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