tcx>,
caller_abi: Abi,
args: &[Immediate<Provenance>],
dest: Option<&PlaceTy<'tcx, Provenance>>,
stack_pop: StackPopCleanup,
) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
let param_env = ty::ParamEnv::reveal_all(); // in Miri this is always the param_env we use... and this.param_env is private.
let callee_abi = f.ty(*this.tcx, param_env).fn_sig(*this.tcx).abi();
if this.machine.enforce_abi && callee_abi != caller_abi {
throw_ub_format!(
"calling a function with ABI {} using caller ABI {}",
callee_abi.name(),
caller_abi.name()
)
}
// Push frame.
let mir = this.load_mir(f.def, None)?;
let dest = match dest {
Some(dest) => dest.clone(),
None => MPlaceTy::fake_alloc_zst(this.layout_of(mir.return_ty())?).into(),
};
this.push_stack_frame(f, mir, &dest, stack_pop)?;
// Initialize arguments.
let mut callee_args = this.frame().body.args_iter();
for arg in args {
let callee_arg = this.local_place(
callee_args
.next()
.ok_or_else(|| err_ub_format!("callee has fewer arguments than expected"))?,
)?;
this.write_immediate(*arg, &callee_arg)?;
}
if callee_args.next().is_some() {
throw_ub_format!("callee has more arguments than expected");
}
Ok(())
}
/// Visits the memory covered by `place`, sensitive to freezing: the 2nd parameter
/// of `action` will be true if this is frozen, false if this is in an `UnsafeCell`.
/// The range is relative to `place`.
fn visit_freeze_sensitive(
&self,
place: &MPlaceTy<'tcx, Provenance>,
size: Size,
mut action: impl FnMut(AllocRange, bool) -> InterpResult<'tcx>,
) -> InterpResult<'tcx> {
let this = self.eval_context_ref();
trace!("visit_frozen(place={:?}, size={:?})", *place, size);
debug_assert_eq!(
size,
this.size_and_align_of_mplace(place)?
.map(|(size, _)| size)
.unwrap_or_else(|| place.layout.size)
);
// Store how far we proceeded into the place so far. Everything to the left of
// this offset has already been handled, in the sense that the frozen parts
// have had `action` called on them.
let start_addr = place.ptr.addr();
let mut cur_addr = start_addr;
// Called when we detected an `UnsafeCell` at the given offset and size.
// Calls `action` and advances `cur_ptr`.
let mut unsafe_cell_action = |unsafe_cell_ptr: &Pointer<Option<Provenance>>,
unsafe_cell_size: Size| {
// We assume that we are given the fields in increasing offset order,
// and nothing else changes.
let unsafe_cell_addr = unsafe_cell_ptr.addr();
assert!(unsafe_cell_addr >= cur_addr);
let frozen_size = unsafe_cell_addr - cur_addr;
// Everything between the cur_ptr and this `UnsafeCell` is frozen.
if frozen_size != Size::ZERO {
action(alloc_range(cur_addr - start_addr, frozen_size), /*frozen*/ true)?;
}
cur_addr += frozen_size;
// This `UnsafeCell` is NOT frozen.
if unsafe_cell_size != Size::ZERO {
action(
alloc_range(cur_addr - start_addr, unsafe_cell_size),
/*frozen*/ false,
)?;
}
cur_addr += unsafe_cell_size;
// Done
Ok(())
};
// Run a visitor
{
let mut visitor = UnsafeCellVisitor {
ecx: this,
unsafe_cell_action: |place| {
trace!("unsafe_cell_action on {:?}", place.ptr);
// We need a size to go on.
let unsafe_cell_size = this
.size_and_align_of_mplace(place)?
.map(|(size, _)| size)
// for extern types, just cover what we can
.unwrap_or_else(|| place.layout.size);
// Now handle this `UnsafeCell`, unless it is empty.
if unsafe_cell_size != Size::ZERO {
unsafe_cell_action(&place.ptr, unsafe_cell_size)
} else {
Ok(())
}
},
};
visitor.visit_value(place)?;
}
// The part between the end_ptr and the end of the place is also frozen.
// So pretend there is a 0-sized `UnsafeCell` at the end.
unsafe_cell_action(&place.ptr.offset(size, this)?, Size::ZERO)?;
// Done!
return Ok(());
/// Visiting the memory covered by a `MemPlace`, being aware of
/// whether we are inside an `UnsafeCell` or not.
struct UnsafeCellVisitor<'ecx, 'mir, 'tcx, F>
where
F: FnMut(&MPlaceTy<'tcx, Provenance>) -> InterpResult<'tcx>,
{
ecx: &'ecx MiriEvalContext<'mir, 'tcx>,
unsafe_cell_action: F,
}
impl<'ecx, 'mir, 'tcx: 'mir, F> ValueVisitor<'mir, 'tcx, Evaluator<'mir, 'tcx>>
for UnsafeCellVisitor<'ecx, 'mir, 'tcx, F>
where
F: FnMut(&MPlaceTy<'tcx, Provenance>) -> InterpResult<'tcx>,
{
type V = MPlaceTy<'tcx, Provenance>;
#[inline(always)]
fn ecx(&self) -> &MiriEvalContext<'mir, 'tcx> {
self.ecx
}
// Hook to detect `UnsafeCell`.
fn visit_value(&mut self, v: &MPlaceTy<'tcx, Provenance>) -> InterpResult<'tcx> {
trace!("UnsafeCellVisitor: {:?} {:?}", *v, v.layout.ty);
let is_unsafe_cell = match v.layout.ty.kind() {
ty::Adt(adt, _) =>
Some(adt.did()) == self.ecx.tcx.lang_items().unsafe_cell_type(),
_ => false,
};
if is_unsafe_cell {
// We do not have to recurse further, this is an `UnsafeCell`.
(self.unsafe_cell_action)(v)
} else if self.ecx.type_is_freeze(v.layout.ty) {
// This is `Freeze`, there cannot be an `UnsafeCell`
Ok(())
} else if matches!(v.layout.fields, FieldsShape::Union(..)) {
// A (non-frozen) union. We fall back to whatever the type says.
(self.unsafe_cell_action)(v)
} else {
// We want to not actually read from memory for this visit. So, before
// walking this value, we have to make sure it is not a
// `Variants::Multiple`.
match v.layout.variants {
Variants::Multiple { .. } => {
// A multi-variant enum, or generator, or so.
// Treat this like a union: without reading from memory,
// we cannot determine the variant we are in. Reading from
// memory would be subject to Stacked Borrows rules, leading
// to all sorts of "funny" recursion.
// We only end up here if the type is *not* freeze, so we just call the
// `UnsafeCell` action.
(self.unsafe_cell_action)(v)
}
Variants::Single { .. } => {
// Proceed further, try to find where exactly that `UnsafeCell`
// is hiding.
self.walk_value(v)
}
}
}
}
// Make sure we visit aggregrates in increasing offset order.
fn visit_aggregate(
&mut self,
place: &MPlaceTy<'tcx, Provenance>,
fields: impl Iterator<Item = InterpResult<'tcx, MPlaceTy<'tcx, Provenance>>>,
) -> InterpResult<'tcx> {
match place.layout.fields {
FieldsShape::Array { .. } => {
// For the array layout, we know the iterator will yield sorted elements so
// we can avoid the allocation.
self.walk_aggregate(place, fields)
}
FieldsShape::Arbitrary { .. } => {
// Gather the subplaces and sort them before visiting.
let mut places = fields
.collect::<InterpResult<'tcx, Vec<MPlaceTy<'tcx, Provenance>>>>()?;
// we just compare offsets, the abs. value never matters
places.sort_by_key(|place| place.ptr.addr());
self.walk_aggregate(place, places.into_iter().map(Ok))
}
FieldsShape::Union { .. } | FieldsShape::Primitive => {
// Uh, what?
bug!("unions/primitives are not aggregates we should ever visit")
}
}
}
fn visit_union(
&mut self,
_v: &MPlaceTy<'tcx, Provenance>,
_fields: NonZeroUsize,
) -> InterpResult<'tcx> {
bug!("we should have already handled unions in `visit_value`")
}
}
}
/// Helper function used inside the shims of foreign functions to check that isolation is
/// disabled. It returns an error using the `name` of the foreign function if this is not the
/// case.
fn check_no_isolation(&self, name: &str) -> InterpResult<'tcx> {
if !self.eval_context_ref().machine.communicate() {
self.reject_in_isolation(name, RejectOpWith::Abort)?;
}
Ok(())
}
/// Helper function used inside the shims of foreign functions which reject the op
/// when isolation is enabled. It is used to print a warning/backtrace about the rejection.
fn reject_in_isolation(&self, op_name: &str, reject_with: RejectOpWith) -> InterpResult<'tcx> {
let this = self.eval_context_ref();
match reject_with {
RejectOpWith::Abort => isolation_abort_error(op_name),
RejectOpWith::WarningWithoutBacktrace => {
this.tcx
.sess
.warn(&format!("{} was made to return an error due to isolation", op_name));
Ok(())
}
RejectOpWith::Warning => {
register_diagnostic(NonHaltingDiagnostic::RejectedIsolatedOp(op_name.to_string()));
Ok(())
}
RejectOpWith::NoWarning => Ok(()), // no warning
}
}
/// Helper function used inside the shims of foreign functions to assert that the target OS
/// is `target_os`. It panics showing a message with the `name` of the foreign function
/// if this is not the case.
fn assert_target_os(&self, target_os: &str, name: &str) {
assert_eq!(
self.eval_context_ref().tcx.sess.target.os,
target_os,
"`{}` is only available on the `{}` target OS",
name,
target_os,
)
}
/// Helper function used inside the shims of foreign functions to assert that the target OS
/// is part of the UNIX family. It panics showing a message with the `name` of the foreign function
/// if this is not the case.
fn assert_target_os_is_unix(&self, name: &str) {
assert!(
target_os_is_unix(self.eval_context_ref().tcx.sess.target.os.as_ref()),
"`{}` is only available for supported UNIX family targets",
name,
);
}
/// Get last error variable as a place, lazily allocating thread-local storage for it if
/// necessary.
fn last_error_place(&mut self) -> InterpResult<'tcx, MPlaceTy<'tcx, Provenance>> {
let this = self.eval_context_mut();
if let Some(errno_place) = this.active_thread_ref().last_error {
Ok(errno_place)
} else {
// Allocate new place, set initial value to 0.
let errno_layout = this.machine.layouts.u32;
let errno_place = this.allocate(errno_layout, MiriMemoryKind::Machine.into())?;
this.write_scalar(Scalar::from_u32(0), &errno_place.into())?;
this.active_thread_mut().last_error = Some(errno_place);
Ok(errno_place)
}
}
/// Sets the last error variable.
fn set_last_error(&mut self, scalar: Scalar<Provenance>) -> InterpResult<'tcx> {
let this = self.eval_context_mut();
let errno_place = this.last_error_place()?;
this.write_scalar(scalar, &errno_place.into())
}
/// Gets the last error variable.
fn get_last_error(&mut self) -> InterpResult<'tcx, Scalar<Provenance>> {
let this = self.eval_context_mut();
let errno_place = this.last_error_place()?;
this.read_scalar(&errno_place.into())
}
/// This function tries to produce the most similar OS error from the `std::io::ErrorKind`
/// as a platform-specific errnum.
fn io_error_to_errnum(
&self,
err_kind: std::io::ErrorKind,
) -> InterpResult<'tcx, Scalar<Provenance>> {
let this = self.eval_context_ref();
let target = &this.tcx.sess.target;
if target.families.iter().any(|f| f == "unix") {
for &(name, kind) in UNIX_IO_ERROR_TABLE {
if err_kind == kind {
return this.eval_libc(name);
}
}
throw_unsup_format!("io error {:?} cannot be translated into a raw os error", err_kind)
} else if target.families.iter().any(|f| f == "windows") {
// FIXME: we have to finish implementing the Windows equivalent of this.
use std::io::ErrorKind::*;
this.eval_windows(
"c",
match err_kind {
NotFound => "ERROR_FILE_NOT_FOUND",
PermissionDenied => "ERROR_ACCESS_DENIED",
_ =>
throw_unsup_format!(
"io error {:?} cannot be translated into a raw os error",
err_kind
),
},
)
} else {
throw_unsup_format!(
"converting io::Error into errnum is unsupported for OS {}",
target.os
)
}
}
/// The inverse of `io_error_to_errnum`.
#[allow(clippy::needless_return)]
fn try_errnum_to_io_error(
&self,
errnum: Scalar<Provenance>,
) -> InterpResult<'tcx, Option<std::io::ErrorKind>> {
let this = self.eval_context_ref();
let target = &this.tcx.sess.target;
if target.families.iter().any(|f| f == "unix") {
let errnum = errnum.to_i32()?;
for &(name, kind) in UNIX_IO_ERROR_TABLE {
if errnum == this.eval_libc_i32(name)? {
return Ok(Some(kind));
}
}
// Our table is as complete as the mapping in std, so we are okay with saying "that's a
// strange one" here.
return Ok(None);
} else {
throw_unsup_format!(
"converting errnum into io::Error is unsupported for OS {}",
target.os
)
}
}
/// Sets the last OS error using a `std::io::ErrorKind`.
fn set_last_error_from_io_error(&mut self, err_kind: std::io::ErrorKind) -> InterpResult<'tcx> {
self.set_last_error(self.io_error_to_errnum(err_kind)?)
}
/// Helper function that consumes an `std::io::Result<T>` and returns an
/// `InterpResult<'tcx,T>::Ok` instead. In case the result is an error, this function returns
/// `Ok(-1)` and sets the last OS error accordingly.
///
/// This function uses `T: From<i32>` instead of `i32` directly because some IO related
/// functions return different integer types (like `read`, that returns an `i64`).
fn try_unwrap_io_result<T: From<i32>>(
&mut self,
result: std::io::Result<T>,
) -> InterpResult<'tcx, T> {
match result {
Ok(ok) => Ok(ok),
Err(e) => {
self.eval_context_mut().set_last_error_from_io_error(e.kind())?;
Ok((-1).into())
}
}
}
/// Calculates the MPlaceTy given the offset and layout of an access on an operand
fn deref_operand_and_offset(
&self,
op: &OpTy<'tcx, Provenance>,
offset: u64,
layout: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, MPlaceTy<'tcx, Provenance>> {
let this = self.eval_context_ref();
let op_place = this.deref_operand(op)?;
let offset = Size::from_bytes(offset);
// Ensure that the access is within bounds.
assert!(op_place.layout.size >= offset + layout.size);
let value_place = op_place.offset(offset, layout, this)?;
Ok(value_place)
}
fn read_scalar_at_offset(
&self,
op: &OpTy<'tcx, Provenance>,
offset: u64,
layout: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, Scalar<Provenance>> {
let this = self.eval_context_ref();
let value_place = this.deref_operand_and_offset(op, offset, layout)?;
this.read_scalar(&value_place.into())
}
fn write_immediate_at_offset(
&mut self,
op: &OpTy<'tcx, Provenance>,
offset: u64,
value: &ImmTy<'tcx, Provenance>,
) -> InterpResult<'tcx, ()> {
let this = self.eval_context_mut();
let value_place = this.deref_operand_and_offset(op, offset, value.layout)?;
this.write_immediate(**value, &value_place.into())
}
fn write_scalar_at_offset(
&mut self,
op: &OpTy<'tcx, Provenance>,
offset: u64,
value: impl Into<Scalar<Provenance>>,
layout: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, ()> {
self.write_immediate_at_offset(op, offset, &ImmTy::from_scalar(value.into(), layout))
}
/// Parse a `timespec` struct and return it as a `std::time::Duration`. It returns `None`
/// if the value in the `timespec` struct is invalid. Some libc functions will return
/// `EINVAL` in this case.
fn read_timespec(
&mut self,
tp: &MPlaceTy<'tcx, Provenance>,
) -> InterpResult<'tcx, Option<Duration>> {
let this = self.eval_context_mut();
let seconds_place = this.mplace_field(tp, 0)?;
let seconds_scalar = this.read_scalar(&seconds_place.into())?;
let seconds = seconds_scalar.to_machine_isize(this)?;
let nanoseconds_place = this.mplace_field(tp, 1)?;
let nanoseconds_scalar = this.read_scalar(&nanoseconds_place.into())?;
let nanoseconds = nanoseconds_scalar.to_machine_isize(this)?;
Ok(try {
// tv_sec must be non-negative.
let seconds: u64 = seconds.try_into().ok()?;
// tv_nsec must be non-negative.
let nanoseconds: u32 = nanoseconds.try_into().ok()?;
if nanoseconds >= 1_000_000_000 {
// tv_nsec must not be greater than 999,999,999.
None?
}
Duration::new(seconds, nanoseconds)
})
}
fn read_c_str<'a>(&'a self, ptr: Pointer<Option<Provenance>>) -> InterpResult<'tcx, &'a [u8]>
where
'tcx: 'a,
'mir: 'a,
{
let this = self.eval_context_ref();
let size1 = Size::from_bytes(1);
// Step 1: determine the length.
let mut len = Size::ZERO;
loop {
// FIXME: We are re-getting the allocation each time around the loop.
// Would be nice if we could somehow "extend" an existing AllocRange.
let alloc = this.get_ptr_alloc(ptr.offset(len, this)?, size1, Align::ONE)?.unwrap(); // not a ZST, so we will get a result
let byte = alloc.read_integer(alloc_range(Size::ZERO, size1))?.to_u8()?;
if byte == 0 {
break;
} else {
len += size1;
}
}
// Step 2: get the bytes.
this.read_bytes_ptr_strip_provenance(ptr, len)
}
fn read_wide_str(&self, mut ptr: Pointer<Option<Provenance>>) -> InterpResult<'tcx, Vec<u16>> {
let this = self.eval_context_ref();
let size2 = Size::from_bytes(2);
let align2 = Align::from_bytes(2).unwrap();
let mut wchars = Vec::new();
loop {
// FIXME: We are re-getting the allocation each time around the loop.
// Would be nice if we could somehow "extend" an existing AllocRange.
let alloc = this.get_ptr_alloc(ptr, size2, align2)?.unwrap(); // not a ZST, so we will get a result
let wchar = alloc.read_integer(alloc_range(Size::ZERO, size2))?.to_u16()?;
if wchar == 0 {
break;
} else {
wchars.push(wchar);
ptr = ptr.offset(size2, this)?;
}
}
Ok(wchars)
}
/// Check that the ABI is what we expect.
fn check_abi<'a>(&self, abi: Abi, exp_abi: Abi) -> InterpResult<'a, ()> {
if self.eval_context_ref().machine.enforce_abi && abi != exp_abi {
throw_ub_format!(
"calling a function with ABI {} using caller ABI {}",
exp_abi.name(),
abi.name()
)
}
Ok(())
}
fn frame_in_std(&self) -> bool {
let this = self.eval_context_ref();
let Some(start_fn) = this.tcx.lang_items().start_fn() else {
// no_std situations
return false;
};
let frame = this.frame();
// Make an attempt to get at the instance of the function this is inlined from.
let instance: Option<_> = try {
let scope = frame.current_source_info()?.scope;
let inlined_parent = frame.body.source_scopes[scope].inlined_parent_scope?;
let source = &frame.body.source_scopes[inlined_parent];
source.inlined.expect("inlined_parent_scope points to scope without inline info").0
};
// Fall back to the instance of the function itself.
let instance = instance.unwrap_or(frame.instance);
// Now check if this is in the same crate as start_fn.
// As a special exception we also allow unit tests from
// <https://github.com/rust-lang/miri-test-libstd/tree/master/std_miri_test> to call these
// shims.
let frame_crate = this.tcx.def_path(instance.def_id()).krate;
frame_crate == this.tcx.def_path(start_fn).krate
|| this.tcx.crate_name(frame_crate).as_str() == "std_miri_test"
}
/// Handler that should be called when unsupported functionality is encountered.
/// This function will either panic within the context of the emulated application
/// or return an error in the Miri process context
///
/// Return value of `Ok(bool)` indicates whether execution should continue.
fn handle_unsupported<S: AsRef<str>>(&mut self, error_msg: S) -> InterpResult<'tcx, ()> {
let this = self.eval_context_mut();
if this.machine.panic_on_unsupported {
// message is slightly different here to make automated analysis easier
let error_msg = format!("unsupported Miri functionality: {}", error_msg.as_ref());
this.start_panic(error_msg.as_ref(), StackPopUnwind::Skip)?;
Ok(())
} else {
throw_unsup_format!("{}", error_msg.as_ref());
}
}
fn check_abi_and_shim_symbol_clash(
&mut self,
abi: Abi,
exp_abi: Abi,
link_name: Symbol,
) -> InterpResult<'tcx, ()> {
self.check_abi(abi, exp_abi)?;
if let Some((body, _)) = self.eval_context_mut().lookup_exported_symbol(link_name)? {
throw_machine_stop!(TerminationInfo::SymbolShimClashing {
link_name,
span: body.span.data(),
})
}
Ok(())
}
fn check_shim<'a, const N: usize>(
&mut self,
abi: Abi,
exp_abi: Abi,
link_name: Symbol,
args: &'a [OpTy<'tcx, Provenance>],
) -> InterpResult<'tcx, &'a [OpTy<'tcx, Provenance>; N]>
where
&'a [OpTy<'tcx, Provenance>; N]: TryFrom<&'a [OpTy<'tcx, Provenance>]>,
{
self.check_abi_and_shim_symbol_clash(abi, exp_abi, link_name)?;
check_arg_count(args)
}
/// Mark a machine allocation that was just created as immutable.
fn mark_immutable(&mut self, mplace: &MemPlace<Provenance>) {
let this = self.eval_context_mut();
// This got just allocated, so there definitely is a pointer here.
let provenance = mplace.ptr.into_pointer_or_addr().unwrap().provenance;
this.alloc_mark_immutable(provenance.get_alloc_id().unwrap()).unwrap();
}
fn item_link_name(&self, def_id: DefId) -> Symbol {
let tcx = self.eval_context_ref().tcx;
match tcx.get_attrs(def_id, sym::link_name).filter_map(|a| a.value_str()).next() {
Some(name) => name,
None => tcx.item_name(def_id),
}
}
}
impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
pub fn current_span(&self, tcx: TyCtxt<'tcx>) -> CurrentSpan<'_, 'mir, 'tcx> {
CurrentSpan { current_frame_idx: None, machine: self, tcx }
}
}
/// A `CurrentSpan` should be created infrequently (ideally once) per interpreter step. It does
/// nothing on creation, but when `CurrentSpan::get` is called, searches the current stack for the
/// topmost frame which corresponds to a local crate, and returns the current span in that frame.
/// The result of that search is cached so that later calls are approximately free.
#[derive(Clone)]
pub struct CurrentSpan<'a, 'mir, 'tcx> {
current_frame_idx: Option<usize>,
tcx: TyCtxt<'tcx>,
machine: &'a Evaluator<'mir, 'tcx>,
}
impl<'a, 'mir: 'a, 'tcx: 'a + 'mir> CurrentSpan<'a, 'mir, 'tcx> {
/// Get the current span, skipping non-local frames.
/// This function is backed by a cache, and can be assumed to be very fast.
pub fn get(&mut self) -> Span {
let idx = self.current_frame_idx();
Self::frame_span(self.machine, idx)
}
/// Similar to `CurrentSpan::get`, but retrieves the parent frame of the first non-local frame.
/// This is useful when we are processing something which occurs on function-entry and we want
/// to point at the call to the function, not the function definition generally.
pub fn get_parent(&mut self) -> Span {
let idx = self.current_frame_idx();
Self::frame_span(self.machine, idx.wrapping_sub(1))
}
fn frame_span(machine: &Evaluator<'_, '_>, idx: usize) -> Span {
machine
.threads
.active_thread_stack()
.get(idx)
.map(Frame::current_span)
.unwrap_or(rustc_span::DUMMY_SP)
}
fn current_frame_idx(&mut self) -> usize {
*self
.current_frame_idx
.get_or_insert_with(|| Self::compute_current_frame_index(self.tcx, self.machine))
}
// Find the position of the inner-most frame which is part of the crate being
// compiled/executed, part of the Cargo workspace, and is also not #[track_caller].
#[inline(never)]
fn compute_current_frame_index(tcx: TyCtxt<'_>, machine: &Evaluator<'_, '_>) -> usize {
machine
.threads
.active_thread_stack()
.iter()
.enumerate()
.rev()
.find_map(|(idx, frame)| {
let def_id = frame.instance.def_id();
if (def_id.is_local() || machine.local_crates.contains(&def_id.krate))
&& !frame.instance.def.requires_caller_location(tcx)
{
Some(idx)
} else {
None
}
})
.unwrap_or(0)
}
}
/// Check that the number of args is what we expect.
pub fn check_arg_count<'a, 'tcx, const N: usize>(
args: &'a [OpTy<'tcx, Provenance>],
) -> InterpResult<'tcx, &'a [OpTy<'tcx, Provenance>; N]>
where
&'a [OpTy<'tcx, Provenance>; N]: TryFrom<&'a [OpTy<'tcx, Provenance>]>,
{
if let Ok(ops) = args.try_into() {
return Ok(ops);
}
throw_ub_format!("incorrect number of arguments: got {}, expected {}", args.len(), N)
}
pub fn isolation_abort_error<'tcx>(name: &str) -> InterpResult<'tcx> {
throw_machine_stop!(TerminationInfo::UnsupportedInIsolation(format!(
"{} not available when isolation is enabled",
name,
)))
}
/// Retrieve the list of local crates that should have been passed by cargo-miri in
/// MIRI_LOCAL_CRATES and turn them into `CrateNum`s.
pub fn get_local_crates(tcx: TyCtxt<'_>) -> Vec<CrateNum> {
// Convert the local crate names from the passed-in config into CrateNums so that they can
// be looked up quickly during execution
let local_crate_names = std::env::var("MIRI_LOCAL_CRATES")
.map(|crates| crates.split(',').map(|krate| krate.to_string()).collect::<Vec<_>>())
.unwrap_or_default();
let mut local_crates = Vec::new();
for &crate_num in tcx.crates(()) {
let name = tcx.crate_name(crate_num);
let name = name.as_str();
if local_crate_names.iter().any(|local_name| local_name == name) {
local_crates.push(crate_num);
}
}
local_crates
}
/// Helper function used inside the shims of foreign functions to check that
/// `target_os` is a supported UNIX OS.
pub fn target_os_is_unix(target_os: &str) -> bool {
matches!(target_os, "linux" | "macos" | "freebsd" | "android")
}
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