src/shims/foreign_items.rs

   1 use std::{convert::TryInto, iter};
   2
   3 use rustc_hir::def_id::DefId;
   4 use rustc::mir;
   5 use rustc::ty;
   6 use rustc::ty::layout::{Align, LayoutOf, Size};
   7 use rustc_apfloat::Float;
   8 use rustc_span::symbol::sym;
   9 use syntax::attr;
  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.memory.allocate(Size::from_bytes(size), align, kind.into());
  51             if zero_init {
  52                 // We just allocated this, the access is definitely in-bounds.
  53                 this.memory.write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize)).unwrap();
  54             }
  55             Scalar::Ptr(ptr)
  56         }
  57     }
  58
  59     fn free(&mut self, ptr: Scalar<Tag>, kind: MiriMemoryKind) -> InterpResult<'tcx> {
  60         let this = self.eval_context_mut();
  61         if !this.is_null(ptr)? {
  62             let ptr = this.force_ptr(ptr)?;
  63             this.memory.deallocate(ptr, None, kind.into())?;
  64         }
  65         Ok(())
  66     }
  67
  68     fn realloc(
  69         &mut self,
  70         old_ptr: Scalar<Tag>,
  71         new_size: u64,
  72         kind: MiriMemoryKind,
  73     ) -> InterpResult<'tcx, Scalar<Tag>> {
  74         let this = self.eval_context_mut();
  75         let new_align = this.min_align(new_size, kind);
  76         if this.is_null(old_ptr)? {
  77             if new_size == 0 {
  78                 Ok(Scalar::from_int(0, this.pointer_size()))
  79             } else {
  80                 let new_ptr =
  81                     this.memory.allocate(Size::from_bytes(new_size), new_align, kind.into());
  82                 Ok(Scalar::Ptr(new_ptr))
  83             }
  84         } else {
  85             let old_ptr = this.force_ptr(old_ptr)?;
  86             if new_size == 0 {
  87                 this.memory.deallocate(old_ptr, None, kind.into())?;
  88                 Ok(Scalar::from_int(0, this.pointer_size()))
  89             } else {
  90                 let new_ptr = this.memory.reallocate(
  91                     old_ptr,
  92                     None,
  93                     Size::from_bytes(new_size),
  94                     new_align,
  95                     kind.into(),
  96                 )?;
  97                 Ok(Scalar::Ptr(new_ptr))
  98             }
  99         }
 100     }
 101
 102     /// Emulates calling a foreign item, failing if the item is not supported.
 103     /// This function will handle `goto_block` if needed.
 104     /// Returns Ok(None) if the foreign item was completely handled
 105     /// by this function.
 106     /// Returns Ok(Some(body)) if processing the foreign item
 107     /// is delegated to another function.
 108     #[rustfmt::skip]
 109     fn emulate_foreign_item(
 110         &mut self,
 111         def_id: DefId,
 112         args: &[OpTy<'tcx, Tag>],
 113         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
 114         _unwind: Option<mir::BasicBlock>,
 115     ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
 116         let this = self.eval_context_mut();
 117         let attrs = this.tcx.get_attrs(def_id);
 118         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 119             Some(name) => name.as_str(),
 120             None => this.tcx.item_name(def_id).as_str(),
 121         };
 122         // Strip linker suffixes (seen on 32-bit macOS).
 123         let link_name = link_name.trim_end_matches("$UNIX2003");
 124         let tcx = &{ this.tcx.tcx };
 125
 126         // First: functions that diverge.
 127         let (dest, ret) = match link_name {
 128             // Note that this matches calls to the *foreign* item `__rust_start_panic* -
 129             // that is, calls to `extern "Rust" { fn __rust_start_panic(...) }`.
 130             // We forward this to the underlying *implementation* in the panic runtime crate.
 131             // Normally, this will be either `libpanic_unwind` or `libpanic_abort`, but it could
 132             // also be a custom user-provided implementation via `#![feature(panic_runtime)]`
 133             "__rust_start_panic" => {
 134                 // FIXME we might want to cache this... but it's not really performance-critical.
 135                 let panic_runtime = tcx
 136                     .crates()
 137                     .iter()
 138                     .find(|cnum| tcx.is_panic_runtime(**cnum))
 139                     .expect("No panic runtime found!");
 140                 let panic_runtime = tcx.crate_name(*panic_runtime);
 141                 let start_panic_instance =
 142                     this.resolve_path(&[&*panic_runtime.as_str(), "__rust_start_panic"])?;
 143                 return Ok(Some(&*this.load_mir(start_panic_instance.def, None)?));
 144             }
 145             // Similarly, we forward calls to the `panic_impl` foreign item to its implementation.
 146             // The implementation is provided by the function with the `#[panic_handler]` attribute.
 147             "panic_impl" => {
 148                 let panic_impl_id = this.tcx.lang_items().panic_impl().unwrap();
 149                 let panic_impl_instance = ty::Instance::mono(*this.tcx, panic_impl_id);
 150                 return Ok(Some(&*this.load_mir(panic_impl_instance.def, None)?));
 151             }
 152
 153             | "exit"
 154             | "ExitProcess"
 155             => {
 156                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` variant anyway
 157                 let code = this.read_scalar(args[0])?.to_i32()?;
 158                 throw_machine_stop!(TerminationInfo::Exit(code.into()));
 159             }
 160             _ => {
 161                 if let Some(p) = ret {
 162                     p
 163                 } else {
 164                     throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
 165                 }
 166             }
 167         };
 168
 169         // Next: functions that return.
 170         match link_name {
 171             "malloc" => {
 172                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 173                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 174                 this.write_scalar(res, dest)?;
 175             }
 176             "calloc" => {
 177                 let items = this.read_scalar(args[0])?.to_machine_usize(this)?;
 178                 let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 179                 let size =
 180                     items.checked_mul(len).ok_or_else(|| err_ub_format!("overflow during calloc size computation"))?;
 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.write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize)).unwrap();
 254                 this.write_scalar(ptr, dest)?;
 255             }
 256             "__rust_dealloc" => {
 257                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 258                 let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 259                 let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
 260                 if old_size == 0 {
 261                     throw_unsup!(HeapAllocZeroBytes);
 262                 }
 263                 if !align.is_power_of_two() {
 264                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 265                 }
 266                 let ptr = this.force_ptr(ptr)?;
 267                 this.memory.deallocate(
 268                     ptr,
 269                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 270                     MiriMemoryKind::Rust.into(),
 271                 )?;
 272             }
 273             "__rust_realloc" => {
 274                 let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 275                 let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
 276                 let new_size = this.read_scalar(args[3])?.to_machine_usize(this)?;
 277                 if old_size == 0 || new_size == 0 {
 278                     throw_unsup!(HeapAllocZeroBytes);
 279                 }
 280                 if !align.is_power_of_two() {
 281                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 282                 }
 283                 let ptr = this.force_ptr(this.read_scalar(args[0])?.not_undef()?)?;
 284                 let align = Align::from_bytes(align).unwrap();
 285                 let new_ptr = this.memory.reallocate(
 286                     ptr,
 287                     Some((Size::from_bytes(old_size), align)),
 288                     Size::from_bytes(new_size),
 289                     align,
 290                     MiriMemoryKind::Rust.into(),
 291                 )?;
 292                 this.write_scalar(new_ptr, dest)?;
 293             }
 294
 295             "syscall" => {
 296                 let sys_getrandom = this
 297                     .eval_path_scalar(&["libc", "SYS_getrandom"])?
 298                     .expect("Failed to get libc::SYS_getrandom")
 299                     .to_machine_usize(this)?;
 300
 301                 let sys_statx = this
 302                     .eval_path_scalar(&["libc", "SYS_statx"])?
 303                     .expect("Failed to get libc::SYS_statx")
 304                     .to_machine_usize(this)?;
 305
 306                 match this.read_scalar(args[0])?.to_machine_usize(this)? {
 307                     // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 308                     // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 309                     id if id == sys_getrandom => {
 310                         // The first argument is the syscall id,
 311                         // so skip over it.
 312                         linux_getrandom(this, &args[1..], dest)?;
 313                     }
 314                     id if id == sys_statx => {
 315                         // The first argument is the syscall id,
 316                         // so skip over it.
 317                         let result = this.statx(args[1], args[2], args[3], args[4], args[5])?;
 318                         this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 319                     }
 320                     id => throw_unsup_format!("miri does not support syscall ID {}", id),
 321                 }
 322             }
 323
 324             "getrandom" => {
 325                 linux_getrandom(this, args, dest)?;
 326             }
 327
 328             "dlsym" => {
 329                 let _handle = this.read_scalar(args[0])?;
 330                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 331                 let symbol_name = this.memory.read_c_str(symbol)?;
 332                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 333                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 334                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 335                     let ptr = this.memory.create_fn_alloc(FnVal::Other(dlsym));
 336                     this.write_scalar(Scalar::from(ptr), dest)?;
 337                 } else {
 338                     this.write_null(dest)?;
 339                 }
 340             }
 341
 342             "__rust_maybe_catch_panic" => {
 343                 this.handle_catch_panic(args, dest, ret)?;
 344                 return Ok(None);
 345             }
 346
 347             "memcmp" => {
 348                 let left = this.read_scalar(args[0])?.not_undef()?;
 349                 let right = this.read_scalar(args[1])?.not_undef()?;
 350                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_machine_usize(this)?);
 351
 352                 let result = {
 353                     let left_bytes = this.memory.read_bytes(left, n)?;
 354                     let right_bytes = this.memory.read_bytes(right, n)?;
 355
 356                     use std::cmp::Ordering::*;
 357                     match left_bytes.cmp(right_bytes) {
 358                         Less => -1i32,
 359                         Equal => 0,
 360                         Greater => 1,
 361                     }
 362                 };
 363
 364                 this.write_scalar(Scalar::from_int(result, Size::from_bits(32)), dest)?;
 365             }
 366
 367             "memrchr" => {
 368                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 369                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 370                 let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
 371                 if let Some(idx) = this
 372                     .memory
 373                     .read_bytes(ptr, Size::from_bytes(num))?
 374                     .iter()
 375                     .rev()
 376                     .position(|&c| c == val)
 377                 {
 378                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 379                     this.write_scalar(new_ptr, dest)?;
 380                 } else {
 381                     this.write_null(dest)?;
 382                 }
 383             }
 384
 385             "memchr" => {
 386                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 387                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 388                 let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
 389                 let idx = this
 390                     .memory
 391                     .read_bytes(ptr, Size::from_bytes(num))?
 392                     .iter()
 393                     .position(|&c| c == val);
 394                 if let Some(idx) = idx {
 395                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 396                     this.write_scalar(new_ptr, dest)?;
 397                 } else {
 398                     this.write_null(dest)?;
 399                 }
 400             }
 401
 402             | "__errno_location"
 403             | "__error"
 404             => {
 405                 let errno_place = this.machine.last_error.unwrap();
 406                 this.write_scalar(errno_place.to_ref().to_scalar()?, dest)?;
 407             }
 408
 409             "getenv" => {
 410                 let result = this.getenv(args[0])?;
 411                 this.write_scalar(result, dest)?;
 412             }
 413
 414             "unsetenv" => {
 415                 let result = this.unsetenv(args[0])?;
 416                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 417             }
 418
 419             "setenv" => {
 420                 let result = this.setenv(args[0], args[1])?;
 421                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 422             }
 423
 424             "getcwd" => {
 425                 let result = this.getcwd(args[0], args[1])?;
 426                 this.write_scalar(result, dest)?;
 427             }
 428
 429             "chdir" => {
 430                 let result = this.chdir(args[0])?;
 431                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 432             }
 433
 434             | "open"
 435             | "open64"
 436             => {
 437                 let result = this.open(args[0], args[1])?;
 438                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 439             }
 440
 441             "fcntl" => {
 442                 let result = this.fcntl(args[0], args[1], args.get(2).cloned())?;
 443                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 444             }
 445
 446             | "close"
 447             | "close$NOCANCEL"
 448             => {
 449                 let result = this.close(args[0])?;
 450                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 451             }
 452
 453             "read" => {
 454                 let result = this.read(args[0], args[1], args[2])?;
 455                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 456             }
 457
 458             "write" => {
 459                 let fd = this.read_scalar(args[0])?.to_i32()?;
 460                 let buf = this.read_scalar(args[1])?.not_undef()?;
 461                 let n = this.read_scalar(args[2])?.to_machine_usize(tcx)?;
 462                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 463                 let result = if fd == 1 || fd == 2 {
 464                     // stdout/stderr
 465                     use std::io::{self, Write};
 466
 467                     let buf_cont = this.memory.read_bytes(buf, Size::from_bytes(n))?;
 468                     // We need to flush to make sure this actually appears on the screen
 469                     let res = if fd == 1 {
 470                         // Stdout is buffered, flush to make sure it appears on the screen.
 471                         // This is the write() syscall of the interpreted program, we want it
 472                         // to correspond to a write() syscall on the host -- there is no good
 473                         // in adding extra buffering here.
 474                         let res = io::stdout().write(buf_cont);
 475                         io::stdout().flush().unwrap();
 476                         res
 477                     } else {
 478                         // No need to flush, stderr is not buffered.
 479                         io::stderr().write(buf_cont)
 480                     };
 481                     match res {
 482                         Ok(n) => n as i64,
 483                         Err(_) => -1,
 484                     }
 485                 } else {
 486                     this.write(args[0], args[1], args[2])?
 487                 };
 488                 // Now, `result` is the value we return back to the program.
 489                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 490             }
 491
 492             | "lseek64"
 493             | "lseek"
 494             => {
 495                 let result = this.lseek64(args[0], args[1], args[2])?;
 496                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 497             }
 498
 499             "unlink" => {
 500                 let result = this.unlink(args[0])?;
 501                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 502             }
 503
 504             "symlink" => {
 505                 let result = this.symlink(args[0], args[1])?;
 506                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 507             }
 508
 509             "stat$INODE64" => {
 510                 let result = this.stat(args[0], args[1])?;
 511                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 512             }
 513
 514             "lstat$INODE64" => {
 515                 let result = this.lstat(args[0], args[1])?;
 516                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 517             }
 518
 519             "fstat$INODE64" => {
 520                 let result = this.fstat(args[0], args[1])?;
 521                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 522             }
 523
 524             "rename" => {
 525                 let result = this.rename(args[0], args[1])?;
 526                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 527             }
 528
 529             "clock_gettime" => {
 530                 let result = this.clock_gettime(args[0], args[1])?;
 531                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 532             }
 533
 534             "gettimeofday" => {
 535                 let result = this.gettimeofday(args[0], args[1])?;
 536                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 537             }
 538
 539             "strlen" => {
 540                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 541                 let n = this.memory.read_c_str(ptr)?.len();
 542                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 543             }
 544
 545             // math functions
 546             | "cbrtf"
 547             | "coshf"
 548             | "sinhf"
 549             | "tanf"
 550             | "acosf"
 551             | "asinf"
 552             | "atanf"
 553             => {
 554                 // FIXME: Using host floats.
 555                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 556                 let f = match link_name {
 557                     "cbrtf" => f.cbrt(),
 558                     "coshf" => f.cosh(),
 559                     "sinhf" => f.sinh(),
 560                     "tanf" => f.tan(),
 561                     "acosf" => f.acos(),
 562                     "asinf" => f.asin(),
 563                     "atanf" => f.atan(),
 564                     _ => bug!(),
 565                 };
 566                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 567             }
 568             // underscore case for windows
 569             | "_hypotf"
 570             | "hypotf"
 571             | "atan2f"
 572             => {
 573                 // FIXME: Using host floats.
 574                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 575                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 576                 let n = match link_name {
 577                     "_hypotf" | "hypotf" => f1.hypot(f2),
 578                     "atan2f" => f1.atan2(f2),
 579                     _ => bug!(),
 580                 };
 581                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 582             }
 583
 584             | "cbrt"
 585             | "cosh"
 586             | "sinh"
 587             | "tan"
 588             | "acos"
 589             | "asin"
 590             | "atan"
 591             => {
 592                 // FIXME: Using host floats.
 593                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 594                 let f = match link_name {
 595                     "cbrt" => f.cbrt(),
 596                     "cosh" => f.cosh(),
 597                     "sinh" => f.sinh(),
 598                     "tan" => f.tan(),
 599                     "acos" => f.acos(),
 600                     "asin" => f.asin(),
 601                     "atan" => f.atan(),
 602                     _ => bug!(),
 603                 };
 604                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 605             }
 606             // underscore case for windows, here and below
 607             // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
 608             | "_hypot"
 609             | "hypot"
 610             | "atan2"
 611             => {
 612                 // FIXME: Using host floats.
 613                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 614                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 615                 let n = match link_name {
 616                     "_hypot" | "hypot" => f1.hypot(f2),
 617                     "atan2" => f1.atan2(f2),
 618                     _ => bug!(),
 619                 };
 620                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 621             }
 622             // For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
 623             | "_ldexp"
 624             | "ldexp"
 625             | "scalbn"
 626             => {
 627                 let x = this.read_scalar(args[0])?.to_f64()?;
 628                 let exp = this.read_scalar(args[1])?.to_i32()?;
 629
 630                 // Saturating cast to i16. Even those are outside the valid exponent range to
 631                 // `scalbn` below will do its over/underflow handling.
 632                 let exp = if exp > i16::max_value() as i32 {
 633                     i16::max_value()
 634                 } else if exp < i16::min_value() as i32 {
 635                     i16::min_value()
 636                 } else {
 637                     exp.try_into().unwrap()
 638                 };
 639
 640                 let res = x.scalbn(exp);
 641                 this.write_scalar(Scalar::from_f64(res), dest)?;
 642             }
 643
 644             // Some things needed for `sys::thread` initialization to go through.
 645             | "signal"
 646             | "sigaction"
 647             | "sigaltstack"
 648             => {
 649                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 650             }
 651
 652             "sysconf" => {
 653                 let name = this.read_scalar(args[0])?.to_i32()?;
 654
 655                 trace!("sysconf() called with name {}", name);
 656                 // TODO: Cache the sysconf integers via Miri's global cache.
 657                 let paths = &[
 658                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(PAGE_SIZE, dest.layout.size)),
 659                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 660                     (
 661                         &["libc", "_SC_NPROCESSORS_ONLN"],
 662                         Scalar::from_int(NUM_CPUS, dest.layout.size),
 663                     ),
 664                 ];
 665                 let mut result = None;
 666                 for &(path, path_value) in paths {
 667                     if let Some(val) = this.eval_path_scalar(path)? {
 668                         let val = val.to_i32()?;
 669                         if val == name {
 670                             result = Some(path_value);
 671                             break;
 672                         }
 673                     }
 674                 }
 675                 if let Some(result) = result {
 676                     this.write_scalar(result, dest)?;
 677                 } else {
 678                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 679                 }
 680             }
 681
 682             "sched_getaffinity" => {
 683                 // Return an error; `num_cpus` then falls back to `sysconf`.
 684                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 685             }
 686
 687             "isatty" => {
 688                 this.write_null(dest)?;
 689             }
 690
 691             // Hook pthread calls that go to the thread-local storage memory subsystem.
 692             "pthread_key_create" => {
 693                 let key_place = this.deref_operand(args[0])?;
 694
 695                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 696                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 697                     Some(dtor_ptr) => Some(this.memory.get_fn(dtor_ptr)?.as_instance()?),
 698                     None => None,
 699                 };
 700
 701                 // Figure out how large a pthread TLS key actually is.
 702                 // This is `libc::pthread_key_t`.
 703                 let key_type = args[0].layout.ty
 704                     .builtin_deref(true)
 705                     .ok_or_else(|| err_ub_format!(
 706                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 707                     ))?
 708                     .ty;
 709                 let key_layout = this.layout_of(key_type)?;
 710
 711                 // Create key and write it into the memory where `key_ptr` wants it.
 712                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 713                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128)
 714                 {
 715                     throw_unsup!(OutOfTls);
 716                 }
 717
 718                 this.write_scalar(Scalar::from_uint(key, key_layout.size), key_place.into())?;
 719
 720                 // Return success (`0`).
 721                 this.write_null(dest)?;
 722             }
 723             "pthread_key_delete" => {
 724                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 725                 this.machine.tls.delete_tls_key(key)?;
 726                 // Return success (0)
 727                 this.write_null(dest)?;
 728             }
 729             "pthread_getspecific" => {
 730                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 731                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 732                 this.write_scalar(ptr, dest)?;
 733             }
 734             "pthread_setspecific" => {
 735                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 736                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 737                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 738
 739                 // Return success (`0`).
 740                 this.write_null(dest)?;
 741             }
 742
 743             // Stack size/address stuff.
 744             | "pthread_attr_init"
 745             | "pthread_attr_destroy"
 746             | "pthread_self"
 747             | "pthread_attr_setstacksize" => {
 748                 this.write_null(dest)?;
 749             }
 750             "pthread_attr_getstack" => {
 751                 let addr_place = this.deref_operand(args[1])?;
 752                 let size_place = this.deref_operand(args[2])?;
 753
 754                 this.write_scalar(
 755                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 756                     addr_place.into(),
 757                 )?;
 758                 this.write_scalar(
 759                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 760                     size_place.into(),
 761                 )?;
 762
 763                 // Return success (`0`).
 764                 this.write_null(dest)?;
 765             }
 766
 767             // We don't support threading. (Also for Windows.)
 768             | "pthread_create"
 769             | "CreateThread"
 770             => {
 771                 throw_unsup_format!("Miri does not support threading");
 772             }
 773
 774             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 775             | "pthread_mutexattr_init"
 776             | "pthread_mutexattr_settype"
 777             | "pthread_mutex_init"
 778             | "pthread_mutexattr_destroy"
 779             | "pthread_mutex_lock"
 780             | "pthread_mutex_unlock"
 781             | "pthread_mutex_destroy"
 782             | "pthread_rwlock_rdlock"
 783             | "pthread_rwlock_unlock"
 784             | "pthread_rwlock_wrlock"
 785             | "pthread_rwlock_destroy"
 786             | "pthread_condattr_init"
 787             | "pthread_condattr_setclock"
 788             | "pthread_cond_init"
 789             | "pthread_condattr_destroy"
 790             | "pthread_cond_destroy"
 791             => {
 792                 this.write_null(dest)?;
 793             }
 794
 795             // We don't support fork so we don't have to do anything for atfork.
 796             "pthread_atfork" => {
 797                 this.write_null(dest)?;
 798             }
 799
 800             "posix_fadvise" => {
 801                 // fadvise is only informational, we can ignore it.
 802                 this.write_null(dest)?;
 803             }
 804
 805             "mmap" => {
 806                 // 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.
 807                 let addr = this.read_scalar(args[0])?.not_undef()?;
 808                 this.write_scalar(addr, dest)?;
 809             }
 810             "mprotect" => {
 811                 this.write_null(dest)?;
 812             }
 813
 814             // macOS API stubs.
 815             | "pthread_attr_get_np"
 816             | "pthread_getattr_np"
 817             => {
 818                 this.write_null(dest)?;
 819             }
 820             "pthread_get_stackaddr_np" => {
 821                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 822                 this.write_scalar(stack_addr, dest)?;
 823             }
 824             "pthread_get_stacksize_np" => {
 825                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 826                 this.write_scalar(stack_size, dest)?;
 827             }
 828             "_tlv_atexit" => {
 829                 // FIXME: register the destructor.
 830             }
 831             "_NSGetArgc" => {
 832                 this.write_scalar(this.machine.argc.expect("machine must be initialized"), dest)?;
 833             }
 834             "_NSGetArgv" => {
 835                 this.write_scalar(this.machine.argv.expect("machine must be initialized"), dest)?;
 836             }
 837             "SecRandomCopyBytes" => {
 838                 let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 839                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 840                 this.gen_random(ptr, len as usize)?;
 841                 this.write_null(dest)?;
 842             }
 843
 844             // Windows API stubs.
 845             // HANDLE = isize
 846             // DWORD = ULONG = u32
 847             // BOOL = i32
 848             "GetProcessHeap" => {
 849                 // Just fake a HANDLE
 850                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 851             }
 852             "HeapAlloc" => {
 853                 let _handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 854                 let flags = this.read_scalar(args[1])?.to_u32()?;
 855                 let size = this.read_scalar(args[2])?.to_machine_usize(this)?;
 856                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 857                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 858                 this.write_scalar(res, dest)?;
 859             }
 860             "HeapFree" => {
 861                 let _handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 862                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 863                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 864                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 865                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 866             }
 867             "HeapReAlloc" => {
 868                 let _handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 869                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 870                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 871                 let size = this.read_scalar(args[3])?.to_machine_usize(this)?;
 872                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 873                 this.write_scalar(res, dest)?;
 874             }
 875
 876             "SetLastError" => {
 877                 this.set_last_error(this.read_scalar(args[0])?.not_undef()?)?;
 878             }
 879             "GetLastError" => {
 880                 let last_error = this.get_last_error()?;
 881                 this.write_scalar(last_error, dest)?;
 882             }
 883
 884             "AddVectoredExceptionHandler" => {
 885                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 886                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 887             }
 888
 889             | "InitializeCriticalSection"
 890             | "EnterCriticalSection"
 891             | "LeaveCriticalSection"
 892             | "DeleteCriticalSection"
 893             => {
 894                 // Nothing to do, not even a return value.
 895             }
 896
 897             | "GetModuleHandleW"
 898             | "GetProcAddress"
 899             | "TryEnterCriticalSection"
 900             | "GetConsoleScreenBufferInfo"
 901             | "SetConsoleTextAttribute"
 902             => {
 903                 // Pretend these do not exist / nothing happened, by returning zero.
 904                 this.write_null(dest)?;
 905             }
 906
 907             "GetSystemInfo" => {
 908                 let system_info = this.deref_operand(args[0])?;
 909                 // Initialize with `0`.
 910                 this.memory.write_bytes(
 911                     system_info.ptr,
 912                     iter::repeat(0u8).take(system_info.layout.size.bytes() as usize),
 913                 )?;
 914                 // Set number of processors.
 915                 let dword_size = Size::from_bytes(4);
 916                 let num_cpus = this.mplace_field(system_info, 6)?;
 917                 this.write_scalar(Scalar::from_int(NUM_CPUS, dword_size), num_cpus.into())?;
 918             }
 919
 920             "TlsAlloc" => {
 921                 // This just creates a key; Windows does not natively support TLS destructors.
 922
 923                 // Create key and return it.
 924                 let key = this.machine.tls.create_tls_key(None) as u128;
 925
 926                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 927                 if dest.layout.size.bits() < 128
 928                     && key >= (1u128 << dest.layout.size.bits() as u128)
 929                 {
 930                     throw_unsup!(OutOfTls);
 931                 }
 932                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 933             }
 934             "TlsGetValue" => {
 935                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 936                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 937                 this.write_scalar(ptr, dest)?;
 938             }
 939             "TlsSetValue" => {
 940                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 941                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 942                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 943
 944                 // Return success (`1`).
 945                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 946             }
 947             "GetStdHandle" => {
 948                 let which = this.read_scalar(args[0])?.to_i32()?;
 949                 // We just make this the identity function, so we know later in `WriteFile`
 950                 // which one it is.
 951                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 952             }
 953             "WriteFile" => {
 954                 let handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 955                 let buf = this.read_scalar(args[1])?.not_undef()?;
 956                 let n = this.read_scalar(args[2])?.to_u32()?;
 957                 let written_place = this.deref_operand(args[3])?;
 958                 // Spec says to always write `0` first.
 959                 this.write_null(written_place.into())?;
 960                 let written = if handle == -11 || handle == -12 {
 961                     // stdout/stderr
 962                     use std::io::{self, Write};
 963
 964                     let buf_cont = this.memory.read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 965                     let res = if handle == -11 {
 966                         io::stdout().write(buf_cont)
 967                     } else {
 968                         io::stderr().write(buf_cont)
 969                     };
 970                     res.ok().map(|n| n as u32)
 971                 } else {
 972                     eprintln!("Miri: Ignored output to handle {}", handle);
 973                     // Pretend it all went well.
 974                     Some(n)
 975                 };
 976                 // If there was no error, write back how much was written.
 977                 if let Some(n) = written {
 978                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 979                 }
 980                 // Return whether this was a success.
 981                 this.write_scalar(
 982                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 983                     dest,
 984                 )?;
 985             }
 986             "GetConsoleMode" => {
 987                 // Everything is a pipe.
 988                 this.write_null(dest)?;
 989             }
 990             "GetEnvironmentVariableW" => {
 991                 // args[0] : LPCWSTR lpName (32-bit ptr to a const string of 16-bit Unicode chars)
 992                 // args[1] : LPWSTR lpBuffer (32-bit pointer to a string of 16-bit Unicode chars)
 993                 // lpBuffer : ptr to buffer that receives contents of the env_var as a null-terminated string.
 994                 // Return `# of chars` stored in the buffer pointed to by lpBuffer, excluding null-terminator.
 995                 // Return 0 upon failure.
 996
 997                 // This is not the env var you are looking for.
 998                 this.set_last_error(Scalar::from_u32(203))?; // ERROR_ENVVAR_NOT_FOUND
 999                 this.write_null(dest)?;
1000             }
1001             "SetEnvironmentVariableW" => {
1002                 // args[0] : LPCWSTR lpName (32-bit ptr to a const string of 16-bit Unicode chars)
1003                 // args[1] : LPCWSTR lpValue (32-bit ptr to a const string of 16-bit Unicode chars)
1004                 // Return nonzero if success, else return 0.
1005                 throw_unsup_format!("can't set environment variable on Windows");
1006             }
1007             "GetCommandLineW" => {
1008                 this.write_scalar(
1009                     this.machine.cmd_line.expect("machine must be initialized"),
1010                     dest,
1011                 )?;
1012             }
1013             // The actual name of 'RtlGenRandom'
1014             "SystemFunction036" => {
1015                 let ptr = this.read_scalar(args[0])?.not_undef()?;
1016                 let len = this.read_scalar(args[1])?.to_u32()?;
1017                 this.gen_random(ptr, len as usize)?;
1018                 this.write_scalar(Scalar::from_bool(true), dest)?;
1019             }
1020
1021             // We can't execute anything else.
1022             _ => throw_unsup_format!("can't call foreign function: {}", link_name),
1023         }
1024
1025         this.dump_place(*dest);
1026         this.go_to_block(ret);
1027         Ok(None)
1028     }
1029
1030     /// Evaluates the scalar at the specified path. Returns Some(val)
1031     /// if the path could be resolved, and None otherwise
1032     fn eval_path_scalar(
1033         &mut self,
1034         path: &[&str],
1035     ) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
1036         let this = self.eval_context_mut();
1037         if let Ok(instance) = this.resolve_path(path) {
1038             let cid = GlobalId { instance, promoted: None };
1039             let const_val = this.const_eval_raw(cid)?;
1040             let const_val = this.read_scalar(const_val.into())?;
1041             return Ok(Some(const_val));
1042         }
1043         return Ok(None);
1044     }
1045 }
1046
1047 // Shims the linux 'getrandom()' syscall.
1048 fn linux_getrandom<'tcx>(
1049     this: &mut MiriEvalContext<'_, 'tcx>,
1050     args: &[OpTy<'tcx, Tag>],
1051     dest: PlaceTy<'tcx, Tag>,
1052 ) -> InterpResult<'tcx> {
1053     let ptr = this.read_scalar(args[0])?.not_undef()?;
1054     let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
1055
1056     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
1057     // neither of which have any effect on our current PRNG.
1058     let _flags = this.read_scalar(args[2])?.to_i32()?;
1059
1060     this.gen_random(ptr, len as usize)?;
1061     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
1062     Ok(())
1063 }