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_format!("the evaluated program panicked");
 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_format!("can't call (diverging) foreign function: {}", link_name);
 153             }
 154         }
 155
 156         // Next: functions that assume a ret and dest.
 157         let dest = dest.expect("we already checked for a dest");
 158         let ret = ret.expect("dest is `Some` but ret is `None`");
 159         match link_name {
 160             "malloc" => {
 161                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 162                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 163                 this.write_scalar(res, dest)?;
 164             }
 165             "calloc" => {
 166                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 167                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 168                 let size = items.checked_mul(len).ok_or_else(|| err_panic!(Overflow(mir::BinOp::Mul)))?;
 169                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 170                 this.write_scalar(res, dest)?;
 171             }
 172             "posix_memalign" => {
 173                 let ret = this.deref_operand(args[0])?;
 174                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 175                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 176                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 177                 if !align.is_power_of_two() {
 178                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 179                 }
 180                 if align < this.pointer_size().bytes() {
 181                     throw_ub_format!(
 182                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 183                         align,
 184                     );
 185                 }
 186
 187                 if size == 0 {
 188                     this.write_null(ret.into())?;
 189                 } else {
 190                     let ptr = this.memory_mut().allocate(
 191                         Size::from_bytes(size),
 192                         Align::from_bytes(align).unwrap(),
 193                         MiriMemoryKind::C.into()
 194                     );
 195                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 196                 }
 197                 this.write_null(dest)?;
 198             }
 199             "free" => {
 200                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 201                 this.free(ptr, MiriMemoryKind::C)?;
 202             }
 203             "realloc" => {
 204                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 205                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 206                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 207                 this.write_scalar(res, dest)?;
 208             }
 209
 210             "__rust_alloc" => {
 211                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 212                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 213                 if size == 0 {
 214                     throw_unsup!(HeapAllocZeroBytes);
 215                 }
 216                 if !align.is_power_of_two() {
 217                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 218                 }
 219                 let ptr = this.memory_mut()
 220                     .allocate(
 221                         Size::from_bytes(size),
 222                         Align::from_bytes(align).unwrap(),
 223                         MiriMemoryKind::Rust.into()
 224                     );
 225                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 226             }
 227             "__rust_alloc_zeroed" => {
 228                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 229                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 230                 if size == 0 {
 231                     throw_unsup!(HeapAllocZeroBytes);
 232                 }
 233                 if !align.is_power_of_two() {
 234                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 235                 }
 236                 let ptr = this.memory_mut()
 237                     .allocate(
 238                         Size::from_bytes(size),
 239                         Align::from_bytes(align).unwrap(),
 240                         MiriMemoryKind::Rust.into()
 241                     );
 242                 // We just allocated this, the access cannot fail
 243                 this.memory_mut()
 244                     .get_mut(ptr.alloc_id).unwrap()
 245                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
 246                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 247             }
 248             "__rust_dealloc" => {
 249                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 250                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 251                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 252                 if old_size == 0 {
 253                     throw_unsup!(HeapAllocZeroBytes);
 254                 }
 255                 if !align.is_power_of_two() {
 256                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 257                 }
 258                 let ptr = this.force_ptr(ptr)?;
 259                 this.memory_mut().deallocate(
 260                     ptr,
 261                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 262                     MiriMemoryKind::Rust.into(),
 263                 )?;
 264             }
 265             "__rust_realloc" => {
 266                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 267                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 268                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 269                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 270                 if old_size == 0 || new_size == 0 {
 271                     throw_unsup!(HeapAllocZeroBytes);
 272                 }
 273                 if !align.is_power_of_two() {
 274                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 275                 }
 276                 let align = Align::from_bytes(align).unwrap();
 277                 let new_ptr = this.memory_mut().reallocate(
 278                     ptr,
 279                     Some((Size::from_bytes(old_size), align)),
 280                     Size::from_bytes(new_size),
 281                     align,
 282                     MiriMemoryKind::Rust.into(),
 283                 )?;
 284                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 285             }
 286
 287             "syscall" => {
 288                 let sys_getrandom = this.eval_path_scalar(&["libc", "SYS_getrandom"])?
 289                     .expect("Failed to get libc::SYS_getrandom")
 290                     .to_usize(this)?;
 291
 292                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 293                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 294                 match this.read_scalar(args[0])?.to_usize(this)? {
 295                     id if id == sys_getrandom => {
 296                         let ptr = this.read_scalar(args[1])?.not_undef()?;
 297                         let len = this.read_scalar(args[2])?.to_usize(this)?;
 298
 299                         // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 300                         // neither of which have any effect on our current PRNG
 301                         let _flags = this.read_scalar(args[3])?.to_i32()?;
 302
 303                         this.gen_random(ptr, len as usize)?;
 304                         this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 305                     }
 306                     id => {
 307                         throw_unsup_format!("miri does not support syscall ID {}", id)
 308                     }
 309                 }
 310             }
 311
 312             "dlsym" => {
 313                 let _handle = this.read_scalar(args[0])?;
 314                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 315                 let symbol_name = this.memory().read_c_str(symbol)?;
 316                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 317                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 318                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 319                     let ptr = this.memory_mut().create_fn_alloc(FnVal::Other(dlsym));
 320                     this.write_scalar(Scalar::from(ptr), dest)?;
 321                 } else {
 322                     this.write_null(dest)?;
 323                 }
 324             }
 325
 326             "__rust_maybe_catch_panic" => {
 327                 // fn __rust_maybe_catch_panic(
 328                 //     f: fn(*mut u8),
 329                 //     data: *mut u8,
 330                 //     data_ptr: *mut usize,
 331                 //     vtable_ptr: *mut usize,
 332                 // ) -> u32
 333                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 334                 let f = this.read_scalar(args[0])?.not_undef()?;
 335                 let data = this.read_scalar(args[1])?.not_undef()?;
 336                 let f_instance = this.memory().get_fn(f)?.as_instance()?;
 337                 this.write_null(dest)?;
 338                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 339
 340                 // Now we make a function call.
 341                 // TODO: consider making this reusable? `InterpCx::step` does something similar
 342                 // for the TLS destructors, and of course `eval_main`.
 343                 let mir = this.load_mir(f_instance.def)?;
 344                 let ret_place = MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 345                 this.push_stack_frame(
 346                     f_instance,
 347                     mir.span,
 348                     mir,
 349                     Some(ret_place),
 350                     // Directly return to caller.
 351                     StackPopCleanup::Goto(Some(ret)),
 352                 )?;
 353                 let mut args = this.frame().body.args_iter();
 354
 355                 let arg_local = args.next()
 356                     .expect("Argument to __rust_maybe_catch_panic does not take enough arguments.");
 357                 let arg_dest = this.local_place(arg_local)?;
 358                 this.write_scalar(data, arg_dest)?;
 359
 360                 assert!(args.next().is_none(), "__rust_maybe_catch_panic argument has more arguments than expected");
 361
 362                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 363                 this.write_null(dest)?;
 364
 365                 // Don't fall through, we do *not* want to `goto_block`!
 366                 return Ok(());
 367             }
 368
 369             "memcmp" => {
 370                 let left = this.read_scalar(args[0])?.not_undef()?;
 371                 let right = this.read_scalar(args[1])?.not_undef()?;
 372                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 373
 374                 let result = {
 375                     let left_bytes = this.memory().read_bytes(left, n)?;
 376                     let right_bytes = this.memory().read_bytes(right, n)?;
 377
 378                     use std::cmp::Ordering::*;
 379                     match left_bytes.cmp(right_bytes) {
 380                         Less => -1i32,
 381                         Equal => 0,
 382                         Greater => 1,
 383                     }
 384                 };
 385
 386                 this.write_scalar(
 387                     Scalar::from_int(result, Size::from_bits(32)),
 388                     dest,
 389                 )?;
 390             }
 391
 392             "memrchr" => {
 393                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 394                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 395                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 396                 if let Some(idx) = this.memory().read_bytes(ptr, Size::from_bytes(num))?
 397                     .iter().rev().position(|&c| c == val)
 398                 {
 399                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 400                     this.write_scalar(new_ptr, dest)?;
 401                 } else {
 402                     this.write_null(dest)?;
 403                 }
 404             }
 405
 406             "memchr" => {
 407                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 408                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 409                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 410                 let idx = this
 411                     .memory()
 412                     .read_bytes(ptr, Size::from_bytes(num))?
 413                     .iter()
 414                     .position(|&c| c == val);
 415                 if let Some(idx) = idx {
 416                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 417                     this.write_scalar(new_ptr, dest)?;
 418                 } else {
 419                     this.write_null(dest)?;
 420                 }
 421             }
 422
 423             "getenv" => {
 424                 let result = {
 425                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 426                     let name = this.memory().read_c_str(name_ptr)?;
 427                     match this.machine.env_vars.get(name) {
 428                         Some(&var) => Scalar::Ptr(var),
 429                         None => Scalar::ptr_null(&*this.tcx),
 430                     }
 431                 };
 432                 this.write_scalar(result, dest)?;
 433             }
 434
 435             "unsetenv" => {
 436                 let mut success = None;
 437                 {
 438                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 439                     if !this.is_null(name_ptr)? {
 440                         let name = this.memory().read_c_str(name_ptr)?.to_owned();
 441                         if !name.is_empty() && !name.contains(&b'=') {
 442                             success = Some(this.machine.env_vars.remove(&name));
 443                         }
 444                     }
 445                 }
 446                 if let Some(old) = success {
 447                     if let Some(var) = old {
 448                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 449                     }
 450                     this.write_null(dest)?;
 451                 } else {
 452                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 453                 }
 454             }
 455
 456             "setenv" => {
 457                 let mut new = None;
 458                 {
 459                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 460                     let value_ptr = this.read_scalar(args[1])?.not_undef()?;
 461                     let value = this.memory().read_c_str(value_ptr)?;
 462                     if !this.is_null(name_ptr)? {
 463                         let name = this.memory().read_c_str(name_ptr)?;
 464                         if !name.is_empty() && !name.contains(&b'=') {
 465                             new = Some((name.to_owned(), value.to_owned()));
 466                         }
 467                     }
 468                 }
 469                 if let Some((name, value)) = new {
 470                     // `+1` for the null terminator.
 471                     let value_copy = this.memory_mut().allocate(
 472                         Size::from_bytes((value.len() + 1) as u64),
 473                         Align::from_bytes(1).unwrap(),
 474                         MiriMemoryKind::Env.into(),
 475                     );
 476                     // We just allocated these, so the write cannot fail.
 477                     let alloc = this.memory_mut().get_mut(value_copy.alloc_id).unwrap();
 478                     alloc.write_bytes(tcx, value_copy, &value).unwrap();
 479                     let trailing_zero_ptr = value_copy.offset(
 480                         Size::from_bytes(value.len() as u64),
 481                         tcx,
 482                     ).unwrap();
 483                     alloc.write_bytes(tcx, trailing_zero_ptr, &[0]).unwrap();
 484
 485                     if let Some(var) = this.machine.env_vars.insert(
 486                         name.to_owned(),
 487                         value_copy,
 488                     )
 489                     {
 490                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 491                     }
 492                     this.write_null(dest)?;
 493                 } else {
 494                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 495                 }
 496             }
 497
 498             "write" => {
 499                 let fd = this.read_scalar(args[0])?.to_i32()?;
 500                 let buf = this.read_scalar(args[1])?.not_undef()?;
 501                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 502                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 503                 let result = if fd == 1 || fd == 2 {
 504                     // stdout/stderr
 505                     use std::io::{self, Write};
 506
 507                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 508                     // We need to flush to make sure this actually appears on the screen
 509                     let res = if fd == 1 {
 510                         // Stdout is buffered, flush to make sure it appears on the screen.
 511                         // This is the write() syscall of the interpreted program, we want it
 512                         // to correspond to a write() syscall on the host -- there is no good
 513                         // in adding extra buffering here.
 514                         let res = io::stdout().write(buf_cont);
 515                         io::stdout().flush().unwrap();
 516                         res
 517                     } else {
 518                         // No need to flush, stderr is not buffered.
 519                         io::stderr().write(buf_cont)
 520                     };
 521                     match res {
 522                         Ok(n) => n as i64,
 523                         Err(_) => -1,
 524                     }
 525                 } else {
 526                     eprintln!("Miri: Ignored output to FD {}", fd);
 527                     // Pretend it all went well.
 528                     n as i64
 529                 };
 530                 // Now, `result` is the value we return back to the program.
 531                 this.write_scalar(
 532                     Scalar::from_int(result, dest.layout.size),
 533                     dest,
 534                 )?;
 535             }
 536
 537             "strlen" => {
 538                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 539                 let n = this.memory().read_c_str(ptr)?.len();
 540                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 541             }
 542
 543             // math functions
 544
 545             "cbrtf" | "coshf" | "sinhf" |"tanf" => {
 546                 // FIXME: Using host floats.
 547                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 548                 let f = match link_name {
 549                     "cbrtf" => f.cbrt(),
 550                     "coshf" => f.cosh(),
 551                     "sinhf" => f.sinh(),
 552                     "tanf" => f.tan(),
 553                     _ => bug!(),
 554                 };
 555                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 556             }
 557             // underscore case for windows
 558             "_hypotf" | "hypotf" | "atan2f" => {
 559                 // FIXME: Using host floats.
 560                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 561                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 562                 let n = match link_name {
 563                     "_hypotf" | "hypotf" => f1.hypot(f2),
 564                     "atan2f" => f1.atan2(f2),
 565                     _ => bug!(),
 566                 };
 567                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 568             }
 569
 570             "cbrt" | "cosh" | "sinh" | "tan" => {
 571                 // FIXME: Using host floats.
 572                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 573                 let f = match link_name {
 574                     "cbrt" => f.cbrt(),
 575                     "cosh" => f.cosh(),
 576                     "sinh" => f.sinh(),
 577                     "tan" => f.tan(),
 578                     _ => bug!(),
 579                 };
 580                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 581             }
 582             // underscore case for windows
 583             "_hypot" | "hypot" | "atan2" => {
 584                 // FIXME: Using host floats.
 585                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 586                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 587                 let n = match link_name {
 588                     "_hypot" | "hypot" => f1.hypot(f2),
 589                     "atan2" => f1.atan2(f2),
 590                     _ => bug!(),
 591                 };
 592                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 593             }
 594             // underscore case for windows
 595             "_ldexp" | "ldexp" => {
 596                 // FIXME: Using host floats.
 597                 let x = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 598                 let exp = this.read_scalar(args[1])?.to_i32()?;
 599                 // FIXME: We should use cmath if there are any imprecisions.
 600                 let n = x * 2.0f64.powi(exp);
 601                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 602             }
 603
 604             // Some things needed for `sys::thread` initialization to go through.
 605             "signal" | "sigaction" | "sigaltstack" => {
 606                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 607             }
 608
 609             "sysconf" => {
 610                 let name = this.read_scalar(args[0])?.to_i32()?;
 611
 612                 trace!("sysconf() called with name {}", name);
 613                 // TODO: Cache the sysconf integers via Miri's global cache.
 614                 let paths = &[
 615                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(PAGE_SIZE, dest.layout.size)),
 616                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 617                     (&["libc", "_SC_NPROCESSORS_ONLN"], Scalar::from_int(NUM_CPUS, dest.layout.size)),
 618                 ];
 619                 let mut result = None;
 620                 for &(path, path_value) in paths {
 621                     if let Some(val) = this.eval_path_scalar(path)? {
 622                         let val = val.to_i32()?;
 623                         if val == name {
 624                             result = Some(path_value);
 625                             break;
 626                         }
 627
 628                     }
 629                 }
 630                 if let Some(result) = result {
 631                     this.write_scalar(result, dest)?;
 632                 } else {
 633                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 634                 }
 635             }
 636
 637             "sched_getaffinity" => {
 638                 // Return an error; `num_cpus` then falls back to `sysconf`.
 639                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 640             }
 641
 642             "isatty" => {
 643                 this.write_null(dest)?;
 644             }
 645
 646             // Hook pthread calls that go to the thread-local storage memory subsystem.
 647             "pthread_key_create" => {
 648                 let key_ptr = this.read_scalar(args[0])?.not_undef()?;
 649
 650                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 651                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 652                     Some(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?.as_instance()?),
 653                     None => None,
 654                 };
 655
 656                 // Figure out how large a pthread TLS key actually is.
 657                 // This is `libc::pthread_key_t`.
 658                 let key_type = args[0].layout.ty
 659                     .builtin_deref(true)
 660                     .ok_or_else(|| err_ub!(Ub(format!(
 661                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 662                     ))))?
 663                     .ty;
 664                 let key_layout = this.layout_of(key_type)?;
 665
 666                 // Create key and write it into the memory where `key_ptr` wants it.
 667                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 668                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128) {
 669                     throw_unsup!(OutOfTls);
 670                 }
 671
 672                 let key_ptr = this.memory().check_ptr_access(key_ptr, key_layout.size, key_layout.align.abi)?
 673                     .expect("cannot be a ZST");
 674                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 675                     tcx,
 676                     key_ptr,
 677                     Scalar::from_uint(key, key_layout.size).into(),
 678                     key_layout.size,
 679                 )?;
 680
 681                 // Return success (`0`).
 682                 this.write_null(dest)?;
 683             }
 684             "pthread_key_delete" => {
 685                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 686                 this.machine.tls.delete_tls_key(key)?;
 687                 // Return success (0)
 688                 this.write_null(dest)?;
 689             }
 690             "pthread_getspecific" => {
 691                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 692                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 693                 this.write_scalar(ptr, dest)?;
 694             }
 695             "pthread_setspecific" => {
 696                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 697                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 698                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 699
 700                 // Return success (`0`).
 701                 this.write_null(dest)?;
 702             }
 703
 704             // Stack size/address stuff.
 705             "pthread_attr_init" | "pthread_attr_destroy" | "pthread_self" |
 706             "pthread_attr_setstacksize" => {
 707                 this.write_null(dest)?;
 708             }
 709             "pthread_attr_getstack" => {
 710                 let addr_place = this.deref_operand(args[1])?;
 711                 let size_place = this.deref_operand(args[2])?;
 712
 713                 this.write_scalar(
 714                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 715                     addr_place.into(),
 716                 )?;
 717                 this.write_scalar(
 718                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 719                     size_place.into(),
 720                 )?;
 721
 722                 // Return success (`0`).
 723                 this.write_null(dest)?;
 724             }
 725
 726             // We don't support threading. (Also for Windows.)
 727             "pthread_create" | "CreateThread" => {
 728                 throw_unsup_format!("Miri does not support threading");
 729             }
 730
 731             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 732             "pthread_mutexattr_init" | "pthread_mutexattr_settype" | "pthread_mutex_init" |
 733             "pthread_mutexattr_destroy" | "pthread_mutex_lock" | "pthread_mutex_unlock" |
 734             "pthread_mutex_destroy" | "pthread_rwlock_rdlock" | "pthread_rwlock_unlock" |
 735             "pthread_rwlock_wrlock" | "pthread_rwlock_destroy" | "pthread_condattr_init" |
 736             "pthread_condattr_setclock" | "pthread_cond_init" | "pthread_condattr_destroy" |
 737             "pthread_cond_destroy" => {
 738                 this.write_null(dest)?;
 739             }
 740
 741             // We don't support fork so we don't have to do anything for atfork.
 742             "pthread_atfork" => {
 743                 this.write_null(dest)?;
 744             }
 745
 746             "mmap" => {
 747                 // 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.
 748                 let addr = this.read_scalar(args[0])?.not_undef()?;
 749                 this.write_scalar(addr, dest)?;
 750             }
 751             "mprotect" => {
 752                 this.write_null(dest)?;
 753             }
 754
 755             // macOS API stubs.
 756             "pthread_attr_get_np" | "pthread_getattr_np" => {
 757                 this.write_null(dest)?;
 758             }
 759             "pthread_get_stackaddr_np" => {
 760                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 761                 this.write_scalar(stack_addr, dest)?;
 762             }
 763             "pthread_get_stacksize_np" => {
 764                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 765                 this.write_scalar(stack_size, dest)?;
 766             }
 767             "_tlv_atexit" => {
 768                 // FIXME: register the destructor.
 769             },
 770             "_NSGetArgc" => {
 771                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 772             },
 773             "_NSGetArgv" => {
 774                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 775             },
 776             "SecRandomCopyBytes" => {
 777                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 778                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 779                 this.gen_random(ptr, len as usize)?;
 780                 this.write_null(dest)?;
 781             }
 782
 783             // Windows API stubs.
 784             // HANDLE = isize
 785             // DWORD = ULONG = u32
 786             // BOOL = i32
 787             "GetProcessHeap" => {
 788                 // Just fake a HANDLE
 789                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 790             }
 791             "HeapAlloc" => {
 792                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 793                 let flags = this.read_scalar(args[1])?.to_u32()?;
 794                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 795                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 796                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 797                 this.write_scalar(res, dest)?;
 798             }
 799             "HeapFree" => {
 800                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 801                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 802                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 803                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 804                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 805             }
 806             "HeapReAlloc" => {
 807                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 808                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 809                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 810                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 811                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 812                 this.write_scalar(res, dest)?;
 813             }
 814
 815             "SetLastError" => {
 816                 let err = this.read_scalar(args[0])?.to_u32()?;
 817                 this.machine.last_error = err;
 818             }
 819             "GetLastError" => {
 820                 this.write_scalar(Scalar::from_u32(this.machine.last_error), dest)?;
 821             }
 822
 823             "AddVectoredExceptionHandler" => {
 824                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 825                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 826             },
 827             "InitializeCriticalSection" |
 828             "EnterCriticalSection" |
 829             "LeaveCriticalSection" |
 830             "DeleteCriticalSection" => {
 831                 // Nothing to do, not even a return value.
 832             },
 833             "GetModuleHandleW" |
 834             "GetProcAddress" |
 835             "TryEnterCriticalSection" |
 836             "GetConsoleScreenBufferInfo" |
 837             "SetConsoleTextAttribute" => {
 838                 // Pretend these do not exist / nothing happened, by returning zero.
 839                 this.write_null(dest)?;
 840             },
 841             "GetSystemInfo" => {
 842                 let system_info = this.deref_operand(args[0])?;
 843                 let system_info_ptr = this.check_mplace_access(system_info, None)?
 844                     .expect("cannot be a ZST");
 845                 // Initialize with `0`.
 846                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 847                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 848                 // Set number of processors.
 849                 let dword_size = Size::from_bytes(4);
 850                 let offset = 2*dword_size + 3*tcx.pointer_size();
 851                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 852                     .write_scalar(
 853                         tcx,
 854                         system_info_ptr.offset(offset, tcx)?,
 855                         Scalar::from_int(NUM_CPUS, dword_size).into(),
 856                         dword_size,
 857                     )?;
 858             }
 859
 860             "TlsAlloc" => {
 861                 // This just creates a key; Windows does not natively support TLS destructors.
 862
 863                 // Create key and return it.
 864                 let key = this.machine.tls.create_tls_key(None) as u128;
 865
 866                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 867                 if dest.layout.size.bits() < 128
 868                         && key >= (1u128 << dest.layout.size.bits() as u128) {
 869                     throw_unsup!(OutOfTls);
 870                 }
 871                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 872             }
 873             "TlsGetValue" => {
 874                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 875                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 876                 this.write_scalar(ptr, dest)?;
 877             }
 878             "TlsSetValue" => {
 879                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 880                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 881                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 882
 883                 // Return success (`1`).
 884                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 885             }
 886             "GetStdHandle" => {
 887                 let which = this.read_scalar(args[0])?.to_i32()?;
 888                 // We just make this the identity function, so we know later in `WriteFile`
 889                 // which one it is.
 890                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 891             }
 892             "WriteFile" => {
 893                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 894                 let buf = this.read_scalar(args[1])?.not_undef()?;
 895                 let n = this.read_scalar(args[2])?.to_u32()?;
 896                 let written_place = this.deref_operand(args[3])?;
 897                 // Spec says to always write `0` first.
 898                 this.write_null(written_place.into())?;
 899                 let written = if handle == -11 || handle == -12 {
 900                     // stdout/stderr
 901                     use std::io::{self, Write};
 902
 903                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 904                     let res = if handle == -11 {
 905                         io::stdout().write(buf_cont)
 906                     } else {
 907                         io::stderr().write(buf_cont)
 908                     };
 909                     res.ok().map(|n| n as u32)
 910                 } else {
 911                     eprintln!("Miri: Ignored output to handle {}", handle);
 912                     // Pretend it all went well.
 913                     Some(n)
 914                 };
 915                 // If there was no error, write back how much was written.
 916                 if let Some(n) = written {
 917                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 918                 }
 919                 // Return whether this was a success.
 920                 this.write_scalar(
 921                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 922                     dest,
 923                 )?;
 924             }
 925             "GetConsoleMode" => {
 926                 // Everything is a pipe.
 927                 this.write_null(dest)?;
 928             }
 929             "GetEnvironmentVariableW" => {
 930                 // This is not the env var you are looking for.
 931                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 932                 this.write_null(dest)?;
 933             }
 934             "GetCommandLineW" => {
 935                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 936             }
 937             // The actual name of 'RtlGenRandom'
 938             "SystemFunction036" => {
 939                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 940                 let len = this.read_scalar(args[1])?.to_u32()?;
 941                 this.gen_random(ptr, len as usize)?;
 942                 this.write_scalar(Scalar::from_bool(true), dest)?;
 943             }
 944
 945             // We can't execute anything else.
 946             _ => {
 947                 throw_unsup_format!("can't call foreign function: {}", link_name)
 948             }
 949         }
 950
 951         this.goto_block(Some(ret))?;
 952         this.dump_place(*dest);
 953         Ok(())
 954     }
 955
 956     /// Evaluates the scalar at the specified path. Returns Some(val)
 957     /// if the path could be resolved, and None otherwise
 958     fn eval_path_scalar(&mut self, path: &[&str]) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 959         let this = self.eval_context_mut();
 960         if let Ok(instance) = this.resolve_path(path) {
 961             let cid = GlobalId {
 962                 instance,
 963                 promoted: None,
 964             };
 965             let const_val = this.const_eval_raw(cid)?;
 966             let const_val = this.read_scalar(const_val.into())?;
 967             return Ok(Some(const_val));
 968         }
 969         return Ok(None);
 970     }
 971 }