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             "__errno_location" | "__error" => {
 422                 let errno_scalar: Scalar<Tag> = this.machine.last_error.unwrap().into();
 423                 this.write_scalar(errno_scalar, dest)?;
 424             }
 425
 426             "getenv" => {
 427                 let result = this.getenv(args[0])?;
 428                 this.write_scalar(result, dest)?;
 429             }
 430
 431             "unsetenv" => {
 432                 let result = this.unsetenv(args[0])?;
 433                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 434             }
 435
 436             "setenv" => {
 437                 let result = this.setenv(args[0], args[1])?;
 438                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 439             }
 440
 441             "getcwd" => {
 442                 let result = this.getcwd(args[0], args[1])?;
 443                 this.write_scalar(result, dest)?;
 444             }
 445
 446             "chdir" => {
 447                 let result = this.chdir(args[0])?;
 448                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 449             }
 450
 451             "open" | "open64" => {
 452                 let result = this.open(args[0], args[1])?;
 453                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 454             }
 455
 456             "fcntl" => {
 457                 let result = this.fcntl(args[0], args[1], args.get(2).cloned())?;
 458                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 459             }
 460
 461             "close" | "close$NOCANCEL" => {
 462                 let result = this.close(args[0])?;
 463                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 464             }
 465
 466             "read" => {
 467                 let result = this.read(args[0], args[1], args[2])?;
 468                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 469             }
 470
 471             "write" => {
 472                 let fd = this.read_scalar(args[0])?.to_i32()?;
 473                 let buf = this.read_scalar(args[1])?.not_undef()?;
 474                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 475                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 476                 let result = if fd == 1 || fd == 2 {
 477                     // stdout/stderr
 478                     use std::io::{self, Write};
 479
 480                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 481                     // We need to flush to make sure this actually appears on the screen
 482                     let res = if fd == 1 {
 483                         // Stdout is buffered, flush to make sure it appears on the screen.
 484                         // This is the write() syscall of the interpreted program, we want it
 485                         // to correspond to a write() syscall on the host -- there is no good
 486                         // in adding extra buffering here.
 487                         let res = io::stdout().write(buf_cont);
 488                         io::stdout().flush().unwrap();
 489                         res
 490                     } else {
 491                         // No need to flush, stderr is not buffered.
 492                         io::stderr().write(buf_cont)
 493                     };
 494                     match res {
 495                         Ok(n) => n as i64,
 496                         Err(_) => -1,
 497                     }
 498                 } else {
 499                     this.write(args[0], args[1], args[2])?
 500                 };
 501                 // Now, `result` is the value we return back to the program.
 502                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 503             }
 504
 505             "unlink" => {
 506                 let result = this.unlink(args[0])?;
 507                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 508             }
 509
 510             "strlen" => {
 511                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 512                 let n = this.memory().read_c_str(ptr)?.len();
 513                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 514             }
 515
 516             // math functions
 517             "cbrtf" | "coshf" | "sinhf" | "tanf" => {
 518                 // FIXME: Using host floats.
 519                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 520                 let f = match link_name {
 521                     "cbrtf" => f.cbrt(),
 522                     "coshf" => f.cosh(),
 523                     "sinhf" => f.sinh(),
 524                     "tanf" => f.tan(),
 525                     _ => bug!(),
 526                 };
 527                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 528             }
 529             // underscore case for windows
 530             "_hypotf" | "hypotf" | "atan2f" => {
 531                 // FIXME: Using host floats.
 532                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 533                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 534                 let n = match link_name {
 535                     "_hypotf" | "hypotf" => f1.hypot(f2),
 536                     "atan2f" => f1.atan2(f2),
 537                     _ => bug!(),
 538                 };
 539                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 540             }
 541
 542             "cbrt" | "cosh" | "sinh" | "tan" => {
 543                 // FIXME: Using host floats.
 544                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 545                 let f = match link_name {
 546                     "cbrt" => f.cbrt(),
 547                     "cosh" => f.cosh(),
 548                     "sinh" => f.sinh(),
 549                     "tan" => f.tan(),
 550                     _ => bug!(),
 551                 };
 552                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 553             }
 554             // underscore case for windows, here and below
 555             // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
 556             "_hypot" | "hypot" | "atan2" => {
 557                 // FIXME: Using host floats.
 558                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 559                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 560                 let n = match link_name {
 561                     "_hypot" | "hypot" => f1.hypot(f2),
 562                     "atan2" => f1.atan2(f2),
 563                     _ => bug!(),
 564                 };
 565                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 566             }
 567             // For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
 568             "_ldexp" | "ldexp" | "scalbn" => {
 569                 let x = this.read_scalar(args[0])?.to_f64()?;
 570                 let exp = this.read_scalar(args[1])?.to_i32()?;
 571
 572                 // Saturating cast to i16. Even those are outside the valid exponent range to
 573                 // `scalbn` below will do its over/underflow handling.
 574                 let exp = if exp > i16::max_value() as i32 {
 575                     i16::max_value()
 576                 } else if exp < i16::min_value() as i32 {
 577                     i16::min_value()
 578                 } else {
 579                     exp.try_into().unwrap()
 580                 };
 581
 582                 let res = x.scalbn(exp);
 583                 this.write_scalar(Scalar::from_f64(res), dest)?;
 584             }
 585
 586             // Some things needed for `sys::thread` initialization to go through.
 587             "signal" | "sigaction" | "sigaltstack" => {
 588                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 589             }
 590
 591             "sysconf" => {
 592                 let name = this.read_scalar(args[0])?.to_i32()?;
 593
 594                 trace!("sysconf() called with name {}", name);
 595                 // TODO: Cache the sysconf integers via Miri's global cache.
 596                 let paths = &[
 597                     (
 598                         &["libc", "_SC_PAGESIZE"],
 599                         Scalar::from_int(PAGE_SIZE, dest.layout.size),
 600                     ),
 601                     (
 602                         &["libc", "_SC_GETPW_R_SIZE_MAX"],
 603                         Scalar::from_int(-1, dest.layout.size),
 604                     ),
 605                     (
 606                         &["libc", "_SC_NPROCESSORS_ONLN"],
 607                         Scalar::from_int(NUM_CPUS, dest.layout.size),
 608                     ),
 609                 ];
 610                 let mut result = None;
 611                 for &(path, path_value) in paths {
 612                     if let Some(val) = this.eval_path_scalar(path)? {
 613                         let val = val.to_i32()?;
 614                         if val == name {
 615                             result = Some(path_value);
 616                             break;
 617                         }
 618                     }
 619                 }
 620                 if let Some(result) = result {
 621                     this.write_scalar(result, dest)?;
 622                 } else {
 623                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 624                 }
 625             }
 626
 627             "sched_getaffinity" => {
 628                 // Return an error; `num_cpus` then falls back to `sysconf`.
 629                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 630             }
 631
 632             "isatty" => {
 633                 this.write_null(dest)?;
 634             }
 635
 636             // Hook pthread calls that go to the thread-local storage memory subsystem.
 637             "pthread_key_create" => {
 638                 let key_ptr = this.read_scalar(args[0])?.not_undef()?;
 639
 640                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 641                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 642                     Some(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?.as_instance()?),
 643                     None => None,
 644                 };
 645
 646                 // Figure out how large a pthread TLS key actually is.
 647                 // This is `libc::pthread_key_t`.
 648                 let key_type = args[0].layout.ty
 649                     .builtin_deref(true)
 650                     .ok_or_else(|| err_ub_format!(
 651                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 652                     ))?
 653                     .ty;
 654                 let key_layout = this.layout_of(key_type)?;
 655
 656                 // Create key and write it into the memory where `key_ptr` wants it.
 657                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 658                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128)
 659                 {
 660                     throw_unsup!(OutOfTls);
 661                 }
 662
 663                 let key_ptr = this
 664                     .memory()
 665                     .check_ptr_access(key_ptr, key_layout.size, key_layout.align.abi)?
 666                     .expect("cannot be a ZST");
 667                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 668                     tcx,
 669                     key_ptr,
 670                     Scalar::from_uint(key, key_layout.size).into(),
 671                     key_layout.size,
 672                 )?;
 673
 674                 // Return success (`0`).
 675                 this.write_null(dest)?;
 676             }
 677             "pthread_key_delete" => {
 678                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 679                 this.machine.tls.delete_tls_key(key)?;
 680                 // Return success (0)
 681                 this.write_null(dest)?;
 682             }
 683             "pthread_getspecific" => {
 684                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 685                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 686                 this.write_scalar(ptr, dest)?;
 687             }
 688             "pthread_setspecific" => {
 689                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 690                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 691                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 692
 693                 // Return success (`0`).
 694                 this.write_null(dest)?;
 695             }
 696
 697             // Stack size/address stuff.
 698             "pthread_attr_init"
 699             | "pthread_attr_destroy"
 700             | "pthread_self"
 701             | "pthread_attr_setstacksize" => {
 702                 this.write_null(dest)?;
 703             }
 704             "pthread_attr_getstack" => {
 705                 let addr_place = this.deref_operand(args[1])?;
 706                 let size_place = this.deref_operand(args[2])?;
 707
 708                 this.write_scalar(
 709                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 710                     addr_place.into(),
 711                 )?;
 712                 this.write_scalar(
 713                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 714                     size_place.into(),
 715                 )?;
 716
 717                 // Return success (`0`).
 718                 this.write_null(dest)?;
 719             }
 720
 721             // We don't support threading. (Also for Windows.)
 722             "pthread_create" | "CreateThread" => {
 723                 throw_unsup_format!("Miri does not support threading");
 724             }
 725
 726             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 727             "pthread_mutexattr_init"
 728             | "pthread_mutexattr_settype"
 729             | "pthread_mutex_init"
 730             | "pthread_mutexattr_destroy"
 731             | "pthread_mutex_lock"
 732             | "pthread_mutex_unlock"
 733             | "pthread_mutex_destroy"
 734             | "pthread_rwlock_rdlock"
 735             | "pthread_rwlock_unlock"
 736             | "pthread_rwlock_wrlock"
 737             | "pthread_rwlock_destroy"
 738             | "pthread_condattr_init"
 739             | "pthread_condattr_setclock"
 740             | "pthread_cond_init"
 741             | "pthread_condattr_destroy"
 742             | "pthread_cond_destroy" => {
 743                 this.write_null(dest)?;
 744             }
 745
 746             // We don't support fork so we don't have to do anything for atfork.
 747             "pthread_atfork" => {
 748                 this.write_null(dest)?;
 749             }
 750
 751             "mmap" => {
 752                 // 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.
 753                 let addr = this.read_scalar(args[0])?.not_undef()?;
 754                 this.write_scalar(addr, dest)?;
 755             }
 756             "mprotect" => {
 757                 this.write_null(dest)?;
 758             }
 759
 760             // macOS API stubs.
 761             "pthread_attr_get_np" | "pthread_getattr_np" => {
 762                 this.write_null(dest)?;
 763             }
 764             "pthread_get_stackaddr_np" => {
 765                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 766                 this.write_scalar(stack_addr, dest)?;
 767             }
 768             "pthread_get_stacksize_np" => {
 769                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 770                 this.write_scalar(stack_size, dest)?;
 771             }
 772             "_tlv_atexit" => {
 773                 // FIXME: register the destructor.
 774             }
 775             "_NSGetArgc" => {
 776                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 777             }
 778             "_NSGetArgv" => {
 779                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 780             }
 781             "SecRandomCopyBytes" => {
 782                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 783                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 784                 this.gen_random(ptr, len as usize)?;
 785                 this.write_null(dest)?;
 786             }
 787
 788             // Windows API stubs.
 789             // HANDLE = isize
 790             // DWORD = ULONG = u32
 791             // BOOL = i32
 792             "GetProcessHeap" => {
 793                 // Just fake a HANDLE
 794                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 795             }
 796             "HeapAlloc" => {
 797                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 798                 let flags = this.read_scalar(args[1])?.to_u32()?;
 799                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 800                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 801                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 802                 this.write_scalar(res, dest)?;
 803             }
 804             "HeapFree" => {
 805                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 806                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 807                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 808                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 809                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 810             }
 811             "HeapReAlloc" => {
 812                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 813                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 814                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 815                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 816                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 817                 this.write_scalar(res, dest)?;
 818             }
 819
 820             "SetLastError" => {
 821                 this.set_last_error(this.read_scalar(args[0])?.not_undef()?)?;
 822             }
 823             "GetLastError" => {
 824                 let last_error = this.get_last_error()?;
 825                 this.write_scalar(last_error, dest)?;
 826             }
 827
 828             "AddVectoredExceptionHandler" => {
 829                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 830                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 831             }
 832             "InitializeCriticalSection"
 833             | "EnterCriticalSection"
 834             | "LeaveCriticalSection"
 835             | "DeleteCriticalSection" => {
 836                 // Nothing to do, not even a return value.
 837             }
 838             "GetModuleHandleW"
 839             | "GetProcAddress"
 840             | "TryEnterCriticalSection"
 841             | "GetConsoleScreenBufferInfo"
 842             | "SetConsoleTextAttribute" => {
 843                 // Pretend these do not exist / nothing happened, by returning zero.
 844                 this.write_null(dest)?;
 845             }
 846             "GetSystemInfo" => {
 847                 let system_info = this.deref_operand(args[0])?;
 848                 let system_info_ptr = this
 849                     .check_mplace_access(system_info, None)?
 850                     .expect("cannot be a ZST");
 851                 // Initialize with `0`.
 852                 this.memory_mut()
 853                     .get_mut(system_info_ptr.alloc_id)?
 854                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 855                 // Set number of processors.
 856                 let dword_size = Size::from_bytes(4);
 857                 let offset = 2 * dword_size + 3 * tcx.pointer_size();
 858                 this.memory_mut()
 859                     .get_mut(system_info_ptr.alloc_id)?
 860                     .write_scalar(
 861                         tcx,
 862                         system_info_ptr.offset(offset, tcx)?,
 863                         Scalar::from_int(NUM_CPUS, dword_size).into(),
 864                         dword_size,
 865                     )?;
 866             }
 867
 868             "TlsAlloc" => {
 869                 // This just creates a key; Windows does not natively support TLS destructors.
 870
 871                 // Create key and return it.
 872                 let key = this.machine.tls.create_tls_key(None) as u128;
 873
 874                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 875                 if dest.layout.size.bits() < 128
 876                     && key >= (1u128 << dest.layout.size.bits() as u128)
 877                 {
 878                     throw_unsup!(OutOfTls);
 879                 }
 880                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 881             }
 882             "TlsGetValue" => {
 883                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 884                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 885                 this.write_scalar(ptr, dest)?;
 886             }
 887             "TlsSetValue" => {
 888                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 889                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 890                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 891
 892                 // Return success (`1`).
 893                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 894             }
 895             "GetStdHandle" => {
 896                 let which = this.read_scalar(args[0])?.to_i32()?;
 897                 // We just make this the identity function, so we know later in `WriteFile`
 898                 // which one it is.
 899                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 900             }
 901             "WriteFile" => {
 902                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 903                 let buf = this.read_scalar(args[1])?.not_undef()?;
 904                 let n = this.read_scalar(args[2])?.to_u32()?;
 905                 let written_place = this.deref_operand(args[3])?;
 906                 // Spec says to always write `0` first.
 907                 this.write_null(written_place.into())?;
 908                 let written = if handle == -11 || handle == -12 {
 909                     // stdout/stderr
 910                     use std::io::{self, Write};
 911
 912                     let buf_cont = this
 913                         .memory()
 914                         .read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 915                     let res = if handle == -11 {
 916                         io::stdout().write(buf_cont)
 917                     } else {
 918                         io::stderr().write(buf_cont)
 919                     };
 920                     res.ok().map(|n| n as u32)
 921                 } else {
 922                     eprintln!("Miri: Ignored output to handle {}", handle);
 923                     // Pretend it all went well.
 924                     Some(n)
 925                 };
 926                 // If there was no error, write back how much was written.
 927                 if let Some(n) = written {
 928                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 929                 }
 930                 // Return whether this was a success.
 931                 this.write_scalar(
 932                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 933                     dest,
 934                 )?;
 935             }
 936             "GetConsoleMode" => {
 937                 // Everything is a pipe.
 938                 this.write_null(dest)?;
 939             }
 940             "GetEnvironmentVariableW" => {
 941                 // This is not the env var you are looking for.
 942                 this.set_last_error(Scalar::from_u32(203))?; // ERROR_ENVVAR_NOT_FOUND
 943                 this.write_null(dest)?;
 944             }
 945             "GetCommandLineW" => {
 946                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 947             }
 948             // The actual name of 'RtlGenRandom'
 949             "SystemFunction036" => {
 950                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 951                 let len = this.read_scalar(args[1])?.to_u32()?;
 952                 this.gen_random(ptr, len as usize)?;
 953                 this.write_scalar(Scalar::from_bool(true), dest)?;
 954             }
 955
 956             // We can't execute anything else.
 957             _ => throw_unsup_format!("can't call foreign function: {}", link_name),
 958         }
 959
 960         this.goto_block(Some(ret))?;
 961         this.dump_place(*dest);
 962         Ok(())
 963     }
 964
 965     /// Evaluates the scalar at the specified path. Returns Some(val)
 966     /// if the path could be resolved, and None otherwise
 967     fn eval_path_scalar(
 968         &mut self,
 969         path: &[&str],
 970     ) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 971         let this = self.eval_context_mut();
 972         if let Ok(instance) = this.resolve_path(path) {
 973             let cid = GlobalId {
 974                 instance,
 975                 promoted: None,
 976             };
 977             let const_val = this.const_eval_raw(cid)?;
 978             let const_val = this.read_scalar(const_val.into())?;
 979             return Ok(Some(const_val));
 980         }
 981         return Ok(None);
 982     }
 983
 984     fn set_last_error(&mut self, scalar: Scalar<Tag>) -> InterpResult<'tcx> {
 985         let this = self.eval_context_mut();
 986         let tcx = &{ this.tcx.tcx };
 987         let errno_ptr = this.machine.last_error.unwrap();
 988         this.memory_mut().get_mut(errno_ptr.alloc_id)?.write_scalar(
 989             tcx,
 990             errno_ptr,
 991             scalar.into(),
 992             Size::from_bits(32),
 993         )
 994     }
 995
 996     fn get_last_error(&mut self) -> InterpResult<'tcx, Scalar<Tag>> {
 997         let this = self.eval_context_mut();
 998         let tcx = &{ this.tcx.tcx };
 999         let errno_ptr = this.machine.last_error.unwrap();
1000         this.memory()
1001             .get(errno_ptr.alloc_id)?
1002             .read_scalar(tcx, errno_ptr, Size::from_bits(32))?
1003             .not_undef()
1004     }
1005
1006     fn consume_io_error(&mut self, e: std::io::Error) -> InterpResult<'tcx> {
1007         self.eval_context_mut().set_last_error(Scalar::from_int(
1008             e.raw_os_error().unwrap(),
1009             Size::from_bits(32),
1010         ))
1011     }
1012 }
1013
1014 // Shims the linux 'getrandom()' syscall.
1015 fn linux_getrandom<'tcx>(
1016     this: &mut MiriEvalContext<'_, 'tcx>,
1017     args: &[OpTy<'tcx, Tag>],
1018     dest: PlaceTy<'tcx, Tag>,
1019 ) -> InterpResult<'tcx> {
1020     let ptr = this.read_scalar(args[0])?.not_undef()?;
1021     let len = this.read_scalar(args[1])?.to_usize(this)?;
1022
1023     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
1024     // neither of which have any effect on our current PRNG.
1025     let _flags = this.read_scalar(args[2])?.to_i32()?;
1026
1027     this.gen_random(ptr, len as usize)?;
1028     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
1029     Ok(())
1030 }