src/shims/foreign_items.rs

   1 use rustc::ty::layout::{Align, LayoutOf, Size};
   2 use rustc::hir::def_id::DefId;
   3 use rustc::mir;
   4 use syntax::attr;
   5 use syntax::symbol::sym;
   6
   7 use crate::*;
   8 use crate::shims::env::alloc_env_value;
   9
  10 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  11 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  12     /// Returns the minimum alignment for the target architecture for allocations of the given size.
  13     fn min_align(&self, size: u64, kind: MiriMemoryKind) -> Align {
  14         let this = self.eval_context_ref();
  15         // List taken from `libstd/sys_common/alloc.rs`.
  16         let min_align = match this.tcx.tcx.sess.target.target.arch.as_str() {
  17             "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
  18             "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" => 16,
  19             arch => bug!("Unsupported target architecture: {}", arch),
  20         };
  21         // Windows always aligns, even small allocations.
  22         // Source: <https://support.microsoft.com/en-us/help/286470/how-to-use-pageheap-exe-in-windows-xp-windows-2000-and-windows-server>
  23         // But jemalloc does not, so for the C heap we only align if the allocation is sufficiently big.
  24         if kind == MiriMemoryKind::WinHeap || size >= min_align {
  25             return Align::from_bytes(min_align).unwrap();
  26         }
  27         // We have `size < min_align`. Round `size` *down* to the next power of two and use that.
  28         fn prev_power_of_two(x: u64) -> u64 {
  29             let next_pow2 = x.next_power_of_two();
  30             if next_pow2 == x {
  31                 // x *is* a power of two, just use that.
  32                 x
  33             } else {
  34                 // x is between two powers, so next = 2*prev.
  35                 next_pow2 / 2
  36             }
  37         }
  38         Align::from_bytes(prev_power_of_two(size)).unwrap()
  39     }
  40
  41     fn malloc(
  42         &mut self,
  43         size: u64,
  44         zero_init: bool,
  45         kind: MiriMemoryKind,
  46     ) -> Scalar<Tag> {
  47         let this = self.eval_context_mut();
  48         let tcx = &{this.tcx.tcx};
  49         if size == 0 {
  50             Scalar::from_int(0, this.pointer_size())
  51         } else {
  52             let align = this.min_align(size, kind);
  53             let ptr = this.memory_mut().allocate(Size::from_bytes(size), align, kind.into());
  54             if zero_init {
  55                 // We just allocated this, the access cannot fail
  56                 this.memory_mut()
  57                     .get_mut(ptr.alloc_id).unwrap()
  58                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
  59             }
  60             Scalar::Ptr(ptr)
  61         }
  62     }
  63
  64     fn free(
  65         &mut self,
  66         ptr: Scalar<Tag>,
  67         kind: MiriMemoryKind,
  68     ) -> InterpResult<'tcx> {
  69         let this = self.eval_context_mut();
  70         if !this.is_null(ptr)? {
  71             let ptr = this.force_ptr(ptr)?;
  72             this.memory_mut().deallocate(
  73                 ptr,
  74                 None,
  75                 kind.into(),
  76             )?;
  77         }
  78         Ok(())
  79     }
  80
  81     fn realloc(
  82         &mut self,
  83         old_ptr: Scalar<Tag>,
  84         new_size: u64,
  85         kind: MiriMemoryKind,
  86     ) -> InterpResult<'tcx, Scalar<Tag>> {
  87         let this = self.eval_context_mut();
  88         let new_align = this.min_align(new_size, kind);
  89         if this.is_null(old_ptr)? {
  90             if new_size == 0 {
  91                 Ok(Scalar::from_int(0, this.pointer_size()))
  92             } else {
  93                 let new_ptr = this.memory_mut().allocate(
  94                     Size::from_bytes(new_size),
  95                     new_align,
  96                     kind.into()
  97                 );
  98                 Ok(Scalar::Ptr(new_ptr))
  99             }
 100         } else {
 101             let old_ptr = this.force_ptr(old_ptr)?;
 102             let memory = this.memory_mut();
 103             if new_size == 0 {
 104                 memory.deallocate(
 105                     old_ptr,
 106                     None,
 107                     kind.into(),
 108                 )?;
 109                 Ok(Scalar::from_int(0, this.pointer_size()))
 110             } else {
 111                 let new_ptr = memory.reallocate(
 112                     old_ptr,
 113                     None,
 114                     Size::from_bytes(new_size),
 115                     new_align,
 116                     kind.into(),
 117                 )?;
 118                 Ok(Scalar::Ptr(new_ptr))
 119             }
 120         }
 121     }
 122
 123     /// Emulates calling a foreign item, failing if the item is not supported.
 124     /// This function will handle `goto_block` if needed.
 125     fn emulate_foreign_item(
 126         &mut self,
 127         def_id: DefId,
 128         args: &[OpTy<'tcx, Tag>],
 129         dest: Option<PlaceTy<'tcx, Tag>>,
 130         ret: Option<mir::BasicBlock>,
 131     ) -> InterpResult<'tcx> {
 132         let this = self.eval_context_mut();
 133         let attrs = this.tcx.get_attrs(def_id);
 134         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 135             Some(name) => name.as_str(),
 136             None => this.tcx.item_name(def_id).as_str(),
 137         };
 138         // Strip linker suffixes (seen on 32-bit macOS).
 139         let link_name = link_name.get().trim_end_matches("$UNIX2003");
 140         let tcx = &{this.tcx.tcx};
 141
 142         // First: functions that diverge.
 143         match link_name {
 144             "__rust_start_panic" | "panic_impl" => {
 145                 throw_unsup_format!("the evaluated program panicked");
 146             }
 147             "exit" | "ExitProcess" => {
 148                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` error variant anyway
 149                 let code = this.read_scalar(args[0])?.to_i32()?;
 150                 return Err(InterpError::Exit(code).into());
 151             }
 152             _ => if dest.is_none() {
 153                 throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
 154             }
 155         }
 156
 157         // Next: functions that assume a ret and dest.
 158         let dest = dest.expect("we already checked for a dest");
 159         let ret = ret.expect("dest is `Some` but ret is `None`");
 160         match link_name {
 161             "malloc" => {
 162                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 163                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 164                 this.write_scalar(res, dest)?;
 165             }
 166             "calloc" => {
 167                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 168                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 169                 let size = items.checked_mul(len).ok_or_else(|| err_panic!(Overflow(mir::BinOp::Mul)))?;
 170                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 171                 this.write_scalar(res, dest)?;
 172             }
 173             "posix_memalign" => {
 174                 let ret = this.deref_operand(args[0])?;
 175                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 176                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 177                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 178                 if !align.is_power_of_two() {
 179                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 180                 }
 181                 if align < this.pointer_size().bytes() {
 182                     throw_ub_format!(
 183                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 184                         align,
 185                     );
 186                 }
 187
 188                 if size == 0 {
 189                     this.write_null(ret.into())?;
 190                 } else {
 191                     let ptr = this.memory_mut().allocate(
 192                         Size::from_bytes(size),
 193                         Align::from_bytes(align).unwrap(),
 194                         MiriMemoryKind::C.into()
 195                     );
 196                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 197                 }
 198                 this.write_null(dest)?;
 199             }
 200             "free" => {
 201                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 202                 this.free(ptr, MiriMemoryKind::C)?;
 203             }
 204             "realloc" => {
 205                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 206                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 207                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 208                 this.write_scalar(res, dest)?;
 209             }
 210
 211             "__rust_alloc" => {
 212                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 213                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 214                 if size == 0 {
 215                     throw_unsup!(HeapAllocZeroBytes);
 216                 }
 217                 if !align.is_power_of_two() {
 218                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 219                 }
 220                 let ptr = this.memory_mut()
 221                     .allocate(
 222                         Size::from_bytes(size),
 223                         Align::from_bytes(align).unwrap(),
 224                         MiriMemoryKind::Rust.into()
 225                     );
 226                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 227             }
 228             "__rust_alloc_zeroed" => {
 229                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 230                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 231                 if size == 0 {
 232                     throw_unsup!(HeapAllocZeroBytes);
 233                 }
 234                 if !align.is_power_of_two() {
 235                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 236                 }
 237                 let ptr = this.memory_mut()
 238                     .allocate(
 239                         Size::from_bytes(size),
 240                         Align::from_bytes(align).unwrap(),
 241                         MiriMemoryKind::Rust.into()
 242                     );
 243                 // We just allocated this, the access cannot fail
 244                 this.memory_mut()
 245                     .get_mut(ptr.alloc_id).unwrap()
 246                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
 247                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 248             }
 249             "__rust_dealloc" => {
 250                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 251                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 252                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 253                 if old_size == 0 {
 254                     throw_unsup!(HeapAllocZeroBytes);
 255                 }
 256                 if !align.is_power_of_two() {
 257                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 258                 }
 259                 let ptr = this.force_ptr(ptr)?;
 260                 this.memory_mut().deallocate(
 261                     ptr,
 262                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 263                     MiriMemoryKind::Rust.into(),
 264                 )?;
 265             }
 266             "__rust_realloc" => {
 267                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 268                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 269                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 270                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 271                 if old_size == 0 || new_size == 0 {
 272                     throw_unsup!(HeapAllocZeroBytes);
 273                 }
 274                 if !align.is_power_of_two() {
 275                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 276                 }
 277                 let align = Align::from_bytes(align).unwrap();
 278                 let new_ptr = this.memory_mut().reallocate(
 279                     ptr,
 280                     Some((Size::from_bytes(old_size), align)),
 281                     Size::from_bytes(new_size),
 282                     align,
 283                     MiriMemoryKind::Rust.into(),
 284                 )?;
 285                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 286             }
 287
 288             "syscall" => {
 289                 let sys_getrandom = this.eval_path_scalar(&["libc", "SYS_getrandom"])?
 290                     .expect("Failed to get libc::SYS_getrandom")
 291                     .to_usize(this)?;
 292
 293                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 294                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 295                 match this.read_scalar(args[0])?.to_usize(this)? {
 296                     id if id == sys_getrandom => {
 297                         // The first argument is the syscall id,
 298                         // so skip over it.
 299                         linux_getrandom(this, &args[1..], dest)?;
 300                     }
 301                     id => {
 302                         throw_unsup_format!("miri does not support syscall ID {}", id)
 303                     }
 304                 }
 305             }
 306
 307             "getrandom" => {
 308                 linux_getrandom(this, args, dest)?;
 309             }
 310
 311             "dlsym" => {
 312                 let _handle = this.read_scalar(args[0])?;
 313                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 314                 let symbol_name = this.memory().read_c_str(symbol)?;
 315                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 316                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 317                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 318                     let ptr = this.memory_mut().create_fn_alloc(FnVal::Other(dlsym));
 319                     this.write_scalar(Scalar::from(ptr), dest)?;
 320                 } else {
 321                     this.write_null(dest)?;
 322                 }
 323             }
 324
 325             "__rust_maybe_catch_panic" => {
 326                 // fn __rust_maybe_catch_panic(
 327                 //     f: fn(*mut u8),
 328                 //     data: *mut u8,
 329                 //     data_ptr: *mut usize,
 330                 //     vtable_ptr: *mut usize,
 331                 // ) -> u32
 332                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 333                 let f = this.read_scalar(args[0])?.not_undef()?;
 334                 let data = this.read_scalar(args[1])?.not_undef()?;
 335                 let f_instance = this.memory().get_fn(f)?.as_instance()?;
 336                 this.write_null(dest)?;
 337                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 338
 339                 // Now we make a function call.
 340                 // TODO: consider making this reusable? `InterpCx::step` does something similar
 341                 // for the TLS destructors, and of course `eval_main`.
 342                 let mir = this.load_mir(f_instance.def)?;
 343                 let ret_place = MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 344                 this.push_stack_frame(
 345                     f_instance,
 346                     mir.span,
 347                     mir,
 348                     Some(ret_place),
 349                     // Directly return to caller.
 350                     StackPopCleanup::Goto(Some(ret)),
 351                 )?;
 352                 let mut args = this.frame().body.args_iter();
 353
 354                 let arg_local = args.next()
 355                     .expect("Argument to __rust_maybe_catch_panic does not take enough arguments.");
 356                 let arg_dest = this.local_place(arg_local)?;
 357                 this.write_scalar(data, arg_dest)?;
 358
 359                 assert!(args.next().is_none(), "__rust_maybe_catch_panic argument has more arguments than expected");
 360
 361                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 362                 this.write_null(dest)?;
 363
 364                 // Don't fall through, we do *not* want to `goto_block`!
 365                 return Ok(());
 366             }
 367
 368             "memcmp" => {
 369                 let left = this.read_scalar(args[0])?.not_undef()?;
 370                 let right = this.read_scalar(args[1])?.not_undef()?;
 371                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 372
 373                 let result = {
 374                     let left_bytes = this.memory().read_bytes(left, n)?;
 375                     let right_bytes = this.memory().read_bytes(right, n)?;
 376
 377                     use std::cmp::Ordering::*;
 378                     match left_bytes.cmp(right_bytes) {
 379                         Less => -1i32,
 380                         Equal => 0,
 381                         Greater => 1,
 382                     }
 383                 };
 384
 385                 this.write_scalar(
 386                     Scalar::from_int(result, Size::from_bits(32)),
 387                     dest,
 388                 )?;
 389             }
 390
 391             "memrchr" => {
 392                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 393                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 394                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 395                 if let Some(idx) = this.memory().read_bytes(ptr, Size::from_bytes(num))?
 396                     .iter().rev().position(|&c| c == val)
 397                 {
 398                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 399                     this.write_scalar(new_ptr, dest)?;
 400                 } else {
 401                     this.write_null(dest)?;
 402                 }
 403             }
 404
 405             "memchr" => {
 406                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 407                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 408                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 409                 let idx = this
 410                     .memory()
 411                     .read_bytes(ptr, Size::from_bytes(num))?
 412                     .iter()
 413                     .position(|&c| c == val);
 414                 if let Some(idx) = idx {
 415                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 416                     this.write_scalar(new_ptr, dest)?;
 417                 } else {
 418                     this.write_null(dest)?;
 419                 }
 420             }
 421
 422             "getenv" => {
 423                 let result = {
 424                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 425                     let name = this.memory().read_c_str(name_ptr)?;
 426                     match this.machine.env_vars.get(name) {
 427                         Some(&var) => Scalar::Ptr(var),
 428                         None => Scalar::ptr_null(&*this.tcx),
 429                     }
 430                 };
 431                 this.write_scalar(result, dest)?;
 432             }
 433
 434             "unsetenv" => {
 435                 let mut success = None;
 436                 {
 437                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 438                     if !this.is_null(name_ptr)? {
 439                         let name = this.memory().read_c_str(name_ptr)?.to_owned();
 440                         if !name.is_empty() && !name.contains(&b'=') {
 441                             success = Some(this.machine.env_vars.unset(&name));
 442                         }
 443                     }
 444                 }
 445                 if let Some(old) = success {
 446                     if let Some(var) = old {
 447                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 448                     }
 449                     this.write_null(dest)?;
 450                 } else {
 451                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 452                 }
 453             }
 454
 455             "setenv" => {
 456                 let mut new = None;
 457                 {
 458                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 459                     let value_ptr = this.read_scalar(args[1])?.not_undef()?;
 460                     let value = this.memory().read_c_str(value_ptr)?;
 461                     if !this.is_null(name_ptr)? {
 462                         let name = this.memory().read_c_str(name_ptr)?;
 463                         if !name.is_empty() && !name.contains(&b'=') {
 464                             new = Some((name.to_owned(), value.to_owned()));
 465                         }
 466                     }
 467                 }
 468                 if let Some((name, value)) = new {
 469                     let value_copy = alloc_env_value(&value, this.memory_mut(), tcx);
 470                     if let Some(var) = this.machine.env_vars.set(name.to_owned(), value_copy) {
 471                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 472                     }
 473                     this.write_null(dest)?;
 474                 } else {
 475                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 476                 }
 477             }
 478
 479             "write" => {
 480                 let fd = this.read_scalar(args[0])?.to_i32()?;
 481                 let buf = this.read_scalar(args[1])?.not_undef()?;
 482                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 483                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 484                 let result = if fd == 1 || fd == 2 {
 485                     // stdout/stderr
 486                     use std::io::{self, Write};
 487
 488                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 489                     // We need to flush to make sure this actually appears on the screen
 490                     let res = if fd == 1 {
 491                         // Stdout is buffered, flush to make sure it appears on the screen.
 492                         // This is the write() syscall of the interpreted program, we want it
 493                         // to correspond to a write() syscall on the host -- there is no good
 494                         // in adding extra buffering here.
 495                         let res = io::stdout().write(buf_cont);
 496                         io::stdout().flush().unwrap();
 497                         res
 498                     } else {
 499                         // No need to flush, stderr is not buffered.
 500                         io::stderr().write(buf_cont)
 501                     };
 502                     match res {
 503                         Ok(n) => n as i64,
 504                         Err(_) => -1,
 505                     }
 506                 } else {
 507                     eprintln!("Miri: Ignored output to FD {}", fd);
 508                     // Pretend it all went well.
 509                     n as i64
 510                 };
 511                 // Now, `result` is the value we return back to the program.
 512                 this.write_scalar(
 513                     Scalar::from_int(result, dest.layout.size),
 514                     dest,
 515                 )?;
 516             }
 517
 518             "strlen" => {
 519                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 520                 let n = this.memory().read_c_str(ptr)?.len();
 521                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 522             }
 523
 524             // math functions
 525
 526             "cbrtf" | "coshf" | "sinhf" |"tanf" => {
 527                 // FIXME: Using host floats.
 528                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 529                 let f = match link_name {
 530                     "cbrtf" => f.cbrt(),
 531                     "coshf" => f.cosh(),
 532                     "sinhf" => f.sinh(),
 533                     "tanf" => f.tan(),
 534                     _ => bug!(),
 535                 };
 536                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 537             }
 538             // underscore case for windows
 539             "_hypotf" | "hypotf" | "atan2f" => {
 540                 // FIXME: Using host floats.
 541                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 542                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 543                 let n = match link_name {
 544                     "_hypotf" | "hypotf" => f1.hypot(f2),
 545                     "atan2f" => f1.atan2(f2),
 546                     _ => bug!(),
 547                 };
 548                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 549             }
 550
 551             "cbrt" | "cosh" | "sinh" | "tan" => {
 552                 // FIXME: Using host floats.
 553                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 554                 let f = match link_name {
 555                     "cbrt" => f.cbrt(),
 556                     "cosh" => f.cosh(),
 557                     "sinh" => f.sinh(),
 558                     "tan" => f.tan(),
 559                     _ => bug!(),
 560                 };
 561                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 562             }
 563             // underscore case for windows
 564             "_hypot" | "hypot" | "atan2" => {
 565                 // FIXME: Using host floats.
 566                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 567                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 568                 let n = match link_name {
 569                     "_hypot" | "hypot" => f1.hypot(f2),
 570                     "atan2" => f1.atan2(f2),
 571                     _ => bug!(),
 572                 };
 573                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 574             }
 575             // underscore case for windows
 576             "_ldexp" | "ldexp" => {
 577                 // FIXME: Using host floats.
 578                 let x = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 579                 let exp = this.read_scalar(args[1])?.to_i32()?;
 580                 // FIXME: We should use cmath if there are any imprecisions.
 581                 let n = x * 2.0f64.powi(exp);
 582                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 583             }
 584
 585             // Some things needed for `sys::thread` initialization to go through.
 586             "signal" | "sigaction" | "sigaltstack" => {
 587                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 588             }
 589
 590             "sysconf" => {
 591                 let name = this.read_scalar(args[0])?.to_i32()?;
 592
 593                 trace!("sysconf() called with name {}", name);
 594                 // TODO: Cache the sysconf integers via Miri's global cache.
 595                 let paths = &[
 596                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(PAGE_SIZE, dest.layout.size)),
 597                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 598                     (&["libc", "_SC_NPROCESSORS_ONLN"], Scalar::from_int(NUM_CPUS, dest.layout.size)),
 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                 }
 611                 if let Some(result) = result {
 612                     this.write_scalar(result, dest)?;
 613                 } else {
 614                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 615                 }
 616             }
 617
 618             "sched_getaffinity" => {
 619                 // Return an error; `num_cpus` then falls back to `sysconf`.
 620                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 621             }
 622
 623             "isatty" => {
 624                 this.write_null(dest)?;
 625             }
 626
 627             // Hook pthread calls that go to the thread-local storage memory subsystem.
 628             "pthread_key_create" => {
 629                 let key_ptr = this.read_scalar(args[0])?.not_undef()?;
 630
 631                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 632                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 633                     Some(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?.as_instance()?),
 634                     None => None,
 635                 };
 636
 637                 // Figure out how large a pthread TLS key actually is.
 638                 // This is `libc::pthread_key_t`.
 639                 let key_type = args[0].layout.ty
 640                     .builtin_deref(true)
 641                     .ok_or_else(|| err_ub_format!(
 642                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 643                     ))?
 644                     .ty;
 645                 let key_layout = this.layout_of(key_type)?;
 646
 647                 // Create key and write it into the memory where `key_ptr` wants it.
 648                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 649                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128) {
 650                     throw_unsup!(OutOfTls);
 651                 }
 652
 653                 let key_ptr = this.memory().check_ptr_access(key_ptr, key_layout.size, key_layout.align.abi)?
 654                     .expect("cannot be a ZST");
 655                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 656                     tcx,
 657                     key_ptr,
 658                     Scalar::from_uint(key, key_layout.size).into(),
 659                     key_layout.size,
 660                 )?;
 661
 662                 // Return success (`0`).
 663                 this.write_null(dest)?;
 664             }
 665             "pthread_key_delete" => {
 666                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 667                 this.machine.tls.delete_tls_key(key)?;
 668                 // Return success (0)
 669                 this.write_null(dest)?;
 670             }
 671             "pthread_getspecific" => {
 672                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 673                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 674                 this.write_scalar(ptr, dest)?;
 675             }
 676             "pthread_setspecific" => {
 677                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 678                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 679                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 680
 681                 // Return success (`0`).
 682                 this.write_null(dest)?;
 683             }
 684
 685             // Stack size/address stuff.
 686             "pthread_attr_init" | "pthread_attr_destroy" | "pthread_self" |
 687             "pthread_attr_setstacksize" => {
 688                 this.write_null(dest)?;
 689             }
 690             "pthread_attr_getstack" => {
 691                 let addr_place = this.deref_operand(args[1])?;
 692                 let size_place = this.deref_operand(args[2])?;
 693
 694                 this.write_scalar(
 695                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 696                     addr_place.into(),
 697                 )?;
 698                 this.write_scalar(
 699                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 700                     size_place.into(),
 701                 )?;
 702
 703                 // Return success (`0`).
 704                 this.write_null(dest)?;
 705             }
 706
 707             // We don't support threading. (Also for Windows.)
 708             "pthread_create" | "CreateThread" => {
 709                 throw_unsup_format!("Miri does not support threading");
 710             }
 711
 712             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 713             "pthread_mutexattr_init" | "pthread_mutexattr_settype" | "pthread_mutex_init" |
 714             "pthread_mutexattr_destroy" | "pthread_mutex_lock" | "pthread_mutex_unlock" |
 715             "pthread_mutex_destroy" | "pthread_rwlock_rdlock" | "pthread_rwlock_unlock" |
 716             "pthread_rwlock_wrlock" | "pthread_rwlock_destroy" | "pthread_condattr_init" |
 717             "pthread_condattr_setclock" | "pthread_cond_init" | "pthread_condattr_destroy" |
 718             "pthread_cond_destroy" => {
 719                 this.write_null(dest)?;
 720             }
 721
 722             // We don't support fork so we don't have to do anything for atfork.
 723             "pthread_atfork" => {
 724                 this.write_null(dest)?;
 725             }
 726
 727             "mmap" => {
 728                 // This is a horrible hack, but since the guard page mechanism calls mmap and expects a particular return value, we just give it that value.
 729                 let addr = this.read_scalar(args[0])?.not_undef()?;
 730                 this.write_scalar(addr, dest)?;
 731             }
 732             "mprotect" => {
 733                 this.write_null(dest)?;
 734             }
 735
 736             // macOS API stubs.
 737             "pthread_attr_get_np" | "pthread_getattr_np" => {
 738                 this.write_null(dest)?;
 739             }
 740             "pthread_get_stackaddr_np" => {
 741                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 742                 this.write_scalar(stack_addr, dest)?;
 743             }
 744             "pthread_get_stacksize_np" => {
 745                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 746                 this.write_scalar(stack_size, dest)?;
 747             }
 748             "_tlv_atexit" => {
 749                 // FIXME: register the destructor.
 750             },
 751             "_NSGetArgc" => {
 752                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 753             },
 754             "_NSGetArgv" => {
 755                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 756             },
 757             "SecRandomCopyBytes" => {
 758                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 759                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 760                 this.gen_random(ptr, len as usize)?;
 761                 this.write_null(dest)?;
 762             }
 763
 764             // Windows API stubs.
 765             // HANDLE = isize
 766             // DWORD = ULONG = u32
 767             // BOOL = i32
 768             "GetProcessHeap" => {
 769                 // Just fake a HANDLE
 770                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 771             }
 772             "HeapAlloc" => {
 773                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 774                 let flags = this.read_scalar(args[1])?.to_u32()?;
 775                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 776                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 777                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 778                 this.write_scalar(res, dest)?;
 779             }
 780             "HeapFree" => {
 781                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 782                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 783                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 784                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 785                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 786             }
 787             "HeapReAlloc" => {
 788                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 789                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 790                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 791                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 792                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 793                 this.write_scalar(res, dest)?;
 794             }
 795
 796             "SetLastError" => {
 797                 let err = this.read_scalar(args[0])?.to_u32()?;
 798                 this.machine.last_error = err;
 799             }
 800             "GetLastError" => {
 801                 this.write_scalar(Scalar::from_u32(this.machine.last_error), dest)?;
 802             }
 803
 804             "AddVectoredExceptionHandler" => {
 805                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 806                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 807             },
 808             "InitializeCriticalSection" |
 809             "EnterCriticalSection" |
 810             "LeaveCriticalSection" |
 811             "DeleteCriticalSection" => {
 812                 // Nothing to do, not even a return value.
 813             },
 814             "GetModuleHandleW" |
 815             "GetProcAddress" |
 816             "TryEnterCriticalSection" |
 817             "GetConsoleScreenBufferInfo" |
 818             "SetConsoleTextAttribute" => {
 819                 // Pretend these do not exist / nothing happened, by returning zero.
 820                 this.write_null(dest)?;
 821             },
 822             "GetSystemInfo" => {
 823                 let system_info = this.deref_operand(args[0])?;
 824                 let system_info_ptr = this.check_mplace_access(system_info, None)?
 825                     .expect("cannot be a ZST");
 826                 // Initialize with `0`.
 827                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 828                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 829                 // Set number of processors.
 830                 let dword_size = Size::from_bytes(4);
 831                 let offset = 2*dword_size + 3*tcx.pointer_size();
 832                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 833                     .write_scalar(
 834                         tcx,
 835                         system_info_ptr.offset(offset, tcx)?,
 836                         Scalar::from_int(NUM_CPUS, dword_size).into(),
 837                         dword_size,
 838                     )?;
 839             }
 840
 841             "TlsAlloc" => {
 842                 // This just creates a key; Windows does not natively support TLS destructors.
 843
 844                 // Create key and return it.
 845                 let key = this.machine.tls.create_tls_key(None) as u128;
 846
 847                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 848                 if dest.layout.size.bits() < 128
 849                         && key >= (1u128 << dest.layout.size.bits() as u128) {
 850                     throw_unsup!(OutOfTls);
 851                 }
 852                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 853             }
 854             "TlsGetValue" => {
 855                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 856                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 857                 this.write_scalar(ptr, dest)?;
 858             }
 859             "TlsSetValue" => {
 860                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 861                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 862                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 863
 864                 // Return success (`1`).
 865                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 866             }
 867             "GetStdHandle" => {
 868                 let which = this.read_scalar(args[0])?.to_i32()?;
 869                 // We just make this the identity function, so we know later in `WriteFile`
 870                 // which one it is.
 871                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 872             }
 873             "WriteFile" => {
 874                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 875                 let buf = this.read_scalar(args[1])?.not_undef()?;
 876                 let n = this.read_scalar(args[2])?.to_u32()?;
 877                 let written_place = this.deref_operand(args[3])?;
 878                 // Spec says to always write `0` first.
 879                 this.write_null(written_place.into())?;
 880                 let written = if handle == -11 || handle == -12 {
 881                     // stdout/stderr
 882                     use std::io::{self, Write};
 883
 884                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 885                     let res = if handle == -11 {
 886                         io::stdout().write(buf_cont)
 887                     } else {
 888                         io::stderr().write(buf_cont)
 889                     };
 890                     res.ok().map(|n| n as u32)
 891                 } else {
 892                     eprintln!("Miri: Ignored output to handle {}", handle);
 893                     // Pretend it all went well.
 894                     Some(n)
 895                 };
 896                 // If there was no error, write back how much was written.
 897                 if let Some(n) = written {
 898                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 899                 }
 900                 // Return whether this was a success.
 901                 this.write_scalar(
 902                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 903                     dest,
 904                 )?;
 905             }
 906             "GetConsoleMode" => {
 907                 // Everything is a pipe.
 908                 this.write_null(dest)?;
 909             }
 910             "GetEnvironmentVariableW" => {
 911                 // This is not the env var you are looking for.
 912                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 913                 this.write_null(dest)?;
 914             }
 915             "GetCommandLineW" => {
 916                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 917             }
 918             // The actual name of 'RtlGenRandom'
 919             "SystemFunction036" => {
 920                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 921                 let len = this.read_scalar(args[1])?.to_u32()?;
 922                 this.gen_random(ptr, len as usize)?;
 923                 this.write_scalar(Scalar::from_bool(true), dest)?;
 924             }
 925
 926             // We can't execute anything else.
 927             _ => {
 928                 throw_unsup_format!("can't call foreign function: {}", link_name)
 929             }
 930         }
 931
 932         this.goto_block(Some(ret))?;
 933         this.dump_place(*dest);
 934         Ok(())
 935     }
 936
 937     /// Evaluates the scalar at the specified path. Returns Some(val)
 938     /// if the path could be resolved, and None otherwise
 939     fn eval_path_scalar(&mut self, path: &[&str]) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 940         let this = self.eval_context_mut();
 941         if let Ok(instance) = this.resolve_path(path) {
 942             let cid = GlobalId {
 943                 instance,
 944                 promoted: None,
 945             };
 946             let const_val = this.const_eval_raw(cid)?;
 947             let const_val = this.read_scalar(const_val.into())?;
 948             return Ok(Some(const_val));
 949         }
 950         return Ok(None);
 951     }
 952 }
 953
 954 // Shims the linux 'getrandom()' syscall.
 955 fn linux_getrandom<'tcx>(
 956     this: &mut MiriEvalContext<'_, 'tcx>,
 957     args: &[OpTy<'tcx, Tag>],
 958     dest: PlaceTy<'tcx, Tag>,
 959 ) -> InterpResult<'tcx> {
 960     let ptr = this.read_scalar(args[0])?.not_undef()?;
 961     let len = this.read_scalar(args[1])?.to_usize(this)?;
 962
 963     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 964     // neither of which have any effect on our current PRNG.
 965     let _flags = this.read_scalar(args[2])?.to_i32()?;
 966
 967     this.gen_random(ptr, len as usize)?;
 968     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 969     Ok(())
 970 }