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
   9 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  10 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  11     /// Returns the minimum alignment for the target architecture for allocations of the given size.
  12     fn min_align(&self, size: u64, kind: MiriMemoryKind) -> Align {
  13         let this = self.eval_context_ref();
  14         // List taken from `libstd/sys_common/alloc.rs`.
  15         let min_align = match this.tcx.tcx.sess.target.target.arch.as_str() {
  16             "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
  17             "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" => 16,
  18             arch => bug!("Unsupported target architecture: {}", arch),
  19         };
  20         // Windows always aligns, even small allocations.
  21         // Source: <https://support.microsoft.com/en-us/help/286470/how-to-use-pageheap-exe-in-windows-xp-windows-2000-and-windows-server>
  22         // But jemalloc does not, so for the C heap we only align if the allocation is sufficiently big.
  23         if kind == MiriMemoryKind::WinHeap || size >= min_align {
  24             return Align::from_bytes(min_align).unwrap();
  25         }
  26         // We have `size < min_align`. Round `size` *down* to the next power of two and use that.
  27         fn prev_power_of_two(x: u64) -> u64 {
  28             let next_pow2 = x.next_power_of_two();
  29             if next_pow2 == x {
  30                 // x *is* a power of two, just use that.
  31                 x
  32             } else {
  33                 // x is between two powers, so next = 2*prev.
  34                 next_pow2 / 2
  35             }
  36         }
  37         Align::from_bytes(prev_power_of_two(size)).unwrap()
  38     }
  39
  40     fn malloc(
  41         &mut self,
  42         size: u64,
  43         zero_init: bool,
  44         kind: MiriMemoryKind,
  45     ) -> Scalar<Tag> {
  46         let this = self.eval_context_mut();
  47         let tcx = &{this.tcx.tcx};
  48         if size == 0 {
  49             Scalar::from_int(0, this.pointer_size())
  50         } else {
  51             let align = this.min_align(size, kind);
  52             let ptr = this.memory_mut().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).unwrap()
  57                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
  58             }
  59             Scalar::Ptr(ptr)
  60         }
  61     }
  62
  63     fn free(
  64         &mut self,
  65         ptr: Scalar<Tag>,
  66         kind: MiriMemoryKind,
  67     ) -> InterpResult<'tcx> {
  68         let this = self.eval_context_mut();
  69         if !this.is_null(ptr)? {
  70             let ptr = this.force_ptr(ptr)?;
  71             this.memory_mut().deallocate(
  72                 ptr,
  73                 None,
  74                 kind.into(),
  75             )?;
  76         }
  77         Ok(())
  78     }
  79
  80     fn realloc(
  81         &mut self,
  82         old_ptr: Scalar<Tag>,
  83         new_size: u64,
  84         kind: MiriMemoryKind,
  85     ) -> InterpResult<'tcx, Scalar<Tag>> {
  86         let this = self.eval_context_mut();
  87         let new_align = this.min_align(new_size, kind);
  88         if this.is_null(old_ptr)? {
  89             if new_size == 0 {
  90                 Ok(Scalar::from_int(0, this.pointer_size()))
  91             } else {
  92                 let new_ptr = this.memory_mut().allocate(
  93                     Size::from_bytes(new_size),
  94                     new_align,
  95                     kind.into()
  96                 );
  97                 Ok(Scalar::Ptr(new_ptr))
  98             }
  99         } else {
 100             let old_ptr = this.force_ptr(old_ptr)?;
 101             let memory = this.memory_mut();
 102             if new_size == 0 {
 103                 memory.deallocate(
 104                     old_ptr,
 105                     None,
 106                     kind.into(),
 107                 )?;
 108                 Ok(Scalar::from_int(0, this.pointer_size()))
 109             } else {
 110                 let new_ptr = memory.reallocate(
 111                     old_ptr,
 112                     None,
 113                     Size::from_bytes(new_size),
 114                     new_align,
 115                     kind.into(),
 116                 )?;
 117                 Ok(Scalar::Ptr(new_ptr))
 118             }
 119         }
 120     }
 121
 122     /// Emulates calling a foreign item, failing if the item is not supported.
 123     /// This function will handle `goto_block` if needed.
 124     fn emulate_foreign_item(
 125         &mut self,
 126         def_id: DefId,
 127         args: &[OpTy<'tcx, Tag>],
 128         dest: Option<PlaceTy<'tcx, Tag>>,
 129         ret: Option<mir::BasicBlock>,
 130     ) -> InterpResult<'tcx> {
 131         let this = self.eval_context_mut();
 132         let attrs = this.tcx.get_attrs(def_id);
 133         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 134             Some(name) => name.as_str(),
 135             None => this.tcx.item_name(def_id).as_str(),
 136         };
 137         // Strip linker suffixes (seen on 32-bit macOS).
 138         let link_name = link_name.get().trim_end_matches("$UNIX2003");
 139         let tcx = &{this.tcx.tcx};
 140
 141         // First: functions that diverge.
 142         match link_name {
 143             "__rust_start_panic" | "panic_impl" => {
 144                 throw_unsup_format!("the evaluated program panicked");
 145             }
 146             "exit" | "ExitProcess" => {
 147                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` error variant anyway
 148                 let code = this.read_scalar(args[0])?.to_i32()?;
 149                 return Err(InterpError::Exit(code).into());
 150             }
 151             _ => if dest.is_none() {
 152                 throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
 153             }
 154         }
 155
 156         // Next: functions that assume a ret and dest.
 157         let dest = dest.expect("we already checked for a dest");
 158         let ret = ret.expect("dest is `Some` but ret is `None`");
 159         match link_name {
 160             "malloc" => {
 161                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 162                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 163                 this.write_scalar(res, dest)?;
 164             }
 165             "calloc" => {
 166                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 167                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 168                 let size = items.checked_mul(len).ok_or_else(|| err_panic!(Overflow(mir::BinOp::Mul)))?;
 169                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 170                 this.write_scalar(res, dest)?;
 171             }
 172             "posix_memalign" => {
 173                 let ret = this.deref_operand(args[0])?;
 174                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 175                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 176                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 177                 if !align.is_power_of_two() {
 178                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 179                 }
 180                 /*
 181                 FIXME: This check is disabled because rustc violates it.
 182                 See <https://github.com/rust-lang/rust/issues/62251>.
 183                 if align < this.pointer_size().bytes() {
 184                     throw_ub_format!(
 185                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 186                         align,
 187                     );
 188                 }
 189                 */
 190                 if size == 0 {
 191                     this.write_null(ret.into())?;
 192                 } else {
 193                     let ptr = this.memory_mut().allocate(
 194                         Size::from_bytes(size),
 195                         Align::from_bytes(align).unwrap(),
 196                         MiriMemoryKind::C.into()
 197                     );
 198                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 199                 }
 200                 this.write_null(dest)?;
 201             }
 202             "free" => {
 203                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 204                 this.free(ptr, MiriMemoryKind::C)?;
 205             }
 206             "realloc" => {
 207                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 208                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 209                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 210                 this.write_scalar(res, dest)?;
 211             }
 212
 213             "__rust_alloc" => {
 214                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 215                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 216                 if size == 0 {
 217                     throw_unsup!(HeapAllocZeroBytes);
 218                 }
 219                 if !align.is_power_of_two() {
 220                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 221                 }
 222                 let ptr = this.memory_mut()
 223                     .allocate(
 224                         Size::from_bytes(size),
 225                         Align::from_bytes(align).unwrap(),
 226                         MiriMemoryKind::Rust.into()
 227                     );
 228                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 229             }
 230             "__rust_alloc_zeroed" => {
 231                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 232                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 233                 if size == 0 {
 234                     throw_unsup!(HeapAllocZeroBytes);
 235                 }
 236                 if !align.is_power_of_two() {
 237                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 238                 }
 239                 let ptr = this.memory_mut()
 240                     .allocate(
 241                         Size::from_bytes(size),
 242                         Align::from_bytes(align).unwrap(),
 243                         MiriMemoryKind::Rust.into()
 244                     );
 245                 // We just allocated this, the access cannot fail
 246                 this.memory_mut()
 247                     .get_mut(ptr.alloc_id).unwrap()
 248                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
 249                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 250             }
 251             "__rust_dealloc" => {
 252                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 253                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 254                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 255                 if old_size == 0 {
 256                     throw_unsup!(HeapAllocZeroBytes);
 257                 }
 258                 if !align.is_power_of_two() {
 259                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 260                 }
 261                 let ptr = this.force_ptr(ptr)?;
 262                 this.memory_mut().deallocate(
 263                     ptr,
 264                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 265                     MiriMemoryKind::Rust.into(),
 266                 )?;
 267             }
 268             "__rust_realloc" => {
 269                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 270                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 271                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 272                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 273                 if old_size == 0 || new_size == 0 {
 274                     throw_unsup!(HeapAllocZeroBytes);
 275                 }
 276                 if !align.is_power_of_two() {
 277                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 278                 }
 279                 let align = Align::from_bytes(align).unwrap();
 280                 let new_ptr = this.memory_mut().reallocate(
 281                     ptr,
 282                     Some((Size::from_bytes(old_size), align)),
 283                     Size::from_bytes(new_size),
 284                     align,
 285                     MiriMemoryKind::Rust.into(),
 286                 )?;
 287                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 288             }
 289
 290             "syscall" => {
 291                 let sys_getrandom = this.eval_path_scalar(&["libc", "SYS_getrandom"])?
 292                     .expect("Failed to get libc::SYS_getrandom")
 293                     .to_usize(this)?;
 294
 295                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 296                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 297                 match this.read_scalar(args[0])?.to_usize(this)? {
 298                     id if id == sys_getrandom => {
 299                         let ptr = this.read_scalar(args[1])?.not_undef()?;
 300                         let len = this.read_scalar(args[2])?.to_usize(this)?;
 301
 302                         // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 303                         // neither of which have any effect on our current PRNG
 304                         let _flags = this.read_scalar(args[3])?.to_i32()?;
 305
 306                         this.gen_random(len as usize, ptr)?;
 307                         this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 308                     }
 309                     id => {
 310                         throw_unsup_format!("miri does not support syscall ID {}", id)
 311                     }
 312                 }
 313             }
 314
 315             "dlsym" => {
 316                 let _handle = this.read_scalar(args[0])?;
 317                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 318                 let symbol_name = this.memory().read_c_str(symbol)?;
 319                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 320                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 321                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 322                     let ptr = this.memory_mut().create_fn_alloc(FnVal::Other(dlsym));
 323                     this.write_scalar(Scalar::from(ptr), dest)?;
 324                 } else {
 325                     this.write_null(dest)?;
 326                 }
 327             }
 328
 329             "__rust_maybe_catch_panic" => {
 330                 // fn __rust_maybe_catch_panic(
 331                 //     f: fn(*mut u8),
 332                 //     data: *mut u8,
 333                 //     data_ptr: *mut usize,
 334                 //     vtable_ptr: *mut usize,
 335                 // ) -> u32
 336                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 337                 let f = this.read_scalar(args[0])?.not_undef()?;
 338                 let data = this.read_scalar(args[1])?.not_undef()?;
 339                 let f_instance = this.memory().get_fn(f)?.as_instance()?;
 340                 this.write_null(dest)?;
 341                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 342
 343                 // Now we make a function call.
 344                 // TODO: consider making this reusable? `InterpCx::step` does something similar
 345                 // for the TLS destructors, and of course `eval_main`.
 346                 let mir = this.load_mir(f_instance.def)?;
 347                 let ret_place = MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 348                 this.push_stack_frame(
 349                     f_instance,
 350                     mir.span,
 351                     mir,
 352                     Some(ret_place),
 353                     // Directly return to caller.
 354                     StackPopCleanup::Goto(Some(ret)),
 355                 )?;
 356                 let mut args = this.frame().body.args_iter();
 357
 358                 let arg_local = args.next()
 359                     .expect("Argument to __rust_maybe_catch_panic does not take enough arguments.");
 360                 let arg_dest = this.local_place(arg_local)?;
 361                 this.write_scalar(data, arg_dest)?;
 362
 363                 assert!(args.next().is_none(), "__rust_maybe_catch_panic argument has more arguments than expected");
 364
 365                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 366                 this.write_null(dest)?;
 367
 368                 // Don't fall through, we do *not* want to `goto_block`!
 369                 return Ok(());
 370             }
 371
 372             "memcmp" => {
 373                 let left = this.read_scalar(args[0])?.not_undef()?;
 374                 let right = this.read_scalar(args[1])?.not_undef()?;
 375                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 376
 377                 let result = {
 378                     let left_bytes = this.memory().read_bytes(left, n)?;
 379                     let right_bytes = this.memory().read_bytes(right, n)?;
 380
 381                     use std::cmp::Ordering::*;
 382                     match left_bytes.cmp(right_bytes) {
 383                         Less => -1i32,
 384                         Equal => 0,
 385                         Greater => 1,
 386                     }
 387                 };
 388
 389                 this.write_scalar(
 390                     Scalar::from_int(result, Size::from_bits(32)),
 391                     dest,
 392                 )?;
 393             }
 394
 395             "memrchr" => {
 396                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 397                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 398                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 399                 if let Some(idx) = this.memory().read_bytes(ptr, Size::from_bytes(num))?
 400                     .iter().rev().position(|&c| c == val)
 401                 {
 402                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 403                     this.write_scalar(new_ptr, dest)?;
 404                 } else {
 405                     this.write_null(dest)?;
 406                 }
 407             }
 408
 409             "memchr" => {
 410                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 411                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 412                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 413                 let idx = this
 414                     .memory()
 415                     .read_bytes(ptr, Size::from_bytes(num))?
 416                     .iter()
 417                     .position(|&c| c == val);
 418                 if let Some(idx) = idx {
 419                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 420                     this.write_scalar(new_ptr, dest)?;
 421                 } else {
 422                     this.write_null(dest)?;
 423                 }
 424             }
 425
 426             "getenv" => {
 427                 let result = {
 428                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 429                     let name = this.memory().read_c_str(name_ptr)?;
 430                     match this.machine.env_vars.get(name) {
 431                         Some(&var) => Scalar::Ptr(var),
 432                         None => Scalar::ptr_null(&*this.tcx),
 433                     }
 434                 };
 435                 this.write_scalar(result, dest)?;
 436             }
 437
 438             "unsetenv" => {
 439                 let mut success = None;
 440                 {
 441                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 442                     if !this.is_null(name_ptr)? {
 443                         let name = this.memory().read_c_str(name_ptr)?.to_owned();
 444                         if !name.is_empty() && !name.contains(&b'=') {
 445                             success = Some(this.machine.env_vars.remove(&name));
 446                         }
 447                     }
 448                 }
 449                 if let Some(old) = success {
 450                     if let Some(var) = old {
 451                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 452                     }
 453                     this.write_null(dest)?;
 454                 } else {
 455                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 456                 }
 457             }
 458
 459             "setenv" => {
 460                 let mut new = None;
 461                 {
 462                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 463                     let value_ptr = this.read_scalar(args[1])?.not_undef()?;
 464                     let value = this.memory().read_c_str(value_ptr)?;
 465                     if !this.is_null(name_ptr)? {
 466                         let name = this.memory().read_c_str(name_ptr)?;
 467                         if !name.is_empty() && !name.contains(&b'=') {
 468                             new = Some((name.to_owned(), value.to_owned()));
 469                         }
 470                     }
 471                 }
 472                 if let Some((name, value)) = new {
 473                     // `+1` for the null terminator.
 474                     let value_copy = this.memory_mut().allocate(
 475                         Size::from_bytes((value.len() + 1) as u64),
 476                         Align::from_bytes(1).unwrap(),
 477                         MiriMemoryKind::Env.into(),
 478                     );
 479                     // We just allocated these, so the write cannot fail.
 480                     let alloc = this.memory_mut().get_mut(value_copy.alloc_id).unwrap();
 481                     alloc.write_bytes(tcx, value_copy, &value).unwrap();
 482                     let trailing_zero_ptr = value_copy.offset(
 483                         Size::from_bytes(value.len() as u64),
 484                         tcx,
 485                     ).unwrap();
 486                     alloc.write_bytes(tcx, trailing_zero_ptr, &[0]).unwrap();
 487
 488                     if let Some(var) = this.machine.env_vars.insert(
 489                         name.to_owned(),
 490                         value_copy,
 491                     )
 492                     {
 493                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 494                     }
 495                     this.write_null(dest)?;
 496                 } else {
 497                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 498                 }
 499             }
 500
 501             "write" => {
 502                 let fd = this.read_scalar(args[0])?.to_i32()?;
 503                 let buf = this.read_scalar(args[1])?.not_undef()?;
 504                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 505                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 506                 let result = if fd == 1 || fd == 2 {
 507                     // stdout/stderr
 508                     use std::io::{self, Write};
 509
 510                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 511                     // We need to flush to make sure this actually appears on the screen
 512                     let res = if fd == 1 {
 513                         // Stdout is buffered, flush to make sure it appears on the screen.
 514                         // This is the write() syscall of the interpreted program, we want it
 515                         // to correspond to a write() syscall on the host -- there is no good
 516                         // in adding extra buffering here.
 517                         let res = io::stdout().write(buf_cont);
 518                         io::stdout().flush().unwrap();
 519                         res
 520                     } else {
 521                         // No need to flush, stderr is not buffered.
 522                         io::stderr().write(buf_cont)
 523                     };
 524                     match res {
 525                         Ok(n) => n as i64,
 526                         Err(_) => -1,
 527                     }
 528                 } else {
 529                     eprintln!("Miri: Ignored output to FD {}", fd);
 530                     // Pretend it all went well.
 531                     n as i64
 532                 };
 533                 // Now, `result` is the value we return back to the program.
 534                 this.write_scalar(
 535                     Scalar::from_int(result, dest.layout.size),
 536                     dest,
 537                 )?;
 538             }
 539
 540             "strlen" => {
 541                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 542                 let n = this.memory().read_c_str(ptr)?.len();
 543                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 544             }
 545
 546             // math functions
 547
 548             "cbrtf" | "coshf" | "sinhf" |"tanf" => {
 549                 // FIXME: Using host floats.
 550                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 551                 let f = match link_name {
 552                     "cbrtf" => f.cbrt(),
 553                     "coshf" => f.cosh(),
 554                     "sinhf" => f.sinh(),
 555                     "tanf" => f.tan(),
 556                     _ => bug!(),
 557                 };
 558                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 559             }
 560             // underscore case for windows
 561             "_hypotf" | "hypotf" | "atan2f" => {
 562                 // FIXME: Using host floats.
 563                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 564                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 565                 let n = match link_name {
 566                     "_hypotf" | "hypotf" => f1.hypot(f2),
 567                     "atan2f" => f1.atan2(f2),
 568                     _ => bug!(),
 569                 };
 570                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 571             }
 572
 573             "cbrt" | "cosh" | "sinh" | "tan" => {
 574                 // FIXME: Using host floats.
 575                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 576                 let f = match link_name {
 577                     "cbrt" => f.cbrt(),
 578                     "cosh" => f.cosh(),
 579                     "sinh" => f.sinh(),
 580                     "tan" => f.tan(),
 581                     _ => bug!(),
 582                 };
 583                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 584             }
 585             // underscore case for windows
 586             "_hypot" | "hypot" | "atan2" => {
 587                 // FIXME: Using host floats.
 588                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 589                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 590                 let n = match link_name {
 591                     "_hypot" | "hypot" => f1.hypot(f2),
 592                     "atan2" => f1.atan2(f2),
 593                     _ => bug!(),
 594                 };
 595                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 596             }
 597
 598             // Some things needed for `sys::thread` initialization to go through.
 599             "signal" | "sigaction" | "sigaltstack" => {
 600                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 601             }
 602
 603             "sysconf" => {
 604                 let name = this.read_scalar(args[0])?.to_i32()?;
 605
 606                 trace!("sysconf() called with name {}", name);
 607                 // TODO: Cache the sysconf integers via Miri's global cache.
 608                 let paths = &[
 609                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(PAGE_SIZE, dest.layout.size)),
 610                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 611                     (&["libc", "_SC_NPROCESSORS_ONLN"], Scalar::from_int(NUM_CPUS, dest.layout.size)),
 612                 ];
 613                 let mut result = None;
 614                 for &(path, path_value) in paths {
 615                     if let Some(val) = this.eval_path_scalar(path)? {
 616                         let val = val.to_i32()?;
 617                         if val == name {
 618                             result = Some(path_value);
 619                             break;
 620                         }
 621
 622                     }
 623                 }
 624                 if let Some(result) = result {
 625                     this.write_scalar(result, dest)?;
 626                 } else {
 627                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 628                 }
 629             }
 630
 631             "sched_getaffinity" => {
 632                 // Return an error; `num_cpus` then falls back to `sysconf`.
 633                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 634             }
 635
 636             "isatty" => {
 637                 this.write_null(dest)?;
 638             }
 639
 640             // Hook pthread calls that go to the thread-local storage memory subsystem.
 641             "pthread_key_create" => {
 642                 let key_ptr = this.read_scalar(args[0])?.not_undef()?;
 643
 644                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 645                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 646                     Some(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?.as_instance()?),
 647                     None => None,
 648                 };
 649
 650                 // Figure out how large a pthread TLS key actually is.
 651                 // This is `libc::pthread_key_t`.
 652                 let key_type = args[0].layout.ty
 653                     .builtin_deref(true)
 654                     .ok_or_else(|| err_ub!(Ub(format!(
 655                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 656                     ))))?
 657                     .ty;
 658                 let key_layout = this.layout_of(key_type)?;
 659
 660                 // Create key and write it into the memory where `key_ptr` wants it.
 661                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 662                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128) {
 663                     throw_unsup!(OutOfTls);
 664                 }
 665
 666                 let key_ptr = this.memory().check_ptr_access(key_ptr, key_layout.size, key_layout.align.abi)?
 667                     .expect("cannot be a ZST");
 668                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 669                     tcx,
 670                     key_ptr,
 671                     Scalar::from_uint(key, key_layout.size).into(),
 672                     key_layout.size,
 673                 )?;
 674
 675                 // Return success (`0`).
 676                 this.write_null(dest)?;
 677             }
 678             "pthread_key_delete" => {
 679                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 680                 this.machine.tls.delete_tls_key(key)?;
 681                 // Return success (0)
 682                 this.write_null(dest)?;
 683             }
 684             "pthread_getspecific" => {
 685                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 686                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 687                 this.write_scalar(ptr, dest)?;
 688             }
 689             "pthread_setspecific" => {
 690                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 691                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 692                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 693
 694                 // Return success (`0`).
 695                 this.write_null(dest)?;
 696             }
 697
 698             // Stack size/address stuff.
 699             "pthread_attr_init" | "pthread_attr_destroy" | "pthread_self" |
 700             "pthread_attr_setstacksize" => {
 701                 this.write_null(dest)?;
 702             }
 703             "pthread_attr_getstack" => {
 704                 let addr_place = this.deref_operand(args[1])?;
 705                 let size_place = this.deref_operand(args[2])?;
 706
 707                 this.write_scalar(
 708                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 709                     addr_place.into(),
 710                 )?;
 711                 this.write_scalar(
 712                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 713                     size_place.into(),
 714                 )?;
 715
 716                 // Return success (`0`).
 717                 this.write_null(dest)?;
 718             }
 719
 720             // We don't support threading. (Also for Windows.)
 721             "pthread_create" | "CreateThread" => {
 722                 throw_unsup_format!("Miri does not support threading");
 723             }
 724
 725             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 726             "pthread_mutexattr_init" | "pthread_mutexattr_settype" | "pthread_mutex_init" |
 727             "pthread_mutexattr_destroy" | "pthread_mutex_lock" | "pthread_mutex_unlock" |
 728             "pthread_mutex_destroy" | "pthread_rwlock_rdlock" | "pthread_rwlock_unlock" |
 729             "pthread_rwlock_wrlock" | "pthread_rwlock_destroy" | "pthread_condattr_init" |
 730             "pthread_condattr_setclock" | "pthread_cond_init" | "pthread_condattr_destroy" |
 731             "pthread_cond_destroy" => {
 732                 this.write_null(dest)?;
 733             }
 734
 735             // We don't support fork so we don't have to do anything for atfork.
 736             "pthread_atfork" => {
 737                 this.write_null(dest)?;
 738             }
 739
 740             "mmap" => {
 741                 // 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.
 742                 let addr = this.read_scalar(args[0])?.not_undef()?;
 743                 this.write_scalar(addr, dest)?;
 744             }
 745             "mprotect" => {
 746                 this.write_null(dest)?;
 747             }
 748
 749             // macOS API stubs.
 750             "pthread_attr_get_np" | "pthread_getattr_np" => {
 751                 this.write_null(dest)?;
 752             }
 753             "pthread_get_stackaddr_np" => {
 754                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 755                 this.write_scalar(stack_addr, dest)?;
 756             }
 757             "pthread_get_stacksize_np" => {
 758                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 759                 this.write_scalar(stack_size, dest)?;
 760             }
 761             "_tlv_atexit" => {
 762                 // FIXME: register the destructor.
 763             },
 764             "_NSGetArgc" => {
 765                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 766             },
 767             "_NSGetArgv" => {
 768                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 769             },
 770             "SecRandomCopyBytes" => {
 771                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 772                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 773                 this.gen_random(len as usize, ptr)?;
 774                 this.write_null(dest)?;
 775             }
 776
 777             // Windows API stubs.
 778             // HANDLE = isize
 779             // DWORD = ULONG = u32
 780             // BOOL = i32
 781             "GetProcessHeap" => {
 782                 // Just fake a HANDLE
 783                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 784             }
 785             "HeapAlloc" => {
 786                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 787                 let flags = this.read_scalar(args[1])?.to_u32()?;
 788                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 789                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 790                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 791                 this.write_scalar(res, dest)?;
 792             }
 793             "HeapFree" => {
 794                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 795                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 796                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 797                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 798                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 799             }
 800             "HeapReAlloc" => {
 801                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 802                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 803                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 804                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 805                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 806                 this.write_scalar(res, dest)?;
 807             }
 808
 809             "SetLastError" => {
 810                 let err = this.read_scalar(args[0])?.to_u32()?;
 811                 this.machine.last_error = err;
 812             }
 813             "GetLastError" => {
 814                 this.write_scalar(Scalar::from_u32(this.machine.last_error), dest)?;
 815             }
 816
 817             "AddVectoredExceptionHandler" => {
 818                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 819                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 820             },
 821             "InitializeCriticalSection" |
 822             "EnterCriticalSection" |
 823             "LeaveCriticalSection" |
 824             "DeleteCriticalSection" => {
 825                 // Nothing to do, not even a return value.
 826             },
 827             "GetModuleHandleW" |
 828             "GetProcAddress" |
 829             "TryEnterCriticalSection" |
 830             "GetConsoleScreenBufferInfo" |
 831             "SetConsoleTextAttribute" => {
 832                 // Pretend these do not exist / nothing happened, by returning zero.
 833                 this.write_null(dest)?;
 834             },
 835             "GetSystemInfo" => {
 836                 let system_info = this.deref_operand(args[0])?;
 837                 let system_info_ptr = this.check_mplace_access(system_info, None)?
 838                     .expect("cannot be a ZST");
 839                 // Initialize with `0`.
 840                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 841                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 842                 // Set number of processors.
 843                 let dword_size = Size::from_bytes(4);
 844                 let offset = 2*dword_size + 3*tcx.pointer_size();
 845                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 846                     .write_scalar(
 847                         tcx,
 848                         system_info_ptr.offset(offset, tcx)?,
 849                         Scalar::from_int(NUM_CPUS, dword_size).into(),
 850                         dword_size,
 851                     )?;
 852             }
 853
 854             "TlsAlloc" => {
 855                 // This just creates a key; Windows does not natively support TLS destructors.
 856
 857                 // Create key and return it.
 858                 let key = this.machine.tls.create_tls_key(None) as u128;
 859
 860                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 861                 if dest.layout.size.bits() < 128
 862                         && key >= (1u128 << dest.layout.size.bits() as u128) {
 863                     throw_unsup!(OutOfTls);
 864                 }
 865                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 866             }
 867             "TlsGetValue" => {
 868                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 869                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 870                 this.write_scalar(ptr, dest)?;
 871             }
 872             "TlsSetValue" => {
 873                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 874                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 875                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 876
 877                 // Return success (`1`).
 878                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 879             }
 880             "GetStdHandle" => {
 881                 let which = this.read_scalar(args[0])?.to_i32()?;
 882                 // We just make this the identity function, so we know later in `WriteFile`
 883                 // which one it is.
 884                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 885             }
 886             "WriteFile" => {
 887                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 888                 let buf = this.read_scalar(args[1])?.not_undef()?;
 889                 let n = this.read_scalar(args[2])?.to_u32()?;
 890                 let written_place = this.deref_operand(args[3])?;
 891                 // Spec says to always write `0` first.
 892                 this.write_null(written_place.into())?;
 893                 let written = if handle == -11 || handle == -12 {
 894                     // stdout/stderr
 895                     use std::io::{self, Write};
 896
 897                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 898                     let res = if handle == -11 {
 899                         io::stdout().write(buf_cont)
 900                     } else {
 901                         io::stderr().write(buf_cont)
 902                     };
 903                     res.ok().map(|n| n as u32)
 904                 } else {
 905                     eprintln!("Miri: Ignored output to handle {}", handle);
 906                     // Pretend it all went well.
 907                     Some(n)
 908                 };
 909                 // If there was no error, write back how much was written.
 910                 if let Some(n) = written {
 911                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 912                 }
 913                 // Return whether this was a success.
 914                 this.write_scalar(
 915                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 916                     dest,
 917                 )?;
 918             }
 919             "GetConsoleMode" => {
 920                 // Everything is a pipe.
 921                 this.write_null(dest)?;
 922             }
 923             "GetEnvironmentVariableW" => {
 924                 // This is not the env var you are looking for.
 925                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 926                 this.write_null(dest)?;
 927             }
 928             "GetCommandLineW" => {
 929                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 930             }
 931             // The actual name of 'RtlGenRandom'
 932             "SystemFunction036" => {
 933                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 934                 let len = this.read_scalar(args[1])?.to_u32()?;
 935                 this.gen_random(len as usize, ptr)?;
 936                 this.write_scalar(Scalar::from_bool(true), dest)?;
 937             }
 938
 939             // We can't execute anything else.
 940             _ => {
 941                 throw_unsup_format!("can't call foreign function: {}", link_name)
 942             }
 943         }
 944
 945         this.goto_block(Some(ret))?;
 946         this.dump_place(*dest);
 947         Ok(())
 948     }
 949
 950     /// Evaluates the scalar at the specified path. Returns Some(val)
 951     /// if the path could be resolved, and None otherwise
 952     fn eval_path_scalar(&mut self, path: &[&str]) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 953         let this = self.eval_context_mut();
 954         if let Ok(instance) = this.resolve_path(path) {
 955             let cid = GlobalId {
 956                 instance,
 957                 promoted: None,
 958             };
 959             let const_val = this.const_eval_raw(cid)?;
 960             let const_val = this.read_scalar(const_val.into())?;
 961             return Ok(Some(const_val));
 962         }
 963         return Ok(None);
 964     }
 965 }