rust/src/eval.rs

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//! Main evaluator loop and setting up the initial stack frame.
use std::ffi::OsStr;
use rand::rngs::StdRng;
use rand::SeedableRng;
use rustc::ty::layout::{LayoutOf, Size};
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use rustc::ty::{self, TyCtxt};
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use rustc_hir::def_id::DefId;
use crate::*;
/// Configuration needed to spawn a Miri instance.
#[derive(Clone)]
pub struct MiriConfig {
/// Determine if validity checking is enabled.
pub validate: bool,
/// Determines if Stacked Borrows is enabled.
pub stacked_borrows: bool,
/// Determines if communication with the host environment is enabled.
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pub communicate: bool,
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/// Determines if memory leaks should be ignored.
pub ignore_leaks: bool,
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/// Environment variables that should always be isolated from the host.
pub excluded_env_vars: Vec<String>,
/// Command-line arguments passed to the interpreted program.
pub args: Vec<String>,
/// The seed to use when non-determinism or randomness are required (e.g. ptr-to-int cast, `getrandom()`).
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pub seed: Option<u64>,
/// The stacked borrow id to report about
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pub tracked_pointer_tag: Option<PtrId>,
}
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/// Details of premature program termination.
pub enum TerminationInfo {
Exit(i64),
Abort,
}
/// Returns a freshly created `InterpCx`, along with an `MPlaceTy` representing
/// the location where the return value of the `start` lang item will be
/// written to.
/// Public because this is also used by `priroda`.
pub fn create_ecx<'mir, 'tcx: 'mir>(
tcx: TyCtxt<'tcx>,
main_id: DefId,
config: MiriConfig,
) -> InterpResult<'tcx, (InterpCx<'mir, 'tcx, Evaluator<'tcx>>, MPlaceTy<'tcx, Tag>)> {
let mut ecx = InterpCx::new(
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tcx.at(rustc_span::source_map::DUMMY_SP),
ty::ParamEnv::reveal_all(),
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Evaluator::new(config.communicate, config.validate),
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MemoryExtra::new(
StdRng::seed_from_u64(config.seed.unwrap_or(0)),
config.stacked_borrows,
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config.tracked_pointer_tag,
),
);
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// Complete initialization.
MemoryExtra::init_extern_statics(&mut ecx)?;
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EnvVars::init(&mut ecx, config.excluded_env_vars);
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// Setup first stack-frame
let main_instance = ty::Instance::mono(tcx, main_id);
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let main_mir = ecx.load_mir(main_instance.def, None)?;
if main_mir.arg_count != 0 {
bug!("main function must not take any arguments");
}
let start_id = tcx.lang_items().start_fn().unwrap();
let main_ret_ty = tcx.fn_sig(main_id).output();
let main_ret_ty = main_ret_ty.no_bound_vars().unwrap();
let start_instance = ty::Instance::resolve(
tcx,
ty::ParamEnv::reveal_all(),
start_id,
tcx.mk_substs(::std::iter::once(ty::subst::GenericArg::from(main_ret_ty))),
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)
.unwrap();
// First argument: pointer to `main()`.
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let main_ptr = ecx.memory.create_fn_alloc(FnVal::Instance(main_instance));
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// Second argument (argc): length of `config.args`.
let argc = Scalar::from_uint(config.args.len() as u128, ecx.pointer_size());
// Third argument (`argv`): created from `config.args`.
let argv = {
// Put each argument in memory, collect pointers.
let mut argvs = Vec::<Scalar<Tag>>::new();
for arg in config.args.iter() {
// Make space for `0` terminator.
let size = arg.len() as u64 + 1;
let arg_type = tcx.mk_array(tcx.types.u8, size);
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let arg_place = ecx.allocate(ecx.layout_of(arg_type)?, MiriMemoryKind::Machine.into());
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ecx.write_os_str_to_c_str(OsStr::new(arg), arg_place.ptr, size)?;
argvs.push(arg_place.ptr);
}
// Make an array with all these pointers, in the Miri memory.
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let argvs_layout =
ecx.layout_of(tcx.mk_array(tcx.mk_imm_ptr(tcx.types.u8), argvs.len() as u64))?;
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let argvs_place = ecx.allocate(argvs_layout, MiriMemoryKind::Machine.into());
for (idx, arg) in argvs.into_iter().enumerate() {
let place = ecx.mplace_field(argvs_place, idx as u64)?;
ecx.write_scalar(arg, place.into())?;
}
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ecx.memory.mark_immutable(argvs_place.ptr.assert_ptr().alloc_id)?;
// A pointer to that place is the 3rd argument for main.
let argv = argvs_place.ptr;
// Store `argc` and `argv` for macOS `_NSGetArg{c,v}`.
{
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let argc_place =
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ecx.allocate(ecx.layout_of(tcx.types.isize)?, MiriMemoryKind::Machine.into());
ecx.write_scalar(argc, argc_place.into())?;
ecx.machine.argc = Some(argc_place.ptr);
let argv_place = ecx.allocate(
ecx.layout_of(tcx.mk_imm_ptr(tcx.types.unit))?,
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MiriMemoryKind::Machine.into(),
);
ecx.write_scalar(argv, argv_place.into())?;
ecx.machine.argv = Some(argv_place.ptr);
}
// Store command line as UTF-16 for Windows `GetCommandLineW`.
{
// Construct a command string with all the aguments.
let mut cmd = String::new();
for arg in config.args.iter() {
if !cmd.is_empty() {
cmd.push(' ');
}
cmd.push_str(&*shell_escape::windows::escape(arg.as_str().into()));
}
// Don't forget `0` terminator.
cmd.push(std::char::from_u32(0).unwrap());
let cmd_utf16: Vec<u16> = cmd.encode_utf16().collect();
let cmd_type = tcx.mk_array(tcx.types.u16, cmd_utf16.len() as u64);
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let cmd_place = ecx.allocate(ecx.layout_of(cmd_type)?, MiriMemoryKind::Machine.into());
ecx.machine.cmd_line = Some(cmd_place.ptr);
// Store the UTF-16 string. We just allocated so we know the bounds are fine.
let char_size = Size::from_bytes(2);
for (idx, &c) in cmd_utf16.iter().enumerate() {
let place = ecx.mplace_field(cmd_place, idx as u64)?;
ecx.write_scalar(Scalar::from_uint(c, char_size), place.into())?;
}
}
argv
};
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// Return place (in static memory so that it does not count as leak).
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let ret_place = ecx.allocate(ecx.layout_of(tcx.types.isize)?, MiriMemoryKind::Machine.into());
// Call start function.
ecx.call_function(
start_instance,
&[main_ptr.into(), argc.into(), argv.into()],
Some(ret_place.into()),
StackPopCleanup::None { cleanup: true },
)?;
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// Set the last_error to 0
let errno_layout = ecx.layout_of(tcx.types.u32)?;
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let errno_place = ecx.allocate(errno_layout, MiriMemoryKind::Machine.into());
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ecx.write_scalar(Scalar::from_u32(0), errno_place.into())?;
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ecx.machine.last_error = Some(errno_place);
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Ok((ecx, ret_place))
}
/// Evaluates the main function specified by `main_id`.
/// Returns `Some(return_code)` if program executed completed.
/// Returns `None` if an evaluation error occured.
pub fn eval_main<'tcx>(tcx: TyCtxt<'tcx>, main_id: DefId, config: MiriConfig) -> Option<i64> {
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// FIXME: We always ignore leaks on some platforms where we do not
// correctly implement TLS destructors.
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let target_os = tcx.sess.target.target.target_os.as_str();
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let ignore_leaks = config.ignore_leaks || target_os == "windows" || target_os == "macos";
let (mut ecx, ret_place) = match create_ecx(tcx, main_id, config) {
Ok(v) => v,
Err(mut err) => {
err.print_backtrace();
panic!("Miri initialziation error: {}", err.kind)
}
};
// Perform the main execution.
let res: InterpResult<'_, i64> = (|| {
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while ecx.step()? {
ecx.process_diagnostics();
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}
// Read the return code pointer *before* we run TLS destructors, to assert
// that it was written to by the time that `start` lang item returned.
let return_code = ecx.read_scalar(ret_place.into())?.not_undef()?.to_machine_isize(&ecx)?;
ecx.run_tls_dtors()?;
Ok(return_code)
})();
// Process the result.
match res {
Ok(return_code) => {
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if !ignore_leaks {
let leaks = ecx.memory.leak_report();
if leaks != 0 {
tcx.sess.err("the evaluated program leaked memory");
// Ignore the provided return code - let the reported error
// determine the return code.
return None;
}
}
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Some(return_code)
}
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Err(e) => report_diagnostic(&ecx, e),
}
}