src/shims/foreign_items.rs

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