src/shims/foreign_items.rs

   1 use std::{iter, 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                     .write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize))
  56                     .unwrap();
  57             }
  58             Scalar::Ptr(ptr)
  59         }
  60     }
  61
  62     fn free(&mut self, ptr: Scalar<Tag>, kind: MiriMemoryKind) -> InterpResult<'tcx> {
  63         let this = self.eval_context_mut();
  64         if !this.is_null(ptr)? {
  65             let ptr = this.force_ptr(ptr)?;
  66             this.memory.deallocate(ptr, None, kind.into())?;
  67         }
  68         Ok(())
  69     }
  70
  71     fn realloc(
  72         &mut self,
  73         old_ptr: Scalar<Tag>,
  74         new_size: u64,
  75         kind: MiriMemoryKind,
  76     ) -> InterpResult<'tcx, Scalar<Tag>> {
  77         let this = self.eval_context_mut();
  78         let new_align = this.min_align(new_size, kind);
  79         if this.is_null(old_ptr)? {
  80             if new_size == 0 {
  81                 Ok(Scalar::from_int(0, this.pointer_size()))
  82             } else {
  83                 let new_ptr =
  84                     this.memory
  85                         .allocate(Size::from_bytes(new_size), new_align, kind.into());
  86                 Ok(Scalar::Ptr(new_ptr))
  87             }
  88         } else {
  89             let old_ptr = this.force_ptr(old_ptr)?;
  90             if new_size == 0 {
  91                 this.memory.deallocate(old_ptr, None, kind.into())?;
  92                 Ok(Scalar::from_int(0, this.pointer_size()))
  93             } else {
  94                 let new_ptr = this.memory.reallocate(
  95                     old_ptr,
  96                     None,
  97                     Size::from_bytes(new_size),
  98                     new_align,
  99                     kind.into(),
 100                 )?;
 101                 Ok(Scalar::Ptr(new_ptr))
 102             }
 103         }
 104     }
 105
 106     /// Emulates calling a foreign item, failing if the item is not supported.
 107     /// This function will handle `goto_block` if needed.
 108     fn emulate_foreign_item(
 109         &mut self,
 110         def_id: DefId,
 111         args: &[OpTy<'tcx, Tag>],
 112         dest: Option<PlaceTy<'tcx, Tag>>,
 113         ret: Option<mir::BasicBlock>,
 114     ) -> InterpResult<'tcx> {
 115         let this = self.eval_context_mut();
 116         let attrs = this.tcx.get_attrs(def_id);
 117         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 118             Some(name) => name.as_str(),
 119             None => this.tcx.item_name(def_id).as_str(),
 120         };
 121         // Strip linker suffixes (seen on 32-bit macOS).
 122         let link_name = link_name.trim_end_matches("$UNIX2003");
 123         let tcx = &{ this.tcx.tcx };
 124
 125         // First: functions that diverge.
 126         match link_name {
 127             "__rust_start_panic" | "panic_impl" => {
 128                 throw_unsup_format!("the evaluated program panicked");
 129             }
 130             "exit" | "ExitProcess" => {
 131                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` error variant anyway
 132                 let code = this.read_scalar(args[0])?.to_i32()?;
 133                 return Err(InterpError::Exit(code).into());
 134             }
 135             _ => {
 136                 if dest.is_none() {
 137                     throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
 138                 }
 139             }
 140         }
 141
 142         // Next: functions that assume a ret and dest.
 143         let dest = dest.expect("we already checked for a dest");
 144         let ret = ret.expect("dest is `Some` but ret is `None`");
 145         match link_name {
 146             "malloc" => {
 147                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 148                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 149                 this.write_scalar(res, dest)?;
 150             }
 151             "calloc" => {
 152                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 153                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 154                 let size = items
 155                     .checked_mul(len)
 156                     .ok_or_else(|| err_panic!(Overflow(mir::BinOp::Mul)))?;
 157                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 158                 this.write_scalar(res, dest)?;
 159             }
 160             "posix_memalign" => {
 161                 let ret = this.deref_operand(args[0])?;
 162                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 163                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 164                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 165                 if !align.is_power_of_two() {
 166                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 167                 }
 168                 if align < this.pointer_size().bytes() {
 169                     throw_ub_format!(
 170                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 171                         align,
 172                     );
 173                 }
 174
 175                 if size == 0 {
 176                     this.write_null(ret.into())?;
 177                 } else {
 178                     let ptr = this.memory.allocate(
 179                         Size::from_bytes(size),
 180                         Align::from_bytes(align).unwrap(),
 181                         MiriMemoryKind::C.into(),
 182                     );
 183                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 184                 }
 185                 this.write_null(dest)?;
 186             }
 187             "free" => {
 188                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 189                 this.free(ptr, MiriMemoryKind::C)?;
 190             }
 191             "realloc" => {
 192                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 193                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 194                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 195                 this.write_scalar(res, dest)?;
 196             }
 197
 198             "__rust_alloc" => {
 199                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 200                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 201                 if size == 0 {
 202                     throw_unsup!(HeapAllocZeroBytes);
 203                 }
 204                 if !align.is_power_of_two() {
 205                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 206                 }
 207                 let ptr = this.memory.allocate(
 208                     Size::from_bytes(size),
 209                     Align::from_bytes(align).unwrap(),
 210                     MiriMemoryKind::Rust.into(),
 211                 );
 212                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 213             }
 214             "__rust_alloc_zeroed" => {
 215                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 216                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 217                 if size == 0 {
 218                     throw_unsup!(HeapAllocZeroBytes);
 219                 }
 220                 if !align.is_power_of_two() {
 221                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 222                 }
 223                 let ptr = this.memory.allocate(
 224                     Size::from_bytes(size),
 225                     Align::from_bytes(align).unwrap(),
 226                     MiriMemoryKind::Rust.into(),
 227                 );
 228                 // We just allocated this, the access is definitely in-bounds.
 229                 this.memory
 230                     .write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize))
 231                     .unwrap();
 232                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 233             }
 234             "__rust_dealloc" => {
 235                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 236                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 237                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 238                 if old_size == 0 {
 239                     throw_unsup!(HeapAllocZeroBytes);
 240                 }
 241                 if !align.is_power_of_two() {
 242                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 243                 }
 244                 let ptr = this.force_ptr(ptr)?;
 245                 this.memory.deallocate(
 246                     ptr,
 247                     Some((
 248                         Size::from_bytes(old_size),
 249                         Align::from_bytes(align).unwrap(),
 250                     )),
 251                     MiriMemoryKind::Rust.into(),
 252                 )?;
 253             }
 254             "__rust_realloc" => {
 255                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 256                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 257                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 258                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 259                 if old_size == 0 || new_size == 0 {
 260                     throw_unsup!(HeapAllocZeroBytes);
 261                 }
 262                 if !align.is_power_of_two() {
 263                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 264                 }
 265                 let align = Align::from_bytes(align).unwrap();
 266                 let new_ptr = this.memory.reallocate(
 267                     ptr,
 268                     Some((Size::from_bytes(old_size), align)),
 269                     Size::from_bytes(new_size),
 270                     align,
 271                     MiriMemoryKind::Rust.into(),
 272                 )?;
 273                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 274             }
 275
 276             "syscall" => {
 277                 let sys_getrandom = this
 278                     .eval_path_scalar(&["libc", "SYS_getrandom"])?
 279                     .expect("Failed to get libc::SYS_getrandom")
 280                     .to_usize(this)?;
 281
 282                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 283                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 284                 match this.read_scalar(args[0])?.to_usize(this)? {
 285                     id if id == sys_getrandom => {
 286                         // The first argument is the syscall id,
 287                         // so skip over it.
 288                         linux_getrandom(this, &args[1..], dest)?;
 289                     }
 290                     id => throw_unsup_format!("miri does not support syscall ID {}", id),
 291                 }
 292             }
 293
 294             "getrandom" => {
 295                 linux_getrandom(this, args, dest)?;
 296             }
 297
 298             "dlsym" => {
 299                 let _handle = this.read_scalar(args[0])?;
 300                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 301                 let symbol_name = this.memory.read_c_str(symbol)?;
 302                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 303                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 304                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 305                     let ptr = this.memory.create_fn_alloc(FnVal::Other(dlsym));
 306                     this.write_scalar(Scalar::from(ptr), dest)?;
 307                 } else {
 308                     this.write_null(dest)?;
 309                 }
 310             }
 311
 312             "__rust_maybe_catch_panic" => {
 313                 // fn __rust_maybe_catch_panic(
 314                 //     f: fn(*mut u8),
 315                 //     data: *mut u8,
 316                 //     data_ptr: *mut usize,
 317                 //     vtable_ptr: *mut usize,
 318                 // ) -> u32
 319                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 320                 let f = this.read_scalar(args[0])?.not_undef()?;
 321                 let data = this.read_scalar(args[1])?.not_undef()?;
 322                 let f_instance = this.memory.get_fn(f)?.as_instance()?;
 323                 this.write_null(dest)?;
 324                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 325
 326                 // Now we make a function call.
 327                 // TODO: consider making this reusable? `InterpCx::step` does something similar
 328                 // for the TLS destructors, and of course `eval_main`.
 329                 let mir = this.load_mir(f_instance.def, None)?;
 330                 let ret_place =
 331                     MPlaceTy::dangling(this.layout_of(tcx.mk_unit())?, this).into();
 332                 this.push_stack_frame(
 333                     f_instance,
 334                     mir.span,
 335                     mir,
 336                     Some(ret_place),
 337                     // Directly return to caller.
 338                     StackPopCleanup::Goto(Some(ret)),
 339                 )?;
 340                 let mut args = this.frame().body.args_iter();
 341
 342                 let arg_local = args
 343                     .next()
 344                     .expect("Argument to __rust_maybe_catch_panic does not take enough arguments.");
 345                 let arg_dest = this.local_place(arg_local)?;
 346                 this.write_scalar(data, arg_dest)?;
 347
 348                 args.next().expect_none("__rust_maybe_catch_panic argument has more arguments than expected");
 349
 350                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 351                 this.write_null(dest)?;
 352
 353                 // Don't fall through, we do *not* want to `goto_block`!
 354                 return Ok(());
 355             }
 356
 357             "memcmp" => {
 358                 let left = this.read_scalar(args[0])?.not_undef()?;
 359                 let right = this.read_scalar(args[1])?.not_undef()?;
 360                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 361
 362                 let result = {
 363                     let left_bytes = this.memory.read_bytes(left, n)?;
 364                     let right_bytes = this.memory.read_bytes(right, n)?;
 365
 366                     use std::cmp::Ordering::*;
 367                     match left_bytes.cmp(right_bytes) {
 368                         Less => -1i32,
 369                         Equal => 0,
 370                         Greater => 1,
 371                     }
 372                 };
 373
 374                 this.write_scalar(Scalar::from_int(result, Size::from_bits(32)), dest)?;
 375             }
 376
 377             "memrchr" => {
 378                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 379                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 380                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 381                 if let Some(idx) = this
 382                     .memory
 383                     .read_bytes(ptr, Size::from_bytes(num))?
 384                     .iter()
 385                     .rev()
 386                     .position(|&c| c == val)
 387                 {
 388                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 389                     this.write_scalar(new_ptr, dest)?;
 390                 } else {
 391                     this.write_null(dest)?;
 392                 }
 393             }
 394
 395             "memchr" => {
 396                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 397                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 398                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 399                 let idx = this
 400                     .memory
 401                     .read_bytes(ptr, Size::from_bytes(num))?
 402                     .iter()
 403                     .position(|&c| c == val);
 404                 if let Some(idx) = idx {
 405                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 406                     this.write_scalar(new_ptr, dest)?;
 407                 } else {
 408                     this.write_null(dest)?;
 409                 }
 410             }
 411
 412             "__errno_location" | "__error" => {
 413                 let errno_place = this.machine.last_error.unwrap();
 414                 this.write_scalar(errno_place.to_ref().to_scalar()?, dest)?;
 415             }
 416
 417             "getenv" => {
 418                 let result = this.getenv(args[0])?;
 419                 this.write_scalar(result, dest)?;
 420             }
 421
 422             "unsetenv" => {
 423                 let result = this.unsetenv(args[0])?;
 424                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 425             }
 426
 427             "setenv" => {
 428                 let result = this.setenv(args[0], args[1])?;
 429                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 430             }
 431
 432             "getcwd" => {
 433                 let result = this.getcwd(args[0], args[1])?;
 434                 this.write_scalar(result, dest)?;
 435             }
 436
 437             "chdir" => {
 438                 let result = this.chdir(args[0])?;
 439                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 440             }
 441
 442             "open" | "open64" => {
 443                 let result = this.open(args[0], args[1])?;
 444                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 445             }
 446
 447             "fcntl" => {
 448                 let result = this.fcntl(args[0], args[1], args.get(2).cloned())?;
 449                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 450             }
 451
 452             "close" | "close$NOCANCEL" => {
 453                 let result = this.close(args[0])?;
 454                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 455             }
 456
 457             "read" => {
 458                 let result = this.read(args[0], args[1], args[2])?;
 459                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 460             }
 461
 462             "write" => {
 463                 let fd = this.read_scalar(args[0])?.to_i32()?;
 464                 let buf = this.read_scalar(args[1])?.not_undef()?;
 465                 let n = this.read_scalar(args[2])?.to_usize(tcx)?;
 466                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 467                 let result = if fd == 1 || fd == 2 {
 468                     // stdout/stderr
 469                     use std::io::{self, Write};
 470
 471                     let buf_cont = this.memory.read_bytes(buf, Size::from_bytes(n))?;
 472                     // We need to flush to make sure this actually appears on the screen
 473                     let res = if fd == 1 {
 474                         // Stdout is buffered, flush to make sure it appears on the screen.
 475                         // This is the write() syscall of the interpreted program, we want it
 476                         // to correspond to a write() syscall on the host -- there is no good
 477                         // in adding extra buffering here.
 478                         let res = io::stdout().write(buf_cont);
 479                         io::stdout().flush().unwrap();
 480                         res
 481                     } else {
 482                         // No need to flush, stderr is not buffered.
 483                         io::stderr().write(buf_cont)
 484                     };
 485                     match res {
 486                         Ok(n) => n as i64,
 487                         Err(_) => -1,
 488                     }
 489                 } else {
 490                     this.write(args[0], args[1], args[2])?
 491                 };
 492                 // Now, `result` is the value we return back to the program.
 493                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 494             }
 495
 496             "unlink" => {
 497                 let result = this.unlink(args[0])?;
 498                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 499             }
 500
 501             "clock_gettime" => {
 502                 let result = this.clock_gettime(args[0], args[1])?;
 503                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 504             }
 505
 506             "gettimeofday" => {
 507                 let result = this.gettimeofday(args[0], args[1])?;
 508                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 509             }
 510
 511             "strlen" => {
 512                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 513                 let n = this.memory.read_c_str(ptr)?.len();
 514                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 515             }
 516
 517             // math functions
 518             "cbrtf" | "coshf" | "sinhf" | "tanf" => {
 519                 // FIXME: Using host floats.
 520                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 521                 let f = match link_name {
 522                     "cbrtf" => f.cbrt(),
 523                     "coshf" => f.cosh(),
 524                     "sinhf" => f.sinh(),
 525                     "tanf" => f.tan(),
 526                     _ => bug!(),
 527                 };
 528                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 529             }
 530             // underscore case for windows
 531             "_hypotf" | "hypotf" | "atan2f" => {
 532                 // FIXME: Using host floats.
 533                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 534                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 535                 let n = match link_name {
 536                     "_hypotf" | "hypotf" => f1.hypot(f2),
 537                     "atan2f" => f1.atan2(f2),
 538                     _ => bug!(),
 539                 };
 540                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 541             }
 542
 543             "cbrt" | "cosh" | "sinh" | "tan" => {
 544                 // FIXME: Using host floats.
 545                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 546                 let f = match link_name {
 547                     "cbrt" => f.cbrt(),
 548                     "cosh" => f.cosh(),
 549                     "sinh" => f.sinh(),
 550                     "tan" => f.tan(),
 551                     _ => bug!(),
 552                 };
 553                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 554             }
 555             // underscore case for windows, here and below
 556             // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
 557             "_hypot" | "hypot" | "atan2" => {
 558                 // FIXME: Using host floats.
 559                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 560                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 561                 let n = match link_name {
 562                     "_hypot" | "hypot" => f1.hypot(f2),
 563                     "atan2" => f1.atan2(f2),
 564                     _ => bug!(),
 565                 };
 566                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 567             }
 568             // For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
 569             "_ldexp" | "ldexp" | "scalbn" => {
 570                 let x = this.read_scalar(args[0])?.to_f64()?;
 571                 let exp = this.read_scalar(args[1])?.to_i32()?;
 572
 573                 // Saturating cast to i16. Even those are outside the valid exponent range to
 574                 // `scalbn` below will do its over/underflow handling.
 575                 let exp = if exp > i16::max_value() as i32 {
 576                     i16::max_value()
 577                 } else if exp < i16::min_value() as i32 {
 578                     i16::min_value()
 579                 } else {
 580                     exp.try_into().unwrap()
 581                 };
 582
 583                 let res = x.scalbn(exp);
 584                 this.write_scalar(Scalar::from_f64(res), dest)?;
 585             }
 586
 587             // Some things needed for `sys::thread` initialization to go through.
 588             "signal" | "sigaction" | "sigaltstack" => {
 589                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 590             }
 591
 592             "sysconf" => {
 593                 let name = this.read_scalar(args[0])?.to_i32()?;
 594
 595                 trace!("sysconf() called with name {}", name);
 596                 // TODO: Cache the sysconf integers via Miri's global cache.
 597                 let paths = &[
 598                     (
 599                         &["libc", "_SC_PAGESIZE"],
 600                         Scalar::from_int(PAGE_SIZE, dest.layout.size),
 601                     ),
 602                     (
 603                         &["libc", "_SC_GETPW_R_SIZE_MAX"],
 604                         Scalar::from_int(-1, dest.layout.size),
 605                     ),
 606                     (
 607                         &["libc", "_SC_NPROCESSORS_ONLN"],
 608                         Scalar::from_int(NUM_CPUS, dest.layout.size),
 609                     ),
 610                 ];
 611                 let mut result = None;
 612                 for &(path, path_value) in paths {
 613                     if let Some(val) = this.eval_path_scalar(path)? {
 614                         let val = val.to_i32()?;
 615                         if val == name {
 616                             result = Some(path_value);
 617                             break;
 618                         }
 619                     }
 620                 }
 621                 if let Some(result) = result {
 622                     this.write_scalar(result, dest)?;
 623                 } else {
 624                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 625                 }
 626             }
 627
 628             "sched_getaffinity" => {
 629                 // Return an error; `num_cpus` then falls back to `sysconf`.
 630                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 631             }
 632
 633             "isatty" => {
 634                 this.write_null(dest)?;
 635             }
 636
 637             // Hook pthread calls that go to the thread-local storage memory subsystem.
 638             "pthread_key_create" => {
 639                 let key_place = this.deref_operand(args[0])?;
 640
 641                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 642                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 643                     Some(dtor_ptr) => Some(this.memory.get_fn(dtor_ptr)?.as_instance()?),
 644                     None => None,
 645                 };
 646
 647                 // Figure out how large a pthread TLS key actually is.
 648                 // This is `libc::pthread_key_t`.
 649                 let key_type = args[0].layout.ty
 650                     .builtin_deref(true)
 651                     .ok_or_else(|| err_ub_format!(
 652                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 653                     ))?
 654                     .ty;
 655                 let key_layout = this.layout_of(key_type)?;
 656
 657                 // Create key and write it into the memory where `key_ptr` wants it.
 658                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 659                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128)
 660                 {
 661                     throw_unsup!(OutOfTls);
 662                 }
 663
 664                 this.write_scalar(Scalar::from_uint(key, key_layout.size), key_place.into())?;
 665
 666                 // Return success (`0`).
 667                 this.write_null(dest)?;
 668             }
 669             "pthread_key_delete" => {
 670                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 671                 this.machine.tls.delete_tls_key(key)?;
 672                 // Return success (0)
 673                 this.write_null(dest)?;
 674             }
 675             "pthread_getspecific" => {
 676                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 677                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 678                 this.write_scalar(ptr, dest)?;
 679             }
 680             "pthread_setspecific" => {
 681                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 682                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 683                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 684
 685                 // Return success (`0`).
 686                 this.write_null(dest)?;
 687             }
 688
 689             // Stack size/address stuff.
 690             "pthread_attr_init"
 691             | "pthread_attr_destroy"
 692             | "pthread_self"
 693             | "pthread_attr_setstacksize" => {
 694                 this.write_null(dest)?;
 695             }
 696             "pthread_attr_getstack" => {
 697                 let addr_place = this.deref_operand(args[1])?;
 698                 let size_place = this.deref_operand(args[2])?;
 699
 700                 this.write_scalar(
 701                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 702                     addr_place.into(),
 703                 )?;
 704                 this.write_scalar(
 705                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 706                     size_place.into(),
 707                 )?;
 708
 709                 // Return success (`0`).
 710                 this.write_null(dest)?;
 711             }
 712
 713             // We don't support threading. (Also for Windows.)
 714             "pthread_create" | "CreateThread" => {
 715                 throw_unsup_format!("Miri does not support threading");
 716             }
 717
 718             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 719             "pthread_mutexattr_init"
 720             | "pthread_mutexattr_settype"
 721             | "pthread_mutex_init"
 722             | "pthread_mutexattr_destroy"
 723             | "pthread_mutex_lock"
 724             | "pthread_mutex_unlock"
 725             | "pthread_mutex_destroy"
 726             | "pthread_rwlock_rdlock"
 727             | "pthread_rwlock_unlock"
 728             | "pthread_rwlock_wrlock"
 729             | "pthread_rwlock_destroy"
 730             | "pthread_condattr_init"
 731             | "pthread_condattr_setclock"
 732             | "pthread_cond_init"
 733             | "pthread_condattr_destroy"
 734             | "pthread_cond_destroy" => {
 735                 this.write_null(dest)?;
 736             }
 737
 738             // We don't support fork so we don't have to do anything for atfork.
 739             "pthread_atfork" => {
 740                 this.write_null(dest)?;
 741             }
 742
 743             "mmap" => {
 744                 // 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.
 745                 let addr = this.read_scalar(args[0])?.not_undef()?;
 746                 this.write_scalar(addr, dest)?;
 747             }
 748             "mprotect" => {
 749                 this.write_null(dest)?;
 750             }
 751
 752             // macOS API stubs.
 753             "pthread_attr_get_np" | "pthread_getattr_np" => {
 754                 this.write_null(dest)?;
 755             }
 756             "pthread_get_stackaddr_np" => {
 757                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 758                 this.write_scalar(stack_addr, dest)?;
 759             }
 760             "pthread_get_stacksize_np" => {
 761                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 762                 this.write_scalar(stack_size, dest)?;
 763             }
 764             "_tlv_atexit" => {
 765                 // FIXME: register the destructor.
 766             }
 767             "_NSGetArgc" => {
 768                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 769             }
 770             "_NSGetArgv" => {
 771                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 772             }
 773             "SecRandomCopyBytes" => {
 774                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 775                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 776                 this.gen_random(ptr, len as usize)?;
 777                 this.write_null(dest)?;
 778             }
 779
 780             // Windows API stubs.
 781             // HANDLE = isize
 782             // DWORD = ULONG = u32
 783             // BOOL = i32
 784             "GetProcessHeap" => {
 785                 // Just fake a HANDLE
 786                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 787             }
 788             "HeapAlloc" => {
 789                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 790                 let flags = this.read_scalar(args[1])?.to_u32()?;
 791                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 792                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 793                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 794                 this.write_scalar(res, dest)?;
 795             }
 796             "HeapFree" => {
 797                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 798                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 799                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 800                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 801                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 802             }
 803             "HeapReAlloc" => {
 804                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 805                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 806                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 807                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 808                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 809                 this.write_scalar(res, dest)?;
 810             }
 811
 812             "SetLastError" => {
 813                 this.set_last_error(this.read_scalar(args[0])?.not_undef()?)?;
 814             }
 815             "GetLastError" => {
 816                 let last_error = this.get_last_error()?;
 817                 this.write_scalar(last_error, dest)?;
 818             }
 819
 820             "AddVectoredExceptionHandler" => {
 821                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 822                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 823             }
 824             "InitializeCriticalSection"
 825             | "EnterCriticalSection"
 826             | "LeaveCriticalSection"
 827             | "DeleteCriticalSection" => {
 828                 // Nothing to do, not even a return value.
 829             }
 830             "GetModuleHandleW"
 831             | "GetProcAddress"
 832             | "TryEnterCriticalSection"
 833             | "GetConsoleScreenBufferInfo"
 834             | "SetConsoleTextAttribute" => {
 835                 // Pretend these do not exist / nothing happened, by returning zero.
 836                 this.write_null(dest)?;
 837             }
 838             "GetSystemInfo" => {
 839                 let system_info = this.deref_operand(args[0])?;
 840                 // Initialize with `0`.
 841                 this.memory
 842                     .write_bytes(system_info.ptr, iter::repeat(0u8).take(system_info.layout.size.bytes() as usize))?;
 843                 // Set number of processors.
 844                 let dword_size = Size::from_bytes(4);
 845                 let num_cpus = this.mplace_field(system_info, 6)?;
 846                 this.write_scalar(
 847                     Scalar::from_int(NUM_CPUS, dword_size),
 848                     num_cpus.into(),
 849                 )?;
 850             }
 851
 852             "TlsAlloc" => {
 853                 // This just creates a key; Windows does not natively support TLS destructors.
 854
 855                 // Create key and return it.
 856                 let key = this.machine.tls.create_tls_key(None) as u128;
 857
 858                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 859                 if dest.layout.size.bits() < 128
 860                     && key >= (1u128 << dest.layout.size.bits() as u128)
 861                 {
 862                     throw_unsup!(OutOfTls);
 863                 }
 864                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 865             }
 866             "TlsGetValue" => {
 867                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 868                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 869                 this.write_scalar(ptr, dest)?;
 870             }
 871             "TlsSetValue" => {
 872                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 873                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 874                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 875
 876                 // Return success (`1`).
 877                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 878             }
 879             "GetStdHandle" => {
 880                 let which = this.read_scalar(args[0])?.to_i32()?;
 881                 // We just make this the identity function, so we know later in `WriteFile`
 882                 // which one it is.
 883                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 884             }
 885             "WriteFile" => {
 886                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 887                 let buf = this.read_scalar(args[1])?.not_undef()?;
 888                 let n = this.read_scalar(args[2])?.to_u32()?;
 889                 let written_place = this.deref_operand(args[3])?;
 890                 // Spec says to always write `0` first.
 891                 this.write_null(written_place.into())?;
 892                 let written = if handle == -11 || handle == -12 {
 893                     // stdout/stderr
 894                     use std::io::{self, Write};
 895
 896                     let buf_cont = this
 897                         .memory
 898                         .read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 899                     let res = if handle == -11 {
 900                         io::stdout().write(buf_cont)
 901                     } else {
 902                         io::stderr().write(buf_cont)
 903                     };
 904                     res.ok().map(|n| n as u32)
 905                 } else {
 906                     eprintln!("Miri: Ignored output to handle {}", handle);
 907                     // Pretend it all went well.
 908                     Some(n)
 909                 };
 910                 // If there was no error, write back how much was written.
 911                 if let Some(n) = written {
 912                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 913                 }
 914                 // Return whether this was a success.
 915                 this.write_scalar(
 916                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 917                     dest,
 918                 )?;
 919             }
 920             "GetConsoleMode" => {
 921                 // Everything is a pipe.
 922                 this.write_null(dest)?;
 923             }
 924             "GetEnvironmentVariableW" => {
 925                 // This is not the env var you are looking for.
 926                 this.set_last_error(Scalar::from_u32(203))?; // ERROR_ENVVAR_NOT_FOUND
 927                 this.write_null(dest)?;
 928             }
 929             "GetCommandLineW" => {
 930                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 931             }
 932             // The actual name of 'RtlGenRandom'
 933             "SystemFunction036" => {
 934                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 935                 let len = this.read_scalar(args[1])?.to_u32()?;
 936                 this.gen_random(ptr, len as usize)?;
 937                 this.write_scalar(Scalar::from_bool(true), dest)?;
 938             }
 939
 940             // We can't execute anything else.
 941             _ => throw_unsup_format!("can't call foreign function: {}", link_name),
 942         }
 943
 944         this.goto_block(Some(ret))?;
 945         this.dump_place(*dest);
 946         Ok(())
 947     }
 948
 949     /// Evaluates the scalar at the specified path. Returns Some(val)
 950     /// if the path could be resolved, and None otherwise
 951     fn eval_path_scalar(
 952         &mut self,
 953         path: &[&str],
 954     ) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 955         let this = self.eval_context_mut();
 956         if let Ok(instance) = this.resolve_path(path) {
 957             let cid = GlobalId {
 958                 instance,
 959                 promoted: None,
 960             };
 961             let const_val = this.const_eval_raw(cid)?;
 962             let const_val = this.read_scalar(const_val.into())?;
 963             return Ok(Some(const_val));
 964         }
 965         return Ok(None);
 966     }
 967 }
 968
 969 // Shims the linux 'getrandom()' syscall.
 970 fn linux_getrandom<'tcx>(
 971     this: &mut MiriEvalContext<'_, 'tcx>,
 972     args: &[OpTy<'tcx, Tag>],
 973     dest: PlaceTy<'tcx, Tag>,
 974 ) -> InterpResult<'tcx> {
 975     let ptr = this.read_scalar(args[0])?.not_undef()?;
 976     let len = this.read_scalar(args[1])?.to_usize(this)?;
 977
 978     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 979     // neither of which have any effect on our current PRNG.
 980     let _flags = this.read_scalar(args[2])?.to_i32()?;
 981
 982     this.gen_random(ptr, len as usize)?;
 983     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 984     Ok(())
 985 }