src/shims/foreign_items.rs

   1 use std::convert::TryInto;
   2
   3 use rustc::hir::def_id::DefId;
   4 use rustc::mir;
   5 use rustc::ty::layout::{Align, LayoutOf, Size};
   6 use rustc_apfloat::Float;
   7 use syntax::attr;
   8 use syntax::symbol::sym;
   9
  10 use crate::*;
  11
  12 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  13 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  14     /// Returns the minimum alignment for the target architecture for allocations of the given size.
  15     fn min_align(&self, size: u64, kind: MiriMemoryKind) -> Align {
  16         let this = self.eval_context_ref();
  17         // List taken from `libstd/sys_common/alloc.rs`.
  18         let min_align = match this.tcx.tcx.sess.target.target.arch.as_str() {
  19             "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
  20             "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" => 16,
  21             arch => bug!("Unsupported target architecture: {}", arch),
  22         };
  23         // Windows always aligns, even small allocations.
  24         // Source: <https://support.microsoft.com/en-us/help/286470/how-to-use-pageheap-exe-in-windows-xp-windows-2000-and-windows-server>
  25         // But jemalloc does not, so for the C heap we only align if the allocation is sufficiently big.
  26         if kind == MiriMemoryKind::WinHeap || size >= min_align {
  27             return Align::from_bytes(min_align).unwrap();
  28         }
  29         // We have `size < min_align`. Round `size` *down* to the next power of two and use that.
  30         fn prev_power_of_two(x: u64) -> u64 {
  31             let next_pow2 = x.next_power_of_two();
  32             if next_pow2 == x {
  33                 // x *is* a power of two, just use that.
  34                 x
  35             } else {
  36                 // x is between two powers, so next = 2*prev.
  37                 next_pow2 / 2
  38             }
  39         }
  40         Align::from_bytes(prev_power_of_two(size)).unwrap()
  41     }
  42
  43     fn malloc(&mut self, size: u64, zero_init: bool, kind: MiriMemoryKind) -> Scalar<Tag> {
  44         let this = self.eval_context_mut();
  45         let tcx = &{ this.tcx.tcx };
  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_mut()
  52                 .allocate(Size::from_bytes(size), align, kind.into());
  53             if zero_init {
  54                 // We just allocated this, the access cannot fail
  55                 this.memory_mut()
  56                     .get_mut(ptr.alloc_id)
  57                     .unwrap()
  58                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size))
  59                     .unwrap();
  60             }
  61             Scalar::Ptr(ptr)
  62         }
  63     }
  64
  65     fn free(&mut self, ptr: Scalar<Tag>, kind: MiriMemoryKind) -> InterpResult<'tcx> {
  66         let this = self.eval_context_mut();
  67         if !this.is_null(ptr)? {
  68             let ptr = this.force_ptr(ptr)?;
  69             this.memory_mut().deallocate(ptr, None, kind.into())?;
  70         }
  71         Ok(())
  72     }
  73
  74     fn realloc(
  75         &mut self,
  76         old_ptr: Scalar<Tag>,
  77         new_size: u64,
  78         kind: MiriMemoryKind,
  79     ) -> InterpResult<'tcx, Scalar<Tag>> {
  80         let this = self.eval_context_mut();
  81         let new_align = this.min_align(new_size, kind);
  82         if this.is_null(old_ptr)? {
  83             if new_size == 0 {
  84                 Ok(Scalar::from_int(0, this.pointer_size()))
  85             } else {
  86                 let new_ptr =
  87                     this.memory_mut()
  88                         .allocate(Size::from_bytes(new_size), new_align, kind.into());
  89                 Ok(Scalar::Ptr(new_ptr))
  90             }
  91         } else {
  92             let old_ptr = this.force_ptr(old_ptr)?;
  93             let memory = this.memory_mut();
  94             if new_size == 0 {
  95                 memory.deallocate(old_ptr, None, kind.into())?;
  96                 Ok(Scalar::from_int(0, this.pointer_size()))
  97             } else {
  98                 let new_ptr = memory.reallocate(
  99                     old_ptr,
 100                     None,
 101                     Size::from_bytes(new_size),
 102                     new_align,
 103                     kind.into(),
 104                 )?;
 105                 Ok(Scalar::Ptr(new_ptr))
 106             }
 107         }
 108     }
 109
 110     /// Emulates calling a foreign item, failing if the item is not supported.
 111     /// This function will handle `goto_block` if needed.
 112     fn emulate_foreign_item(
 113         &mut self,
 114         def_id: DefId,
 115         args: &[OpTy<'tcx, Tag>],
 116         dest: Option<PlaceTy<'tcx, Tag>>,
 117         ret: Option<mir::BasicBlock>,
 118     ) -> InterpResult<'tcx> {
 119         let this = self.eval_context_mut();
 120         let attrs = this.tcx.get_attrs(def_id);
 121         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 122             Some(name) => name.as_str(),
 123             None => this.tcx.item_name(def_id).as_str(),
 124         };
 125         // Strip linker suffixes (seen on 32-bit macOS).
 126         let link_name = link_name.trim_end_matches("$UNIX2003");
 127         let tcx = &{ this.tcx.tcx };
 128
 129         // First: functions that diverge.
 130         match link_name {
 131             "__rust_start_panic" | "panic_impl" => {
 132                 throw_unsup_format!("the evaluated program panicked");
 133             }
 134             "exit" | "ExitProcess" => {
 135                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` error variant anyway
 136                 let code = this.read_scalar(args[0])?.to_i32()?;
 137                 return Err(InterpError::Exit(code).into());
 138             }
 139             _ => {
 140                 if dest.is_none() {
 141                     throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
 142                 }
 143             }
 144         }
 145
 146         // Next: functions that assume a ret and dest.
 147         let dest = dest.expect("we already checked for a dest");
 148         let ret = ret.expect("dest is `Some` but ret is `None`");
 149         match link_name {
 150             "malloc" => {
 151                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 152                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 153                 this.write_scalar(res, dest)?;
 154             }
 155             "calloc" => {
 156                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 157                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 158                 let size = items
 159                     .checked_mul(len)
 160                     .ok_or_else(|| err_panic!(Overflow(mir::BinOp::Mul)))?;
 161                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 162                 this.write_scalar(res, dest)?;
 163             }
 164             "posix_memalign" => {
 165                 let ret = this.deref_operand(args[0])?;
 166                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 167                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 168                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 169                 if !align.is_power_of_two() {
 170                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 171                 }
 172                 if align < this.pointer_size().bytes() {
 173                     throw_ub_format!(
 174                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 175                         align,
 176                     );
 177                 }
 178
 179                 if size == 0 {
 180                     this.write_null(ret.into())?;
 181                 } else {
 182                     let ptr = this.memory_mut().allocate(
 183                         Size::from_bytes(size),
 184                         Align::from_bytes(align).unwrap(),
 185                         MiriMemoryKind::C.into(),
 186                     );
 187                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 188                 }
 189                 this.write_null(dest)?;
 190             }
 191             "free" => {
 192                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 193                 this.free(ptr, MiriMemoryKind::C)?;
 194             }
 195             "realloc" => {
 196                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 197                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 198                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 199                 this.write_scalar(res, dest)?;
 200             }
 201
 202             "__rust_alloc" => {
 203                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 204                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 205                 if size == 0 {
 206                     throw_unsup!(HeapAllocZeroBytes);
 207                 }
 208                 if !align.is_power_of_two() {
 209                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 210                 }
 211                 let ptr = this.memory_mut().allocate(
 212                     Size::from_bytes(size),
 213                     Align::from_bytes(align).unwrap(),
 214                     MiriMemoryKind::Rust.into(),
 215                 );
 216                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 217             }
 218             "__rust_alloc_zeroed" => {
 219                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 220                 let align = this.read_scalar(args[1])?.to_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_mut().allocate(
 228                     Size::from_bytes(size),
 229                     Align::from_bytes(align).unwrap(),
 230                     MiriMemoryKind::Rust.into(),
 231                 );
 232                 // We just allocated this, the access cannot fail
 233                 this.memory_mut()
 234                     .get_mut(ptr.alloc_id)
 235                     .unwrap()
 236                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size))
 237                     .unwrap();
 238                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 239             }
 240             "__rust_dealloc" => {
 241                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 242                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 243                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 244                 if old_size == 0 {
 245                     throw_unsup!(HeapAllocZeroBytes);
 246                 }
 247                 if !align.is_power_of_two() {
 248                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 249                 }
 250                 let ptr = this.force_ptr(ptr)?;
 251                 this.memory_mut().deallocate(
 252                     ptr,
 253                     Some((
 254                         Size::from_bytes(old_size),
 255                         Align::from_bytes(align).unwrap(),
 256                     )),
 257                     MiriMemoryKind::Rust.into(),
 258                 )?;
 259             }
 260             "__rust_realloc" => {
 261                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 262                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 263                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 264                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 265                 if old_size == 0 || new_size == 0 {
 266                     throw_unsup!(HeapAllocZeroBytes);
 267                 }
 268                 if !align.is_power_of_two() {
 269                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 270                 }
 271                 let align = Align::from_bytes(align).unwrap();
 272                 let new_ptr = this.memory_mut().reallocate(
 273                     ptr,
 274                     Some((Size::from_bytes(old_size), align)),
 275                     Size::from_bytes(new_size),
 276                     align,
 277                     MiriMemoryKind::Rust.into(),
 278                 )?;
 279                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 280             }
 281
 282             "syscall" => {
 283                 let sys_getrandom = this
 284                     .eval_path_scalar(&["libc", "SYS_getrandom"])?
 285                     .expect("Failed to get libc::SYS_getrandom")
 286                     .to_usize(this)?;
 287
 288                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 289                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 290                 match this.read_scalar(args[0])?.to_usize(this)? {
 291                     id if id == sys_getrandom => {
 292                         // The first argument is the syscall id,
 293                         // so skip over it.
 294                         linux_getrandom(this, &args[1..], dest)?;
 295                     }
 296                     id => throw_unsup_format!("miri does not support syscall ID {}", id),
 297                 }
 298             }
 299
 300             "getrandom" => {
 301                 linux_getrandom(this, args, dest)?;
 302             }
 303
 304             "dlsym" => {
 305                 let _handle = this.read_scalar(args[0])?;
 306                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 307                 let symbol_name = this.memory().read_c_str(symbol)?;
 308                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 309                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 310                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 311                     let ptr = this.memory_mut().create_fn_alloc(FnVal::Other(dlsym));
 312                     this.write_scalar(Scalar::from(ptr), dest)?;
 313                 } else {
 314                     this.write_null(dest)?;
 315                 }
 316             }
 317
 318             "__rust_maybe_catch_panic" => {
 319                 // fn __rust_maybe_catch_panic(
 320                 //     f: fn(*mut u8),
 321                 //     data: *mut u8,
 322                 //     data_ptr: *mut usize,
 323                 //     vtable_ptr: *mut usize,
 324                 // ) -> u32
 325                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 326                 let f = this.read_scalar(args[0])?.not_undef()?;
 327                 let data = this.read_scalar(args[1])?.not_undef()?;
 328                 let f_instance = this.memory().get_fn(f)?.as_instance()?;
 329                 this.write_null(dest)?;
 330                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 331
 332                 // Now we make a function call.
 333                 // TODO: consider making this reusable? `InterpCx::step` does something similar
 334                 // for the TLS destructors, and of course `eval_main`.
 335                 let mir = this.load_mir(f_instance.def, None)?;
 336                 let ret_place =
 337                     MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 338                 this.push_stack_frame(
 339                     f_instance,
 340                     mir.span,
 341                     mir,
 342                     Some(ret_place),
 343                     // Directly return to caller.
 344                     StackPopCleanup::Goto(Some(ret)),
 345                 )?;
 346                 let mut args = this.frame().body.args_iter();
 347
 348                 let arg_local = args
 349                     .next()
 350                     .expect("Argument to __rust_maybe_catch_panic does not take enough arguments.");
 351                 let arg_dest = this.local_place(arg_local)?;
 352                 this.write_scalar(data, arg_dest)?;
 353
 354                 assert!(
 355                     args.next().is_none(),
 356                     "__rust_maybe_catch_panic argument has more arguments than expected"
 357                 );
 358
 359                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 360                 this.write_null(dest)?;
 361
 362                 // Don't fall through, we do *not* want to `goto_block`!
 363                 return Ok(());
 364             }
 365
 366             "memcmp" => {
 367                 let left = this.read_scalar(args[0])?.not_undef()?;
 368                 let right = this.read_scalar(args[1])?.not_undef()?;
 369                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 370
 371                 let result = {
 372                     let left_bytes = this.memory().read_bytes(left, n)?;
 373                     let right_bytes = this.memory().read_bytes(right, n)?;
 374
 375                     use std::cmp::Ordering::*;
 376                     match left_bytes.cmp(right_bytes) {
 377                         Less => -1i32,
 378                         Equal => 0,
 379                         Greater => 1,
 380                     }
 381                 };
 382
 383                 this.write_scalar(Scalar::from_int(result, Size::from_bits(32)), dest)?;
 384             }
 385
 386             "memrchr" => {
 387                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 388                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 389                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 390                 if let Some(idx) = this
 391                     .memory()
 392                     .read_bytes(ptr, Size::from_bytes(num))?
 393                     .iter()
 394                     .rev()
 395                     .position(|&c| c == val)
 396                 {
 397                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 398                     this.write_scalar(new_ptr, dest)?;
 399                 } else {
 400                     this.write_null(dest)?;
 401                 }
 402             }
 403
 404             "memchr" => {
 405                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 406                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 407                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 408                 let idx = this
 409                     .memory()
 410                     .read_bytes(ptr, Size::from_bytes(num))?
 411                     .iter()
 412                     .position(|&c| c == val);
 413                 if let Some(idx) = idx {
 414                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 415                     this.write_scalar(new_ptr, dest)?;
 416                 } else {
 417                     this.write_null(dest)?;
 418                 }
 419             }
 420
 421             "getenv" => {
 422                 let result = this.getenv(args[0])?;
 423                 this.write_scalar(result, dest)?;
 424             }
 425
 426             "unsetenv" => {
 427                 let result = this.unsetenv(args[0])?;
 428                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 429             }
 430
 431             "setenv" => {
 432                 let result = this.setenv(args[0], args[1])?;
 433                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 434             }
 435
 436             "getcwd" => {
 437                 let result = this.getcwd(args[0], args[1])?;
 438                 this.write_scalar(result, dest)?;
 439             }
 440
 441             "chdir" => {
 442                 let result = this.chdir(args[0])?;
 443                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 444             }
 445
 446             "open" | "open64" => {
 447                 let result = this.open(args[0], args[1])?;
 448                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 449             }
 450
 451             "fcntl" => {
 452                 let result = this.fcntl(args[0], args[1], args.get(2).cloned())?;
 453                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 454             }
 455
 456             "close" | "close$NOCANCEL" => {
 457                 let result = this.close(args[0])?;
 458                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 459             }
 460
 461             "read" => {
 462                 let result = this.read(args[0], args[1], args[2])?;
 463                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 464             }
 465
 466             "write" => {
 467                 let fd = this.read_scalar(args[0])?.to_i32()?;
 468                 let buf = this.read_scalar(args[1])?.not_undef()?;
 469                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 470                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 471                 let result = if fd == 1 || fd == 2 {
 472                     // stdout/stderr
 473                     use std::io::{self, Write};
 474
 475                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 476                     // We need to flush to make sure this actually appears on the screen
 477                     let res = if fd == 1 {
 478                         // Stdout is buffered, flush to make sure it appears on the screen.
 479                         // This is the write() syscall of the interpreted program, we want it
 480                         // to correspond to a write() syscall on the host -- there is no good
 481                         // in adding extra buffering here.
 482                         let res = io::stdout().write(buf_cont);
 483                         io::stdout().flush().unwrap();
 484                         res
 485                     } else {
 486                         // No need to flush, stderr is not buffered.
 487                         io::stderr().write(buf_cont)
 488                     };
 489                     match res {
 490                         Ok(n) => n as i64,
 491                         Err(_) => -1,
 492                     }
 493                 } else {
 494                     this.write(args[0], args[1], args[2])?
 495                 };
 496                 // Now, `result` is the value we return back to the program.
 497                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 498             }
 499
 500             "strlen" => {
 501                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 502                 let n = this.memory().read_c_str(ptr)?.len();
 503                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 504             }
 505
 506             // math functions
 507             "cbrtf" | "coshf" | "sinhf" | "tanf" => {
 508                 // FIXME: Using host floats.
 509                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 510                 let f = match link_name {
 511                     "cbrtf" => f.cbrt(),
 512                     "coshf" => f.cosh(),
 513                     "sinhf" => f.sinh(),
 514                     "tanf" => f.tan(),
 515                     _ => bug!(),
 516                 };
 517                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 518             }
 519             // underscore case for windows
 520             "_hypotf" | "hypotf" | "atan2f" => {
 521                 // FIXME: Using host floats.
 522                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 523                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 524                 let n = match link_name {
 525                     "_hypotf" | "hypotf" => f1.hypot(f2),
 526                     "atan2f" => f1.atan2(f2),
 527                     _ => bug!(),
 528                 };
 529                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 530             }
 531
 532             "cbrt" | "cosh" | "sinh" | "tan" => {
 533                 // FIXME: Using host floats.
 534                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 535                 let f = match link_name {
 536                     "cbrt" => f.cbrt(),
 537                     "cosh" => f.cosh(),
 538                     "sinh" => f.sinh(),
 539                     "tan" => f.tan(),
 540                     _ => bug!(),
 541                 };
 542                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 543             }
 544             // underscore case for windows, here and below
 545             // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
 546             "_hypot" | "hypot" | "atan2" => {
 547                 // FIXME: Using host floats.
 548                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 549                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 550                 let n = match link_name {
 551                     "_hypot" | "hypot" => f1.hypot(f2),
 552                     "atan2" => f1.atan2(f2),
 553                     _ => bug!(),
 554                 };
 555                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 556             }
 557             // For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
 558             "_ldexp" | "ldexp" | "scalbn" => {
 559                 let x = this.read_scalar(args[0])?.to_f64()?;
 560                 let exp = this.read_scalar(args[1])?.to_i32()?;
 561
 562                 // Saturating cast to i16. Even those are outside the valid exponent range to
 563                 // `scalbn` below will do its over/underflow handling.
 564                 let exp = if exp > i16::max_value() as i32 {
 565                     i16::max_value()
 566                 } else if exp < i16::min_value() as i32 {
 567                     i16::min_value()
 568                 } else {
 569                     exp.try_into().unwrap()
 570                 };
 571
 572                 let res = x.scalbn(exp);
 573                 this.write_scalar(Scalar::from_f64(res), dest)?;
 574             }
 575
 576             // Some things needed for `sys::thread` initialization to go through.
 577             "signal" | "sigaction" | "sigaltstack" => {
 578                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 579             }
 580
 581             "sysconf" => {
 582                 let name = this.read_scalar(args[0])?.to_i32()?;
 583
 584                 trace!("sysconf() called with name {}", name);
 585                 // TODO: Cache the sysconf integers via Miri's global cache.
 586                 let paths = &[
 587                     (
 588                         &["libc", "_SC_PAGESIZE"],
 589                         Scalar::from_int(PAGE_SIZE, dest.layout.size),
 590                     ),
 591                     (
 592                         &["libc", "_SC_GETPW_R_SIZE_MAX"],
 593                         Scalar::from_int(-1, dest.layout.size),
 594                     ),
 595                     (
 596                         &["libc", "_SC_NPROCESSORS_ONLN"],
 597                         Scalar::from_int(NUM_CPUS, dest.layout.size),
 598                     ),
 599                 ];
 600                 let mut result = None;
 601                 for &(path, path_value) in paths {
 602                     if let Some(val) = this.eval_path_scalar(path)? {
 603                         let val = val.to_i32()?;
 604                         if val == name {
 605                             result = Some(path_value);
 606                             break;
 607                         }
 608                     }
 609                 }
 610                 if let Some(result) = result {
 611                     this.write_scalar(result, dest)?;
 612                 } else {
 613                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 614                 }
 615             }
 616
 617             "sched_getaffinity" => {
 618                 // Return an error; `num_cpus` then falls back to `sysconf`.
 619                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 620             }
 621
 622             "isatty" => {
 623                 this.write_null(dest)?;
 624             }
 625
 626             // Hook pthread calls that go to the thread-local storage memory subsystem.
 627             "pthread_key_create" => {
 628                 let key_ptr = this.read_scalar(args[0])?.not_undef()?;
 629
 630                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 631                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 632                     Some(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?.as_instance()?),
 633                     None => None,
 634                 };
 635
 636                 // Figure out how large a pthread TLS key actually is.
 637                 // This is `libc::pthread_key_t`.
 638                 let key_type = args[0].layout.ty
 639                     .builtin_deref(true)
 640                     .ok_or_else(|| err_ub_format!(
 641                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 642                     ))?
 643                     .ty;
 644                 let key_layout = this.layout_of(key_type)?;
 645
 646                 // Create key and write it into the memory where `key_ptr` wants it.
 647                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 648                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128)
 649                 {
 650                     throw_unsup!(OutOfTls);
 651                 }
 652
 653                 let key_ptr = this
 654                     .memory()
 655                     .check_ptr_access(key_ptr, key_layout.size, key_layout.align.abi)?
 656                     .expect("cannot be a ZST");
 657                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 658                     tcx,
 659                     key_ptr,
 660                     Scalar::from_uint(key, key_layout.size).into(),
 661                     key_layout.size,
 662                 )?;
 663
 664                 // Return success (`0`).
 665                 this.write_null(dest)?;
 666             }
 667             "pthread_key_delete" => {
 668                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 669                 this.machine.tls.delete_tls_key(key)?;
 670                 // Return success (0)
 671                 this.write_null(dest)?;
 672             }
 673             "pthread_getspecific" => {
 674                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 675                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 676                 this.write_scalar(ptr, dest)?;
 677             }
 678             "pthread_setspecific" => {
 679                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 680                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 681                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 682
 683                 // Return success (`0`).
 684                 this.write_null(dest)?;
 685             }
 686
 687             // Stack size/address stuff.
 688             "pthread_attr_init"
 689             | "pthread_attr_destroy"
 690             | "pthread_self"
 691             | "pthread_attr_setstacksize" => {
 692                 this.write_null(dest)?;
 693             }
 694             "pthread_attr_getstack" => {
 695                 let addr_place = this.deref_operand(args[1])?;
 696                 let size_place = this.deref_operand(args[2])?;
 697
 698                 this.write_scalar(
 699                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 700                     addr_place.into(),
 701                 )?;
 702                 this.write_scalar(
 703                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 704                     size_place.into(),
 705                 )?;
 706
 707                 // Return success (`0`).
 708                 this.write_null(dest)?;
 709             }
 710
 711             // We don't support threading. (Also for Windows.)
 712             "pthread_create" | "CreateThread" => {
 713                 throw_unsup_format!("Miri does not support threading");
 714             }
 715
 716             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 717             "pthread_mutexattr_init"
 718             | "pthread_mutexattr_settype"
 719             | "pthread_mutex_init"
 720             | "pthread_mutexattr_destroy"
 721             | "pthread_mutex_lock"
 722             | "pthread_mutex_unlock"
 723             | "pthread_mutex_destroy"
 724             | "pthread_rwlock_rdlock"
 725             | "pthread_rwlock_unlock"
 726             | "pthread_rwlock_wrlock"
 727             | "pthread_rwlock_destroy"
 728             | "pthread_condattr_init"
 729             | "pthread_condattr_setclock"
 730             | "pthread_cond_init"
 731             | "pthread_condattr_destroy"
 732             | "pthread_cond_destroy" => {
 733                 this.write_null(dest)?;
 734             }
 735
 736             // We don't support fork so we don't have to do anything for atfork.
 737             "pthread_atfork" => {
 738                 this.write_null(dest)?;
 739             }
 740
 741             "mmap" => {
 742                 // 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.
 743                 let addr = this.read_scalar(args[0])?.not_undef()?;
 744                 this.write_scalar(addr, dest)?;
 745             }
 746             "mprotect" => {
 747                 this.write_null(dest)?;
 748             }
 749
 750             // macOS API stubs.
 751             "pthread_attr_get_np" | "pthread_getattr_np" => {
 752                 this.write_null(dest)?;
 753             }
 754             "pthread_get_stackaddr_np" => {
 755                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 756                 this.write_scalar(stack_addr, dest)?;
 757             }
 758             "pthread_get_stacksize_np" => {
 759                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 760                 this.write_scalar(stack_size, dest)?;
 761             }
 762             "_tlv_atexit" => {
 763                 // FIXME: register the destructor.
 764             }
 765             "_NSGetArgc" => {
 766                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 767             }
 768             "_NSGetArgv" => {
 769                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 770             }
 771             "SecRandomCopyBytes" => {
 772                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 773                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 774                 this.gen_random(ptr, len as usize)?;
 775                 this.write_null(dest)?;
 776             }
 777
 778             // Windows API stubs.
 779             // HANDLE = isize
 780             // DWORD = ULONG = u32
 781             // BOOL = i32
 782             "GetProcessHeap" => {
 783                 // Just fake a HANDLE
 784                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 785             }
 786             "HeapAlloc" => {
 787                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 788                 let flags = this.read_scalar(args[1])?.to_u32()?;
 789                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 790                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 791                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 792                 this.write_scalar(res, dest)?;
 793             }
 794             "HeapFree" => {
 795                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 796                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 797                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 798                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 799                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 800             }
 801             "HeapReAlloc" => {
 802                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 803                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 804                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 805                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 806                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 807                 this.write_scalar(res, dest)?;
 808             }
 809
 810             "SetLastError" => {
 811                 let err = this.read_scalar(args[0])?.to_u32()?;
 812                 this.machine.last_error = err;
 813             }
 814             "GetLastError" => {
 815                 this.write_scalar(Scalar::from_u32(this.machine.last_error), dest)?;
 816             }
 817
 818             "AddVectoredExceptionHandler" => {
 819                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 820                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 821             }
 822             "InitializeCriticalSection"
 823             | "EnterCriticalSection"
 824             | "LeaveCriticalSection"
 825             | "DeleteCriticalSection" => {
 826                 // Nothing to do, not even a return value.
 827             }
 828             "GetModuleHandleW"
 829             | "GetProcAddress"
 830             | "TryEnterCriticalSection"
 831             | "GetConsoleScreenBufferInfo"
 832             | "SetConsoleTextAttribute" => {
 833                 // Pretend these do not exist / nothing happened, by returning zero.
 834                 this.write_null(dest)?;
 835             }
 836             "GetSystemInfo" => {
 837                 let system_info = this.deref_operand(args[0])?;
 838                 let system_info_ptr = this
 839                     .check_mplace_access(system_info, None)?
 840                     .expect("cannot be a ZST");
 841                 // Initialize with `0`.
 842                 this.memory_mut()
 843                     .get_mut(system_info_ptr.alloc_id)?
 844                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 845                 // Set number of processors.
 846                 let dword_size = Size::from_bytes(4);
 847                 let offset = 2 * dword_size + 3 * tcx.pointer_size();
 848                 this.memory_mut()
 849                     .get_mut(system_info_ptr.alloc_id)?
 850                     .write_scalar(
 851                         tcx,
 852                         system_info_ptr.offset(offset, tcx)?,
 853                         Scalar::from_int(NUM_CPUS, dword_size).into(),
 854                         dword_size,
 855                     )?;
 856             }
 857
 858             "TlsAlloc" => {
 859                 // This just creates a key; Windows does not natively support TLS destructors.
 860
 861                 // Create key and return it.
 862                 let key = this.machine.tls.create_tls_key(None) as u128;
 863
 864                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 865                 if dest.layout.size.bits() < 128
 866                     && key >= (1u128 << dest.layout.size.bits() as u128)
 867                 {
 868                     throw_unsup!(OutOfTls);
 869                 }
 870                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 871             }
 872             "TlsGetValue" => {
 873                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 874                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 875                 this.write_scalar(ptr, dest)?;
 876             }
 877             "TlsSetValue" => {
 878                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 879                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 880                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 881
 882                 // Return success (`1`).
 883                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 884             }
 885             "GetStdHandle" => {
 886                 let which = this.read_scalar(args[0])?.to_i32()?;
 887                 // We just make this the identity function, so we know later in `WriteFile`
 888                 // which one it is.
 889                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 890             }
 891             "WriteFile" => {
 892                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 893                 let buf = this.read_scalar(args[1])?.not_undef()?;
 894                 let n = this.read_scalar(args[2])?.to_u32()?;
 895                 let written_place = this.deref_operand(args[3])?;
 896                 // Spec says to always write `0` first.
 897                 this.write_null(written_place.into())?;
 898                 let written = if handle == -11 || handle == -12 {
 899                     // stdout/stderr
 900                     use std::io::{self, Write};
 901
 902                     let buf_cont = this
 903                         .memory()
 904                         .read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 905                     let res = if handle == -11 {
 906                         io::stdout().write(buf_cont)
 907                     } else {
 908                         io::stderr().write(buf_cont)
 909                     };
 910                     res.ok().map(|n| n as u32)
 911                 } else {
 912                     eprintln!("Miri: Ignored output to handle {}", handle);
 913                     // Pretend it all went well.
 914                     Some(n)
 915                 };
 916                 // If there was no error, write back how much was written.
 917                 if let Some(n) = written {
 918                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 919                 }
 920                 // Return whether this was a success.
 921                 this.write_scalar(
 922                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 923                     dest,
 924                 )?;
 925             }
 926             "GetConsoleMode" => {
 927                 // Everything is a pipe.
 928                 this.write_null(dest)?;
 929             }
 930             "GetEnvironmentVariableW" => {
 931                 // This is not the env var you are looking for.
 932                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 933                 this.write_null(dest)?;
 934             }
 935             "GetCommandLineW" => {
 936                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 937             }
 938             // The actual name of 'RtlGenRandom'
 939             "SystemFunction036" => {
 940                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 941                 let len = this.read_scalar(args[1])?.to_u32()?;
 942                 this.gen_random(ptr, len as usize)?;
 943                 this.write_scalar(Scalar::from_bool(true), dest)?;
 944             }
 945
 946             // We can't execute anything else.
 947             _ => throw_unsup_format!("can't call foreign function: {}", link_name),
 948         }
 949
 950         this.goto_block(Some(ret))?;
 951         this.dump_place(*dest);
 952         Ok(())
 953     }
 954
 955     /// Evaluates the scalar at the specified path. Returns Some(val)
 956     /// if the path could be resolved, and None otherwise
 957     fn eval_path_scalar(
 958         &mut self,
 959         path: &[&str],
 960     ) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 961         let this = self.eval_context_mut();
 962         if let Ok(instance) = this.resolve_path(path) {
 963             let cid = GlobalId {
 964                 instance,
 965                 promoted: None,
 966             };
 967             let const_val = this.const_eval_raw(cid)?;
 968             let const_val = this.read_scalar(const_val.into())?;
 969             return Ok(Some(const_val));
 970         }
 971         return Ok(None);
 972     }
 973
 974     fn eval_libc_i32(&mut self, name: &str) -> InterpResult<'tcx, i32> {
 975         self.eval_context_mut()
 976             .eval_path_scalar(&["libc", name])?
 977             .ok_or_else(|| err_unsup_format!("Path libc::{} cannot be resolved.", name).into())
 978             .and_then(|scalar| scalar.to_i32())
 979     }
 980 }
 981
 982 // Shims the linux 'getrandom()' syscall.
 983 fn linux_getrandom<'tcx>(
 984     this: &mut MiriEvalContext<'_, 'tcx>,
 985     args: &[OpTy<'tcx, Tag>],
 986     dest: PlaceTy<'tcx, Tag>,
 987 ) -> InterpResult<'tcx> {
 988     let ptr = this.read_scalar(args[0])?.not_undef()?;
 989     let len = this.read_scalar(args[1])?.to_usize(this)?;
 990
 991     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 992     // neither of which have any effect on our current PRNG.
 993     let _flags = this.read_scalar(args[2])?.to_i32()?;
 994
 995     this.gen_random(ptr, len as usize)?;
 996     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 997     Ok(())
 998 }