src/shims/foreign_items.rs

   1 use std::{iter, convert::TryInto};
   2
   3 use rustc::mir;
   4 use rustc::ty::layout::{Align, LayoutOf, Size};
   5 use rustc::hir::def_id::DefId;
   6 use rustc_apfloat::Float;
   7 use rustc::ty;
   8 use syntax::attr;
   9 use syntax::symbol::sym;
  10
  11 use crate::*;
  12
  13 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  14 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  15     /// Returns the minimum alignment for the target architecture for allocations of the given size.
  16     fn min_align(&self, size: u64, kind: MiriMemoryKind) -> Align {
  17         let this = self.eval_context_ref();
  18         // List taken from `libstd/sys_common/alloc.rs`.
  19         let min_align = match this.tcx.tcx.sess.target.target.arch.as_str() {
  20             "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
  21             "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" => 16,
  22             arch => bug!("Unsupported target architecture: {}", arch),
  23         };
  24         // Windows always aligns, even small allocations.
  25         // Source: <https://support.microsoft.com/en-us/help/286470/how-to-use-pageheap-exe-in-windows-xp-windows-2000-and-windows-server>
  26         // But jemalloc does not, so for the C heap we only align if the allocation is sufficiently big.
  27         if kind == MiriMemoryKind::WinHeap || size >= min_align {
  28             return Align::from_bytes(min_align).unwrap();
  29         }
  30         // We have `size < min_align`. Round `size` *down* to the next power of two and use that.
  31         fn prev_power_of_two(x: u64) -> u64 {
  32             let next_pow2 = x.next_power_of_two();
  33             if next_pow2 == x {
  34                 // x *is* a power of two, just use that.
  35                 x
  36             } else {
  37                 // x is between two powers, so next = 2*prev.
  38                 next_pow2 / 2
  39             }
  40         }
  41         Align::from_bytes(prev_power_of_two(size)).unwrap()
  42     }
  43
  44     fn malloc(&mut self, size: u64, zero_init: bool, kind: MiriMemoryKind) -> Scalar<Tag> {
  45         let this = self.eval_context_mut();
  46         if size == 0 {
  47             Scalar::from_int(0, this.pointer_size())
  48         } else {
  49             let align = this.min_align(size, kind);
  50             let ptr = this
  51                 .memory
  52                 .allocate(Size::from_bytes(size), align, kind.into());
  53             if zero_init {
  54                 // We just allocated this, the access is definitely in-bounds.
  55                 this.memory
  56                     .write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize))
  57                     .unwrap();
  58             }
  59             Scalar::Ptr(ptr)
  60         }
  61     }
  62
  63     fn free(&mut self, ptr: Scalar<Tag>, kind: MiriMemoryKind) -> InterpResult<'tcx> {
  64         let this = self.eval_context_mut();
  65         if !this.is_null(ptr)? {
  66             let ptr = this.force_ptr(ptr)?;
  67             this.memory.deallocate(ptr, None, kind.into())?;
  68         }
  69         Ok(())
  70     }
  71
  72     fn realloc(
  73         &mut self,
  74         old_ptr: Scalar<Tag>,
  75         new_size: u64,
  76         kind: MiriMemoryKind,
  77     ) -> InterpResult<'tcx, Scalar<Tag>> {
  78         let this = self.eval_context_mut();
  79         let new_align = this.min_align(new_size, kind);
  80         if this.is_null(old_ptr)? {
  81             if new_size == 0 {
  82                 Ok(Scalar::from_int(0, this.pointer_size()))
  83             } else {
  84                 let new_ptr =
  85                     this.memory
  86                         .allocate(Size::from_bytes(new_size), new_align, kind.into());
  87                 Ok(Scalar::Ptr(new_ptr))
  88             }
  89         } else {
  90             let old_ptr = this.force_ptr(old_ptr)?;
  91             if new_size == 0 {
  92                 this.memory.deallocate(old_ptr, None, kind.into())?;
  93                 Ok(Scalar::from_int(0, this.pointer_size()))
  94             } else {
  95                 let new_ptr = this.memory.reallocate(
  96                     old_ptr,
  97                     None,
  98                     Size::from_bytes(new_size),
  99                     new_align,
 100                     kind.into(),
 101                 )?;
 102                 Ok(Scalar::Ptr(new_ptr))
 103             }
 104         }
 105     }
 106
 107     /// Emulates calling a foreign item, failing if the item is not supported.
 108     /// This function will handle `goto_block` if needed.
 109     /// Returns Ok(None) if the foreign item was completely handled
 110     /// by this function.
 111     /// Returns Ok(Some(body)) if processing the foreign item
 112     /// is delegated to another function.
 113     fn emulate_foreign_item(
 114         &mut self,
 115         def_id: DefId,
 116         args: &[OpTy<'tcx, Tag>],
 117         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
 118         _unwind: Option<mir::BasicBlock>
 119     ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
 120         let this = self.eval_context_mut();
 121         let attrs = this.tcx.get_attrs(def_id);
 122         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 123             Some(name) => name.as_str(),
 124             None => this.tcx.item_name(def_id).as_str(),
 125         };
 126         // Strip linker suffixes (seen on 32-bit macOS).
 127         let link_name = link_name.trim_end_matches("$UNIX2003");
 128         let tcx = &{ this.tcx.tcx };
 129
 130         // First: functions that diverge.
 131         let (dest, ret) = match link_name {
 132             // Note that this matches calls to the *foreign* item `__rust_start_panic* -
 133             // that is, calls to `extern "Rust" { fn __rust_start_panic(...) }`.
 134             // We forward this to the underlying *implementation* in the panic runtime crate.
 135             // Normally, this will be either `libpanic_unwind` or `libpanic_abort`, but it could
 136             // also be a custom user-provided implementation via `#![feature(panic_runtime)]`
 137             "__rust_start_panic" => {
 138                 // FIXME we might want to cache this... but it's not really performance-critical.
 139                 let panic_runtime = tcx.crates().iter()
 140                     .find(|cnum| tcx.is_panic_runtime(**cnum))
 141                     .expect("No panic runtime found!");
 142                 let panic_runtime = tcx.crate_name(*panic_runtime);
 143                 let start_panic_instance = this.resolve_path(&[&*panic_runtime.as_str(), "__rust_start_panic"])?;
 144                 return Ok(Some(&*this.load_mir(start_panic_instance.def, None)?));
 145             }
 146             // Similarly, we forward calls to the `panic_impl` foreign item to its implementation.
 147             // The implementation is provided by the function with the `#[panic_handler]` attribute.
 148             "panic_impl" => {
 149                 let panic_impl_id = this.tcx.lang_items().panic_impl().unwrap();
 150                 let panic_impl_instance = ty::Instance::mono(*this.tcx, panic_impl_id);
 151                 return Ok(Some(&*this.load_mir(panic_impl_instance.def, None)?));
 152             }
 153
 154             "exit" | "ExitProcess" => {
 155                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` variant anyway
 156                 let code = this.read_scalar(args[0])?.to_i32()?;
 157                 throw_machine_stop!(TerminationInfo::Exit(code.into()));
 158             }
 159             _ => {
 160                 if let Some(p) = ret {
 161                     p
 162                 } else {
 163                     throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
 164                 }
 165             }
 166         };
 167
 168         // Next: functions that return.
 169         match link_name {
 170             "malloc" => {
 171                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 172                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 173                 this.write_scalar(res, dest)?;
 174             }
 175             "calloc" => {
 176                 let items = this.read_scalar(args[0])?.to_machine_usize(this)?;
 177                 let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 178                 let size = items
 179                     .checked_mul(len)
 180                     .ok_or_else(|| err_panic!(Overflow(mir::BinOp::Mul)))?;
 181                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 182                 this.write_scalar(res, dest)?;
 183             }
 184             "posix_memalign" => {
 185                 let ret = this.deref_operand(args[0])?;
 186                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 187                 let size = this.read_scalar(args[2])?.to_machine_usize(this)?;
 188                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 189                 if !align.is_power_of_two() {
 190                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 191                 }
 192                 if align < this.pointer_size().bytes() {
 193                     throw_ub_format!(
 194                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 195                         align,
 196                     );
 197                 }
 198
 199                 if size == 0 {
 200                     this.write_null(ret.into())?;
 201                 } else {
 202                     let ptr = this.memory.allocate(
 203                         Size::from_bytes(size),
 204                         Align::from_bytes(align).unwrap(),
 205                         MiriMemoryKind::C.into(),
 206                     );
 207                     this.write_scalar(ptr, ret.into())?;
 208                 }
 209                 this.write_null(dest)?;
 210             }
 211             "free" => {
 212                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 213                 this.free(ptr, MiriMemoryKind::C)?;
 214             }
 215             "realloc" => {
 216                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 217                 let new_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 218                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 219                 this.write_scalar(res, dest)?;
 220             }
 221
 222             "__rust_alloc" => {
 223                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 224                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 225                 if size == 0 {
 226                     throw_unsup!(HeapAllocZeroBytes);
 227                 }
 228                 if !align.is_power_of_two() {
 229                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 230                 }
 231                 let ptr = this.memory.allocate(
 232                     Size::from_bytes(size),
 233                     Align::from_bytes(align).unwrap(),
 234                     MiriMemoryKind::Rust.into(),
 235                 );
 236                 this.write_scalar(ptr, dest)?;
 237             }
 238             "__rust_alloc_zeroed" => {
 239                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 240                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 241                 if size == 0 {
 242                     throw_unsup!(HeapAllocZeroBytes);
 243                 }
 244                 if !align.is_power_of_two() {
 245                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 246                 }
 247                 let ptr = this.memory.allocate(
 248                     Size::from_bytes(size),
 249                     Align::from_bytes(align).unwrap(),
 250                     MiriMemoryKind::Rust.into(),
 251                 );
 252                 // We just allocated this, the access is definitely in-bounds.
 253                 this.memory
 254                     .write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize))
 255                     .unwrap();
 256                 this.write_scalar(ptr, dest)?;
 257             }
 258             "__rust_dealloc" => {
 259                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 260                 let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 261                 let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
 262                 if old_size == 0 {
 263                     throw_unsup!(HeapAllocZeroBytes);
 264                 }
 265                 if !align.is_power_of_two() {
 266                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 267                 }
 268                 let ptr = this.force_ptr(ptr)?;
 269                 this.memory.deallocate(
 270                     ptr,
 271                     Some((
 272                         Size::from_bytes(old_size),
 273                         Align::from_bytes(align).unwrap(),
 274                     )),
 275                     MiriMemoryKind::Rust.into(),
 276                 )?;
 277             }
 278             "__rust_realloc" => {
 279                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 280                 let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 281                 let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
 282                 let new_size = this.read_scalar(args[3])?.to_machine_usize(this)?;
 283                 if old_size == 0 || new_size == 0 {
 284                     throw_unsup!(HeapAllocZeroBytes);
 285                 }
 286                 if !align.is_power_of_two() {
 287                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 288                 }
 289                 let align = Align::from_bytes(align).unwrap();
 290                 let new_ptr = this.memory.reallocate(
 291                     ptr,
 292                     Some((Size::from_bytes(old_size), align)),
 293                     Size::from_bytes(new_size),
 294                     align,
 295                     MiriMemoryKind::Rust.into(),
 296                 )?;
 297                 this.write_scalar(new_ptr, dest)?;
 298             }
 299
 300             "syscall" => {
 301                 let sys_getrandom = this
 302                     .eval_path_scalar(&["libc", "SYS_getrandom"])?
 303                     .expect("Failed to get libc::SYS_getrandom")
 304                     .to_machine_usize(this)?;
 305
 306                 let sys_statx = this
 307                     .eval_path_scalar(&["libc", "SYS_statx"])?
 308                     .expect("Failed to get libc::SYS_statx")
 309                     .to_machine_usize(this)?;
 310
 311                 match this.read_scalar(args[0])?.to_machine_usize(this)? {
 312                     // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 313                     // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 314                     id if id == sys_getrandom => {
 315                         // The first argument is the syscall id,
 316                         // so skip over it.
 317                         linux_getrandom(this, &args[1..], dest)?;
 318                     }
 319                     id if id == sys_statx => {
 320                         // The first argument is the syscall id,
 321                         // so skip over it.
 322                         let result = this.statx(args[1], args[2], args[3], args[4], args[5])?;
 323                         this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 324                     }
 325                     id => throw_unsup_format!("miri does not support syscall ID {}", id),
 326                 }
 327             }
 328
 329             "getrandom" => {
 330                 linux_getrandom(this, args, dest)?;
 331             }
 332
 333             "dlsym" => {
 334                 let _handle = this.read_scalar(args[0])?;
 335                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 336                 let symbol_name = this.memory.read_c_str(symbol)?;
 337                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 338                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 339                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 340                     let ptr = this.memory.create_fn_alloc(FnVal::Other(dlsym));
 341                     this.write_scalar(Scalar::from(ptr), dest)?;
 342                 } else {
 343                     this.write_null(dest)?;
 344                 }
 345             }
 346
 347             "__rust_maybe_catch_panic" => {
 348                 this.handle_catch_panic(args, dest, ret)?;
 349                 return Ok(None)
 350             }
 351
 352             "memcmp" => {
 353                 let left = this.read_scalar(args[0])?.not_undef()?;
 354                 let right = this.read_scalar(args[1])?.not_undef()?;
 355                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_machine_usize(this)?);
 356
 357                 let result = {
 358                     let left_bytes = this.memory.read_bytes(left, n)?;
 359                     let right_bytes = this.memory.read_bytes(right, n)?;
 360
 361                     use std::cmp::Ordering::*;
 362                     match left_bytes.cmp(right_bytes) {
 363                         Less => -1i32,
 364                         Equal => 0,
 365                         Greater => 1,
 366                     }
 367                 };
 368
 369                 this.write_scalar(Scalar::from_int(result, Size::from_bits(32)), dest)?;
 370             }
 371
 372             "memrchr" => {
 373                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 374                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 375                 let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
 376                 if let Some(idx) = this
 377                     .memory
 378                     .read_bytes(ptr, Size::from_bytes(num))?
 379                     .iter()
 380                     .rev()
 381                     .position(|&c| c == val)
 382                 {
 383                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 384                     this.write_scalar(new_ptr, dest)?;
 385                 } else {
 386                     this.write_null(dest)?;
 387                 }
 388             }
 389
 390             "memchr" => {
 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_machine_usize(this)?;
 394                 let idx = this
 395                     .memory
 396                     .read_bytes(ptr, Size::from_bytes(num))?
 397                     .iter()
 398                     .position(|&c| c == val);
 399                 if let Some(idx) = idx {
 400                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 401                     this.write_scalar(new_ptr, dest)?;
 402                 } else {
 403                     this.write_null(dest)?;
 404                 }
 405             }
 406
 407             "__errno_location" | "__error" => {
 408                 let errno_place = this.machine.last_error.unwrap();
 409                 this.write_scalar(errno_place.to_ref().to_scalar()?, dest)?;
 410             }
 411
 412             "getenv" => {
 413                 let result = this.getenv(args[0])?;
 414                 this.write_scalar(result, dest)?;
 415             }
 416
 417             "unsetenv" => {
 418                 let result = this.unsetenv(args[0])?;
 419                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 420             }
 421
 422             "setenv" => {
 423                 let result = this.setenv(args[0], args[1])?;
 424                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 425             }
 426
 427             "getcwd" => {
 428                 let result = this.getcwd(args[0], args[1])?;
 429                 this.write_scalar(result, dest)?;
 430             }
 431
 432             "chdir" => {
 433                 let result = this.chdir(args[0])?;
 434                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 435             }
 436
 437             "open" | "open64" => {
 438                 let result = this.open(args[0], args[1])?;
 439                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 440             }
 441
 442             "fcntl" => {
 443                 let result = this.fcntl(args[0], args[1], args.get(2).cloned())?;
 444                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 445             }
 446
 447             "close" | "close$NOCANCEL" => {
 448                 let result = this.close(args[0])?;
 449                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 450             }
 451
 452             "read" => {
 453                 let result = this.read(args[0], args[1], args[2])?;
 454                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 455             }
 456
 457             "write" => {
 458                 let fd = this.read_scalar(args[0])?.to_i32()?;
 459                 let buf = this.read_scalar(args[1])?.not_undef()?;
 460                 let n = this.read_scalar(args[2])?.to_machine_usize(tcx)?;
 461                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 462                 let result = if fd == 1 || fd == 2 {
 463                     // stdout/stderr
 464                     use std::io::{self, Write};
 465
 466                     let buf_cont = this.memory.read_bytes(buf, Size::from_bytes(n))?;
 467                     // We need to flush to make sure this actually appears on the screen
 468                     let res = if fd == 1 {
 469                         // Stdout is buffered, flush to make sure it appears on the screen.
 470                         // This is the write() syscall of the interpreted program, we want it
 471                         // to correspond to a write() syscall on the host -- there is no good
 472                         // in adding extra buffering here.
 473                         let res = io::stdout().write(buf_cont);
 474                         io::stdout().flush().unwrap();
 475                         res
 476                     } else {
 477                         // No need to flush, stderr is not buffered.
 478                         io::stderr().write(buf_cont)
 479                     };
 480                     match res {
 481                         Ok(n) => n as i64,
 482                         Err(_) => -1,
 483                     }
 484                 } else {
 485                     this.write(args[0], args[1], args[2])?
 486                 };
 487                 // Now, `result` is the value we return back to the program.
 488                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 489             }
 490
 491             "unlink" => {
 492                 let result = this.unlink(args[0])?;
 493                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 494             }
 495
 496             "clock_gettime" => {
 497                 let result = this.clock_gettime(args[0], args[1])?;
 498                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 499             }
 500
 501             "gettimeofday" => {
 502                 let result = this.gettimeofday(args[0], args[1])?;
 503                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 504             }
 505
 506             "strlen" => {
 507                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 508                 let n = this.memory.read_c_str(ptr)?.len();
 509                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 510             }
 511
 512             // math functions
 513             "cbrtf" | "coshf" | "sinhf" | "tanf" | "acosf" | "asinf" | "atanf" => {
 514                 // FIXME: Using host floats.
 515                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 516                 let f = match link_name {
 517                     "cbrtf" => f.cbrt(),
 518                     "coshf" => f.cosh(),
 519                     "sinhf" => f.sinh(),
 520                     "tanf" => f.tan(),
 521                     "acosf" => f.acos(),
 522                     "asinf" => f.asin(),
 523                     "atanf" => f.atan(),
 524                     _ => bug!(),
 525                 };
 526                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 527             }
 528             // underscore case for windows
 529             "_hypotf" | "hypotf" | "atan2f" => {
 530                 // FIXME: Using host floats.
 531                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 532                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 533                 let n = match link_name {
 534                     "_hypotf" | "hypotf" => f1.hypot(f2),
 535                     "atan2f" => f1.atan2(f2),
 536                     _ => bug!(),
 537                 };
 538                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 539             }
 540
 541             "cbrt" | "cosh" | "sinh" | "tan" | "acos" | "asin" | "atan" => {
 542                 // FIXME: Using host floats.
 543                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 544                 let f = match link_name {
 545                     "cbrt" => f.cbrt(),
 546                     "cosh" => f.cosh(),
 547                     "sinh" => f.sinh(),
 548                     "tan" => f.tan(),
 549                     "acos" => f.acos(),
 550                     "asin" => f.asin(),
 551                     "atan" => f.atan(),
 552                     _ => bug!(),
 553                 };
 554                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 555             }
 556             // underscore case for windows, here and below
 557             // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
 558             "_hypot" | "hypot" | "atan2" => {
 559                 // FIXME: Using host floats.
 560                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 561                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 562                 let n = match link_name {
 563                     "_hypot" | "hypot" => f1.hypot(f2),
 564                     "atan2" => f1.atan2(f2),
 565                     _ => bug!(),
 566                 };
 567                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 568             }
 569             // For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
 570             "_ldexp" | "ldexp" | "scalbn" => {
 571                 let x = this.read_scalar(args[0])?.to_f64()?;
 572                 let exp = this.read_scalar(args[1])?.to_i32()?;
 573
 574                 // Saturating cast to i16. Even those are outside the valid exponent range to
 575                 // `scalbn` below will do its over/underflow handling.
 576                 let exp = if exp > i16::max_value() as i32 {
 577                     i16::max_value()
 578                 } else if exp < i16::min_value() as i32 {
 579                     i16::min_value()
 580                 } else {
 581                     exp.try_into().unwrap()
 582                 };
 583
 584                 let res = x.scalbn(exp);
 585                 this.write_scalar(Scalar::from_f64(res), dest)?;
 586             }
 587
 588             // Some things needed for `sys::thread` initialization to go through.
 589             "signal" | "sigaction" | "sigaltstack" => {
 590                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 591             }
 592
 593             "sysconf" => {
 594                 let name = this.read_scalar(args[0])?.to_i32()?;
 595
 596                 trace!("sysconf() called with name {}", name);
 597                 // TODO: Cache the sysconf integers via Miri's global cache.
 598                 let paths = &[
 599                     (
 600                         &["libc", "_SC_PAGESIZE"],
 601                         Scalar::from_int(PAGE_SIZE, dest.layout.size),
 602                     ),
 603                     (
 604                         &["libc", "_SC_GETPW_R_SIZE_MAX"],
 605                         Scalar::from_int(-1, dest.layout.size),
 606                     ),
 607                     (
 608                         &["libc", "_SC_NPROCESSORS_ONLN"],
 609                         Scalar::from_int(NUM_CPUS, dest.layout.size),
 610                     ),
 611                 ];
 612                 let mut result = None;
 613                 for &(path, path_value) in paths {
 614                     if let Some(val) = this.eval_path_scalar(path)? {
 615                         let val = val.to_i32()?;
 616                         if val == name {
 617                             result = Some(path_value);
 618                             break;
 619                         }
 620                     }
 621                 }
 622                 if let Some(result) = result {
 623                     this.write_scalar(result, dest)?;
 624                 } else {
 625                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 626                 }
 627             }
 628
 629             "sched_getaffinity" => {
 630                 // Return an error; `num_cpus` then falls back to `sysconf`.
 631                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 632             }
 633
 634             "isatty" => {
 635                 this.write_null(dest)?;
 636             }
 637
 638             // Hook pthread calls that go to the thread-local storage memory subsystem.
 639             "pthread_key_create" => {
 640                 let key_place = this.deref_operand(args[0])?;
 641
 642                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 643                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 644                     Some(dtor_ptr) => Some(this.memory.get_fn(dtor_ptr)?.as_instance()?),
 645                     None => None,
 646                 };
 647
 648                 // Figure out how large a pthread TLS key actually is.
 649                 // This is `libc::pthread_key_t`.
 650                 let key_type = args[0].layout.ty
 651                     .builtin_deref(true)
 652                     .ok_or_else(|| err_ub_format!(
 653                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 654                     ))?
 655                     .ty;
 656                 let key_layout = this.layout_of(key_type)?;
 657
 658                 // Create key and write it into the memory where `key_ptr` wants it.
 659                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 660                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128)
 661                 {
 662                     throw_unsup!(OutOfTls);
 663                 }
 664
 665                 this.write_scalar(Scalar::from_uint(key, key_layout.size), key_place.into())?;
 666
 667                 // Return success (`0`).
 668                 this.write_null(dest)?;
 669             }
 670             "pthread_key_delete" => {
 671                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 672                 this.machine.tls.delete_tls_key(key)?;
 673                 // Return success (0)
 674                 this.write_null(dest)?;
 675             }
 676             "pthread_getspecific" => {
 677                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 678                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 679                 this.write_scalar(ptr, dest)?;
 680             }
 681             "pthread_setspecific" => {
 682                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 683                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 684                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 685
 686                 // Return success (`0`).
 687                 this.write_null(dest)?;
 688             }
 689
 690             // Stack size/address stuff.
 691             "pthread_attr_init"
 692             | "pthread_attr_destroy"
 693             | "pthread_self"
 694             | "pthread_attr_setstacksize" => {
 695                 this.write_null(dest)?;
 696             }
 697             "pthread_attr_getstack" => {
 698                 let addr_place = this.deref_operand(args[1])?;
 699                 let size_place = this.deref_operand(args[2])?;
 700
 701                 this.write_scalar(
 702                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 703                     addr_place.into(),
 704                 )?;
 705                 this.write_scalar(
 706                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 707                     size_place.into(),
 708                 )?;
 709
 710                 // Return success (`0`).
 711                 this.write_null(dest)?;
 712             }
 713
 714             // We don't support threading. (Also for Windows.)
 715             "pthread_create" | "CreateThread" => {
 716                 throw_unsup_format!("Miri does not support threading");
 717             }
 718
 719             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 720             "pthread_mutexattr_init"
 721             | "pthread_mutexattr_settype"
 722             | "pthread_mutex_init"
 723             | "pthread_mutexattr_destroy"
 724             | "pthread_mutex_lock"
 725             | "pthread_mutex_unlock"
 726             | "pthread_mutex_destroy"
 727             | "pthread_rwlock_rdlock"
 728             | "pthread_rwlock_unlock"
 729             | "pthread_rwlock_wrlock"
 730             | "pthread_rwlock_destroy"
 731             | "pthread_condattr_init"
 732             | "pthread_condattr_setclock"
 733             | "pthread_cond_init"
 734             | "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(this.machine.argc.expect("machine must be initialized"), dest)?;
 770             }
 771             "_NSGetArgv" => {
 772                 this.write_scalar(this.machine.argv.expect("machine must be initialized"), dest)?;
 773             }
 774             "SecRandomCopyBytes" => {
 775                 let len = this.read_scalar(args[1])?.to_machine_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_machine_isize(this)?;
 791                 let flags = this.read_scalar(args[1])?.to_u32()?;
 792                 let size = this.read_scalar(args[2])?.to_machine_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_machine_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_machine_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_machine_usize(this)?;
 809                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 810                 this.write_scalar(res, dest)?;
 811             }
 812
 813             "SetLastError" => {
 814                 this.set_last_error(this.read_scalar(args[0])?.not_undef()?)?;
 815             }
 816             "GetLastError" => {
 817                 let last_error = this.get_last_error()?;
 818                 this.write_scalar(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                 // Initialize with `0`.
 842                 this.memory
 843                     .write_bytes(system_info.ptr, iter::repeat(0u8).take(system_info.layout.size.bytes() as usize))?;
 844                 // Set number of processors.
 845                 let dword_size = Size::from_bytes(4);
 846                 let num_cpus = this.mplace_field(system_info, 6)?;
 847                 this.write_scalar(
 848                     Scalar::from_int(NUM_CPUS, dword_size),
 849                     num_cpus.into(),
 850                 )?;
 851             }
 852
 853             "TlsAlloc" => {
 854                 // This just creates a key; Windows does not natively support TLS destructors.
 855
 856                 // Create key and return it.
 857                 let key = this.machine.tls.create_tls_key(None) as u128;
 858
 859                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 860                 if dest.layout.size.bits() < 128
 861                     && key >= (1u128 << dest.layout.size.bits() as u128)
 862                 {
 863                     throw_unsup!(OutOfTls);
 864                 }
 865                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 866             }
 867             "TlsGetValue" => {
 868                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 869                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 870                 this.write_scalar(ptr, dest)?;
 871             }
 872             "TlsSetValue" => {
 873                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 874                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 875                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 876
 877                 // Return success (`1`).
 878                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 879             }
 880             "GetStdHandle" => {
 881                 let which = this.read_scalar(args[0])?.to_i32()?;
 882                 // We just make this the identity function, so we know later in `WriteFile`
 883                 // which one it is.
 884                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 885             }
 886             "WriteFile" => {
 887                 let handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 888                 let buf = this.read_scalar(args[1])?.not_undef()?;
 889                 let n = this.read_scalar(args[2])?.to_u32()?;
 890                 let written_place = this.deref_operand(args[3])?;
 891                 // Spec says to always write `0` first.
 892                 this.write_null(written_place.into())?;
 893                 let written = if handle == -11 || handle == -12 {
 894                     // stdout/stderr
 895                     use std::io::{self, Write};
 896
 897                     let buf_cont = this
 898                         .memory
 899                         .read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 900                     let res = if handle == -11 {
 901                         io::stdout().write(buf_cont)
 902                     } else {
 903                         io::stderr().write(buf_cont)
 904                     };
 905                     res.ok().map(|n| n as u32)
 906                 } else {
 907                     eprintln!("Miri: Ignored output to handle {}", handle);
 908                     // Pretend it all went well.
 909                     Some(n)
 910                 };
 911                 // If there was no error, write back how much was written.
 912                 if let Some(n) = written {
 913                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 914                 }
 915                 // Return whether this was a success.
 916                 this.write_scalar(
 917                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 918                     dest,
 919                 )?;
 920             }
 921             "GetConsoleMode" => {
 922                 // Everything is a pipe.
 923                 this.write_null(dest)?;
 924             }
 925             "GetEnvironmentVariableW" => {
 926                 // This is not the env var you are looking for.
 927                 this.set_last_error(Scalar::from_u32(203))?; // ERROR_ENVVAR_NOT_FOUND
 928                 this.write_null(dest)?;
 929             }
 930             "GetCommandLineW" => {
 931                 this.write_scalar(this.machine.cmd_line.expect("machine must be initialized"), dest)?;
 932             }
 933             // The actual name of 'RtlGenRandom'
 934             "SystemFunction036" => {
 935                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 936                 let len = this.read_scalar(args[1])?.to_u32()?;
 937                 this.gen_random(ptr, len as usize)?;
 938                 this.write_scalar(Scalar::from_bool(true), dest)?;
 939             }
 940
 941             // We can't execute anything else.
 942             _ => throw_unsup_format!("can't call foreign function: {}", link_name),
 943         }
 944
 945         this.dump_place(*dest);
 946         this.go_to_block(ret);
 947         Ok(None)
 948     }
 949
 950     /// Evaluates the scalar at the specified path. Returns Some(val)
 951     /// if the path could be resolved, and None otherwise
 952     fn eval_path_scalar(
 953         &mut self,
 954         path: &[&str],
 955     ) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 956         let this = self.eval_context_mut();
 957         if let Ok(instance) = this.resolve_path(path) {
 958             let cid = GlobalId {
 959                 instance,
 960                 promoted: None,
 961             };
 962             let const_val = this.const_eval_raw(cid)?;
 963             let const_val = this.read_scalar(const_val.into())?;
 964             return Ok(Some(const_val));
 965         }
 966         return Ok(None);
 967     }
 968 }
 969
 970 // Shims the linux 'getrandom()' syscall.
 971 fn linux_getrandom<'tcx>(
 972     this: &mut MiriEvalContext<'_, 'tcx>,
 973     args: &[OpTy<'tcx, Tag>],
 974     dest: PlaceTy<'tcx, Tag>,
 975 ) -> InterpResult<'tcx> {
 976     let ptr = this.read_scalar(args[0])?.not_undef()?;
 977     let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 978
 979     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 980     // neither of which have any effect on our current PRNG.
 981     let _flags = this.read_scalar(args[2])?.to_i32()?;
 982
 983     this.gen_random(ptr, len as usize)?;
 984     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 985     Ok(())
 986 }