src/shims/foreign_items.rs

   1 use std::convert::TryInto;
   2
   3 use rustc::hir::def_id::DefId;
   4 use rustc::mir;
   5 use rustc::ty::layout::{Align, LayoutOf, Size};
   6 use rustc_apfloat::Float;
   7 use syntax::attr;
   8 use syntax::symbol::sym;
   9
  10 use crate::*;
  11
  12 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  13 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  14     /// Returns the minimum alignment for the target architecture for allocations of the given size.
  15     fn min_align(&self, size: u64, kind: MiriMemoryKind) -> Align {
  16         let this = self.eval_context_ref();
  17         // List taken from `libstd/sys_common/alloc.rs`.
  18         let min_align = match this.tcx.tcx.sess.target.target.arch.as_str() {
  19             "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
  20             "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" => 16,
  21             arch => bug!("Unsupported target architecture: {}", arch),
  22         };
  23         // Windows always aligns, even small allocations.
  24         // Source: <https://support.microsoft.com/en-us/help/286470/how-to-use-pageheap-exe-in-windows-xp-windows-2000-and-windows-server>
  25         // But jemalloc does not, so for the C heap we only align if the allocation is sufficiently big.
  26         if kind == MiriMemoryKind::WinHeap || size >= min_align {
  27             return Align::from_bytes(min_align).unwrap();
  28         }
  29         // We have `size < min_align`. Round `size` *down* to the next power of two and use that.
  30         fn prev_power_of_two(x: u64) -> u64 {
  31             let next_pow2 = x.next_power_of_two();
  32             if next_pow2 == x {
  33                 // x *is* a power of two, just use that.
  34                 x
  35             } else {
  36                 // x is between two powers, so next = 2*prev.
  37                 next_pow2 / 2
  38             }
  39         }
  40         Align::from_bytes(prev_power_of_two(size)).unwrap()
  41     }
  42
  43     fn malloc(&mut self, size: u64, zero_init: bool, kind: MiriMemoryKind) -> Scalar<Tag> {
  44         let this = self.eval_context_mut();
  45         if size == 0 {
  46             Scalar::from_int(0, this.pointer_size())
  47         } else {
  48             let align = this.min_align(size, kind);
  49             let ptr = this
  50                 .memory
  51                 .allocate(Size::from_bytes(size), align, kind.into());
  52             if zero_init {
  53                 // We just allocated this, the access is definitely in-bounds.
  54                 this.memory
  55                     .get_mut(ptr.alloc_id)
  56                     .unwrap()
  57                     .write_repeat(&*this.tcx, ptr, 0, Size::from_bytes(size))
  58                     .unwrap();
  59             }
  60             Scalar::Ptr(ptr)
  61         }
  62     }
  63
  64     fn free(&mut self, ptr: Scalar<Tag>, kind: MiriMemoryKind) -> InterpResult<'tcx> {
  65         let this = self.eval_context_mut();
  66         if !this.is_null(ptr)? {
  67             let ptr = this.force_ptr(ptr)?;
  68             this.memory.deallocate(ptr, None, kind.into())?;
  69         }
  70         Ok(())
  71     }
  72
  73     fn realloc(
  74         &mut self,
  75         old_ptr: Scalar<Tag>,
  76         new_size: u64,
  77         kind: MiriMemoryKind,
  78     ) -> InterpResult<'tcx, Scalar<Tag>> {
  79         let this = self.eval_context_mut();
  80         let new_align = this.min_align(new_size, kind);
  81         if this.is_null(old_ptr)? {
  82             if new_size == 0 {
  83                 Ok(Scalar::from_int(0, this.pointer_size()))
  84             } else {
  85                 let new_ptr =
  86                     this.memory
  87                         .allocate(Size::from_bytes(new_size), new_align, kind.into());
  88                 Ok(Scalar::Ptr(new_ptr))
  89             }
  90         } else {
  91             let old_ptr = this.force_ptr(old_ptr)?;
  92             if new_size == 0 {
  93                 this.memory.deallocate(old_ptr, None, kind.into())?;
  94                 Ok(Scalar::from_int(0, this.pointer_size()))
  95             } else {
  96                 let new_ptr = this.memory.reallocate(
  97                     old_ptr,
  98                     None,
  99                     Size::from_bytes(new_size),
 100                     new_align,
 101                     kind.into(),
 102                 )?;
 103                 Ok(Scalar::Ptr(new_ptr))
 104             }
 105         }
 106     }
 107
 108     /// Emulates calling a foreign item, failing if the item is not supported.
 109     /// This function will handle `goto_block` if needed.
 110     fn emulate_foreign_item(
 111         &mut self,
 112         def_id: DefId,
 113         args: &[OpTy<'tcx, Tag>],
 114         dest: Option<PlaceTy<'tcx, Tag>>,
 115         ret: Option<mir::BasicBlock>,
 116     ) -> InterpResult<'tcx> {
 117         let this = self.eval_context_mut();
 118         let attrs = this.tcx.get_attrs(def_id);
 119         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 120             Some(name) => name.as_str(),
 121             None => this.tcx.item_name(def_id).as_str(),
 122         };
 123         // Strip linker suffixes (seen on 32-bit macOS).
 124         let link_name = link_name.trim_end_matches("$UNIX2003");
 125         let tcx = &{ this.tcx.tcx };
 126
 127         // First: functions that diverge.
 128         match link_name {
 129             "__rust_start_panic" | "panic_impl" => {
 130                 throw_unsup_format!("the evaluated program panicked");
 131             }
 132             "exit" | "ExitProcess" => {
 133                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` error variant anyway
 134                 let code = this.read_scalar(args[0])?.to_i32()?;
 135                 return Err(InterpError::Exit(code).into());
 136             }
 137             _ => {
 138                 if dest.is_none() {
 139                     throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
 140                 }
 141             }
 142         }
 143
 144         // Next: functions that assume a ret and dest.
 145         let dest = dest.expect("we already checked for a dest");
 146         let ret = ret.expect("dest is `Some` but ret is `None`");
 147         match link_name {
 148             "malloc" => {
 149                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 150                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 151                 this.write_scalar(res, dest)?;
 152             }
 153             "calloc" => {
 154                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 155                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 156                 let size = items
 157                     .checked_mul(len)
 158                     .ok_or_else(|| err_panic!(Overflow(mir::BinOp::Mul)))?;
 159                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 160                 this.write_scalar(res, dest)?;
 161             }
 162             "posix_memalign" => {
 163                 let ret = this.deref_operand(args[0])?;
 164                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 165                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 166                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 167                 if !align.is_power_of_two() {
 168                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 169                 }
 170                 if align < this.pointer_size().bytes() {
 171                     throw_ub_format!(
 172                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 173                         align,
 174                     );
 175                 }
 176
 177                 if size == 0 {
 178                     this.write_null(ret.into())?;
 179                 } else {
 180                     let ptr = this.memory.allocate(
 181                         Size::from_bytes(size),
 182                         Align::from_bytes(align).unwrap(),
 183                         MiriMemoryKind::C.into(),
 184                     );
 185                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 186                 }
 187                 this.write_null(dest)?;
 188             }
 189             "free" => {
 190                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 191                 this.free(ptr, MiriMemoryKind::C)?;
 192             }
 193             "realloc" => {
 194                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 195                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 196                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 197                 this.write_scalar(res, dest)?;
 198             }
 199
 200             "__rust_alloc" => {
 201                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 202                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 203                 if size == 0 {
 204                     throw_unsup!(HeapAllocZeroBytes);
 205                 }
 206                 if !align.is_power_of_two() {
 207                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 208                 }
 209                 let ptr = this.memory.allocate(
 210                     Size::from_bytes(size),
 211                     Align::from_bytes(align).unwrap(),
 212                     MiriMemoryKind::Rust.into(),
 213                 );
 214                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 215             }
 216             "__rust_alloc_zeroed" => {
 217                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 218                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 219                 if size == 0 {
 220                     throw_unsup!(HeapAllocZeroBytes);
 221                 }
 222                 if !align.is_power_of_two() {
 223                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 224                 }
 225                 let ptr = this.memory.allocate(
 226                     Size::from_bytes(size),
 227                     Align::from_bytes(align).unwrap(),
 228                     MiriMemoryKind::Rust.into(),
 229                 );
 230                 // We just allocated this, the access is definitely in-bounds.
 231                 this.memory
 232                     .get_mut(ptr.alloc_id)
 233                     .unwrap()
 234                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size))
 235                     .unwrap();
 236                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 237             }
 238             "__rust_dealloc" => {
 239                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 240                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 241                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 242                 if old_size == 0 {
 243                     throw_unsup!(HeapAllocZeroBytes);
 244                 }
 245                 if !align.is_power_of_two() {
 246                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 247                 }
 248                 let ptr = this.force_ptr(ptr)?;
 249                 this.memory.deallocate(
 250                     ptr,
 251                     Some((
 252                         Size::from_bytes(old_size),
 253                         Align::from_bytes(align).unwrap(),
 254                     )),
 255                     MiriMemoryKind::Rust.into(),
 256                 )?;
 257             }
 258             "__rust_realloc" => {
 259                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 260                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 261                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 262                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 263                 if old_size == 0 || new_size == 0 {
 264                     throw_unsup!(HeapAllocZeroBytes);
 265                 }
 266                 if !align.is_power_of_two() {
 267                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 268                 }
 269                 let align = Align::from_bytes(align).unwrap();
 270                 let new_ptr = this.memory.reallocate(
 271                     ptr,
 272                     Some((Size::from_bytes(old_size), align)),
 273                     Size::from_bytes(new_size),
 274                     align,
 275                     MiriMemoryKind::Rust.into(),
 276                 )?;
 277                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 278             }
 279
 280             "syscall" => {
 281                 let sys_getrandom = this
 282                     .eval_path_scalar(&["libc", "SYS_getrandom"])?
 283                     .expect("Failed to get libc::SYS_getrandom")
 284                     .to_usize(this)?;
 285
 286                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 287                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 288                 match this.read_scalar(args[0])?.to_usize(this)? {
 289                     id if id == sys_getrandom => {
 290                         // The first argument is the syscall id,
 291                         // so skip over it.
 292                         linux_getrandom(this, &args[1..], dest)?;
 293                     }
 294                     id => throw_unsup_format!("miri does not support syscall ID {}", id),
 295                 }
 296             }
 297
 298             "getrandom" => {
 299                 linux_getrandom(this, args, dest)?;
 300             }
 301
 302             "dlsym" => {
 303                 let _handle = this.read_scalar(args[0])?;
 304                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 305                 let symbol_name = this.memory.read_c_str(symbol)?;
 306                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 307                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 308                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 309                     let ptr = this.memory.create_fn_alloc(FnVal::Other(dlsym));
 310                     this.write_scalar(Scalar::from(ptr), dest)?;
 311                 } else {
 312                     this.write_null(dest)?;
 313                 }
 314             }
 315
 316             "__rust_maybe_catch_panic" => {
 317                 // fn __rust_maybe_catch_panic(
 318                 //     f: fn(*mut u8),
 319                 //     data: *mut u8,
 320                 //     data_ptr: *mut usize,
 321                 //     vtable_ptr: *mut usize,
 322                 // ) -> u32
 323                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 324                 let f = this.read_scalar(args[0])?.not_undef()?;
 325                 let data = this.read_scalar(args[1])?.not_undef()?;
 326                 let f_instance = this.memory.get_fn(f)?.as_instance()?;
 327                 this.write_null(dest)?;
 328                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 329
 330                 // Now we make a function call.
 331                 // TODO: consider making this reusable? `InterpCx::step` does something similar
 332                 // for the TLS destructors, and of course `eval_main`.
 333                 let mir = this.load_mir(f_instance.def, None)?;
 334                 let ret_place =
 335                     MPlaceTy::dangling(this.layout_of(tcx.mk_unit())?, this).into();
 336                 this.push_stack_frame(
 337                     f_instance,
 338                     mir.span,
 339                     mir,
 340                     Some(ret_place),
 341                     // Directly return to caller.
 342                     StackPopCleanup::Goto(Some(ret)),
 343                 )?;
 344                 let mut args = this.frame().body.args_iter();
 345
 346                 let arg_local = args
 347                     .next()
 348                     .expect("Argument to __rust_maybe_catch_panic does not take enough arguments.");
 349                 let arg_dest = this.local_place(arg_local)?;
 350                 this.write_scalar(data, arg_dest)?;
 351
 352                 args.next().expect_none("__rust_maybe_catch_panic argument has more arguments than expected");
 353
 354                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 355                 this.write_null(dest)?;
 356
 357                 // Don't fall through, we do *not* want to `goto_block`!
 358                 return Ok(());
 359             }
 360
 361             "memcmp" => {
 362                 let left = this.read_scalar(args[0])?.not_undef()?;
 363                 let right = this.read_scalar(args[1])?.not_undef()?;
 364                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 365
 366                 let result = {
 367                     let left_bytes = this.memory.read_bytes(left, n)?;
 368                     let right_bytes = this.memory.read_bytes(right, n)?;
 369
 370                     use std::cmp::Ordering::*;
 371                     match left_bytes.cmp(right_bytes) {
 372                         Less => -1i32,
 373                         Equal => 0,
 374                         Greater => 1,
 375                     }
 376                 };
 377
 378                 this.write_scalar(Scalar::from_int(result, Size::from_bits(32)), dest)?;
 379             }
 380
 381             "memrchr" => {
 382                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 383                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 384                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 385                 if let Some(idx) = this
 386                     .memory
 387                     .read_bytes(ptr, Size::from_bytes(num))?
 388                     .iter()
 389                     .rev()
 390                     .position(|&c| c == val)
 391                 {
 392                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 393                     this.write_scalar(new_ptr, dest)?;
 394                 } else {
 395                     this.write_null(dest)?;
 396                 }
 397             }
 398
 399             "memchr" => {
 400                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 401                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 402                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 403                 let idx = this
 404                     .memory
 405                     .read_bytes(ptr, Size::from_bytes(num))?
 406                     .iter()
 407                     .position(|&c| c == val);
 408                 if let Some(idx) = idx {
 409                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 410                     this.write_scalar(new_ptr, dest)?;
 411                 } else {
 412                     this.write_null(dest)?;
 413                 }
 414             }
 415
 416             "__errno_location" | "__error" => {
 417                 let errno_place = this.machine.last_error.unwrap();
 418                 this.write_scalar(errno_place.to_ref().to_scalar()?, dest)?;
 419             }
 420
 421             "getenv" => {
 422                 let result = this.getenv(args[0])?;
 423                 this.write_scalar(result, dest)?;
 424             }
 425
 426             "unsetenv" => {
 427                 let result = this.unsetenv(args[0])?;
 428                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 429             }
 430
 431             "setenv" => {
 432                 let result = this.setenv(args[0], args[1])?;
 433                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 434             }
 435
 436             "getcwd" => {
 437                 let result = this.getcwd(args[0], args[1])?;
 438                 this.write_scalar(result, dest)?;
 439             }
 440
 441             "chdir" => {
 442                 let result = this.chdir(args[0])?;
 443                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 444             }
 445
 446             "open" | "open64" => {
 447                 let result = this.open(args[0], args[1])?;
 448                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 449             }
 450
 451             "fcntl" => {
 452                 let result = this.fcntl(args[0], args[1], args.get(2).cloned())?;
 453                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 454             }
 455
 456             "close" | "close$NOCANCEL" => {
 457                 let result = this.close(args[0])?;
 458                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 459             }
 460
 461             "read" => {
 462                 let result = this.read(args[0], args[1], args[2])?;
 463                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 464             }
 465
 466             "write" => {
 467                 let fd = this.read_scalar(args[0])?.to_i32()?;
 468                 let buf = this.read_scalar(args[1])?.not_undef()?;
 469                 let n = this.read_scalar(args[2])?.to_usize(tcx)?;
 470                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 471                 let result = if fd == 1 || fd == 2 {
 472                     // stdout/stderr
 473                     use std::io::{self, Write};
 474
 475                     let buf_cont = this.memory.read_bytes(buf, Size::from_bytes(n))?;
 476                     // We need to flush to make sure this actually appears on the screen
 477                     let res = if fd == 1 {
 478                         // Stdout is buffered, flush to make sure it appears on the screen.
 479                         // This is the write() syscall of the interpreted program, we want it
 480                         // to correspond to a write() syscall on the host -- there is no good
 481                         // in adding extra buffering here.
 482                         let res = io::stdout().write(buf_cont);
 483                         io::stdout().flush().unwrap();
 484                         res
 485                     } else {
 486                         // No need to flush, stderr is not buffered.
 487                         io::stderr().write(buf_cont)
 488                     };
 489                     match res {
 490                         Ok(n) => n as i64,
 491                         Err(_) => -1,
 492                     }
 493                 } else {
 494                     this.write(args[0], args[1], args[2])?
 495                 };
 496                 // Now, `result` is the value we return back to the program.
 497                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 498             }
 499
 500             "unlink" => {
 501                 let result = this.unlink(args[0])?;
 502                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 503             }
 504
 505             "clock_gettime" => {
 506                 let result = this.clock_gettime(args[0], args[1])?;
 507                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 508             }
 509
 510             "gettimeofday" => {
 511                 let result = this.gettimeofday(args[0], args[1])?;
 512                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 513             }
 514
 515             "strlen" => {
 516                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 517                 let n = this.memory.read_c_str(ptr)?.len();
 518                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 519             }
 520
 521             // math functions
 522             "cbrtf" | "coshf" | "sinhf" | "tanf" => {
 523                 // FIXME: Using host floats.
 524                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 525                 let f = match link_name {
 526                     "cbrtf" => f.cbrt(),
 527                     "coshf" => f.cosh(),
 528                     "sinhf" => f.sinh(),
 529                     "tanf" => f.tan(),
 530                     _ => bug!(),
 531                 };
 532                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 533             }
 534             // underscore case for windows
 535             "_hypotf" | "hypotf" | "atan2f" => {
 536                 // FIXME: Using host floats.
 537                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 538                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 539                 let n = match link_name {
 540                     "_hypotf" | "hypotf" => f1.hypot(f2),
 541                     "atan2f" => f1.atan2(f2),
 542                     _ => bug!(),
 543                 };
 544                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 545             }
 546
 547             "cbrt" | "cosh" | "sinh" | "tan" => {
 548                 // FIXME: Using host floats.
 549                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 550                 let f = match link_name {
 551                     "cbrt" => f.cbrt(),
 552                     "cosh" => f.cosh(),
 553                     "sinh" => f.sinh(),
 554                     "tan" => f.tan(),
 555                     _ => bug!(),
 556                 };
 557                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 558             }
 559             // underscore case for windows, here and below
 560             // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
 561             "_hypot" | "hypot" | "atan2" => {
 562                 // FIXME: Using host floats.
 563                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 564                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 565                 let n = match link_name {
 566                     "_hypot" | "hypot" => f1.hypot(f2),
 567                     "atan2" => f1.atan2(f2),
 568                     _ => bug!(),
 569                 };
 570                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 571             }
 572             // For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
 573             "_ldexp" | "ldexp" | "scalbn" => {
 574                 let x = this.read_scalar(args[0])?.to_f64()?;
 575                 let exp = this.read_scalar(args[1])?.to_i32()?;
 576
 577                 // Saturating cast to i16. Even those are outside the valid exponent range to
 578                 // `scalbn` below will do its over/underflow handling.
 579                 let exp = if exp > i16::max_value() as i32 {
 580                     i16::max_value()
 581                 } else if exp < i16::min_value() as i32 {
 582                     i16::min_value()
 583                 } else {
 584                     exp.try_into().unwrap()
 585                 };
 586
 587                 let res = x.scalbn(exp);
 588                 this.write_scalar(Scalar::from_f64(res), dest)?;
 589             }
 590
 591             // Some things needed for `sys::thread` initialization to go through.
 592             "signal" | "sigaction" | "sigaltstack" => {
 593                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 594             }
 595
 596             "sysconf" => {
 597                 let name = this.read_scalar(args[0])?.to_i32()?;
 598
 599                 trace!("sysconf() called with name {}", name);
 600                 // TODO: Cache the sysconf integers via Miri's global cache.
 601                 let paths = &[
 602                     (
 603                         &["libc", "_SC_PAGESIZE"],
 604                         Scalar::from_int(PAGE_SIZE, dest.layout.size),
 605                     ),
 606                     (
 607                         &["libc", "_SC_GETPW_R_SIZE_MAX"],
 608                         Scalar::from_int(-1, dest.layout.size),
 609                     ),
 610                     (
 611                         &["libc", "_SC_NPROCESSORS_ONLN"],
 612                         Scalar::from_int(NUM_CPUS, dest.layout.size),
 613                     ),
 614                 ];
 615                 let mut result = None;
 616                 for &(path, path_value) in paths {
 617                     if let Some(val) = this.eval_path_scalar(path)? {
 618                         let val = val.to_i32()?;
 619                         if val == name {
 620                             result = Some(path_value);
 621                             break;
 622                         }
 623                     }
 624                 }
 625                 if let Some(result) = result {
 626                     this.write_scalar(result, dest)?;
 627                 } else {
 628                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 629                 }
 630             }
 631
 632             "sched_getaffinity" => {
 633                 // Return an error; `num_cpus` then falls back to `sysconf`.
 634                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 635             }
 636
 637             "isatty" => {
 638                 this.write_null(dest)?;
 639             }
 640
 641             // Hook pthread calls that go to the thread-local storage memory subsystem.
 642             "pthread_key_create" => {
 643                 let key_place = this.deref_operand(args[0])?;
 644
 645                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 646                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 647                     Some(dtor_ptr) => Some(this.memory.get_fn(dtor_ptr)?.as_instance()?),
 648                     None => None,
 649                 };
 650
 651                 // Figure out how large a pthread TLS key actually is.
 652                 // This is `libc::pthread_key_t`.
 653                 let key_type = args[0].layout.ty
 654                     .builtin_deref(true)
 655                     .ok_or_else(|| err_ub_format!(
 656                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 657                     ))?
 658                     .ty;
 659                 let key_layout = this.layout_of(key_type)?;
 660
 661                 // Create key and write it into the memory where `key_ptr` wants it.
 662                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 663                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128)
 664                 {
 665                     throw_unsup!(OutOfTls);
 666                 }
 667
 668                 this.write_scalar(Scalar::from_uint(key, key_layout.size), key_place.into())?;
 669
 670                 // Return success (`0`).
 671                 this.write_null(dest)?;
 672             }
 673             "pthread_key_delete" => {
 674                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 675                 this.machine.tls.delete_tls_key(key)?;
 676                 // Return success (0)
 677                 this.write_null(dest)?;
 678             }
 679             "pthread_getspecific" => {
 680                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 681                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 682                 this.write_scalar(ptr, dest)?;
 683             }
 684             "pthread_setspecific" => {
 685                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 686                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 687                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 688
 689                 // Return success (`0`).
 690                 this.write_null(dest)?;
 691             }
 692
 693             // Stack size/address stuff.
 694             "pthread_attr_init"
 695             | "pthread_attr_destroy"
 696             | "pthread_self"
 697             | "pthread_attr_setstacksize" => {
 698                 this.write_null(dest)?;
 699             }
 700             "pthread_attr_getstack" => {
 701                 let addr_place = this.deref_operand(args[1])?;
 702                 let size_place = this.deref_operand(args[2])?;
 703
 704                 this.write_scalar(
 705                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 706                     addr_place.into(),
 707                 )?;
 708                 this.write_scalar(
 709                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 710                     size_place.into(),
 711                 )?;
 712
 713                 // Return success (`0`).
 714                 this.write_null(dest)?;
 715             }
 716
 717             // We don't support threading. (Also for Windows.)
 718             "pthread_create" | "CreateThread" => {
 719                 throw_unsup_format!("Miri does not support threading");
 720             }
 721
 722             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 723             "pthread_mutexattr_init"
 724             | "pthread_mutexattr_settype"
 725             | "pthread_mutex_init"
 726             | "pthread_mutexattr_destroy"
 727             | "pthread_mutex_lock"
 728             | "pthread_mutex_unlock"
 729             | "pthread_mutex_destroy"
 730             | "pthread_rwlock_rdlock"
 731             | "pthread_rwlock_unlock"
 732             | "pthread_rwlock_wrlock"
 733             | "pthread_rwlock_destroy"
 734             | "pthread_condattr_init"
 735             | "pthread_condattr_setclock"
 736             | "pthread_cond_init"
 737             | "pthread_condattr_destroy"
 738             | "pthread_cond_destroy" => {
 739                 this.write_null(dest)?;
 740             }
 741
 742             // We don't support fork so we don't have to do anything for atfork.
 743             "pthread_atfork" => {
 744                 this.write_null(dest)?;
 745             }
 746
 747             "mmap" => {
 748                 // 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.
 749                 let addr = this.read_scalar(args[0])?.not_undef()?;
 750                 this.write_scalar(addr, dest)?;
 751             }
 752             "mprotect" => {
 753                 this.write_null(dest)?;
 754             }
 755
 756             // macOS API stubs.
 757             "pthread_attr_get_np" | "pthread_getattr_np" => {
 758                 this.write_null(dest)?;
 759             }
 760             "pthread_get_stackaddr_np" => {
 761                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 762                 this.write_scalar(stack_addr, dest)?;
 763             }
 764             "pthread_get_stacksize_np" => {
 765                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 766                 this.write_scalar(stack_size, dest)?;
 767             }
 768             "_tlv_atexit" => {
 769                 // FIXME: register the destructor.
 770             }
 771             "_NSGetArgc" => {
 772                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 773             }
 774             "_NSGetArgv" => {
 775                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 776             }
 777             "SecRandomCopyBytes" => {
 778                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 779                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 780                 this.gen_random(ptr, len as usize)?;
 781                 this.write_null(dest)?;
 782             }
 783
 784             // Windows API stubs.
 785             // HANDLE = isize
 786             // DWORD = ULONG = u32
 787             // BOOL = i32
 788             "GetProcessHeap" => {
 789                 // Just fake a HANDLE
 790                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 791             }
 792             "HeapAlloc" => {
 793                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 794                 let flags = this.read_scalar(args[1])?.to_u32()?;
 795                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 796                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 797                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 798                 this.write_scalar(res, dest)?;
 799             }
 800             "HeapFree" => {
 801                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 802                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 803                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 804                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 805                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 806             }
 807             "HeapReAlloc" => {
 808                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 809                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 810                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 811                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 812                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 813                 this.write_scalar(res, dest)?;
 814             }
 815
 816             "SetLastError" => {
 817                 this.set_last_error(this.read_scalar(args[0])?.not_undef()?)?;
 818             }
 819             "GetLastError" => {
 820                 let last_error = this.get_last_error()?;
 821                 this.write_scalar(last_error, dest)?;
 822             }
 823
 824             "AddVectoredExceptionHandler" => {
 825                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 826                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 827             }
 828             "InitializeCriticalSection"
 829             | "EnterCriticalSection"
 830             | "LeaveCriticalSection"
 831             | "DeleteCriticalSection" => {
 832                 // Nothing to do, not even a return value.
 833             }
 834             "GetModuleHandleW"
 835             | "GetProcAddress"
 836             | "TryEnterCriticalSection"
 837             | "GetConsoleScreenBufferInfo"
 838             | "SetConsoleTextAttribute" => {
 839                 // Pretend these do not exist / nothing happened, by returning zero.
 840                 this.write_null(dest)?;
 841             }
 842             "GetSystemInfo" => {
 843                 let system_info = this.deref_operand(args[0])?;
 844                 let system_info_ptr = this
 845                     .check_mplace_access(system_info, None)?
 846                     .expect("cannot be a ZST");
 847                 // We rely on `deref_operand` doing bounds checks for us.
 848                 // Initialize with `0`.
 849                 this.memory
 850                     .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
 856                     .get_mut(system_info_ptr.alloc_id)?
 857                     .write_scalar(
 858                         tcx,
 859                         system_info_ptr.offset(offset, tcx)?,
 860                         Scalar::from_int(NUM_CPUS, dword_size).into(),
 861                         dword_size,
 862                     )?;
 863             }
 864
 865             "TlsAlloc" => {
 866                 // This just creates a key; Windows does not natively support TLS destructors.
 867
 868                 // Create key and return it.
 869                 let key = this.machine.tls.create_tls_key(None) as u128;
 870
 871                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 872                 if dest.layout.size.bits() < 128
 873                     && key >= (1u128 << dest.layout.size.bits() as u128)
 874                 {
 875                     throw_unsup!(OutOfTls);
 876                 }
 877                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 878             }
 879             "TlsGetValue" => {
 880                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 881                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 882                 this.write_scalar(ptr, dest)?;
 883             }
 884             "TlsSetValue" => {
 885                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 886                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 887                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 888
 889                 // Return success (`1`).
 890                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 891             }
 892             "GetStdHandle" => {
 893                 let which = this.read_scalar(args[0])?.to_i32()?;
 894                 // We just make this the identity function, so we know later in `WriteFile`
 895                 // which one it is.
 896                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 897             }
 898             "WriteFile" => {
 899                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 900                 let buf = this.read_scalar(args[1])?.not_undef()?;
 901                 let n = this.read_scalar(args[2])?.to_u32()?;
 902                 let written_place = this.deref_operand(args[3])?;
 903                 // Spec says to always write `0` first.
 904                 this.write_null(written_place.into())?;
 905                 let written = if handle == -11 || handle == -12 {
 906                     // stdout/stderr
 907                     use std::io::{self, Write};
 908
 909                     let buf_cont = this
 910                         .memory
 911                         .read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 912                     let res = if handle == -11 {
 913                         io::stdout().write(buf_cont)
 914                     } else {
 915                         io::stderr().write(buf_cont)
 916                     };
 917                     res.ok().map(|n| n as u32)
 918                 } else {
 919                     eprintln!("Miri: Ignored output to handle {}", handle);
 920                     // Pretend it all went well.
 921                     Some(n)
 922                 };
 923                 // If there was no error, write back how much was written.
 924                 if let Some(n) = written {
 925                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 926                 }
 927                 // Return whether this was a success.
 928                 this.write_scalar(
 929                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 930                     dest,
 931                 )?;
 932             }
 933             "GetConsoleMode" => {
 934                 // Everything is a pipe.
 935                 this.write_null(dest)?;
 936             }
 937             "GetEnvironmentVariableW" => {
 938                 // This is not the env var you are looking for.
 939                 this.set_last_error(Scalar::from_u32(203))?; // ERROR_ENVVAR_NOT_FOUND
 940                 this.write_null(dest)?;
 941             }
 942             "GetCommandLineW" => {
 943                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 944             }
 945             // The actual name of 'RtlGenRandom'
 946             "SystemFunction036" => {
 947                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 948                 let len = this.read_scalar(args[1])?.to_u32()?;
 949                 this.gen_random(ptr, len as usize)?;
 950                 this.write_scalar(Scalar::from_bool(true), dest)?;
 951             }
 952
 953             // We can't execute anything else.
 954             _ => throw_unsup_format!("can't call foreign function: {}", link_name),
 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(
 965         &mut self,
 966         path: &[&str],
 967     ) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 968         let this = self.eval_context_mut();
 969         if let Ok(instance) = this.resolve_path(path) {
 970             let cid = GlobalId {
 971                 instance,
 972                 promoted: None,
 973             };
 974             let const_val = this.const_eval_raw(cid)?;
 975             let const_val = this.read_scalar(const_val.into())?;
 976             return Ok(Some(const_val));
 977         }
 978         return Ok(None);
 979     }
 980 }
 981
 982 // Shims the linux 'getrandom()' syscall.
 983 fn linux_getrandom<'tcx>(
 984     this: &mut MiriEvalContext<'_, 'tcx>,
 985     args: &[OpTy<'tcx, Tag>],
 986     dest: PlaceTy<'tcx, Tag>,
 987 ) -> InterpResult<'tcx> {
 988     let ptr = this.read_scalar(args[0])?.not_undef()?;
 989     let len = this.read_scalar(args[1])?.to_usize(this)?;
 990
 991     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 992     // neither of which have any effect on our current PRNG.
 993     let _flags = this.read_scalar(args[2])?.to_i32()?;
 994
 995     this.gen_random(ptr, len as usize)?;
 996     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 997     Ok(())
 998 }