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         let this = self.eval_context_mut();
 132         let attrs = this.tcx.get_attrs(def_id);
 133         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 134             Some(name) => name.as_str(),
 135             None => this.tcx.item_name(def_id).as_str(),
 136         };
 137         // Strip linker suffixes (seen on 32-bit macOS).
 138         let link_name = link_name.get().trim_end_matches("$UNIX2003");
 139         let tcx = &{this.tcx.tcx};
 140
 141         // First: functions that diverge.
 142         match link_name {
 143             "__rust_start_panic" | "panic_impl" => {
 144                 throw_unsup!(MachineError("the evaluated program panicked".to_string()));
 145             }
 146             "exit" | "ExitProcess" => {
 147                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` error variant anyway
 148                 let code = this.read_scalar(args[0])?.to_i32()?;
 149                 return Err(InterpError::Exit(code).into());
 150             }
 151             _ => if dest.is_none() {
 152                 throw_unsup!(Unimplemented(
 153                     format!("can't call diverging foreign function: {}", link_name),
 154                 ));
 155             }
 156         }
 157
 158         // Next: functions that assume a ret and dest.
 159         let dest = dest.expect("we already checked for a dest");
 160         let ret = ret.expect("dest is `Some` but ret is `None`");
 161         match link_name {
 162             "malloc" => {
 163                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 164                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 165                 this.write_scalar(res, dest)?;
 166             }
 167             "calloc" => {
 168                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 169                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 170                 let size = items.checked_mul(len).ok_or_else(|| err_panic!(Overflow(mir::BinOp::Mul)))?;
 171                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 172                 this.write_scalar(res, dest)?;
 173             }
 174             "posix_memalign" => {
 175                 let ret = this.deref_operand(args[0])?;
 176                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 177                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 178                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 179                 if !align.is_power_of_two() {
 180                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 181                 }
 182                 /*
 183                 FIXME: This check is disabled because rustc violates it.
 184                 See <https://github.com/rust-lang/rust/issues/62251>.
 185                 if align < this.pointer_size().bytes() {
 186                     throw_unsup!(MachineError(format!(
 187                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 188                         align,
 189                     )));
 190                 }
 191                 */
 192                 if size == 0 {
 193                     this.write_null(ret.into())?;
 194                 } else {
 195                     let ptr = this.memory_mut().allocate(
 196                         Size::from_bytes(size),
 197                         Align::from_bytes(align).unwrap(),
 198                         MiriMemoryKind::C.into()
 199                     );
 200                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 201                 }
 202                 this.write_null(dest)?;
 203             }
 204             "free" => {
 205                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 206                 this.free(ptr, MiriMemoryKind::C)?;
 207             }
 208             "realloc" => {
 209                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 210                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 211                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 212                 this.write_scalar(res, dest)?;
 213             }
 214
 215             "__rust_alloc" => {
 216                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 217                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 218                 if size == 0 {
 219                     throw_unsup!(HeapAllocZeroBytes);
 220                 }
 221                 if !align.is_power_of_two() {
 222                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 223                 }
 224                 let ptr = this.memory_mut()
 225                     .allocate(
 226                         Size::from_bytes(size),
 227                         Align::from_bytes(align).unwrap(),
 228                         MiriMemoryKind::Rust.into()
 229                     );
 230                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 231             }
 232             "__rust_alloc_zeroed" => {
 233                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 234                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 235                 if size == 0 {
 236                     throw_unsup!(HeapAllocZeroBytes);
 237                 }
 238                 if !align.is_power_of_two() {
 239                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 240                 }
 241                 let ptr = this.memory_mut()
 242                     .allocate(
 243                         Size::from_bytes(size),
 244                         Align::from_bytes(align).unwrap(),
 245                         MiriMemoryKind::Rust.into()
 246                     );
 247                 // We just allocated this, the access cannot fail
 248                 this.memory_mut()
 249                     .get_mut(ptr.alloc_id).unwrap()
 250                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
 251                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 252             }
 253             "__rust_dealloc" => {
 254                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 255                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 256                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 257                 if old_size == 0 {
 258                     throw_unsup!(HeapAllocZeroBytes);
 259                 }
 260                 if !align.is_power_of_two() {
 261                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 262                 }
 263                 let ptr = this.force_ptr(ptr)?;
 264                 this.memory_mut().deallocate(
 265                     ptr,
 266                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 267                     MiriMemoryKind::Rust.into(),
 268                 )?;
 269             }
 270             "__rust_realloc" => {
 271                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 272                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 273                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 274                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 275                 if old_size == 0 || new_size == 0 {
 276                     throw_unsup!(HeapAllocZeroBytes);
 277                 }
 278                 if !align.is_power_of_two() {
 279                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 280                 }
 281                 let align = Align::from_bytes(align).unwrap();
 282                 let new_ptr = this.memory_mut().reallocate(
 283                     ptr,
 284                     Some((Size::from_bytes(old_size), align)),
 285                     Size::from_bytes(new_size),
 286                     align,
 287                     MiriMemoryKind::Rust.into(),
 288                 )?;
 289                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 290             }
 291
 292             "syscall" => {
 293                 let sys_getrandom = this.eval_path_scalar(&["libc", "SYS_getrandom"])?
 294                     .expect("Failed to get libc::SYS_getrandom")
 295                     .to_usize(this)?;
 296
 297                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 298                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 299                 match this.read_scalar(args[0])?.to_usize(this)? {
 300                     id if id == sys_getrandom => {
 301                         let ptr = this.read_scalar(args[1])?.not_undef()?;
 302                         let len = this.read_scalar(args[2])?.to_usize(this)?;
 303
 304                         // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 305                         // neither of which have any effect on our current PRNG
 306                         let _flags = this.read_scalar(args[3])?.to_i32()?;
 307
 308                         this.gen_random(len as usize, ptr)?;
 309                         this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 310                     }
 311                     id => {
 312                         throw_unsup!(Unimplemented(
 313                             format!("miri does not support syscall ID {}", id),
 314                         ))
 315                     }
 316                 }
 317             }
 318
 319             "dlsym" => {
 320                 let _handle = this.read_scalar(args[0])?;
 321                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 322                 let symbol_name = this.memory().read_c_str(symbol)?;
 323                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 324                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 325                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 326                     let ptr = this.memory_mut().create_fn_alloc(FnVal::Other(dlsym));
 327                     this.write_scalar(Scalar::from(ptr), dest)?;
 328                 } else {
 329                     this.write_null(dest)?;
 330                 }
 331             }
 332
 333             "__rust_maybe_catch_panic" => {
 334                 // fn __rust_maybe_catch_panic(
 335                 //     f: fn(*mut u8),
 336                 //     data: *mut u8,
 337                 //     data_ptr: *mut usize,
 338                 //     vtable_ptr: *mut usize,
 339                 // ) -> u32
 340                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 341                 let f = this.read_scalar(args[0])?.not_undef()?;
 342                 let data = this.read_scalar(args[1])?.not_undef()?;
 343                 let f_instance = this.memory().get_fn(f)?.as_instance()?;
 344                 this.write_null(dest)?;
 345                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 346
 347                 // Now we make a function call.
 348                 // TODO: consider making this reusable? `InterpCx::step` does something similar
 349                 // for the TLS destructors, and of course `eval_main`.
 350                 let mir = this.load_mir(f_instance.def)?;
 351                 let ret_place = MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 352                 this.push_stack_frame(
 353                     f_instance,
 354                     mir.span,
 355                     mir,
 356                     Some(ret_place),
 357                     // Directly return to caller.
 358                     StackPopCleanup::Goto(Some(ret)),
 359                 )?;
 360                 let mut args = this.frame().body.args_iter();
 361
 362                 let arg_local = args.next().ok_or_else(||
 363                     err_unsup!(AbiViolation(
 364                         "Argument to __rust_maybe_catch_panic does not take enough arguments."
 365                             .to_owned(),
 366                     )),
 367                 )?;
 368                 let arg_dest = this.local_place(arg_local)?;
 369                 this.write_scalar(data, arg_dest)?;
 370
 371                 assert!(args.next().is_none(), "__rust_maybe_catch_panic argument has more arguments than expected");
 372
 373                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 374                 this.write_null(dest)?;
 375
 376                 // Don't fall through, we do *not* want to `goto_block`!
 377                 return Ok(());
 378             }
 379
 380             "memcmp" => {
 381                 let left = this.read_scalar(args[0])?.not_undef()?;
 382                 let right = this.read_scalar(args[1])?.not_undef()?;
 383                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 384
 385                 let result = {
 386                     let left_bytes = this.memory().read_bytes(left, n)?;
 387                     let right_bytes = this.memory().read_bytes(right, n)?;
 388
 389                     use std::cmp::Ordering::*;
 390                     match left_bytes.cmp(right_bytes) {
 391                         Less => -1i32,
 392                         Equal => 0,
 393                         Greater => 1,
 394                     }
 395                 };
 396
 397                 this.write_scalar(
 398                     Scalar::from_int(result, Size::from_bits(32)),
 399                     dest,
 400                 )?;
 401             }
 402
 403             "memrchr" => {
 404                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 405                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 406                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 407                 if let Some(idx) = this.memory().read_bytes(ptr, Size::from_bytes(num))?
 408                     .iter().rev().position(|&c| c == val)
 409                 {
 410                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 411                     this.write_scalar(new_ptr, dest)?;
 412                 } else {
 413                     this.write_null(dest)?;
 414                 }
 415             }
 416
 417             "memchr" => {
 418                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 419                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 420                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 421                 let idx = this
 422                     .memory()
 423                     .read_bytes(ptr, Size::from_bytes(num))?
 424                     .iter()
 425                     .position(|&c| c == val);
 426                 if let Some(idx) = idx {
 427                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 428                     this.write_scalar(new_ptr, dest)?;
 429                 } else {
 430                     this.write_null(dest)?;
 431                 }
 432             }
 433
 434             "getenv" => {
 435                 let result = {
 436                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 437                     let name = this.memory().read_c_str(name_ptr)?;
 438                     match this.machine.env_vars.get(name) {
 439                         Some(&var) => Scalar::Ptr(var),
 440                         None => Scalar::ptr_null(&*this.tcx),
 441                     }
 442                 };
 443                 this.write_scalar(result, dest)?;
 444             }
 445
 446             "unsetenv" => {
 447                 let mut success = None;
 448                 {
 449                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 450                     if !this.is_null(name_ptr)? {
 451                         let name = this.memory().read_c_str(name_ptr)?.to_owned();
 452                         if !name.is_empty() && !name.contains(&b'=') {
 453                             success = Some(this.machine.env_vars.remove(&name));
 454                         }
 455                     }
 456                 }
 457                 if let Some(old) = success {
 458                     if let Some(var) = old {
 459                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 460                     }
 461                     this.write_null(dest)?;
 462                 } else {
 463                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 464                 }
 465             }
 466
 467             "setenv" => {
 468                 let mut new = None;
 469                 {
 470                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 471                     let value_ptr = this.read_scalar(args[1])?.not_undef()?;
 472                     let value = this.memory().read_c_str(value_ptr)?;
 473                     if !this.is_null(name_ptr)? {
 474                         let name = this.memory().read_c_str(name_ptr)?;
 475                         if !name.is_empty() && !name.contains(&b'=') {
 476                             new = Some((name.to_owned(), value.to_owned()));
 477                         }
 478                     }
 479                 }
 480                 if let Some((name, value)) = new {
 481                     // `+1` for the null terminator.
 482                     let value_copy = this.memory_mut().allocate(
 483                         Size::from_bytes((value.len() + 1) as u64),
 484                         Align::from_bytes(1).unwrap(),
 485                         MiriMemoryKind::Env.into(),
 486                     );
 487                     // We just allocated these, so the write cannot fail.
 488                     let alloc = this.memory_mut().get_mut(value_copy.alloc_id).unwrap();
 489                     alloc.write_bytes(tcx, value_copy, &value).unwrap();
 490                     let trailing_zero_ptr = value_copy.offset(
 491                         Size::from_bytes(value.len() as u64),
 492                         tcx,
 493                     ).unwrap();
 494                     alloc.write_bytes(tcx, trailing_zero_ptr, &[0]).unwrap();
 495
 496                     if let Some(var) = this.machine.env_vars.insert(
 497                         name.to_owned(),
 498                         value_copy,
 499                     )
 500                     {
 501                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 502                     }
 503                     this.write_null(dest)?;
 504                 } else {
 505                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 506                 }
 507             }
 508
 509             "write" => {
 510                 let fd = this.read_scalar(args[0])?.to_i32()?;
 511                 let buf = this.read_scalar(args[1])?.not_undef()?;
 512                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 513                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 514                 let result = if fd == 1 || fd == 2 {
 515                     // stdout/stderr
 516                     use std::io::{self, Write};
 517
 518                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 519                     // We need to flush to make sure this actually appears on the screen
 520                     let res = if fd == 1 {
 521                         // Stdout is buffered, flush to make sure it appears on the screen.
 522                         // This is the write() syscall of the interpreted program, we want it
 523                         // to correspond to a write() syscall on the host -- there is no good
 524                         // in adding extra buffering here.
 525                         let res = io::stdout().write(buf_cont);
 526                         io::stdout().flush().unwrap();
 527                         res
 528                     } else {
 529                         // No need to flush, stderr is not buffered.
 530                         io::stderr().write(buf_cont)
 531                     };
 532                     match res {
 533                         Ok(n) => n as i64,
 534                         Err(_) => -1,
 535                     }
 536                 } else {
 537                     eprintln!("Miri: Ignored output to FD {}", fd);
 538                     // Pretend it all went well.
 539                     n as i64
 540                 };
 541                 // Now, `result` is the value we return back to the program.
 542                 this.write_scalar(
 543                     Scalar::from_int(result, dest.layout.size),
 544                     dest,
 545                 )?;
 546             }
 547
 548             "strlen" => {
 549                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 550                 let n = this.memory().read_c_str(ptr)?.len();
 551                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 552             }
 553
 554             // math functions
 555
 556             "cbrtf" | "coshf" | "sinhf" |"tanf" => {
 557                 // FIXME: Using host floats.
 558                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 559                 let f = match link_name {
 560                     "cbrtf" => f.cbrt(),
 561                     "coshf" => f.cosh(),
 562                     "sinhf" => f.sinh(),
 563                     "tanf" => f.tan(),
 564                     _ => bug!(),
 565                 };
 566                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 567             }
 568             // underscore case for windows
 569             "_hypotf" | "hypotf" | "atan2f" => {
 570                 // FIXME: Using host floats.
 571                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 572                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 573                 let n = match link_name {
 574                     "_hypotf" | "hypotf" => f1.hypot(f2),
 575                     "atan2f" => f1.atan2(f2),
 576                     _ => bug!(),
 577                 };
 578                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 579             }
 580
 581             "cbrt" | "cosh" | "sinh" | "tan" => {
 582                 // FIXME: Using host floats.
 583                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 584                 let f = match link_name {
 585                     "cbrt" => f.cbrt(),
 586                     "cosh" => f.cosh(),
 587                     "sinh" => f.sinh(),
 588                     "tan" => f.tan(),
 589                     _ => bug!(),
 590                 };
 591                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 592             }
 593             // underscore case for windows
 594             "_hypot" | "hypot" | "atan2" => {
 595                 // FIXME: Using host floats.
 596                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 597                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 598                 let n = match link_name {
 599                     "_hypot" | "hypot" => f1.hypot(f2),
 600                     "atan2" => f1.atan2(f2),
 601                     _ => bug!(),
 602                 };
 603                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 604             }
 605
 606             // Some things needed for `sys::thread` initialization to go through.
 607             "signal" | "sigaction" | "sigaltstack" => {
 608                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 609             }
 610
 611             "sysconf" => {
 612                 let name = this.read_scalar(args[0])?.to_i32()?;
 613
 614                 trace!("sysconf() called with name {}", name);
 615                 // TODO: Cache the sysconf integers via Miri's global cache.
 616                 let paths = &[
 617                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(PAGE_SIZE, dest.layout.size)),
 618                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 619                     (&["libc", "_SC_NPROCESSORS_ONLN"], Scalar::from_int(NUM_CPUS, dest.layout.size)),
 620                 ];
 621                 let mut result = None;
 622                 for &(path, path_value) in paths {
 623                     if let Some(val) = this.eval_path_scalar(path)? {
 624                         let val = val.to_i32()?;
 625                         if val == name {
 626                             result = Some(path_value);
 627                             break;
 628                         }
 629
 630                     }
 631                 }
 632                 if let Some(result) = result {
 633                     this.write_scalar(result, dest)?;
 634                 } else {
 635                     throw_unsup!(Unimplemented(
 636                         format!("Unimplemented sysconf name: {}", name),
 637                     ));
 638                 }
 639             }
 640
 641             "sched_getaffinity" => {
 642                 // Return an error; `num_cpus` then falls back to `sysconf`.
 643                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 644             }
 645
 646             "isatty" => {
 647                 this.write_null(dest)?;
 648             }
 649
 650             // Hook pthread calls that go to the thread-local storage memory subsystem.
 651             "pthread_key_create" => {
 652                 let key_ptr = this.read_scalar(args[0])?.not_undef()?;
 653
 654                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 655                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 656                     Some(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?.as_instance()?),
 657                     None => None,
 658                 };
 659
 660                 // Figure out how large a pthread TLS key actually is.
 661                 // This is `libc::pthread_key_t`.
 662                 let key_type = args[0].layout.ty
 663                     .builtin_deref(true)
 664                     .ok_or_else(|| err_unsup!(
 665                         AbiViolation("wrong signature used for `pthread_key_create`: first argument must be a raw pointer.".to_owned())
 666                     ))?
 667                     .ty;
 668                 let key_layout = this.layout_of(key_type)?;
 669
 670                 // Create key and write it into the memory where `key_ptr` wants it.
 671                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 672                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128) {
 673                     throw_unsup!(OutOfTls);
 674                 }
 675
 676                 let key_ptr = this.memory().check_ptr_access(key_ptr, key_layout.size, key_layout.align.abi)?
 677                     .expect("cannot be a ZST");
 678                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 679                     tcx,
 680                     key_ptr,
 681                     Scalar::from_uint(key, key_layout.size).into(),
 682                     key_layout.size,
 683                 )?;
 684
 685                 // Return success (`0`).
 686                 this.write_null(dest)?;
 687             }
 688             "pthread_key_delete" => {
 689                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 690                 this.machine.tls.delete_tls_key(key)?;
 691                 // Return success (0)
 692                 this.write_null(dest)?;
 693             }
 694             "pthread_getspecific" => {
 695                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 696                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 697                 this.write_scalar(ptr, dest)?;
 698             }
 699             "pthread_setspecific" => {
 700                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 701                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 702                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 703
 704                 // Return success (`0`).
 705                 this.write_null(dest)?;
 706             }
 707
 708             // Stack size/address stuff.
 709             "pthread_attr_init" | "pthread_attr_destroy" | "pthread_self" |
 710             "pthread_attr_setstacksize" => {
 711                 this.write_null(dest)?;
 712             }
 713             "pthread_attr_getstack" => {
 714                 let addr_place = this.deref_operand(args[1])?;
 715                 let size_place = this.deref_operand(args[2])?;
 716
 717                 this.write_scalar(
 718                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 719                     addr_place.into(),
 720                 )?;
 721                 this.write_scalar(
 722                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 723                     size_place.into(),
 724                 )?;
 725
 726                 // Return success (`0`).
 727                 this.write_null(dest)?;
 728             }
 729
 730             // We don't support threading. (Also for Windows.)
 731             "pthread_create" | "CreateThread" => {
 732                 throw_unsup!(Unimplemented(format!("Miri does not support threading")));
 733             }
 734
 735             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 736             "pthread_mutexattr_init" | "pthread_mutexattr_settype" | "pthread_mutex_init" |
 737             "pthread_mutexattr_destroy" | "pthread_mutex_lock" | "pthread_mutex_unlock" |
 738             "pthread_mutex_destroy" | "pthread_rwlock_rdlock" | "pthread_rwlock_unlock" |
 739             "pthread_rwlock_wrlock" | "pthread_rwlock_destroy" | "pthread_condattr_init" |
 740             "pthread_condattr_setclock" | "pthread_cond_init" | "pthread_condattr_destroy" |
 741             "pthread_cond_destroy" => {
 742                 this.write_null(dest)?;
 743             }
 744
 745             // We don't support fork so we don't have to do anything for atfork.
 746             "pthread_atfork" => {
 747                 this.write_null(dest)?;
 748             }
 749
 750             "mmap" => {
 751                 // 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.
 752                 let addr = this.read_scalar(args[0])?.not_undef()?;
 753                 this.write_scalar(addr, dest)?;
 754             }
 755             "mprotect" => {
 756                 this.write_null(dest)?;
 757             }
 758
 759             // macOS API stubs.
 760             "pthread_attr_get_np" | "pthread_getattr_np" => {
 761                 this.write_null(dest)?;
 762             }
 763             "pthread_get_stackaddr_np" => {
 764                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 765                 this.write_scalar(stack_addr, dest)?;
 766             }
 767             "pthread_get_stacksize_np" => {
 768                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 769                 this.write_scalar(stack_size, dest)?;
 770             }
 771             "_tlv_atexit" => {
 772                 // FIXME: register the destructor.
 773             },
 774             "_NSGetArgc" => {
 775                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 776             },
 777             "_NSGetArgv" => {
 778                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 779             },
 780             "SecRandomCopyBytes" => {
 781                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 782                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 783                 this.gen_random(len as usize, ptr)?;
 784                 this.write_null(dest)?;
 785             }
 786
 787             // Windows API stubs.
 788             // HANDLE = isize
 789             // DWORD = ULONG = u32
 790             // BOOL = i32
 791             "GetProcessHeap" => {
 792                 // Just fake a HANDLE
 793                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 794             }
 795             "HeapAlloc" => {
 796                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 797                 let flags = this.read_scalar(args[1])?.to_u32()?;
 798                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 799                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 800                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 801                 this.write_scalar(res, dest)?;
 802             }
 803             "HeapFree" => {
 804                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 805                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 806                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 807                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 808                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 809             }
 810             "HeapReAlloc" => {
 811                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 812                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 813                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 814                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 815                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 816                 this.write_scalar(res, dest)?;
 817             }
 818
 819             "SetLastError" => {
 820                 let err = this.read_scalar(args[0])?.to_u32()?;
 821                 this.machine.last_error = err;
 822             }
 823             "GetLastError" => {
 824                 this.write_scalar(Scalar::from_u32(this.machine.last_error), dest)?;
 825             }
 826
 827             "AddVectoredExceptionHandler" => {
 828                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 829                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 830             },
 831             "InitializeCriticalSection" |
 832             "EnterCriticalSection" |
 833             "LeaveCriticalSection" |
 834             "DeleteCriticalSection" => {
 835                 // Nothing to do, not even a return value.
 836             },
 837             "GetModuleHandleW" |
 838             "GetProcAddress" |
 839             "TryEnterCriticalSection" |
 840             "GetConsoleScreenBufferInfo" |
 841             "SetConsoleTextAttribute" => {
 842                 // Pretend these do not exist / nothing happened, by returning zero.
 843                 this.write_null(dest)?;
 844             },
 845             "GetSystemInfo" => {
 846                 let system_info = this.deref_operand(args[0])?;
 847                 let system_info_ptr = this.check_mplace_access(system_info, None)?
 848                     .expect("cannot be a ZST");
 849                 // Initialize with `0`.
 850                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 851                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 852                 // Set number of processors.
 853                 let dword_size = Size::from_bytes(4);
 854                 let offset = 2*dword_size + 3*tcx.pointer_size();
 855                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 856                     .write_scalar(
 857                         tcx,
 858                         system_info_ptr.offset(offset, tcx)?,
 859                         Scalar::from_int(NUM_CPUS, dword_size).into(),
 860                         dword_size,
 861                     )?;
 862             }
 863
 864             "TlsAlloc" => {
 865                 // This just creates a key; Windows does not natively support TLS destructors.
 866
 867                 // Create key and return it.
 868                 let key = this.machine.tls.create_tls_key(None) as u128;
 869
 870                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 871                 if dest.layout.size.bits() < 128
 872                         && key >= (1u128 << dest.layout.size.bits() as u128) {
 873                     throw_unsup!(OutOfTls);
 874                 }
 875                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 876             }
 877             "TlsGetValue" => {
 878                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 879                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 880                 this.write_scalar(ptr, dest)?;
 881             }
 882             "TlsSetValue" => {
 883                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 884                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 885                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 886
 887                 // Return success (`1`).
 888                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 889             }
 890             "GetStdHandle" => {
 891                 let which = this.read_scalar(args[0])?.to_i32()?;
 892                 // We just make this the identity function, so we know later in `WriteFile`
 893                 // which one it is.
 894                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 895             }
 896             "WriteFile" => {
 897                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 898                 let buf = this.read_scalar(args[1])?.not_undef()?;
 899                 let n = this.read_scalar(args[2])?.to_u32()?;
 900                 let written_place = this.deref_operand(args[3])?;
 901                 // Spec says to always write `0` first.
 902                 this.write_null(written_place.into())?;
 903                 let written = if handle == -11 || handle == -12 {
 904                     // stdout/stderr
 905                     use std::io::{self, Write};
 906
 907                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 908                     let res = if handle == -11 {
 909                         io::stdout().write(buf_cont)
 910                     } else {
 911                         io::stderr().write(buf_cont)
 912                     };
 913                     res.ok().map(|n| n as u32)
 914                 } else {
 915                     eprintln!("Miri: Ignored output to handle {}", handle);
 916                     // Pretend it all went well.
 917                     Some(n)
 918                 };
 919                 // If there was no error, write back how much was written.
 920                 if let Some(n) = written {
 921                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 922                 }
 923                 // Return whether this was a success.
 924                 this.write_scalar(
 925                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 926                     dest,
 927                 )?;
 928             }
 929             "GetConsoleMode" => {
 930                 // Everything is a pipe.
 931                 this.write_null(dest)?;
 932             }
 933             "GetEnvironmentVariableW" => {
 934                 // This is not the env var you are looking for.
 935                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 936                 this.write_null(dest)?;
 937             }
 938             "GetCommandLineW" => {
 939                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 940             }
 941             // The actual name of 'RtlGenRandom'
 942             "SystemFunction036" => {
 943                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 944                 let len = this.read_scalar(args[1])?.to_u32()?;
 945                 this.gen_random(len as usize, ptr)?;
 946                 this.write_scalar(Scalar::from_bool(true), dest)?;
 947             }
 948
 949             // We can't execute anything else.
 950             _ => {
 951                 throw_unsup!(Unimplemented(
 952                     format!("can't call foreign function: {}", link_name),
 953                 ));
 954             }
 955         }
 956
 957         this.goto_block(Some(ret))?;
 958         this.dump_place(*dest);
 959         Ok(())
 960     }
 961
 962     /// Evaluates the scalar at the specified path. Returns Some(val)
 963     /// if the path could be resolved, and None otherwise
 964     fn eval_path_scalar(&mut self, path: &[&str]) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 965         let this = self.eval_context_mut();
 966         if let Ok(instance) = this.resolve_path(path) {
 967             let cid = GlobalId {
 968                 instance,
 969                 promoted: None,
 970             };
 971             let const_val = this.const_eval_raw(cid)?;
 972             let const_val = this.read_scalar(const_val.into())?;
 973             return Ok(Some(const_val));
 974         }
 975         return Ok(None);
 976     }
 977 }