src/shims/foreign_items.rs

   1 use std::{iter, convert::TryInto};
   2
   3 use rustc::mir;
   4 use rustc::ty::layout::{Align, LayoutOf, Size};
   5 use rustc::hir::def_id::DefId;
   6 use rustc_apfloat::Float;
   7 use rustc::ty;
   8 use syntax::attr;
   9 use syntax::symbol::sym;
  10
  11 use crate::*;
  12
  13 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  14 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  15     /// Returns the minimum alignment for the target architecture for allocations of the given size.
  16     fn min_align(&self, size: u64, kind: MiriMemoryKind) -> Align {
  17         let this = self.eval_context_ref();
  18         // List taken from `libstd/sys_common/alloc.rs`.
  19         let min_align = match this.tcx.tcx.sess.target.target.arch.as_str() {
  20             "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
  21             "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" => 16,
  22             arch => bug!("Unsupported target architecture: {}", arch),
  23         };
  24         // Windows always aligns, even small allocations.
  25         // Source: <https://support.microsoft.com/en-us/help/286470/how-to-use-pageheap-exe-in-windows-xp-windows-2000-and-windows-server>
  26         // But jemalloc does not, so for the C heap we only align if the allocation is sufficiently big.
  27         if kind == MiriMemoryKind::WinHeap || size >= min_align {
  28             return Align::from_bytes(min_align).unwrap();
  29         }
  30         // We have `size < min_align`. Round `size` *down* to the next power of two and use that.
  31         fn prev_power_of_two(x: u64) -> u64 {
  32             let next_pow2 = x.next_power_of_two();
  33             if next_pow2 == x {
  34                 // x *is* a power of two, just use that.
  35                 x
  36             } else {
  37                 // x is between two powers, so next = 2*prev.
  38                 next_pow2 / 2
  39             }
  40         }
  41         Align::from_bytes(prev_power_of_two(size)).unwrap()
  42     }
  43
  44     fn malloc(&mut self, size: u64, zero_init: bool, kind: MiriMemoryKind) -> Scalar<Tag> {
  45         let this = self.eval_context_mut();
  46         if size == 0 {
  47             Scalar::from_int(0, this.pointer_size())
  48         } else {
  49             let align = this.min_align(size, kind);
  50             let ptr = this
  51                 .memory
  52                 .allocate(Size::from_bytes(size), align, kind.into());
  53             if zero_init {
  54                 // We just allocated this, the access is definitely in-bounds.
  55                 this.memory
  56                     .write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize))
  57                     .unwrap();
  58             }
  59             Scalar::Ptr(ptr)
  60         }
  61     }
  62
  63     fn free(&mut self, ptr: Scalar<Tag>, kind: MiriMemoryKind) -> InterpResult<'tcx> {
  64         let this = self.eval_context_mut();
  65         if !this.is_null(ptr)? {
  66             let ptr = this.force_ptr(ptr)?;
  67             this.memory.deallocate(ptr, None, kind.into())?;
  68         }
  69         Ok(())
  70     }
  71
  72     fn realloc(
  73         &mut self,
  74         old_ptr: Scalar<Tag>,
  75         new_size: u64,
  76         kind: MiriMemoryKind,
  77     ) -> InterpResult<'tcx, Scalar<Tag>> {
  78         let this = self.eval_context_mut();
  79         let new_align = this.min_align(new_size, kind);
  80         if this.is_null(old_ptr)? {
  81             if new_size == 0 {
  82                 Ok(Scalar::from_int(0, this.pointer_size()))
  83             } else {
  84                 let new_ptr =
  85                     this.memory
  86                         .allocate(Size::from_bytes(new_size), new_align, kind.into());
  87                 Ok(Scalar::Ptr(new_ptr))
  88             }
  89         } else {
  90             let old_ptr = this.force_ptr(old_ptr)?;
  91             if new_size == 0 {
  92                 this.memory.deallocate(old_ptr, None, kind.into())?;
  93                 Ok(Scalar::from_int(0, this.pointer_size()))
  94             } else {
  95                 let new_ptr = this.memory.reallocate(
  96                     old_ptr,
  97                     None,
  98                     Size::from_bytes(new_size),
  99                     new_align,
 100                     kind.into(),
 101                 )?;
 102                 Ok(Scalar::Ptr(new_ptr))
 103             }
 104         }
 105     }
 106
 107     /// Emulates calling a foreign item, failing if the item is not supported.
 108     /// This function will handle `goto_block` if needed.
 109     /// Returns Ok(None) if the foreign item was completely handled
 110     /// by this function.
 111     /// Returns Ok(Some(body)) if processing the foreign item
 112     /// is delegated to another function.
 113     fn emulate_foreign_item(
 114         &mut self,
 115         def_id: DefId,
 116         args: &[OpTy<'tcx, Tag>],
 117         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
 118         _unwind: Option<mir::BasicBlock>
 119     ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
 120         let this = self.eval_context_mut();
 121         let attrs = this.tcx.get_attrs(def_id);
 122         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 123             Some(name) => name.as_str(),
 124             None => this.tcx.item_name(def_id).as_str(),
 125         };
 126         // Strip linker suffixes (seen on 32-bit macOS).
 127         let link_name = link_name.trim_end_matches("$UNIX2003");
 128         let tcx = &{ this.tcx.tcx };
 129
 130         // First: functions that diverge.
 131         let (dest, ret) = match link_name {
 132             // Note that this matches calls to the *foreign* item `__rust_start_panic* -
 133             // that is, calls to `extern "Rust" { fn __rust_start_panic(...) }`.
 134             // We forward this to the underlying *implementation* in the panic runtime crate.
 135             // Normally, this will be either `libpanic_unwind` or `libpanic_abort`, but it could
 136             // also be a custom user-provided implementation via `#![feature(panic_runtime)]`
 137             "__rust_start_panic" => {
 138                 let panic_runtime = tcx.crate_name(tcx.injected_panic_runtime().expect("No panic runtime found!"));
 139                 let start_panic_instance = this.resolve_path(&[&*panic_runtime.as_str(), "__rust_start_panic"])?;
 140                 return Ok(Some(this.load_mir(start_panic_instance.def, None)?));
 141             }
 142             // Similarly, we forward calls to the `panic_impl` foreign item to its implementation.
 143             // The implementation is provided by the function with the `#[panic_handler]` attribute.
 144             "panic_impl" => {
 145                 let panic_impl_id = this.tcx.lang_items().panic_impl().unwrap();
 146                 let panic_impl_instance = ty::Instance::mono(*this.tcx, panic_impl_id);
 147                 return Ok(Some(this.load_mir(panic_impl_instance.def, None)?));
 148             }
 149
 150             "exit" | "ExitProcess" => {
 151                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` error variant anyway
 152                 let code = this.read_scalar(args[0])?.to_i32()?;
 153                 return Err(InterpError::Exit(code).into());
 154             }
 155             _ => {
 156                 if let Some(p) = ret {
 157                     p
 158                 } else {
 159                     throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
 160                 }
 161             }
 162         };
 163
 164         // Next: functions that return.
 165         match link_name {
 166             "malloc" => {
 167                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 168                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 169                 this.write_scalar(res, dest)?;
 170             }
 171             "calloc" => {
 172                 let items = this.read_scalar(args[0])?.to_machine_usize(this)?;
 173                 let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 174                 let size = items
 175                     .checked_mul(len)
 176                     .ok_or_else(|| err_panic!(Overflow(mir::BinOp::Mul)))?;
 177                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 178                 this.write_scalar(res, dest)?;
 179             }
 180             "posix_memalign" => {
 181                 let ret = this.deref_operand(args[0])?;
 182                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 183                 let size = this.read_scalar(args[2])?.to_machine_usize(this)?;
 184                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 185                 if !align.is_power_of_two() {
 186                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 187                 }
 188                 if align < this.pointer_size().bytes() {
 189                     throw_ub_format!(
 190                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 191                         align,
 192                     );
 193                 }
 194
 195                 if size == 0 {
 196                     this.write_null(ret.into())?;
 197                 } else {
 198                     let ptr = this.memory.allocate(
 199                         Size::from_bytes(size),
 200                         Align::from_bytes(align).unwrap(),
 201                         MiriMemoryKind::C.into(),
 202                     );
 203                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 204                 }
 205                 this.write_null(dest)?;
 206             }
 207             "free" => {
 208                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 209                 this.free(ptr, MiriMemoryKind::C)?;
 210             }
 211             "realloc" => {
 212                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 213                 let new_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 214                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 215                 this.write_scalar(res, dest)?;
 216             }
 217
 218             "__rust_alloc" => {
 219                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 220                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 221                 if size == 0 {
 222                     throw_unsup!(HeapAllocZeroBytes);
 223                 }
 224                 if !align.is_power_of_two() {
 225                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 226                 }
 227                 let ptr = this.memory.allocate(
 228                     Size::from_bytes(size),
 229                     Align::from_bytes(align).unwrap(),
 230                     MiriMemoryKind::Rust.into(),
 231                 );
 232                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 233             }
 234             "__rust_alloc_zeroed" => {
 235                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 236                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 237                 if size == 0 {
 238                     throw_unsup!(HeapAllocZeroBytes);
 239                 }
 240                 if !align.is_power_of_two() {
 241                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 242                 }
 243                 let ptr = this.memory.allocate(
 244                     Size::from_bytes(size),
 245                     Align::from_bytes(align).unwrap(),
 246                     MiriMemoryKind::Rust.into(),
 247                 );
 248                 // We just allocated this, the access is definitely in-bounds.
 249                 this.memory
 250                     .write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize))
 251                     .unwrap();
 252                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 253             }
 254             "__rust_dealloc" => {
 255                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 256                 let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 257                 let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
 258                 if old_size == 0 {
 259                     throw_unsup!(HeapAllocZeroBytes);
 260                 }
 261                 if !align.is_power_of_two() {
 262                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 263                 }
 264                 let ptr = this.force_ptr(ptr)?;
 265                 this.memory.deallocate(
 266                     ptr,
 267                     Some((
 268                         Size::from_bytes(old_size),
 269                         Align::from_bytes(align).unwrap(),
 270                     )),
 271                     MiriMemoryKind::Rust.into(),
 272                 )?;
 273             }
 274             "__rust_realloc" => {
 275                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 276                 let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 277                 let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
 278                 let new_size = this.read_scalar(args[3])?.to_machine_usize(this)?;
 279                 if old_size == 0 || new_size == 0 {
 280                     throw_unsup!(HeapAllocZeroBytes);
 281                 }
 282                 if !align.is_power_of_two() {
 283                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 284                 }
 285                 let align = Align::from_bytes(align).unwrap();
 286                 let new_ptr = this.memory.reallocate(
 287                     ptr,
 288                     Some((Size::from_bytes(old_size), align)),
 289                     Size::from_bytes(new_size),
 290                     align,
 291                     MiriMemoryKind::Rust.into(),
 292                 )?;
 293                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 294             }
 295
 296             "syscall" => {
 297                 let sys_getrandom = this
 298                     .eval_path_scalar(&["libc", "SYS_getrandom"])?
 299                     .expect("Failed to get libc::SYS_getrandom")
 300                     .to_machine_usize(this)?;
 301
 302                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 303                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 304                 match this.read_scalar(args[0])?.to_machine_usize(this)? {
 305                     id if id == sys_getrandom => {
 306                         // The first argument is the syscall id,
 307                         // so skip over it.
 308                         linux_getrandom(this, &args[1..], dest)?;
 309                     }
 310                     id => throw_unsup_format!("miri does not support syscall ID {}", id),
 311                 }
 312             }
 313
 314             "getrandom" => {
 315                 linux_getrandom(this, args, dest)?;
 316             }
 317
 318             "dlsym" => {
 319                 let _handle = this.read_scalar(args[0])?;
 320                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 321                 let symbol_name = this.memory.read_c_str(symbol)?;
 322                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 323                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 324                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 325                     let ptr = this.memory.create_fn_alloc(FnVal::Other(dlsym));
 326                     this.write_scalar(Scalar::from(ptr), dest)?;
 327                 } else {
 328                     this.write_null(dest)?;
 329                 }
 330             }
 331
 332             "__rust_maybe_catch_panic" => {
 333                 this.handle_catch_panic(args, dest, ret)?;
 334                 return Ok(None)
 335             }
 336
 337             "memcmp" => {
 338                 let left = this.read_scalar(args[0])?.not_undef()?;
 339                 let right = this.read_scalar(args[1])?.not_undef()?;
 340                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_machine_usize(this)?);
 341
 342                 let result = {
 343                     let left_bytes = this.memory.read_bytes(left, n)?;
 344                     let right_bytes = this.memory.read_bytes(right, n)?;
 345
 346                     use std::cmp::Ordering::*;
 347                     match left_bytes.cmp(right_bytes) {
 348                         Less => -1i32,
 349                         Equal => 0,
 350                         Greater => 1,
 351                     }
 352                 };
 353
 354                 this.write_scalar(Scalar::from_int(result, Size::from_bits(32)), dest)?;
 355             }
 356
 357             "memrchr" => {
 358                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 359                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 360                 let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
 361                 if let Some(idx) = this
 362                     .memory
 363                     .read_bytes(ptr, Size::from_bytes(num))?
 364                     .iter()
 365                     .rev()
 366                     .position(|&c| c == val)
 367                 {
 368                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 369                     this.write_scalar(new_ptr, dest)?;
 370                 } else {
 371                     this.write_null(dest)?;
 372                 }
 373             }
 374
 375             "memchr" => {
 376                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 377                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 378                 let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
 379                 let idx = this
 380                     .memory
 381                     .read_bytes(ptr, Size::from_bytes(num))?
 382                     .iter()
 383                     .position(|&c| c == val);
 384                 if let Some(idx) = idx {
 385                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 386                     this.write_scalar(new_ptr, dest)?;
 387                 } else {
 388                     this.write_null(dest)?;
 389                 }
 390             }
 391
 392             "__errno_location" | "__error" => {
 393                 let errno_place = this.machine.last_error.unwrap();
 394                 this.write_scalar(errno_place.to_ref().to_scalar()?, dest)?;
 395             }
 396
 397             "getenv" => {
 398                 let result = this.getenv(args[0])?;
 399                 this.write_scalar(result, dest)?;
 400             }
 401
 402             "unsetenv" => {
 403                 let result = this.unsetenv(args[0])?;
 404                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 405             }
 406
 407             "setenv" => {
 408                 let result = this.setenv(args[0], args[1])?;
 409                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 410             }
 411
 412             "getcwd" => {
 413                 let result = this.getcwd(args[0], args[1])?;
 414                 this.write_scalar(result, dest)?;
 415             }
 416
 417             "chdir" => {
 418                 let result = this.chdir(args[0])?;
 419                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 420             }
 421
 422             "open" | "open64" => {
 423                 let result = this.open(args[0], args[1])?;
 424                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 425             }
 426
 427             "fcntl" => {
 428                 let result = this.fcntl(args[0], args[1], args.get(2).cloned())?;
 429                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 430             }
 431
 432             "close" | "close$NOCANCEL" => {
 433                 let result = this.close(args[0])?;
 434                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 435             }
 436
 437             "read" => {
 438                 let result = this.read(args[0], args[1], args[2])?;
 439                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 440             }
 441
 442             "write" => {
 443                 let fd = this.read_scalar(args[0])?.to_i32()?;
 444                 let buf = this.read_scalar(args[1])?.not_undef()?;
 445                 let n = this.read_scalar(args[2])?.to_machine_usize(tcx)?;
 446                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 447                 let result = if fd == 1 || fd == 2 {
 448                     // stdout/stderr
 449                     use std::io::{self, Write};
 450
 451                     let buf_cont = this.memory.read_bytes(buf, Size::from_bytes(n))?;
 452                     // We need to flush to make sure this actually appears on the screen
 453                     let res = if fd == 1 {
 454                         // Stdout is buffered, flush to make sure it appears on the screen.
 455                         // This is the write() syscall of the interpreted program, we want it
 456                         // to correspond to a write() syscall on the host -- there is no good
 457                         // in adding extra buffering here.
 458                         let res = io::stdout().write(buf_cont);
 459                         io::stdout().flush().unwrap();
 460                         res
 461                     } else {
 462                         // No need to flush, stderr is not buffered.
 463                         io::stderr().write(buf_cont)
 464                     };
 465                     match res {
 466                         Ok(n) => n as i64,
 467                         Err(_) => -1,
 468                     }
 469                 } else {
 470                     this.write(args[0], args[1], args[2])?
 471                 };
 472                 // Now, `result` is the value we return back to the program.
 473                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 474             }
 475
 476             "unlink" => {
 477                 let result = this.unlink(args[0])?;
 478                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 479             }
 480
 481             "clock_gettime" => {
 482                 let result = this.clock_gettime(args[0], args[1])?;
 483                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 484             }
 485
 486             "gettimeofday" => {
 487                 let result = this.gettimeofday(args[0], args[1])?;
 488                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 489             }
 490
 491             "strlen" => {
 492                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 493                 let n = this.memory.read_c_str(ptr)?.len();
 494                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 495             }
 496
 497             // math functions
 498             "cbrtf" | "coshf" | "sinhf" | "tanf" | "acosf" | "asinf" | "atanf" => {
 499                 // FIXME: Using host floats.
 500                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 501                 let f = match link_name {
 502                     "cbrtf" => f.cbrt(),
 503                     "coshf" => f.cosh(),
 504                     "sinhf" => f.sinh(),
 505                     "tanf" => f.tan(),
 506                     "acosf" => f.acos(),
 507                     "asinf" => f.asin(),
 508                     "atanf" => f.atan(),
 509                     _ => bug!(),
 510                 };
 511                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 512             }
 513             // underscore case for windows
 514             "_hypotf" | "hypotf" | "atan2f" => {
 515                 // FIXME: Using host floats.
 516                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 517                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 518                 let n = match link_name {
 519                     "_hypotf" | "hypotf" => f1.hypot(f2),
 520                     "atan2f" => f1.atan2(f2),
 521                     _ => bug!(),
 522                 };
 523                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 524             }
 525
 526             "cbrt" | "cosh" | "sinh" | "tan" | "acos" | "asin" | "atan" => {
 527                 // FIXME: Using host floats.
 528                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 529                 let f = match link_name {
 530                     "cbrt" => f.cbrt(),
 531                     "cosh" => f.cosh(),
 532                     "sinh" => f.sinh(),
 533                     "tan" => f.tan(),
 534                     "acos" => f.acos(),
 535                     "asin" => f.asin(),
 536                     "atan" => f.atan(),
 537                     _ => bug!(),
 538                 };
 539                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 540             }
 541             // underscore case for windows, here and below
 542             // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
 543             "_hypot" | "hypot" | "atan2" => {
 544                 // FIXME: Using host floats.
 545                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 546                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 547                 let n = match link_name {
 548                     "_hypot" | "hypot" => f1.hypot(f2),
 549                     "atan2" => f1.atan2(f2),
 550                     _ => bug!(),
 551                 };
 552                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 553             }
 554             // For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
 555             "_ldexp" | "ldexp" | "scalbn" => {
 556                 let x = this.read_scalar(args[0])?.to_f64()?;
 557                 let exp = this.read_scalar(args[1])?.to_i32()?;
 558
 559                 // Saturating cast to i16. Even those are outside the valid exponent range to
 560                 // `scalbn` below will do its over/underflow handling.
 561                 let exp = if exp > i16::max_value() as i32 {
 562                     i16::max_value()
 563                 } else if exp < i16::min_value() as i32 {
 564                     i16::min_value()
 565                 } else {
 566                     exp.try_into().unwrap()
 567                 };
 568
 569                 let res = x.scalbn(exp);
 570                 this.write_scalar(Scalar::from_f64(res), dest)?;
 571             }
 572
 573             // Some things needed for `sys::thread` initialization to go through.
 574             "signal" | "sigaction" | "sigaltstack" => {
 575                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 576             }
 577
 578             "sysconf" => {
 579                 let name = this.read_scalar(args[0])?.to_i32()?;
 580
 581                 trace!("sysconf() called with name {}", name);
 582                 // TODO: Cache the sysconf integers via Miri's global cache.
 583                 let paths = &[
 584                     (
 585                         &["libc", "_SC_PAGESIZE"],
 586                         Scalar::from_int(PAGE_SIZE, dest.layout.size),
 587                     ),
 588                     (
 589                         &["libc", "_SC_GETPW_R_SIZE_MAX"],
 590                         Scalar::from_int(-1, dest.layout.size),
 591                     ),
 592                     (
 593                         &["libc", "_SC_NPROCESSORS_ONLN"],
 594                         Scalar::from_int(NUM_CPUS, dest.layout.size),
 595                     ),
 596                 ];
 597                 let mut result = None;
 598                 for &(path, path_value) in paths {
 599                     if let Some(val) = this.eval_path_scalar(path)? {
 600                         let val = val.to_i32()?;
 601                         if val == name {
 602                             result = Some(path_value);
 603                             break;
 604                         }
 605                     }
 606                 }
 607                 if let Some(result) = result {
 608                     this.write_scalar(result, dest)?;
 609                 } else {
 610                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 611                 }
 612             }
 613
 614             "sched_getaffinity" => {
 615                 // Return an error; `num_cpus` then falls back to `sysconf`.
 616                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 617             }
 618
 619             "isatty" => {
 620                 this.write_null(dest)?;
 621             }
 622
 623             // Hook pthread calls that go to the thread-local storage memory subsystem.
 624             "pthread_key_create" => {
 625                 let key_place = this.deref_operand(args[0])?;
 626
 627                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 628                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 629                     Some(dtor_ptr) => Some(this.memory.get_fn(dtor_ptr)?.as_instance()?),
 630                     None => None,
 631                 };
 632
 633                 // Figure out how large a pthread TLS key actually is.
 634                 // This is `libc::pthread_key_t`.
 635                 let key_type = args[0].layout.ty
 636                     .builtin_deref(true)
 637                     .ok_or_else(|| err_ub_format!(
 638                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 639                     ))?
 640                     .ty;
 641                 let key_layout = this.layout_of(key_type)?;
 642
 643                 // Create key and write it into the memory where `key_ptr` wants it.
 644                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 645                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128)
 646                 {
 647                     throw_unsup!(OutOfTls);
 648                 }
 649
 650                 this.write_scalar(Scalar::from_uint(key, key_layout.size), key_place.into())?;
 651
 652                 // Return success (`0`).
 653                 this.write_null(dest)?;
 654             }
 655             "pthread_key_delete" => {
 656                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 657                 this.machine.tls.delete_tls_key(key)?;
 658                 // Return success (0)
 659                 this.write_null(dest)?;
 660             }
 661             "pthread_getspecific" => {
 662                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 663                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 664                 this.write_scalar(ptr, dest)?;
 665             }
 666             "pthread_setspecific" => {
 667                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 668                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 669                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 670
 671                 // Return success (`0`).
 672                 this.write_null(dest)?;
 673             }
 674
 675             // Stack size/address stuff.
 676             "pthread_attr_init"
 677             | "pthread_attr_destroy"
 678             | "pthread_self"
 679             | "pthread_attr_setstacksize" => {
 680                 this.write_null(dest)?;
 681             }
 682             "pthread_attr_getstack" => {
 683                 let addr_place = this.deref_operand(args[1])?;
 684                 let size_place = this.deref_operand(args[2])?;
 685
 686                 this.write_scalar(
 687                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 688                     addr_place.into(),
 689                 )?;
 690                 this.write_scalar(
 691                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 692                     size_place.into(),
 693                 )?;
 694
 695                 // Return success (`0`).
 696                 this.write_null(dest)?;
 697             }
 698
 699             // We don't support threading. (Also for Windows.)
 700             "pthread_create" | "CreateThread" => {
 701                 throw_unsup_format!("Miri does not support threading");
 702             }
 703
 704             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 705             "pthread_mutexattr_init"
 706             | "pthread_mutexattr_settype"
 707             | "pthread_mutex_init"
 708             | "pthread_mutexattr_destroy"
 709             | "pthread_mutex_lock"
 710             | "pthread_mutex_unlock"
 711             | "pthread_mutex_destroy"
 712             | "pthread_rwlock_rdlock"
 713             | "pthread_rwlock_unlock"
 714             | "pthread_rwlock_wrlock"
 715             | "pthread_rwlock_destroy"
 716             | "pthread_condattr_init"
 717             | "pthread_condattr_setclock"
 718             | "pthread_cond_init"
 719             | "pthread_condattr_destroy"
 720             | "pthread_cond_destroy" => {
 721                 this.write_null(dest)?;
 722             }
 723
 724             // We don't support fork so we don't have to do anything for atfork.
 725             "pthread_atfork" => {
 726                 this.write_null(dest)?;
 727             }
 728
 729             "mmap" => {
 730                 // 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.
 731                 let addr = this.read_scalar(args[0])?.not_undef()?;
 732                 this.write_scalar(addr, dest)?;
 733             }
 734             "mprotect" => {
 735                 this.write_null(dest)?;
 736             }
 737
 738             // macOS API stubs.
 739             "pthread_attr_get_np" | "pthread_getattr_np" => {
 740                 this.write_null(dest)?;
 741             }
 742             "pthread_get_stackaddr_np" => {
 743                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 744                 this.write_scalar(stack_addr, dest)?;
 745             }
 746             "pthread_get_stacksize_np" => {
 747                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 748                 this.write_scalar(stack_size, dest)?;
 749             }
 750             "_tlv_atexit" => {
 751                 // FIXME: register the destructor.
 752             }
 753             "_NSGetArgc" => {
 754                 this.write_scalar(this.machine.argc.expect("machine must be initialized"), dest)?;
 755             }
 756             "_NSGetArgv" => {
 757                 this.write_scalar(this.machine.argv.expect("machine must be initialized"), dest)?;
 758             }
 759             "SecRandomCopyBytes" => {
 760                 let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 761                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 762                 this.gen_random(ptr, len as usize)?;
 763                 this.write_null(dest)?;
 764             }
 765
 766             // Windows API stubs.
 767             // HANDLE = isize
 768             // DWORD = ULONG = u32
 769             // BOOL = i32
 770             "GetProcessHeap" => {
 771                 // Just fake a HANDLE
 772                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 773             }
 774             "HeapAlloc" => {
 775                 let _handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 776                 let flags = this.read_scalar(args[1])?.to_u32()?;
 777                 let size = this.read_scalar(args[2])?.to_machine_usize(this)?;
 778                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 779                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 780                 this.write_scalar(res, dest)?;
 781             }
 782             "HeapFree" => {
 783                 let _handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 784                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 785                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 786                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 787                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 788             }
 789             "HeapReAlloc" => {
 790                 let _handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 791                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 792                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 793                 let size = this.read_scalar(args[3])?.to_machine_usize(this)?;
 794                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 795                 this.write_scalar(res, dest)?;
 796             }
 797
 798             "SetLastError" => {
 799                 this.set_last_error(this.read_scalar(args[0])?.not_undef()?)?;
 800             }
 801             "GetLastError" => {
 802                 let last_error = this.get_last_error()?;
 803                 this.write_scalar(last_error, dest)?;
 804             }
 805
 806             "AddVectoredExceptionHandler" => {
 807                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 808                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 809             }
 810             "InitializeCriticalSection"
 811             | "EnterCriticalSection"
 812             | "LeaveCriticalSection"
 813             | "DeleteCriticalSection" => {
 814                 // Nothing to do, not even a return value.
 815             }
 816             "GetModuleHandleW"
 817             | "GetProcAddress"
 818             | "TryEnterCriticalSection"
 819             | "GetConsoleScreenBufferInfo"
 820             | "SetConsoleTextAttribute" => {
 821                 // Pretend these do not exist / nothing happened, by returning zero.
 822                 this.write_null(dest)?;
 823             }
 824             "GetSystemInfo" => {
 825                 let system_info = this.deref_operand(args[0])?;
 826                 // Initialize with `0`.
 827                 this.memory
 828                     .write_bytes(system_info.ptr, iter::repeat(0u8).take(system_info.layout.size.bytes() as usize))?;
 829                 // Set number of processors.
 830                 let dword_size = Size::from_bytes(4);
 831                 let num_cpus = this.mplace_field(system_info, 6)?;
 832                 this.write_scalar(
 833                     Scalar::from_int(NUM_CPUS, dword_size),
 834                     num_cpus.into(),
 835                 )?;
 836             }
 837
 838             "TlsAlloc" => {
 839                 // This just creates a key; Windows does not natively support TLS destructors.
 840
 841                 // Create key and return it.
 842                 let key = this.machine.tls.create_tls_key(None) as u128;
 843
 844                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 845                 if dest.layout.size.bits() < 128
 846                     && key >= (1u128 << dest.layout.size.bits() as u128)
 847                 {
 848                     throw_unsup!(OutOfTls);
 849                 }
 850                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 851             }
 852             "TlsGetValue" => {
 853                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 854                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 855                 this.write_scalar(ptr, dest)?;
 856             }
 857             "TlsSetValue" => {
 858                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 859                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 860                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 861
 862                 // Return success (`1`).
 863                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 864             }
 865             "GetStdHandle" => {
 866                 let which = this.read_scalar(args[0])?.to_i32()?;
 867                 // We just make this the identity function, so we know later in `WriteFile`
 868                 // which one it is.
 869                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 870             }
 871             "WriteFile" => {
 872                 let handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 873                 let buf = this.read_scalar(args[1])?.not_undef()?;
 874                 let n = this.read_scalar(args[2])?.to_u32()?;
 875                 let written_place = this.deref_operand(args[3])?;
 876                 // Spec says to always write `0` first.
 877                 this.write_null(written_place.into())?;
 878                 let written = if handle == -11 || handle == -12 {
 879                     // stdout/stderr
 880                     use std::io::{self, Write};
 881
 882                     let buf_cont = this
 883                         .memory
 884                         .read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 885                     let res = if handle == -11 {
 886                         io::stdout().write(buf_cont)
 887                     } else {
 888                         io::stderr().write(buf_cont)
 889                     };
 890                     res.ok().map(|n| n as u32)
 891                 } else {
 892                     eprintln!("Miri: Ignored output to handle {}", handle);
 893                     // Pretend it all went well.
 894                     Some(n)
 895                 };
 896                 // If there was no error, write back how much was written.
 897                 if let Some(n) = written {
 898                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 899                 }
 900                 // Return whether this was a success.
 901                 this.write_scalar(
 902                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 903                     dest,
 904                 )?;
 905             }
 906             "GetConsoleMode" => {
 907                 // Everything is a pipe.
 908                 this.write_null(dest)?;
 909             }
 910             "GetEnvironmentVariableW" => {
 911                 // This is not the env var you are looking for.
 912                 this.set_last_error(Scalar::from_u32(203))?; // ERROR_ENVVAR_NOT_FOUND
 913                 this.write_null(dest)?;
 914             }
 915             "GetCommandLineW" => {
 916                 this.write_scalar(this.machine.cmd_line.expect("machine must be initialized"), dest)?;
 917             }
 918             // The actual name of 'RtlGenRandom'
 919             "SystemFunction036" => {
 920                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 921                 let len = this.read_scalar(args[1])?.to_u32()?;
 922                 this.gen_random(ptr, len as usize)?;
 923                 this.write_scalar(Scalar::from_bool(true), dest)?;
 924             }
 925
 926             // We can't execute anything else.
 927             _ => throw_unsup_format!("can't call foreign function: {}", link_name),
 928         }
 929
 930         this.dump_place(*dest);
 931         this.go_to_block(ret);
 932         Ok(None)
 933     }
 934
 935     /// Evaluates the scalar at the specified path. Returns Some(val)
 936     /// if the path could be resolved, and None otherwise
 937     fn eval_path_scalar(
 938         &mut self,
 939         path: &[&str],
 940     ) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 941         let this = self.eval_context_mut();
 942         if let Ok(instance) = this.resolve_path(path) {
 943             let cid = GlobalId {
 944                 instance,
 945                 promoted: None,
 946             };
 947             let const_val = this.const_eval_raw(cid)?;
 948             let const_val = this.read_scalar(const_val.into())?;
 949             return Ok(Some(const_val));
 950         }
 951         return Ok(None);
 952     }
 953 }
 954
 955 // Shims the linux 'getrandom()' syscall.
 956 fn linux_getrandom<'tcx>(
 957     this: &mut MiriEvalContext<'_, 'tcx>,
 958     args: &[OpTy<'tcx, Tag>],
 959     dest: PlaceTy<'tcx, Tag>,
 960 ) -> InterpResult<'tcx> {
 961     let ptr = this.read_scalar(args[0])?.not_undef()?;
 962     let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 963
 964     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 965     // neither of which have any effect on our current PRNG.
 966     let _flags = this.read_scalar(args[2])?.to_i32()?;
 967
 968     this.gen_random(ptr, len as usize)?;
 969     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 970     Ok(())
 971 }