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                 if align < this.pointer_size().bytes() {
 181                     throw_ub_format!(
 182                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 183                         align,
 184                     );
 185                 }
 186
 187                 if size == 0 {
 188                     this.write_null(ret.into())?;
 189                 } else {
 190                     let ptr = this.memory_mut().allocate(
 191                         Size::from_bytes(size),
 192                         Align::from_bytes(align).unwrap(),
 193                         MiriMemoryKind::C.into()
 194                     );
 195                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 196                 }
 197                 this.write_null(dest)?;
 198             }
 199             "free" => {
 200                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 201                 this.free(ptr, MiriMemoryKind::C)?;
 202             }
 203             "realloc" => {
 204                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 205                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 206                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 207                 this.write_scalar(res, dest)?;
 208             }
 209
 210             "__rust_alloc" => {
 211                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 212                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 213                 if size == 0 {
 214                     throw_unsup!(HeapAllocZeroBytes);
 215                 }
 216                 if !align.is_power_of_two() {
 217                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 218                 }
 219                 let ptr = this.memory_mut()
 220                     .allocate(
 221                         Size::from_bytes(size),
 222                         Align::from_bytes(align).unwrap(),
 223                         MiriMemoryKind::Rust.into()
 224                     );
 225                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 226             }
 227             "__rust_alloc_zeroed" => {
 228                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 229                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 230                 if size == 0 {
 231                     throw_unsup!(HeapAllocZeroBytes);
 232                 }
 233                 if !align.is_power_of_two() {
 234                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 235                 }
 236                 let ptr = this.memory_mut()
 237                     .allocate(
 238                         Size::from_bytes(size),
 239                         Align::from_bytes(align).unwrap(),
 240                         MiriMemoryKind::Rust.into()
 241                     );
 242                 // We just allocated this, the access cannot fail
 243                 this.memory_mut()
 244                     .get_mut(ptr.alloc_id).unwrap()
 245                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
 246                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 247             }
 248             "__rust_dealloc" => {
 249                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 250                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 251                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 252                 if old_size == 0 {
 253                     throw_unsup!(HeapAllocZeroBytes);
 254                 }
 255                 if !align.is_power_of_two() {
 256                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 257                 }
 258                 let ptr = this.force_ptr(ptr)?;
 259                 this.memory_mut().deallocate(
 260                     ptr,
 261                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 262                     MiriMemoryKind::Rust.into(),
 263                 )?;
 264             }
 265             "__rust_realloc" => {
 266                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 267                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 268                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 269                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 270                 if old_size == 0 || new_size == 0 {
 271                     throw_unsup!(HeapAllocZeroBytes);
 272                 }
 273                 if !align.is_power_of_two() {
 274                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 275                 }
 276                 let align = Align::from_bytes(align).unwrap();
 277                 let new_ptr = this.memory_mut().reallocate(
 278                     ptr,
 279                     Some((Size::from_bytes(old_size), align)),
 280                     Size::from_bytes(new_size),
 281                     align,
 282                     MiriMemoryKind::Rust.into(),
 283                 )?;
 284                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 285             }
 286
 287             "syscall" => {
 288                 let sys_getrandom = this.eval_path_scalar(&["libc", "SYS_getrandom"])?
 289                     .expect("Failed to get libc::SYS_getrandom")
 290                     .to_usize(this)?;
 291
 292                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 293                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 294                 match this.read_scalar(args[0])?.to_usize(this)? {
 295                     id if id == sys_getrandom => {
 296                         // The first argument is the syscall id,
 297                         // so skip over it.
 298                         linux_getrandom(this, &args[1..], dest)?;
 299                     }
 300                     id => {
 301                         throw_unsup_format!("miri does not support syscall ID {}", id)
 302                     }
 303                 }
 304             }
 305
 306             "getrandom" => {
 307                 linux_getrandom(this, args, dest)?;
 308             }
 309
 310             "dlsym" => {
 311                 let _handle = this.read_scalar(args[0])?;
 312                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 313                 let symbol_name = this.memory().read_c_str(symbol)?;
 314                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 315                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 316                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 317                     let ptr = this.memory_mut().create_fn_alloc(FnVal::Other(dlsym));
 318                     this.write_scalar(Scalar::from(ptr), dest)?;
 319                 } else {
 320                     this.write_null(dest)?;
 321                 }
 322             }
 323
 324             "__rust_maybe_catch_panic" => {
 325                 // fn __rust_maybe_catch_panic(
 326                 //     f: fn(*mut u8),
 327                 //     data: *mut u8,
 328                 //     data_ptr: *mut usize,
 329                 //     vtable_ptr: *mut usize,
 330                 // ) -> u32
 331                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 332                 let f = this.read_scalar(args[0])?.not_undef()?;
 333                 let data = this.read_scalar(args[1])?.not_undef()?;
 334                 let f_instance = this.memory().get_fn(f)?.as_instance()?;
 335                 this.write_null(dest)?;
 336                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 337
 338                 // Now we make a function call.
 339                 // TODO: consider making this reusable? `InterpCx::step` does something similar
 340                 // for the TLS destructors, and of course `eval_main`.
 341                 let mir = this.load_mir(f_instance.def)?;
 342                 let ret_place = MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 343                 this.push_stack_frame(
 344                     f_instance,
 345                     mir.span,
 346                     mir,
 347                     Some(ret_place),
 348                     // Directly return to caller.
 349                     StackPopCleanup::Goto(Some(ret)),
 350                 )?;
 351                 let mut args = this.frame().body.args_iter();
 352
 353                 let arg_local = args.next()
 354                     .expect("Argument to __rust_maybe_catch_panic does not take enough arguments.");
 355                 let arg_dest = this.local_place(arg_local)?;
 356                 this.write_scalar(data, arg_dest)?;
 357
 358                 assert!(args.next().is_none(), "__rust_maybe_catch_panic argument has more arguments than expected");
 359
 360                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 361                 this.write_null(dest)?;
 362
 363                 // Don't fall through, we do *not* want to `goto_block`!
 364                 return Ok(());
 365             }
 366
 367             "memcmp" => {
 368                 let left = this.read_scalar(args[0])?.not_undef()?;
 369                 let right = this.read_scalar(args[1])?.not_undef()?;
 370                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 371
 372                 let result = {
 373                     let left_bytes = this.memory().read_bytes(left, n)?;
 374                     let right_bytes = this.memory().read_bytes(right, n)?;
 375
 376                     use std::cmp::Ordering::*;
 377                     match left_bytes.cmp(right_bytes) {
 378                         Less => -1i32,
 379                         Equal => 0,
 380                         Greater => 1,
 381                     }
 382                 };
 383
 384                 this.write_scalar(
 385                     Scalar::from_int(result, Size::from_bits(32)),
 386                     dest,
 387                 )?;
 388             }
 389
 390             "memrchr" => {
 391                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 392                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 393                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 394                 if let Some(idx) = this.memory().read_bytes(ptr, Size::from_bytes(num))?
 395                     .iter().rev().position(|&c| c == val)
 396                 {
 397                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 398                     this.write_scalar(new_ptr, dest)?;
 399                 } else {
 400                     this.write_null(dest)?;
 401                 }
 402             }
 403
 404             "memchr" => {
 405                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 406                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 407                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 408                 let idx = this
 409                     .memory()
 410                     .read_bytes(ptr, Size::from_bytes(num))?
 411                     .iter()
 412                     .position(|&c| c == val);
 413                 if let Some(idx) = idx {
 414                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 415                     this.write_scalar(new_ptr, dest)?;
 416                 } else {
 417                     this.write_null(dest)?;
 418                 }
 419             }
 420
 421             "getenv" => {
 422                 let result = {
 423                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 424                     let name = this.memory().read_c_str(name_ptr)?;
 425                     match this.machine.env_vars.get(name) {
 426                         Some(&var) => Scalar::Ptr(var),
 427                         None => Scalar::ptr_null(&*this.tcx),
 428                     }
 429                 };
 430                 this.write_scalar(result, dest)?;
 431             }
 432
 433             "unsetenv" => {
 434                 let mut success = None;
 435                 {
 436                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 437                     if !this.is_null(name_ptr)? {
 438                         let name = this.memory().read_c_str(name_ptr)?.to_owned();
 439                         if !name.is_empty() && !name.contains(&b'=') {
 440                             success = Some(this.machine.env_vars.remove(&name));
 441                         }
 442                     }
 443                 }
 444                 if let Some(old) = success {
 445                     if let Some(var) = old {
 446                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 447                     }
 448                     this.write_null(dest)?;
 449                 } else {
 450                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 451                 }
 452             }
 453
 454             "setenv" => {
 455                 let mut new = None;
 456                 {
 457                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 458                     let value_ptr = this.read_scalar(args[1])?.not_undef()?;
 459                     let value = this.memory().read_c_str(value_ptr)?;
 460                     if !this.is_null(name_ptr)? {
 461                         let name = this.memory().read_c_str(name_ptr)?;
 462                         if !name.is_empty() && !name.contains(&b'=') {
 463                             new = Some((name.to_owned(), value.to_owned()));
 464                         }
 465                     }
 466                 }
 467                 if let Some((name, value)) = new {
 468                     // `+1` for the null terminator.
 469                     let value_copy = this.memory_mut().allocate(
 470                         Size::from_bytes((value.len() + 1) as u64),
 471                         Align::from_bytes(1).unwrap(),
 472                         MiriMemoryKind::Env.into(),
 473                     );
 474                     // We just allocated these, so the write cannot fail.
 475                     let alloc = this.memory_mut().get_mut(value_copy.alloc_id).unwrap();
 476                     alloc.write_bytes(tcx, value_copy, &value).unwrap();
 477                     let trailing_zero_ptr = value_copy.offset(
 478                         Size::from_bytes(value.len() as u64),
 479                         tcx,
 480                     ).unwrap();
 481                     alloc.write_bytes(tcx, trailing_zero_ptr, &[0]).unwrap();
 482
 483                     if let Some(var) = this.machine.env_vars.insert(
 484                         name.to_owned(),
 485                         value_copy,
 486                     )
 487                     {
 488                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 489                     }
 490                     this.write_null(dest)?;
 491                 } else {
 492                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 493                 }
 494             }
 495
 496             "write" => {
 497                 let fd = this.read_scalar(args[0])?.to_i32()?;
 498                 let buf = this.read_scalar(args[1])?.not_undef()?;
 499                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 500                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 501                 let result = if fd == 1 || fd == 2 {
 502                     // stdout/stderr
 503                     use std::io::{self, Write};
 504
 505                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 506                     // We need to flush to make sure this actually appears on the screen
 507                     let res = if fd == 1 {
 508                         // Stdout is buffered, flush to make sure it appears on the screen.
 509                         // This is the write() syscall of the interpreted program, we want it
 510                         // to correspond to a write() syscall on the host -- there is no good
 511                         // in adding extra buffering here.
 512                         let res = io::stdout().write(buf_cont);
 513                         io::stdout().flush().unwrap();
 514                         res
 515                     } else {
 516                         // No need to flush, stderr is not buffered.
 517                         io::stderr().write(buf_cont)
 518                     };
 519                     match res {
 520                         Ok(n) => n as i64,
 521                         Err(_) => -1,
 522                     }
 523                 } else {
 524                     eprintln!("Miri: Ignored output to FD {}", fd);
 525                     // Pretend it all went well.
 526                     n as i64
 527                 };
 528                 // Now, `result` is the value we return back to the program.
 529                 this.write_scalar(
 530                     Scalar::from_int(result, dest.layout.size),
 531                     dest,
 532                 )?;
 533             }
 534
 535             "strlen" => {
 536                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 537                 let n = this.memory().read_c_str(ptr)?.len();
 538                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 539             }
 540
 541             // math functions
 542
 543             "cbrtf" | "coshf" | "sinhf" |"tanf" => {
 544                 // FIXME: Using host floats.
 545                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 546                 let f = match link_name {
 547                     "cbrtf" => f.cbrt(),
 548                     "coshf" => f.cosh(),
 549                     "sinhf" => f.sinh(),
 550                     "tanf" => f.tan(),
 551                     _ => bug!(),
 552                 };
 553                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 554             }
 555             // underscore case for windows
 556             "_hypotf" | "hypotf" | "atan2f" => {
 557                 // FIXME: Using host floats.
 558                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 559                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 560                 let n = match link_name {
 561                     "_hypotf" | "hypotf" => f1.hypot(f2),
 562                     "atan2f" => f1.atan2(f2),
 563                     _ => bug!(),
 564                 };
 565                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 566             }
 567
 568             "cbrt" | "cosh" | "sinh" | "tan" => {
 569                 // FIXME: Using host floats.
 570                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 571                 let f = match link_name {
 572                     "cbrt" => f.cbrt(),
 573                     "cosh" => f.cosh(),
 574                     "sinh" => f.sinh(),
 575                     "tan" => f.tan(),
 576                     _ => bug!(),
 577                 };
 578                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 579             }
 580             // underscore case for windows
 581             "_hypot" | "hypot" | "atan2" => {
 582                 // FIXME: Using host floats.
 583                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 584                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 585                 let n = match link_name {
 586                     "_hypot" | "hypot" => f1.hypot(f2),
 587                     "atan2" => f1.atan2(f2),
 588                     _ => bug!(),
 589                 };
 590                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 591             }
 592             // underscore case for windows
 593             "_ldexp" | "ldexp" => {
 594                 // FIXME: Using host floats.
 595                 let x = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 596                 let exp = this.read_scalar(args[1])?.to_i32()?;
 597                 // FIXME: We should use cmath if there are any imprecisions.
 598                 let n = x * 2.0f64.powi(exp);
 599                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 600             }
 601
 602             // Some things needed for `sys::thread` initialization to go through.
 603             "signal" | "sigaction" | "sigaltstack" => {
 604                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 605             }
 606
 607             "sysconf" => {
 608                 let name = this.read_scalar(args[0])?.to_i32()?;
 609
 610                 trace!("sysconf() called with name {}", name);
 611                 // TODO: Cache the sysconf integers via Miri's global cache.
 612                 let paths = &[
 613                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(PAGE_SIZE, dest.layout.size)),
 614                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 615                     (&["libc", "_SC_NPROCESSORS_ONLN"], Scalar::from_int(NUM_CPUS, dest.layout.size)),
 616                 ];
 617                 let mut result = None;
 618                 for &(path, path_value) in paths {
 619                     if let Some(val) = this.eval_path_scalar(path)? {
 620                         let val = val.to_i32()?;
 621                         if val == name {
 622                             result = Some(path_value);
 623                             break;
 624                         }
 625
 626                     }
 627                 }
 628                 if let Some(result) = result {
 629                     this.write_scalar(result, dest)?;
 630                 } else {
 631                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 632                 }
 633             }
 634
 635             "sched_getaffinity" => {
 636                 // Return an error; `num_cpus` then falls back to `sysconf`.
 637                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 638             }
 639
 640             "isatty" => {
 641                 this.write_null(dest)?;
 642             }
 643
 644             // Hook pthread calls that go to the thread-local storage memory subsystem.
 645             "pthread_key_create" => {
 646                 let key_ptr = this.read_scalar(args[0])?.not_undef()?;
 647
 648                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 649                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 650                     Some(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?.as_instance()?),
 651                     None => None,
 652                 };
 653
 654                 // Figure out how large a pthread TLS key actually is.
 655                 // This is `libc::pthread_key_t`.
 656                 let key_type = args[0].layout.ty
 657                     .builtin_deref(true)
 658                     .ok_or_else(|| err_ub_format!(
 659                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 660                     ))?
 661                     .ty;
 662                 let key_layout = this.layout_of(key_type)?;
 663
 664                 // Create key and write it into the memory where `key_ptr` wants it.
 665                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 666                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128) {
 667                     throw_unsup!(OutOfTls);
 668                 }
 669
 670                 let key_ptr = this.memory().check_ptr_access(key_ptr, key_layout.size, key_layout.align.abi)?
 671                     .expect("cannot be a ZST");
 672                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 673                     tcx,
 674                     key_ptr,
 675                     Scalar::from_uint(key, key_layout.size).into(),
 676                     key_layout.size,
 677                 )?;
 678
 679                 // Return success (`0`).
 680                 this.write_null(dest)?;
 681             }
 682             "pthread_key_delete" => {
 683                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 684                 this.machine.tls.delete_tls_key(key)?;
 685                 // Return success (0)
 686                 this.write_null(dest)?;
 687             }
 688             "pthread_getspecific" => {
 689                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 690                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 691                 this.write_scalar(ptr, dest)?;
 692             }
 693             "pthread_setspecific" => {
 694                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 695                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 696                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 697
 698                 // Return success (`0`).
 699                 this.write_null(dest)?;
 700             }
 701
 702             // Stack size/address stuff.
 703             "pthread_attr_init" | "pthread_attr_destroy" | "pthread_self" |
 704             "pthread_attr_setstacksize" => {
 705                 this.write_null(dest)?;
 706             }
 707             "pthread_attr_getstack" => {
 708                 let addr_place = this.deref_operand(args[1])?;
 709                 let size_place = this.deref_operand(args[2])?;
 710
 711                 this.write_scalar(
 712                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 713                     addr_place.into(),
 714                 )?;
 715                 this.write_scalar(
 716                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 717                     size_place.into(),
 718                 )?;
 719
 720                 // Return success (`0`).
 721                 this.write_null(dest)?;
 722             }
 723
 724             // We don't support threading. (Also for Windows.)
 725             "pthread_create" | "CreateThread" => {
 726                 throw_unsup_format!("Miri does not support threading");
 727             }
 728
 729             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 730             "pthread_mutexattr_init" | "pthread_mutexattr_settype" | "pthread_mutex_init" |
 731             "pthread_mutexattr_destroy" | "pthread_mutex_lock" | "pthread_mutex_unlock" |
 732             "pthread_mutex_destroy" | "pthread_rwlock_rdlock" | "pthread_rwlock_unlock" |
 733             "pthread_rwlock_wrlock" | "pthread_rwlock_destroy" | "pthread_condattr_init" |
 734             "pthread_condattr_setclock" | "pthread_cond_init" | "pthread_condattr_destroy" |
 735             "pthread_cond_destroy" => {
 736                 this.write_null(dest)?;
 737             }
 738
 739             // We don't support fork so we don't have to do anything for atfork.
 740             "pthread_atfork" => {
 741                 this.write_null(dest)?;
 742             }
 743
 744             "mmap" => {
 745                 // 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.
 746                 let addr = this.read_scalar(args[0])?.not_undef()?;
 747                 this.write_scalar(addr, dest)?;
 748             }
 749             "mprotect" => {
 750                 this.write_null(dest)?;
 751             }
 752
 753             // macOS API stubs.
 754             "pthread_attr_get_np" | "pthread_getattr_np" => {
 755                 this.write_null(dest)?;
 756             }
 757             "pthread_get_stackaddr_np" => {
 758                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 759                 this.write_scalar(stack_addr, dest)?;
 760             }
 761             "pthread_get_stacksize_np" => {
 762                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 763                 this.write_scalar(stack_size, dest)?;
 764             }
 765             "_tlv_atexit" => {
 766                 // FIXME: register the destructor.
 767             },
 768             "_NSGetArgc" => {
 769                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 770             },
 771             "_NSGetArgv" => {
 772                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 773             },
 774             "SecRandomCopyBytes" => {
 775                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 776                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 777                 this.gen_random(ptr, len as usize)?;
 778                 this.write_null(dest)?;
 779             }
 780
 781             // Windows API stubs.
 782             // HANDLE = isize
 783             // DWORD = ULONG = u32
 784             // BOOL = i32
 785             "GetProcessHeap" => {
 786                 // Just fake a HANDLE
 787                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 788             }
 789             "HeapAlloc" => {
 790                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 791                 let flags = this.read_scalar(args[1])?.to_u32()?;
 792                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 793                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 794                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 795                 this.write_scalar(res, dest)?;
 796             }
 797             "HeapFree" => {
 798                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 799                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 800                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 801                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 802                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 803             }
 804             "HeapReAlloc" => {
 805                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 806                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 807                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 808                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 809                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 810                 this.write_scalar(res, dest)?;
 811             }
 812
 813             "SetLastError" => {
 814                 let err = this.read_scalar(args[0])?.to_u32()?;
 815                 this.machine.last_error = err;
 816             }
 817             "GetLastError" => {
 818                 this.write_scalar(Scalar::from_u32(this.machine.last_error), dest)?;
 819             }
 820
 821             "AddVectoredExceptionHandler" => {
 822                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 823                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 824             },
 825             "InitializeCriticalSection" |
 826             "EnterCriticalSection" |
 827             "LeaveCriticalSection" |
 828             "DeleteCriticalSection" => {
 829                 // Nothing to do, not even a return value.
 830             },
 831             "GetModuleHandleW" |
 832             "GetProcAddress" |
 833             "TryEnterCriticalSection" |
 834             "GetConsoleScreenBufferInfo" |
 835             "SetConsoleTextAttribute" => {
 836                 // Pretend these do not exist / nothing happened, by returning zero.
 837                 this.write_null(dest)?;
 838             },
 839             "GetSystemInfo" => {
 840                 let system_info = this.deref_operand(args[0])?;
 841                 let system_info_ptr = this.check_mplace_access(system_info, None)?
 842                     .expect("cannot be a ZST");
 843                 // Initialize with `0`.
 844                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 845                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 846                 // Set number of processors.
 847                 let dword_size = Size::from_bytes(4);
 848                 let offset = 2*dword_size + 3*tcx.pointer_size();
 849                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 850                     .write_scalar(
 851                         tcx,
 852                         system_info_ptr.offset(offset, tcx)?,
 853                         Scalar::from_int(NUM_CPUS, dword_size).into(),
 854                         dword_size,
 855                     )?;
 856             }
 857
 858             "TlsAlloc" => {
 859                 // This just creates a key; Windows does not natively support TLS destructors.
 860
 861                 // Create key and return it.
 862                 let key = this.machine.tls.create_tls_key(None) as u128;
 863
 864                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 865                 if dest.layout.size.bits() < 128
 866                         && key >= (1u128 << dest.layout.size.bits() as u128) {
 867                     throw_unsup!(OutOfTls);
 868                 }
 869                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 870             }
 871             "TlsGetValue" => {
 872                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 873                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 874                 this.write_scalar(ptr, dest)?;
 875             }
 876             "TlsSetValue" => {
 877                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 878                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 879                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 880
 881                 // Return success (`1`).
 882                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 883             }
 884             "GetStdHandle" => {
 885                 let which = this.read_scalar(args[0])?.to_i32()?;
 886                 // We just make this the identity function, so we know later in `WriteFile`
 887                 // which one it is.
 888                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 889             }
 890             "WriteFile" => {
 891                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 892                 let buf = this.read_scalar(args[1])?.not_undef()?;
 893                 let n = this.read_scalar(args[2])?.to_u32()?;
 894                 let written_place = this.deref_operand(args[3])?;
 895                 // Spec says to always write `0` first.
 896                 this.write_null(written_place.into())?;
 897                 let written = if handle == -11 || handle == -12 {
 898                     // stdout/stderr
 899                     use std::io::{self, Write};
 900
 901                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 902                     let res = if handle == -11 {
 903                         io::stdout().write(buf_cont)
 904                     } else {
 905                         io::stderr().write(buf_cont)
 906                     };
 907                     res.ok().map(|n| n as u32)
 908                 } else {
 909                     eprintln!("Miri: Ignored output to handle {}", handle);
 910                     // Pretend it all went well.
 911                     Some(n)
 912                 };
 913                 // If there was no error, write back how much was written.
 914                 if let Some(n) = written {
 915                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 916                 }
 917                 // Return whether this was a success.
 918                 this.write_scalar(
 919                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 920                     dest,
 921                 )?;
 922             }
 923             "GetConsoleMode" => {
 924                 // Everything is a pipe.
 925                 this.write_null(dest)?;
 926             }
 927             "GetEnvironmentVariableW" => {
 928                 // This is not the env var you are looking for.
 929                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 930                 this.write_null(dest)?;
 931             }
 932             "GetCommandLineW" => {
 933                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 934             }
 935             // The actual name of 'RtlGenRandom'
 936             "SystemFunction036" => {
 937                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 938                 let len = this.read_scalar(args[1])?.to_u32()?;
 939                 this.gen_random(ptr, len as usize)?;
 940                 this.write_scalar(Scalar::from_bool(true), dest)?;
 941             }
 942
 943             // We can't execute anything else.
 944             _ => {
 945                 throw_unsup_format!("can't call foreign function: {}", link_name)
 946             }
 947         }
 948
 949         this.goto_block(Some(ret))?;
 950         this.dump_place(*dest);
 951         Ok(())
 952     }
 953
 954     /// Evaluates the scalar at the specified path. Returns Some(val)
 955     /// if the path could be resolved, and None otherwise
 956     fn eval_path_scalar(&mut self, path: &[&str]) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 957         let this = self.eval_context_mut();
 958         if let Ok(instance) = this.resolve_path(path) {
 959             let cid = GlobalId {
 960                 instance,
 961                 promoted: None,
 962             };
 963             let const_val = this.const_eval_raw(cid)?;
 964             let const_val = this.read_scalar(const_val.into())?;
 965             return Ok(Some(const_val));
 966         }
 967         return Ok(None);
 968     }
 969 }
 970
 971 // Shims the linux 'getrandom()' syscall.
 972 fn linux_getrandom<'tcx>(
 973     this: &mut MiriEvalContext<'_, 'tcx>,
 974     args: &[OpTy<'tcx, Tag>],
 975     dest: PlaceTy<'tcx, Tag>,
 976 ) -> InterpResult<'tcx> {
 977     let ptr = this.read_scalar(args[0])?.not_undef()?;
 978     let len = this.read_scalar(args[1])?.to_usize(this)?;
 979
 980     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 981     // neither of which have any effect on our current PRNG.
 982     let _flags = this.read_scalar(args[2])?.to_i32()?;
 983
 984     this.gen_random(ptr, len as usize)?;
 985     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 986     Ok(())
 987 }