src/shims/foreign_items.rs

   1 use rustc::ty::layout::{Align, LayoutOf, Size};
   2 use rustc::hir::def_id::DefId;
   3 use rustc::mir;
   4 use syntax::attr;
   5 use syntax::symbol::sym;
   6
   7 use crate::*;
   8
   9 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  10 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  11     /// Returns the minimum alignment for the target architecture for allocations of the given size.
  12     fn min_align(&self, size: u64, kind: MiriMemoryKind) -> Align {
  13         let this = self.eval_context_ref();
  14         // List taken from `libstd/sys_common/alloc.rs`.
  15         let min_align = match this.tcx.tcx.sess.target.target.arch.as_str() {
  16             "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
  17             "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" => 16,
  18             arch => bug!("Unsupported target architecture: {}", arch),
  19         };
  20         // Windows always aligns, even small allocations.
  21         // Source: <https://support.microsoft.com/en-us/help/286470/how-to-use-pageheap-exe-in-windows-xp-windows-2000-and-windows-server>
  22         // But jemalloc does not, so for the C heap we only align if the allocation is sufficiently big.
  23         if kind == MiriMemoryKind::WinHeap || size >= min_align {
  24             return Align::from_bytes(min_align).unwrap();
  25         }
  26         // We have `size < min_align`. Round `size` *down* to the next power of two and use that.
  27         fn prev_power_of_two(x: u64) -> u64 {
  28             let next_pow2 = x.next_power_of_two();
  29             if next_pow2 == x {
  30                 // x *is* a power of two, just use that.
  31                 x
  32             } else {
  33                 // x is between two powers, so next = 2*prev.
  34                 next_pow2 / 2
  35             }
  36         }
  37         Align::from_bytes(prev_power_of_two(size)).unwrap()
  38     }
  39
  40     fn malloc(
  41         &mut self,
  42         size: u64,
  43         zero_init: bool,
  44         kind: MiriMemoryKind,
  45     ) -> Scalar<Tag> {
  46         let this = self.eval_context_mut();
  47         let tcx = &{this.tcx.tcx};
  48         if size == 0 {
  49             Scalar::from_int(0, this.pointer_size())
  50         } else {
  51             let align = this.min_align(size, kind);
  52             let ptr = this.memory_mut().allocate(Size::from_bytes(size), align, kind.into());
  53             if zero_init {
  54                 // We just allocated this, the access cannot fail
  55                 this.memory_mut()
  56                     .get_mut(ptr.alloc_id).unwrap()
  57                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
  58             }
  59             Scalar::Ptr(ptr)
  60         }
  61     }
  62
  63     fn free(
  64         &mut self,
  65         ptr: Scalar<Tag>,
  66         kind: MiriMemoryKind,
  67     ) -> InterpResult<'tcx> {
  68         let this = self.eval_context_mut();
  69         if !this.is_null(ptr)? {
  70             let ptr = this.force_ptr(ptr)?;
  71             this.memory_mut().deallocate(
  72                 ptr,
  73                 None,
  74                 kind.into(),
  75             )?;
  76         }
  77         Ok(())
  78     }
  79
  80     fn realloc(
  81         &mut self,
  82         old_ptr: Scalar<Tag>,
  83         new_size: u64,
  84         kind: MiriMemoryKind,
  85     ) -> InterpResult<'tcx, Scalar<Tag>> {
  86         let this = self.eval_context_mut();
  87         let new_align = this.min_align(new_size, kind);
  88         if this.is_null(old_ptr)? {
  89             if new_size == 0 {
  90                 Ok(Scalar::from_int(0, this.pointer_size()))
  91             } else {
  92                 let new_ptr = this.memory_mut().allocate(
  93                     Size::from_bytes(new_size),
  94                     new_align,
  95                     kind.into()
  96                 );
  97                 Ok(Scalar::Ptr(new_ptr))
  98             }
  99         } else {
 100             let old_ptr = this.force_ptr(old_ptr)?;
 101             let memory = this.memory_mut();
 102             if new_size == 0 {
 103                 memory.deallocate(
 104                     old_ptr,
 105                     None,
 106                     kind.into(),
 107                 )?;
 108                 Ok(Scalar::from_int(0, this.pointer_size()))
 109             } else {
 110                 let new_ptr = memory.reallocate(
 111                     old_ptr,
 112                     None,
 113                     Size::from_bytes(new_size),
 114                     new_align,
 115                     kind.into(),
 116                 )?;
 117                 Ok(Scalar::Ptr(new_ptr))
 118             }
 119         }
 120     }
 121
 122     /// Emulates calling a foreign item, failing if the item is not supported.
 123     /// This function will handle `goto_block` if needed.
 124     fn emulate_foreign_item(
 125         &mut self,
 126         def_id: DefId,
 127         args: &[OpTy<'tcx, Tag>],
 128         dest: Option<PlaceTy<'tcx, Tag>>,
 129         ret: Option<mir::BasicBlock>,
 130     ) -> InterpResult<'tcx> {
 131         use rustc::mir::interpret::InterpError::Panic;
 132         let this = self.eval_context_mut();
 133         let attrs = this.tcx.get_attrs(def_id);
 134         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 135             Some(name) => name.as_str(),
 136             None => this.tcx.item_name(def_id).as_str(),
 137         };
 138         // Strip linker suffixes (seen on 32-bit macOS).
 139         let link_name = link_name.get().trim_end_matches("$UNIX2003");
 140         let tcx = &{this.tcx.tcx};
 141
 142         // First: functions that diverge.
 143         match link_name {
 144             "__rust_start_panic" | "panic_impl" => {
 145                 return err!(MachineError("the evaluated program panicked".to_string()));
 146             }
 147             "exit" | "ExitProcess" => {
 148                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` error variant anyway
 149                 let code = this.read_scalar(args[0])?.to_i32()?;
 150                 return err!(Exit(code));
 151             }
 152             _ => if dest.is_none() {
 153                 return err!(Unimplemented(
 154                     format!("can't call diverging foreign function: {}", link_name),
 155                 ));
 156             }
 157         }
 158
 159         // Next: functions that assume a ret and dest.
 160         let dest = dest.expect("we already checked for a dest");
 161         let ret = ret.expect("dest is `Some` but ret is `None`");
 162         match link_name {
 163             "malloc" => {
 164                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 165                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 166                 this.write_scalar(res, dest)?;
 167             }
 168             "calloc" => {
 169                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 170                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 171                 let size = items.checked_mul(len).ok_or_else(|| Panic(PanicMessage::Overflow(mir::BinOp::Mul)))?;
 172                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 173                 this.write_scalar(res, dest)?;
 174             }
 175             "posix_memalign" => {
 176                 let ret = this.deref_operand(args[0])?;
 177                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 178                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 179                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 180                 if !align.is_power_of_two() {
 181                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 182                 }
 183                 /*
 184                 FIXME: This check is disabled because rustc violates it.
 185                 See <https://github.com/rust-lang/rust/issues/62251>.
 186                 if align < this.pointer_size().bytes() {
 187                     return err!(MachineError(format!(
 188                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 189                         align,
 190                     )));
 191                 }
 192                 */
 193                 if size == 0 {
 194                     this.write_null(ret.into())?;
 195                 } else {
 196                     let ptr = this.memory_mut().allocate(
 197                         Size::from_bytes(size),
 198                         Align::from_bytes(align).unwrap(),
 199                         MiriMemoryKind::C.into()
 200                     );
 201                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 202                 }
 203                 this.write_null(dest)?;
 204             }
 205             "free" => {
 206                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 207                 this.free(ptr, MiriMemoryKind::C)?;
 208             }
 209             "realloc" => {
 210                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 211                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 212                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 213                 this.write_scalar(res, dest)?;
 214             }
 215
 216             "__rust_alloc" => {
 217                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 218                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 219                 if size == 0 {
 220                     return err!(HeapAllocZeroBytes);
 221                 }
 222                 if !align.is_power_of_two() {
 223                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 224                 }
 225                 let ptr = this.memory_mut()
 226                     .allocate(
 227                         Size::from_bytes(size),
 228                         Align::from_bytes(align).unwrap(),
 229                         MiriMemoryKind::Rust.into()
 230                     );
 231                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 232             }
 233             "__rust_alloc_zeroed" => {
 234                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 235                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 236                 if size == 0 {
 237                     return err!(HeapAllocZeroBytes);
 238                 }
 239                 if !align.is_power_of_two() {
 240                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 241                 }
 242                 let ptr = this.memory_mut()
 243                     .allocate(
 244                         Size::from_bytes(size),
 245                         Align::from_bytes(align).unwrap(),
 246                         MiriMemoryKind::Rust.into()
 247                     );
 248                 // We just allocated this, the access cannot fail
 249                 this.memory_mut()
 250                     .get_mut(ptr.alloc_id).unwrap()
 251                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
 252                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 253             }
 254             "__rust_dealloc" => {
 255                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 256                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 257                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 258                 if old_size == 0 {
 259                     return err!(HeapAllocZeroBytes);
 260                 }
 261                 if !align.is_power_of_two() {
 262                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 263                 }
 264                 let ptr = this.force_ptr(ptr)?;
 265                 this.memory_mut().deallocate(
 266                     ptr,
 267                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 268                     MiriMemoryKind::Rust.into(),
 269                 )?;
 270             }
 271             "__rust_realloc" => {
 272                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 273                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 274                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 275                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 276                 if old_size == 0 || new_size == 0 {
 277                     return err!(HeapAllocZeroBytes);
 278                 }
 279                 if !align.is_power_of_two() {
 280                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 281                 }
 282                 let align = Align::from_bytes(align).unwrap();
 283                 let new_ptr = this.memory_mut().reallocate(
 284                     ptr,
 285                     Some((Size::from_bytes(old_size), align)),
 286                     Size::from_bytes(new_size),
 287                     align,
 288                     MiriMemoryKind::Rust.into(),
 289                 )?;
 290                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 291             }
 292
 293             "syscall" => {
 294                 let sys_getrandom = this.eval_path_scalar(&["libc", "SYS_getrandom"])?
 295                     .expect("Failed to get libc::SYS_getrandom")
 296                     .to_usize(this)?;
 297
 298                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 299                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 300                 match this.read_scalar(args[0])?.to_usize(this)? {
 301                     id if id == sys_getrandom => {
 302                         let ptr = this.read_scalar(args[1])?.not_undef()?;
 303                         let len = this.read_scalar(args[2])?.to_usize(this)?;
 304
 305                         // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 306                         // neither of which have any effect on our current PRNG
 307                         let _flags = this.read_scalar(args[3])?.to_i32()?;
 308
 309                         this.gen_random(len as usize, ptr)?;
 310                         this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 311                     }
 312                     id => {
 313                         return err!(Unimplemented(
 314                             format!("miri does not support syscall ID {}", id),
 315                         ))
 316                     }
 317                 }
 318             }
 319
 320             "dlsym" => {
 321                 let _handle = this.read_scalar(args[0])?;
 322                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 323                 let symbol_name = this.memory().read_c_str(symbol)?;
 324                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 325                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 326                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 327                     let ptr = this.memory_mut().create_fn_alloc(FnVal::Other(dlsym));
 328                     this.write_scalar(Scalar::from(ptr), dest)?;
 329                 } else {
 330                     this.write_null(dest)?;
 331                 }
 332             }
 333
 334             "__rust_maybe_catch_panic" => {
 335                 // fn __rust_maybe_catch_panic(
 336                 //     f: fn(*mut u8),
 337                 //     data: *mut u8,
 338                 //     data_ptr: *mut usize,
 339                 //     vtable_ptr: *mut usize,
 340                 // ) -> u32
 341                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 342                 let f = this.read_scalar(args[0])?.not_undef()?;
 343                 let data = this.read_scalar(args[1])?.not_undef()?;
 344                 let f_instance = this.memory().get_fn(f)?.as_instance()?;
 345                 this.write_null(dest)?;
 346                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 347
 348                 // Now we make a function call.
 349                 // TODO: consider making this reusable? `InterpCx::step` does something similar
 350                 // for the TLS destructors, and of course `eval_main`.
 351                 let mir = this.load_mir(f_instance.def)?;
 352                 let ret_place = MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 353                 this.push_stack_frame(
 354                     f_instance,
 355                     mir.span,
 356                     mir,
 357                     Some(ret_place),
 358                     // Directly return to caller.
 359                     StackPopCleanup::Goto(Some(ret)),
 360                 )?;
 361                 let mut args = this.frame().body.args_iter();
 362
 363                 let arg_local = args.next().ok_or_else(||
 364                     InterpError::AbiViolation(
 365                         "Argument to __rust_maybe_catch_panic does not take enough arguments."
 366                             .to_owned(),
 367                     ),
 368                 )?;
 369                 let arg_dest = this.local_place(arg_local)?;
 370                 this.write_scalar(data, arg_dest)?;
 371
 372                 assert!(args.next().is_none(), "__rust_maybe_catch_panic argument has more arguments than expected");
 373
 374                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 375                 this.write_null(dest)?;
 376
 377                 // Don't fall through, we do *not* want to `goto_block`!
 378                 return Ok(());
 379             }
 380
 381             "memcmp" => {
 382                 let left = this.read_scalar(args[0])?.not_undef()?;
 383                 let right = this.read_scalar(args[1])?.not_undef()?;
 384                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 385
 386                 let result = {
 387                     let left_bytes = this.memory().read_bytes(left, n)?;
 388                     let right_bytes = this.memory().read_bytes(right, n)?;
 389
 390                     use std::cmp::Ordering::*;
 391                     match left_bytes.cmp(right_bytes) {
 392                         Less => -1i32,
 393                         Equal => 0,
 394                         Greater => 1,
 395                     }
 396                 };
 397
 398                 this.write_scalar(
 399                     Scalar::from_int(result, Size::from_bits(32)),
 400                     dest,
 401                 )?;
 402             }
 403
 404             "memrchr" => {
 405                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 406                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 407                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 408                 if let Some(idx) = this.memory().read_bytes(ptr, Size::from_bytes(num))?
 409                     .iter().rev().position(|&c| c == val)
 410                 {
 411                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 412                     this.write_scalar(new_ptr, dest)?;
 413                 } else {
 414                     this.write_null(dest)?;
 415                 }
 416             }
 417
 418             "memchr" => {
 419                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 420                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 421                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 422                 let idx = this
 423                     .memory()
 424                     .read_bytes(ptr, Size::from_bytes(num))?
 425                     .iter()
 426                     .position(|&c| c == val);
 427                 if let Some(idx) = idx {
 428                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 429                     this.write_scalar(new_ptr, dest)?;
 430                 } else {
 431                     this.write_null(dest)?;
 432                 }
 433             }
 434
 435             "getenv" => {
 436                 let result = {
 437                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 438                     let name = this.memory().read_c_str(name_ptr)?;
 439                     match this.machine.env_vars.get(name) {
 440                         Some(&var) => Scalar::Ptr(var),
 441                         None => Scalar::ptr_null(&*this.tcx),
 442                     }
 443                 };
 444                 this.write_scalar(result, dest)?;
 445             }
 446
 447             "unsetenv" => {
 448                 let mut success = None;
 449                 {
 450                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 451                     if !this.is_null(name_ptr)? {
 452                         let name = this.memory().read_c_str(name_ptr)?.to_owned();
 453                         if !name.is_empty() && !name.contains(&b'=') {
 454                             success = Some(this.machine.env_vars.remove(&name));
 455                         }
 456                     }
 457                 }
 458                 if let Some(old) = success {
 459                     if let Some(var) = old {
 460                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 461                     }
 462                     this.write_null(dest)?;
 463                 } else {
 464                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 465                 }
 466             }
 467
 468             "setenv" => {
 469                 let mut new = None;
 470                 {
 471                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 472                     let value_ptr = this.read_scalar(args[1])?.not_undef()?;
 473                     let value = this.memory().read_c_str(value_ptr)?;
 474                     if !this.is_null(name_ptr)? {
 475                         let name = this.memory().read_c_str(name_ptr)?;
 476                         if !name.is_empty() && !name.contains(&b'=') {
 477                             new = Some((name.to_owned(), value.to_owned()));
 478                         }
 479                     }
 480                 }
 481                 if let Some((name, value)) = new {
 482                     // `+1` for the null terminator.
 483                     let value_copy = this.memory_mut().allocate(
 484                         Size::from_bytes((value.len() + 1) as u64),
 485                         Align::from_bytes(1).unwrap(),
 486                         MiriMemoryKind::Env.into(),
 487                     );
 488                     // We just allocated these, so the write cannot fail.
 489                     let alloc = this.memory_mut().get_mut(value_copy.alloc_id).unwrap();
 490                     alloc.write_bytes(tcx, value_copy, &value).unwrap();
 491                     let trailing_zero_ptr = value_copy.offset(
 492                         Size::from_bytes(value.len() as u64),
 493                         tcx,
 494                     ).unwrap();
 495                     alloc.write_bytes(tcx, trailing_zero_ptr, &[0]).unwrap();
 496
 497                     if let Some(var) = this.machine.env_vars.insert(
 498                         name.to_owned(),
 499                         value_copy,
 500                     )
 501                     {
 502                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 503                     }
 504                     this.write_null(dest)?;
 505                 } else {
 506                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 507                 }
 508             }
 509
 510             "write" => {
 511                 let fd = this.read_scalar(args[0])?.to_i32()?;
 512                 let buf = this.read_scalar(args[1])?.not_undef()?;
 513                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 514                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 515                 let result = if fd == 1 || fd == 2 {
 516                     // stdout/stderr
 517                     use std::io::{self, Write};
 518
 519                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 520                     // We need to flush to make sure this actually appears on the screen
 521                     let res = if fd == 1 {
 522                         // Stdout is buffered, flush to make sure it appears on the screen.
 523                         // This is the write() syscall of the interpreted program, we want it
 524                         // to correspond to a write() syscall on the host -- there is no good
 525                         // in adding extra buffering here.
 526                         let res = io::stdout().write(buf_cont);
 527                         io::stdout().flush().unwrap();
 528                         res
 529                     } else {
 530                         // No need to flush, stderr is not buffered.
 531                         io::stderr().write(buf_cont)
 532                     };
 533                     match res {
 534                         Ok(n) => n as i64,
 535                         Err(_) => -1,
 536                     }
 537                 } else {
 538                     eprintln!("Miri: Ignored output to FD {}", fd);
 539                     // Pretend it all went well.
 540                     n as i64
 541                 };
 542                 // Now, `result` is the value we return back to the program.
 543                 this.write_scalar(
 544                     Scalar::from_int(result, dest.layout.size),
 545                     dest,
 546                 )?;
 547             }
 548
 549             "strlen" => {
 550                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 551                 let n = this.memory().read_c_str(ptr)?.len();
 552                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 553             }
 554
 555             // math functions
 556
 557             "cbrtf" | "coshf" | "sinhf" |"tanf" => {
 558                 // FIXME: Using host floats.
 559                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 560                 let f = match link_name {
 561                     "cbrtf" => f.cbrt(),
 562                     "coshf" => f.cosh(),
 563                     "sinhf" => f.sinh(),
 564                     "tanf" => f.tan(),
 565                     _ => bug!(),
 566                 };
 567                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 568             }
 569             // underscore case for windows
 570             "_hypotf" | "hypotf" | "atan2f" => {
 571                 // FIXME: Using host floats.
 572                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 573                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 574                 let n = match link_name {
 575                     "_hypotf" | "hypotf" => f1.hypot(f2),
 576                     "atan2f" => f1.atan2(f2),
 577                     _ => bug!(),
 578                 };
 579                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 580             }
 581
 582             "cbrt" | "cosh" | "sinh" | "tan" => {
 583                 // FIXME: Using host floats.
 584                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 585                 let f = match link_name {
 586                     "cbrt" => f.cbrt(),
 587                     "cosh" => f.cosh(),
 588                     "sinh" => f.sinh(),
 589                     "tan" => f.tan(),
 590                     _ => bug!(),
 591                 };
 592                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 593             }
 594             // underscore case for windows
 595             "_hypot" | "hypot" | "atan2" => {
 596                 // FIXME: Using host floats.
 597                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 598                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 599                 let n = match link_name {
 600                     "_hypot" | "hypot" => f1.hypot(f2),
 601                     "atan2" => f1.atan2(f2),
 602                     _ => bug!(),
 603                 };
 604                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 605             }
 606
 607             // Some things needed for `sys::thread` initialization to go through.
 608             "signal" | "sigaction" | "sigaltstack" => {
 609                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 610             }
 611
 612             "sysconf" => {
 613                 let name = this.read_scalar(args[0])?.to_i32()?;
 614
 615                 trace!("sysconf() called with name {}", name);
 616                 // TODO: Cache the sysconf integers via Miri's global cache.
 617                 let paths = &[
 618                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(PAGE_SIZE, dest.layout.size)),
 619                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 620                     (&["libc", "_SC_NPROCESSORS_ONLN"], Scalar::from_int(NUM_CPUS, dest.layout.size)),
 621                 ];
 622                 let mut result = None;
 623                 for &(path, path_value) in paths {
 624                     if let Some(val) = this.eval_path_scalar(path)? {
 625                         let val = val.to_i32()?;
 626                         if val == name {
 627                             result = Some(path_value);
 628                             break;
 629                         }
 630
 631                     }
 632                 }
 633                 if let Some(result) = result {
 634                     this.write_scalar(result, dest)?;
 635                 } else {
 636                     return err!(Unimplemented(
 637                         format!("Unimplemented sysconf name: {}", name),
 638                     ));
 639                 }
 640             }
 641
 642             "sched_getaffinity" => {
 643                 // Return an error; `num_cpus` then falls back to `sysconf`.
 644                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 645             }
 646
 647             "isatty" => {
 648                 this.write_null(dest)?;
 649             }
 650
 651             // Hook pthread calls that go to the thread-local storage memory subsystem.
 652             "pthread_key_create" => {
 653                 let key_ptr = this.read_scalar(args[0])?.not_undef()?;
 654
 655                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 656                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 657                     Some(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?.as_instance()?),
 658                     None => None,
 659                 };
 660
 661                 // Figure out how large a pthread TLS key actually is.
 662                 // This is `libc::pthread_key_t`.
 663                 let key_type = args[0].layout.ty
 664                     .builtin_deref(true)
 665                     .ok_or_else(|| InterpError::AbiViolation("wrong signature used for `pthread_key_create`: first argument must be a raw pointer.".to_owned()))?
 666                     .ty;
 667                 let key_layout = this.layout_of(key_type)?;
 668
 669                 // Create key and write it into the memory where `key_ptr` wants it.
 670                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 671                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128) {
 672                     return err!(OutOfTls);
 673                 }
 674
 675                 let key_ptr = this.memory().check_ptr_access(key_ptr, key_layout.size, key_layout.align.abi)?
 676                     .expect("cannot be a ZST");
 677                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 678                     tcx,
 679                     key_ptr,
 680                     Scalar::from_uint(key, key_layout.size).into(),
 681                     key_layout.size,
 682                 )?;
 683
 684                 // Return success (`0`).
 685                 this.write_null(dest)?;
 686             }
 687             "pthread_key_delete" => {
 688                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 689                 this.machine.tls.delete_tls_key(key)?;
 690                 // Return success (0)
 691                 this.write_null(dest)?;
 692             }
 693             "pthread_getspecific" => {
 694                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 695                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 696                 this.write_scalar(ptr, dest)?;
 697             }
 698             "pthread_setspecific" => {
 699                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 700                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 701                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 702
 703                 // Return success (`0`).
 704                 this.write_null(dest)?;
 705             }
 706
 707             // Stack size/address stuff.
 708             "pthread_attr_init" | "pthread_attr_destroy" | "pthread_self" |
 709             "pthread_attr_setstacksize" => {
 710                 this.write_null(dest)?;
 711             }
 712             "pthread_attr_getstack" => {
 713                 let addr_place = this.deref_operand(args[1])?;
 714                 let size_place = this.deref_operand(args[2])?;
 715
 716                 this.write_scalar(
 717                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 718                     addr_place.into(),
 719                 )?;
 720                 this.write_scalar(
 721                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 722                     size_place.into(),
 723                 )?;
 724
 725                 // Return success (`0`).
 726                 this.write_null(dest)?;
 727             }
 728
 729             // We don't support threading. (Also for Windows.)
 730             "pthread_create" | "CreateThread" => {
 731                 return err!(Unimplemented(format!("Miri does not support threading")));
 732             }
 733
 734             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 735             "pthread_mutexattr_init" | "pthread_mutexattr_settype" | "pthread_mutex_init" |
 736             "pthread_mutexattr_destroy" | "pthread_mutex_lock" | "pthread_mutex_unlock" |
 737             "pthread_mutex_destroy" | "pthread_rwlock_rdlock" | "pthread_rwlock_unlock" |
 738             "pthread_rwlock_wrlock" | "pthread_rwlock_destroy" | "pthread_condattr_init" |
 739             "pthread_condattr_setclock" | "pthread_cond_init" | "pthread_condattr_destroy" |
 740             "pthread_cond_destroy" => {
 741                 this.write_null(dest)?;
 742             }
 743
 744             // We don't support fork so we don't have to do anything for atfork.
 745             "pthread_atfork" => {
 746                 this.write_null(dest)?;
 747             }
 748
 749             "mmap" => {
 750                 // 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.
 751                 let addr = this.read_scalar(args[0])?.not_undef()?;
 752                 this.write_scalar(addr, dest)?;
 753             }
 754             "mprotect" => {
 755                 this.write_null(dest)?;
 756             }
 757
 758             // macOS API stubs.
 759             "pthread_attr_get_np" | "pthread_getattr_np" => {
 760                 this.write_null(dest)?;
 761             }
 762             "pthread_get_stackaddr_np" => {
 763                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 764                 this.write_scalar(stack_addr, dest)?;
 765             }
 766             "pthread_get_stacksize_np" => {
 767                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 768                 this.write_scalar(stack_size, dest)?;
 769             }
 770             "_tlv_atexit" => {
 771                 // FIXME: register the destructor.
 772             },
 773             "_NSGetArgc" => {
 774                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 775             },
 776             "_NSGetArgv" => {
 777                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 778             },
 779             "SecRandomCopyBytes" => {
 780                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 781                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 782                 this.gen_random(len as usize, ptr)?;
 783                 this.write_null(dest)?;
 784             }
 785
 786             // Windows API stubs.
 787             // HANDLE = isize
 788             // DWORD = ULONG = u32
 789             // BOOL = i32
 790             "GetProcessHeap" => {
 791                 // Just fake a HANDLE
 792                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 793             }
 794             "HeapAlloc" => {
 795                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 796                 let flags = this.read_scalar(args[1])?.to_u32()?;
 797                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 798                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 799                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 800                 this.write_scalar(res, dest)?;
 801             }
 802             "HeapFree" => {
 803                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 804                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 805                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 806                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 807                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 808             }
 809             "HeapReAlloc" => {
 810                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 811                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 812                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 813                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 814                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 815                 this.write_scalar(res, dest)?;
 816             }
 817
 818             "SetLastError" => {
 819                 let err = this.read_scalar(args[0])?.to_u32()?;
 820                 this.machine.last_error = err;
 821             }
 822             "GetLastError" => {
 823                 this.write_scalar(Scalar::from_u32(this.machine.last_error), dest)?;
 824             }
 825
 826             "AddVectoredExceptionHandler" => {
 827                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 828                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 829             },
 830             "InitializeCriticalSection" |
 831             "EnterCriticalSection" |
 832             "LeaveCriticalSection" |
 833             "DeleteCriticalSection" => {
 834                 // Nothing to do, not even a return value.
 835             },
 836             "GetModuleHandleW" |
 837             "GetProcAddress" |
 838             "TryEnterCriticalSection" |
 839             "GetConsoleScreenBufferInfo" |
 840             "SetConsoleTextAttribute" => {
 841                 // Pretend these do not exist / nothing happened, by returning zero.
 842                 this.write_null(dest)?;
 843             },
 844             "GetSystemInfo" => {
 845                 let system_info = this.deref_operand(args[0])?;
 846                 let system_info_ptr = this.check_mplace_access(system_info, None)?
 847                     .expect("cannot be a ZST");
 848                 // Initialize with `0`.
 849                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 850                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 851                 // Set number of processors.
 852                 let dword_size = Size::from_bytes(4);
 853                 let offset = 2*dword_size + 3*tcx.pointer_size();
 854                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 855                     .write_scalar(
 856                         tcx,
 857                         system_info_ptr.offset(offset, tcx)?,
 858                         Scalar::from_int(NUM_CPUS, dword_size).into(),
 859                         dword_size,
 860                     )?;
 861             }
 862
 863             "TlsAlloc" => {
 864                 // This just creates a key; Windows does not natively support TLS destructors.
 865
 866                 // Create key and return it.
 867                 let key = this.machine.tls.create_tls_key(None) as u128;
 868
 869                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 870                 if dest.layout.size.bits() < 128
 871                         && key >= (1u128 << dest.layout.size.bits() as u128) {
 872                     return err!(OutOfTls);
 873                 }
 874                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 875             }
 876             "TlsGetValue" => {
 877                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 878                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 879                 this.write_scalar(ptr, dest)?;
 880             }
 881             "TlsSetValue" => {
 882                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 883                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 884                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 885
 886                 // Return success (`1`).
 887                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 888             }
 889             "GetStdHandle" => {
 890                 let which = this.read_scalar(args[0])?.to_i32()?;
 891                 // We just make this the identity function, so we know later in `WriteFile`
 892                 // which one it is.
 893                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 894             }
 895             "WriteFile" => {
 896                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 897                 let buf = this.read_scalar(args[1])?.not_undef()?;
 898                 let n = this.read_scalar(args[2])?.to_u32()?;
 899                 let written_place = this.deref_operand(args[3])?;
 900                 // Spec says to always write `0` first.
 901                 this.write_null(written_place.into())?;
 902                 let written = if handle == -11 || handle == -12 {
 903                     // stdout/stderr
 904                     use std::io::{self, Write};
 905
 906                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 907                     let res = if handle == -11 {
 908                         io::stdout().write(buf_cont)
 909                     } else {
 910                         io::stderr().write(buf_cont)
 911                     };
 912                     res.ok().map(|n| n as u32)
 913                 } else {
 914                     eprintln!("Miri: Ignored output to handle {}", handle);
 915                     // Pretend it all went well.
 916                     Some(n)
 917                 };
 918                 // If there was no error, write back how much was written.
 919                 if let Some(n) = written {
 920                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 921                 }
 922                 // Return whether this was a success.
 923                 this.write_scalar(
 924                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 925                     dest,
 926                 )?;
 927             }
 928             "GetConsoleMode" => {
 929                 // Everything is a pipe.
 930                 this.write_null(dest)?;
 931             }
 932             "GetEnvironmentVariableW" => {
 933                 // This is not the env var you are looking for.
 934                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 935                 this.write_null(dest)?;
 936             }
 937             "GetCommandLineW" => {
 938                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 939             }
 940             // The actual name of 'RtlGenRandom'
 941             "SystemFunction036" => {
 942                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 943                 let len = this.read_scalar(args[1])?.to_u32()?;
 944                 this.gen_random(len as usize, ptr)?;
 945                 this.write_scalar(Scalar::from_bool(true), dest)?;
 946             }
 947
 948             // We can't execute anything else.
 949             _ => {
 950                 return err!(Unimplemented(
 951                     format!("can't call foreign function: {}", link_name),
 952                 ));
 953             }
 954         }
 955
 956         this.goto_block(Some(ret))?;
 957         this.dump_place(*dest);
 958         Ok(())
 959     }
 960
 961     /// Evaluates the scalar at the specified path. Returns Some(val)
 962     /// if the path could be resolved, and None otherwise
 963     fn eval_path_scalar(&mut self, path: &[&str]) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 964         let this = self.eval_context_mut();
 965         if let Ok(instance) = this.resolve_path(path) {
 966             let cid = GlobalId {
 967                 instance,
 968                 promoted: None,
 969             };
 970             let const_val = this.const_eval_raw(cid)?;
 971             let const_val = this.read_scalar(const_val.into())?;
 972             return Ok(Some(const_val));
 973         }
 974         return Ok(None);
 975     }
 976 }