src/fn_call.rs

   1 use rustc::ty;
   2 use rustc::ty::layout::{Align, LayoutOf, Size};
   3 use rustc::hir::def_id::DefId;
   4 use rustc::mir;
   5 use syntax::attr;
   6
   7 use rand::RngCore;
   8
   9 use crate::*;
  10
  11 impl<'a, 'mir, 'tcx> EvalContextExt<'a, 'mir, 'tcx> for crate::MiriEvalContext<'a, 'mir, 'tcx> {}
  12 pub trait EvalContextExt<'a, 'mir, 'tcx: 'a + 'mir>: crate::MiriEvalContextExt<'a, 'mir, 'tcx> {
  13     fn find_fn(
  14         &mut self,
  15         instance: ty::Instance<'tcx>,
  16         args: &[OpTy<'tcx, Borrow>],
  17         dest: Option<PlaceTy<'tcx, Borrow>>,
  18         ret: Option<mir::BasicBlock>,
  19     ) -> EvalResult<'tcx, Option<&'mir mir::Mir<'tcx>>> {
  20         let this = self.eval_context_mut();
  21         trace!("eval_fn_call: {:#?}, {:?}", instance, dest.map(|place| *place));
  22
  23         // First, run the common hooks also supported by CTFE.
  24         if this.hook_fn(instance, args, dest)? {
  25             this.goto_block(ret)?;
  26             return Ok(None);
  27         }
  28         // There are some more lang items we want to hook that CTFE does not hook (yet).
  29         if this.tcx.lang_items().align_offset_fn() == Some(instance.def.def_id()) {
  30             // FIXME: return a real value in case the target allocation has an
  31             // alignment bigger than the one requested.
  32             let n = u128::max_value();
  33             let dest = dest.unwrap();
  34             let n = this.truncate(n, dest.layout);
  35             this.write_scalar(Scalar::from_uint(n, dest.layout.size), dest)?;
  36             this.goto_block(ret)?;
  37             return Ok(None);
  38         }
  39
  40         // Try to see if we can do something about foreign items.
  41         if this.tcx.is_foreign_item(instance.def_id()) {
  42             // An external function that we cannot find MIR for, but we can still run enough
  43             // of them to make miri viable.
  44             this.emulate_foreign_item(instance.def_id(), args, dest, ret)?;
  45             // `goto_block` already handled.
  46             return Ok(None);
  47         }
  48
  49         // Otherwise, load the MIR.
  50         Ok(Some(this.load_mir(instance.def)?))
  51     }
  52
  53     /// Emulates calling a foreign item, failing if the item is not supported.
  54     /// This function will handle `goto_block` if needed.
  55     fn emulate_foreign_item(
  56         &mut self,
  57         def_id: DefId,
  58         args: &[OpTy<'tcx, Borrow>],
  59         dest: Option<PlaceTy<'tcx, Borrow>>,
  60         ret: Option<mir::BasicBlock>,
  61     ) -> EvalResult<'tcx> {
  62         let this = self.eval_context_mut();
  63         let attrs = this.tcx.get_attrs(def_id);
  64         let link_name = match attr::first_attr_value_str_by_name(&attrs, "link_name") {
  65             Some(name) => name.as_str(),
  66             None => this.tcx.item_name(def_id).as_str(),
  67         };
  68         // Strip linker suffixes (seen on 32-bit macOS).
  69         let link_name = link_name.get().trim_end_matches("$UNIX2003");
  70         let tcx = &{this.tcx.tcx};
  71
  72         // First: functions that could diverge.
  73         match link_name {
  74             "__rust_start_panic" | "panic_impl" => {
  75                 return err!(MachineError("the evaluated program panicked".to_string()));
  76             }
  77             _ => if dest.is_none() {
  78                 return err!(Unimplemented(
  79                     format!("can't call diverging foreign function: {}", link_name),
  80                 ));
  81             }
  82         }
  83
  84         // Next: functions that assume a ret and dest.
  85         let dest = dest.expect("we already checked for a dest");
  86         let ret = ret.expect("dest is `Some` but ret is `None`");
  87         match link_name {
  88             "malloc" => {
  89                 let size = this.read_scalar(args[0])?.to_usize(this)?;
  90                 if size == 0 {
  91                     this.write_null(dest)?;
  92                 } else {
  93                     let align = this.tcx.data_layout.pointer_align.abi;
  94                     let ptr = this.memory_mut().allocate(Size::from_bytes(size), align, MiriMemoryKind::C.into());
  95                     this.write_scalar(Scalar::Ptr(ptr.with_default_tag()), dest)?;
  96                 }
  97             }
  98             "calloc" => {
  99                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 100                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 101                 let bytes = items.checked_mul(len).ok_or_else(|| InterpError::Overflow(mir::BinOp::Mul))?;
 102
 103                 if bytes == 0 {
 104                     this.write_null(dest)?;
 105                 } else {
 106                     let size = Size::from_bytes(bytes);
 107                     let align = this.tcx.data_layout.pointer_align.abi;
 108                     let ptr = this.memory_mut().allocate(size, align, MiriMemoryKind::C.into()).with_default_tag();
 109                     this.memory_mut().get_mut(ptr.alloc_id)?.write_repeat(tcx, ptr, 0, size)?;
 110                     this.write_scalar(Scalar::Ptr(ptr), dest)?;
 111                 }
 112             }
 113             "posix_memalign" => {
 114                 let ret = this.deref_operand(args[0])?;
 115                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 116                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 117                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 118                 if !align.is_power_of_two() {
 119                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 120                 }
 121                 if align < this.pointer_size().bytes() {
 122                     return err!(MachineError(format!(
 123                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 124                         align,
 125                     )));
 126                 }
 127                 if size == 0 {
 128                     this.write_null(ret.into())?;
 129                 } else {
 130                     let ptr = this.memory_mut().allocate(
 131                         Size::from_bytes(size),
 132                         Align::from_bytes(align).unwrap(),
 133                         MiriMemoryKind::C.into()
 134                     );
 135                     this.write_scalar(Scalar::Ptr(ptr.with_default_tag()), ret.into())?;
 136                 }
 137                 this.write_null(dest)?;
 138             }
 139
 140             "free" => {
 141                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 142                 if !ptr.is_null_ptr(this) {
 143                     this.memory_mut().deallocate(
 144                         ptr.to_ptr()?,
 145                         None,
 146                         MiriMemoryKind::C.into(),
 147                     )?;
 148                 }
 149             }
 150
 151             "__rust_alloc" => {
 152                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 153                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 154                 if size == 0 {
 155                     return err!(HeapAllocZeroBytes);
 156                 }
 157                 if !align.is_power_of_two() {
 158                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 159                 }
 160                 let ptr = this.memory_mut()
 161                     .allocate(
 162                         Size::from_bytes(size),
 163                         Align::from_bytes(align).unwrap(),
 164                         MiriMemoryKind::Rust.into()
 165                     )
 166                     .with_default_tag();
 167                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 168             }
 169             "__rust_alloc_zeroed" => {
 170                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 171                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 172                 if size == 0 {
 173                     return err!(HeapAllocZeroBytes);
 174                 }
 175                 if !align.is_power_of_two() {
 176                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 177                 }
 178                 let ptr = this.memory_mut()
 179                     .allocate(
 180                         Size::from_bytes(size),
 181                         Align::from_bytes(align).unwrap(),
 182                         MiriMemoryKind::Rust.into()
 183                     )
 184                     .with_default_tag();
 185                 this.memory_mut()
 186                     .get_mut(ptr.alloc_id)?
 187                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size))?;
 188                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 189             }
 190             "__rust_dealloc" => {
 191                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 192                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 193                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 194                 if old_size == 0 {
 195                     return err!(HeapAllocZeroBytes);
 196                 }
 197                 if !align.is_power_of_two() {
 198                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 199                 }
 200                 this.memory_mut().deallocate(
 201                     ptr,
 202                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 203                     MiriMemoryKind::Rust.into(),
 204                 )?;
 205             }
 206             "__rust_realloc" => {
 207                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 208                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 209                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 210                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 211                 if old_size == 0 || new_size == 0 {
 212                     return err!(HeapAllocZeroBytes);
 213                 }
 214                 if !align.is_power_of_two() {
 215                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 216                 }
 217                 let new_ptr = this.memory_mut().reallocate(
 218                     ptr,
 219                     Size::from_bytes(old_size),
 220                     Align::from_bytes(align).unwrap(),
 221                     Size::from_bytes(new_size),
 222                     Align::from_bytes(align).unwrap(),
 223                     MiriMemoryKind::Rust.into(),
 224                 )?;
 225                 this.write_scalar(Scalar::Ptr(new_ptr.with_default_tag()), dest)?;
 226             }
 227
 228             "syscall" => {
 229                 let sys_getrandom = this.eval_path_scalar(&["libc", "SYS_getrandom"])?
 230                     .expect("Failed to get libc::SYS_getrandom")
 231                     .to_usize(this)?;
 232
 233                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 234                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 235                 match this.read_scalar(args[0])?.to_usize(this)? {
 236                     id if id == sys_getrandom => {
 237                         let ptr = this.read_scalar(args[1])?.to_ptr()?;
 238                         let len = this.read_scalar(args[2])?.to_usize(this)?;
 239
 240                         // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 241                         // neither of which have any effect on our current PRNG
 242                         let _flags = this.read_scalar(args[3])?.to_i32()?;
 243
 244                         let data = gen_random(this, len as usize)?;
 245                         this.memory_mut().get_mut(ptr.alloc_id)?
 246                                     .write_bytes(tcx, ptr, &data)?;
 247
 248                         this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 249                     }
 250                     id => {
 251                         return err!(Unimplemented(
 252                             format!("miri does not support syscall ID {}", id),
 253                         ))
 254                     }
 255                 }
 256             }
 257
 258             "dlsym" => {
 259                 let _handle = this.read_scalar(args[0])?;
 260                 let symbol = this.read_scalar(args[1])?.to_ptr()?;
 261                 let symbol_name = this.memory().get(symbol.alloc_id)?.read_c_str(tcx, symbol)?;
 262                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 263                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 264                 return err!(Unimplemented(format!(
 265                     "miri does not support dynamically loading libraries (requested symbol: {})",
 266                     symbol_name
 267                 )));
 268             }
 269
 270             "__rust_maybe_catch_panic" => {
 271                 // fn __rust_maybe_catch_panic(
 272                 //     f: fn(*mut u8),
 273                 //     data: *mut u8,
 274                 //     data_ptr: *mut usize,
 275                 //     vtable_ptr: *mut usize,
 276                 // ) -> u32
 277                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 278                 let f = this.read_scalar(args[0])?.to_ptr()?;
 279                 let data = this.read_scalar(args[1])?.not_undef()?;
 280                 let f_instance = this.memory().get_fn(f)?;
 281                 this.write_null(dest)?;
 282                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 283
 284                 // Now we make a function call.
 285                 // TODO: consider making this reusable? `InterpretCx::step` does something similar
 286                 // for the TLS destructors, and of course `eval_main`.
 287                 let mir = this.load_mir(f_instance.def)?;
 288                 let ret_place = MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 289                 this.push_stack_frame(
 290                     f_instance,
 291                     mir.span,
 292                     mir,
 293                     Some(ret_place),
 294                     // Directly return to caller.
 295                     StackPopCleanup::Goto(Some(ret)),
 296                 )?;
 297                 let mut args = this.frame().mir.args_iter();
 298
 299                 let arg_local = args.next().ok_or_else(||
 300                     InterpError::AbiViolation(
 301                         "Argument to __rust_maybe_catch_panic does not take enough arguments."
 302                             .to_owned(),
 303                     ),
 304                 )?;
 305                 let arg_dest = this.eval_place(&mir::Place::Base(mir::PlaceBase::Local(arg_local)))?;
 306                 this.write_scalar(data, arg_dest)?;
 307
 308                 assert!(args.next().is_none(), "__rust_maybe_catch_panic argument has more arguments than expected");
 309
 310                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 311                 this.write_null(dest)?;
 312
 313                 // Don't fall through, we do *not* want to `goto_block`!
 314                 return Ok(());
 315             }
 316
 317             "memcmp" => {
 318                 let left = this.read_scalar(args[0])?.not_undef()?;
 319                 let right = this.read_scalar(args[1])?.not_undef()?;
 320                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 321
 322                 let result = {
 323                     let left_bytes = this.memory().read_bytes(left, n)?;
 324                     let right_bytes = this.memory().read_bytes(right, n)?;
 325
 326                     use std::cmp::Ordering::*;
 327                     match left_bytes.cmp(right_bytes) {
 328                         Less => -1i32,
 329                         Equal => 0,
 330                         Greater => 1,
 331                     }
 332                 };
 333
 334                 this.write_scalar(
 335                     Scalar::from_int(result, Size::from_bits(32)),
 336                     dest,
 337                 )?;
 338             }
 339
 340             "memrchr" => {
 341                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 342                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 343                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 344                 if let Some(idx) = this.memory().read_bytes(ptr, Size::from_bytes(num))?
 345                     .iter().rev().position(|&c| c == val)
 346                 {
 347                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 348                     this.write_scalar(new_ptr, dest)?;
 349                 } else {
 350                     this.write_null(dest)?;
 351                 }
 352             }
 353
 354             "memchr" => {
 355                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 356                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 357                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 358                 let idx = this
 359                     .memory()
 360                     .read_bytes(ptr, Size::from_bytes(num))?
 361                     .iter()
 362                     .position(|&c| c == val);
 363                 if let Some(idx) = idx {
 364                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 365                     this.write_scalar(new_ptr, dest)?;
 366                 } else {
 367                     this.write_null(dest)?;
 368                 }
 369             }
 370
 371             "getenv" => {
 372                 let result = {
 373                     let name_ptr = this.read_scalar(args[0])?.to_ptr()?;
 374                     let name = this.memory().get(name_ptr.alloc_id)?.read_c_str(tcx, name_ptr)?;
 375                     match this.machine.env_vars.get(name) {
 376                         Some(&var) => Scalar::Ptr(var),
 377                         None => Scalar::ptr_null(&*this.tcx),
 378                     }
 379                 };
 380                 this.write_scalar(result, dest)?;
 381             }
 382
 383             "unsetenv" => {
 384                 let mut success = None;
 385                 {
 386                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 387                     if !name_ptr.is_null_ptr(this) {
 388                         let name_ptr = name_ptr.to_ptr()?;
 389                         let name = this
 390                             .memory()
 391                             .get(name_ptr.alloc_id)?
 392                             .read_c_str(tcx, name_ptr)?
 393                             .to_owned();
 394                         if !name.is_empty() && !name.contains(&b'=') {
 395                             success = Some(this.machine.env_vars.remove(&name));
 396                         }
 397                     }
 398                 }
 399                 if let Some(old) = success {
 400                     if let Some(var) = old {
 401                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 402                     }
 403                     this.write_null(dest)?;
 404                 } else {
 405                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 406                 }
 407             }
 408
 409             "setenv" => {
 410                 let mut new = None;
 411                 {
 412                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 413                     let value_ptr = this.read_scalar(args[1])?.to_ptr()?;
 414                     let value = this.memory().get(value_ptr.alloc_id)?.read_c_str(tcx, value_ptr)?;
 415                     if !name_ptr.is_null_ptr(this) {
 416                         let name_ptr = name_ptr.to_ptr()?;
 417                         let name = this.memory().get(name_ptr.alloc_id)?.read_c_str(tcx, name_ptr)?;
 418                         if !name.is_empty() && !name.contains(&b'=') {
 419                             new = Some((name.to_owned(), value.to_owned()));
 420                         }
 421                     }
 422                 }
 423                 if let Some((name, value)) = new {
 424                     // `+1` for the null terminator.
 425                     let value_copy = this.memory_mut().allocate(
 426                         Size::from_bytes((value.len() + 1) as u64),
 427                         Align::from_bytes(1).unwrap(),
 428                         MiriMemoryKind::Env.into(),
 429                     ).with_default_tag();
 430                     {
 431                         let alloc = this.memory_mut().get_mut(value_copy.alloc_id)?;
 432                         alloc.write_bytes(tcx, value_copy, &value)?;
 433                         let trailing_zero_ptr = value_copy.offset(
 434                             Size::from_bytes(value.len() as u64),
 435                             tcx,
 436                         )?;
 437                         alloc.write_bytes(tcx, trailing_zero_ptr, &[0])?;
 438                     }
 439                     if let Some(var) = this.machine.env_vars.insert(
 440                         name.to_owned(),
 441                         value_copy,
 442                     )
 443                     {
 444                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 445                     }
 446                     this.write_null(dest)?;
 447                 } else {
 448                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 449                 }
 450             }
 451
 452             "write" => {
 453                 let fd = this.read_scalar(args[0])?.to_i32()?;
 454                 let buf = this.read_scalar(args[1])?.not_undef()?;
 455                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 456                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 457                 let result = if fd == 1 || fd == 2 {
 458                     // stdout/stderr
 459                     use std::io::{self, Write};
 460
 461                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 462                     // We need to flush to make sure this actually appears on the screen
 463                     let res = if fd == 1 {
 464                         // Stdout is buffered, flush to make sure it appears on the screen.
 465                         // This is the write() syscall of the interpreted program, we want it
 466                         // to correspond to a write() syscall on the host -- there is no good
 467                         // in adding extra buffering here.
 468                         let res = io::stdout().write(buf_cont);
 469                         io::stdout().flush().unwrap();
 470                         res
 471                     } else {
 472                         // No need to flush, stderr is not buffered.
 473                         io::stderr().write(buf_cont)
 474                     };
 475                     match res {
 476                         Ok(n) => n as i64,
 477                         Err(_) => -1,
 478                     }
 479                 } else {
 480                     eprintln!("Miri: Ignored output to FD {}", fd);
 481                     // Pretend it all went well.
 482                     n as i64
 483                 };
 484                 // Now, `result` is the value we return back to the program.
 485                 this.write_scalar(
 486                     Scalar::from_int(result, dest.layout.size),
 487                     dest,
 488                 )?;
 489             }
 490
 491             "strlen" => {
 492                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 493                 let n = this.memory().get(ptr.alloc_id)?.read_c_str(tcx, ptr)?.len();
 494                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 495             }
 496
 497             // Some things needed for `sys::thread` initialization to go through.
 498             "signal" | "sigaction" | "sigaltstack" => {
 499                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 500             }
 501
 502             "sysconf" => {
 503                 let name = this.read_scalar(args[0])?.to_i32()?;
 504
 505                 trace!("sysconf() called with name {}", name);
 506                 // Cache the sysconf integers via Miri's global cache.
 507                 let paths = &[
 508                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(4096, dest.layout.size)),
 509                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 510                     (&["libc", "_SC_NPROCESSORS_ONLN"], Scalar::from_int(1, dest.layout.size)),
 511                 ];
 512                 let mut result = None;
 513                 for &(path, path_value) in paths {
 514                     if let Some(val) = this.eval_path_scalar(path)? {
 515                         let val = val.to_i32()?;
 516                         if val == name {
 517                             result = Some(path_value);
 518                             break;
 519                         }
 520
 521                     }
 522                 }
 523                 if let Some(result) = result {
 524                     this.write_scalar(result, dest)?;
 525                 } else {
 526                     return err!(Unimplemented(
 527                         format!("Unimplemented sysconf name: {}", name),
 528                     ));
 529                 }
 530             }
 531
 532             "isatty" => {
 533                 this.write_null(dest)?;
 534             }
 535
 536             // Hook pthread calls that go to the thread-local storage memory subsystem.
 537             "pthread_key_create" => {
 538                 let key_ptr = this.read_scalar(args[0])?.to_ptr()?;
 539
 540                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 541                 let dtor = match this.read_scalar(args[1])?.not_undef()? {
 542                     Scalar::Ptr(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?),
 543                     Scalar::Bits { bits: 0, size } => {
 544                         assert_eq!(size as u64, this.memory().pointer_size().bytes());
 545                         None
 546                     },
 547                     Scalar::Bits { .. } => return err!(ReadBytesAsPointer),
 548                 };
 549
 550                 // Figure out how large a pthread TLS key actually is.
 551                 // This is `libc::pthread_key_t`.
 552                 let key_type = args[0].layout.ty
 553                     .builtin_deref(true)
 554                     .ok_or_else(|| InterpError::AbiViolation("wrong signature used for `pthread_key_create`: first argument must be a raw pointer.".to_owned()))?
 555                     .ty;
 556                 let key_layout = this.layout_of(key_type)?;
 557
 558                 // Create key and write it into the memory where `key_ptr` wants it.
 559                 let key = this.machine.tls.create_tls_key(dtor, tcx) as u128;
 560                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128) {
 561                     return err!(OutOfTls);
 562                 }
 563
 564                 this.memory().check_align(key_ptr.into(), key_layout.align.abi)?;
 565                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 566                     tcx,
 567                     key_ptr,
 568                     Scalar::from_uint(key, key_layout.size).into(),
 569                     key_layout.size,
 570                 )?;
 571
 572                 // Return success (`0`).
 573                 this.write_null(dest)?;
 574             }
 575             "pthread_key_delete" => {
 576                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 577                 this.machine.tls.delete_tls_key(key)?;
 578                 // Return success (0)
 579                 this.write_null(dest)?;
 580             }
 581             "pthread_getspecific" => {
 582                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 583                 let ptr = this.machine.tls.load_tls(key)?;
 584                 this.write_scalar(ptr, dest)?;
 585             }
 586             "pthread_setspecific" => {
 587                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 588                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 589                 this.machine.tls.store_tls(key, new_ptr)?;
 590
 591                 // Return success (`0`).
 592                 this.write_null(dest)?;
 593             }
 594
 595             // Determine stack base address.
 596             "pthread_attr_init" | "pthread_attr_destroy" | "pthread_attr_get_np" |
 597             "pthread_getattr_np" | "pthread_self" | "pthread_get_stacksize_np" => {
 598                 this.write_null(dest)?;
 599             }
 600             "pthread_attr_getstack" => {
 601                 // Second argument is where we are supposed to write the stack size.
 602                 let ptr = this.deref_operand(args[1])?;
 603                 // Just any address.
 604                 let stack_addr = Scalar::from_int(0x80000, args[1].layout.size);
 605                 this.write_scalar(stack_addr, ptr.into())?;
 606                 // Return success (`0`).
 607                 this.write_null(dest)?;
 608             }
 609             "pthread_get_stackaddr_np" => {
 610                 // Just any address.
 611                 let stack_addr = Scalar::from_int(0x80000, dest.layout.size);
 612                 this.write_scalar(stack_addr, dest)?;
 613             }
 614
 615             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 616             "pthread_mutexattr_init" | "pthread_mutexattr_settype" | "pthread_mutex_init" |
 617             "pthread_mutexattr_destroy" | "pthread_mutex_lock" | "pthread_mutex_unlock" |
 618             "pthread_mutex_destroy" | "pthread_rwlock_rdlock" | "pthread_rwlock_unlock" |
 619             "pthread_rwlock_wrlock" | "pthread_rwlock_destroy" | "pthread_condattr_init" |
 620             "pthread_condattr_setclock" | "pthread_cond_init" | "pthread_condattr_destroy" |
 621             "pthread_cond_destroy" => {
 622                 this.write_null(dest)?;
 623             }
 624
 625             "mmap" => {
 626                 // This is a horrible hack, but since the guard page mechanism calls mmap and expects a particular return value, we just give it that value.
 627                 let addr = this.read_scalar(args[0])?.not_undef()?;
 628                 this.write_scalar(addr, dest)?;
 629             }
 630             "mprotect" => {
 631                 this.write_null(dest)?;
 632             }
 633
 634             // macOS API stubs.
 635             "_tlv_atexit" => {
 636                 // FIXME: register the destructor.
 637             },
 638             "_NSGetArgc" => {
 639                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 640             },
 641             "_NSGetArgv" => {
 642                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 643             },
 644
 645             // Windows API stubs.
 646             "SetLastError" => {
 647                 let err = this.read_scalar(args[0])?.to_u32()?;
 648                 this.machine.last_error = err;
 649             }
 650             "GetLastError" => {
 651                 this.write_scalar(Scalar::from_uint(this.machine.last_error, Size::from_bits(32)), dest)?;
 652             }
 653
 654             "AddVectoredExceptionHandler" => {
 655                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 656                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 657             },
 658             "InitializeCriticalSection" |
 659             "EnterCriticalSection" |
 660             "LeaveCriticalSection" |
 661             "DeleteCriticalSection" => {
 662                 // Nothing to do, not even a return value.
 663             },
 664             "GetModuleHandleW" |
 665             "GetProcAddress" |
 666             "TryEnterCriticalSection" |
 667             "GetConsoleScreenBufferInfo" |
 668             "SetConsoleTextAttribute" => {
 669                 // Pretend these do not exist / nothing happened, by returning zero.
 670                 this.write_null(dest)?;
 671             },
 672             "GetSystemInfo" => {
 673                 let system_info = this.deref_operand(args[0])?;
 674                 let system_info_ptr = system_info.ptr.to_ptr()?;
 675                 // Initialize with `0`.
 676                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 677                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 678                 // Set number of processors to `1`.
 679                 let dword_size = Size::from_bytes(4);
 680                 let offset = 2*dword_size + 3*tcx.pointer_size();
 681                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 682                     .write_scalar(
 683                         tcx,
 684                         system_info_ptr.offset(offset, tcx)?,
 685                         Scalar::from_int(1, dword_size).into(),
 686                         dword_size,
 687                     )?;
 688             }
 689
 690             "TlsAlloc" => {
 691                 // This just creates a key; Windows does not natively support TLS destructors.
 692
 693                 // Create key and return it.
 694                 let key = this.machine.tls.create_tls_key(None, tcx) as u128;
 695
 696                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 697                 if dest.layout.size.bits() < 128
 698                         && key >= (1u128 << dest.layout.size.bits() as u128) {
 699                     return err!(OutOfTls);
 700                 }
 701                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 702             }
 703             "TlsGetValue" => {
 704                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 705                 let ptr = this.machine.tls.load_tls(key)?;
 706                 this.write_scalar(ptr, dest)?;
 707             }
 708             "TlsSetValue" => {
 709                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 710                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 711                 this.machine.tls.store_tls(key, new_ptr)?;
 712
 713                 // Return success (`1`).
 714                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 715             }
 716             "GetStdHandle" => {
 717                 let which = this.read_scalar(args[0])?.to_i32()?;
 718                 // We just make this the identity function, so we know later in `WriteFile`
 719                 // which one it is.
 720                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 721             }
 722             "WriteFile" => {
 723                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 724                 let buf = this.read_scalar(args[1])?.not_undef()?;
 725                 let n = this.read_scalar(args[2])?.to_u32()?;
 726                 let written_place = this.deref_operand(args[3])?;
 727                 // Spec says to always write `0` first.
 728                 this.write_null(written_place.into())?;
 729                 let written = if handle == -11 || handle == -12 {
 730                     // stdout/stderr
 731                     use std::io::{self, Write};
 732
 733                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 734                     let res = if handle == -11 {
 735                         io::stdout().write(buf_cont)
 736                     } else {
 737                         io::stderr().write(buf_cont)
 738                     };
 739                     res.ok().map(|n| n as u32)
 740                 } else {
 741                     eprintln!("Miri: Ignored output to handle {}", handle);
 742                     // Pretend it all went well.
 743                     Some(n)
 744                 };
 745                 // If there was no error, write back how much was written.
 746                 if let Some(n) = written {
 747                     this.write_scalar(Scalar::from_uint(n, Size::from_bits(32)), written_place.into())?;
 748                 }
 749                 // Return whether this was a success.
 750                 this.write_scalar(
 751                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 752                     dest,
 753                 )?;
 754             }
 755             "GetConsoleMode" => {
 756                 // Everything is a pipe.
 757                 this.write_null(dest)?;
 758             }
 759             "GetEnvironmentVariableW" => {
 760                 // This is not the env var you are looking for.
 761                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 762                 this.write_null(dest)?;
 763             }
 764             "GetCommandLineW" => {
 765                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 766             }
 767             // The actual name of 'RtlGenRandom'
 768             "SystemFunction036" => {
 769                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 770                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 771
 772                 let data = gen_random(this, len as usize)?;
 773                 this.memory_mut().get_mut(ptr.alloc_id)?
 774                     .write_bytes(tcx, ptr, &data)?;
 775
 776                 this.write_scalar(Scalar::from_bool(true), dest)?;
 777             }
 778
 779             // We can't execute anything else.
 780             _ => {
 781                 return err!(Unimplemented(
 782                     format!("can't call foreign function: {}", link_name),
 783                 ));
 784             }
 785         }
 786
 787         this.goto_block(Some(ret))?;
 788         this.dump_place(*dest);
 789         Ok(())
 790     }
 791
 792     fn write_null(&mut self, dest: PlaceTy<'tcx, Borrow>) -> EvalResult<'tcx> {
 793         self.eval_context_mut().write_scalar(Scalar::from_int(0, dest.layout.size), dest)
 794     }
 795
 796     /// Evaluates the scalar at the specified path. Returns Some(val)
 797     /// if the path could be resolved, and None otherwise
 798     fn eval_path_scalar(&mut self, path: &[&str]) -> EvalResult<'tcx, Option<ScalarMaybeUndef<stacked_borrows::Borrow>>> {
 799         let this = self.eval_context_mut();
 800         if let Ok(instance) = this.resolve_path(path) {
 801             let cid = GlobalId {
 802                 instance,
 803                 promoted: None,
 804             };
 805             let const_val = this.const_eval_raw(cid)?;
 806             let const_val = this.read_scalar(const_val.into())?;
 807             return Ok(Some(const_val));
 808         }
 809         return Ok(None);
 810     }
 811 }
 812
 813 fn gen_random<'a, 'mir, 'tcx>(
 814     this: &mut MiriEvalContext<'a, 'mir, 'tcx>,
 815     len: usize,
 816 ) -> Result<Vec<u8>, EvalError<'tcx>>  {
 817
 818     match &mut this.machine.rng {
 819         Some(rng) => {
 820             let mut data = vec![0; len];
 821             rng.fill_bytes(&mut data);
 822             Ok(data)
 823         }
 824         None => {
 825             err!(Unimplemented(
 826                 "miri does not support gathering system entropy in deterministic mode!
 827                 Use '-Zmiri-seed=<seed>' to enable random number generation.
 828                 WARNING: Miri does *not* generate cryptographically secure entropy -
 829                 do not use Miri to run any program that needs secure random number generation".to_owned(),
 830             ))
 831         }
 832     }
 833 }