src/shims/foreign_items.rs

   1 mod windows;
   2 mod posix;
   3
   4 use std::{convert::TryInto, iter};
   5
   6 use rustc_hir::def_id::DefId;
   7 use rustc::mir;
   8 use rustc::ty;
   9 use rustc::ty::layout::{Align, LayoutOf, Size};
  10 use rustc_apfloat::Float;
  11 use rustc_span::symbol::sym;
  12 use syntax::attr;
  13
  14 use crate::*;
  15
  16 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  17 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  18     /// Returns the minimum alignment for the target architecture for allocations of the given size.
  19     fn min_align(&self, size: u64, kind: MiriMemoryKind) -> Align {
  20         let this = self.eval_context_ref();
  21         // List taken from `libstd/sys_common/alloc.rs`.
  22         let min_align = match this.tcx.tcx.sess.target.target.arch.as_str() {
  23             "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
  24             "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" => 16,
  25             arch => bug!("Unsupported target architecture: {}", arch),
  26         };
  27         // Windows always aligns, even small allocations.
  28         // Source: <https://support.microsoft.com/en-us/help/286470/how-to-use-pageheap-exe-in-windows-xp-windows-2000-and-windows-server>
  29         // But jemalloc does not, so for the C heap we only align if the allocation is sufficiently big.
  30         if kind == MiriMemoryKind::WinHeap || size >= min_align {
  31             return Align::from_bytes(min_align).unwrap();
  32         }
  33         // We have `size < min_align`. Round `size` *down* to the next power of two and use that.
  34         fn prev_power_of_two(x: u64) -> u64 {
  35             let next_pow2 = x.next_power_of_two();
  36             if next_pow2 == x {
  37                 // x *is* a power of two, just use that.
  38                 x
  39             } else {
  40                 // x is between two powers, so next = 2*prev.
  41                 next_pow2 / 2
  42             }
  43         }
  44         Align::from_bytes(prev_power_of_two(size)).unwrap()
  45     }
  46
  47     fn malloc(&mut self, size: u64, zero_init: bool, kind: MiriMemoryKind) -> Scalar<Tag> {
  48         let this = self.eval_context_mut();
  49         if size == 0 {
  50             Scalar::from_int(0, this.pointer_size())
  51         } else {
  52             let align = this.min_align(size, kind);
  53             let ptr = this.memory.allocate(Size::from_bytes(size), align, kind.into());
  54             if zero_init {
  55                 // We just allocated this, the access is definitely in-bounds.
  56                 this.memory.write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize)).unwrap();
  57             }
  58             Scalar::Ptr(ptr)
  59         }
  60     }
  61
  62     fn free(&mut self, ptr: Scalar<Tag>, kind: MiriMemoryKind) -> InterpResult<'tcx> {
  63         let this = self.eval_context_mut();
  64         if !this.is_null(ptr)? {
  65             let ptr = this.force_ptr(ptr)?;
  66             this.memory.deallocate(ptr, None, kind.into())?;
  67         }
  68         Ok(())
  69     }
  70
  71     fn realloc(
  72         &mut self,
  73         old_ptr: Scalar<Tag>,
  74         new_size: u64,
  75         kind: MiriMemoryKind,
  76     ) -> InterpResult<'tcx, Scalar<Tag>> {
  77         let this = self.eval_context_mut();
  78         let new_align = this.min_align(new_size, kind);
  79         if this.is_null(old_ptr)? {
  80             if new_size == 0 {
  81                 Ok(Scalar::from_int(0, this.pointer_size()))
  82             } else {
  83                 let new_ptr =
  84                     this.memory.allocate(Size::from_bytes(new_size), new_align, kind.into());
  85                 Ok(Scalar::Ptr(new_ptr))
  86             }
  87         } else {
  88             let old_ptr = this.force_ptr(old_ptr)?;
  89             if new_size == 0 {
  90                 this.memory.deallocate(old_ptr, None, kind.into())?;
  91                 Ok(Scalar::from_int(0, this.pointer_size()))
  92             } else {
  93                 let new_ptr = this.memory.reallocate(
  94                     old_ptr,
  95                     None,
  96                     Size::from_bytes(new_size),
  97                     new_align,
  98                     kind.into(),
  99                 )?;
 100                 Ok(Scalar::Ptr(new_ptr))
 101             }
 102         }
 103     }
 104
 105     /// Emulates calling a foreign item, failing if the item is not supported.
 106     /// This function will handle `goto_block` if needed.
 107     /// Returns Ok(None) if the foreign item was completely handled
 108     /// by this function.
 109     /// Returns Ok(Some(body)) if processing the foreign item
 110     /// is delegated to another function.
 111     #[rustfmt::skip]
 112     fn emulate_foreign_item(
 113         &mut self,
 114         def_id: DefId,
 115         args: &[OpTy<'tcx, Tag>],
 116         ret: Option<(PlaceTy<'tcx, Tag>, mir::BasicBlock)>,
 117         _unwind: Option<mir::BasicBlock>,
 118     ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
 119         let this = self.eval_context_mut();
 120         let attrs = this.tcx.get_attrs(def_id);
 121         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 122             Some(name) => name.as_str(),
 123             None => this.tcx.item_name(def_id).as_str(),
 124         };
 125         // Strip linker suffixes (seen on 32-bit macOS).
 126         let link_name = link_name.trim_end_matches("$UNIX2003");
 127         let tcx = &{ this.tcx.tcx };
 128
 129         // First: functions that diverge.
 130         let (dest, ret) = match link_name {
 131             // Note that this matches calls to the *foreign* item `__rust_start_panic* -
 132             // that is, calls to `extern "Rust" { fn __rust_start_panic(...) }`.
 133             // We forward this to the underlying *implementation* in the panic runtime crate.
 134             // Normally, this will be either `libpanic_unwind` or `libpanic_abort`, but it could
 135             // also be a custom user-provided implementation via `#![feature(panic_runtime)]`
 136             "__rust_start_panic" => {
 137                 // FIXME we might want to cache this... but it's not really performance-critical.
 138                 let panic_runtime = tcx
 139                     .crates()
 140                     .iter()
 141                     .find(|cnum| tcx.is_panic_runtime(**cnum))
 142                     .expect("No panic runtime found!");
 143                 let panic_runtime = tcx.crate_name(*panic_runtime);
 144                 let start_panic_instance =
 145                     this.resolve_path(&[&*panic_runtime.as_str(), "__rust_start_panic"])?;
 146                 return Ok(Some(&*this.load_mir(start_panic_instance.def, None)?));
 147             }
 148             // Similarly, we forward calls to the `panic_impl` foreign item to its implementation.
 149             // The implementation is provided by the function with the `#[panic_handler]` attribute.
 150             "panic_impl" => {
 151                 let panic_impl_id = this.tcx.lang_items().panic_impl().unwrap();
 152                 let panic_impl_instance = ty::Instance::mono(*this.tcx, panic_impl_id);
 153                 return Ok(Some(&*this.load_mir(panic_impl_instance.def, None)?));
 154             }
 155
 156             | "exit"
 157             | "ExitProcess"
 158             => {
 159                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` variant anyway
 160                 let code = this.read_scalar(args[0])?.to_i32()?;
 161                 throw_machine_stop!(TerminationInfo::Exit(code.into()));
 162             }
 163             _ => {
 164                 if let Some(p) = ret {
 165                     p
 166                 } else {
 167                     throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
 168                 }
 169             }
 170         };
 171
 172         // Next: functions that return.
 173         match link_name {
 174             "__rust_maybe_catch_panic" => {
 175                 this.handle_catch_panic(args, dest, ret)?;
 176                 return Ok(None);
 177             }
 178
 179             _ => this.emulate_foreign_item_by_name(link_name, args, dest)?,
 180         };
 181
 182         this.dump_place(*dest);
 183         this.go_to_block(ret);
 184
 185         Ok(None)
 186     }
 187
 188     fn emulate_foreign_item_by_name(
 189         &mut self,
 190         link_name: &str,
 191         args: &[OpTy<'tcx, Tag>],
 192         dest: PlaceTy<'tcx, Tag>,
 193     ) -> InterpResult<'tcx> {
 194         let this = self.eval_context_mut();
 195         let tcx = &{ this.tcx.tcx };
 196
 197         match link_name {
 198             "malloc" => {
 199                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 200                 let res = this.malloc(size, /*zero_init:*/ false, MiriMemoryKind::C);
 201                 this.write_scalar(res, dest)?;
 202             }
 203             "calloc" => {
 204                 let items = this.read_scalar(args[0])?.to_machine_usize(this)?;
 205                 let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 206                 let size =
 207                     items.checked_mul(len).ok_or_else(|| err_ub_format!("overflow during calloc size computation"))?;
 208                 let res = this.malloc(size, /*zero_init:*/ true, MiriMemoryKind::C);
 209                 this.write_scalar(res, dest)?;
 210             }
 211             "posix_memalign" => {
 212                 let ret = this.deref_operand(args[0])?;
 213                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 214                 let size = this.read_scalar(args[2])?.to_machine_usize(this)?;
 215                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 216                 if !align.is_power_of_two() {
 217                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 218                 }
 219                 if align < this.pointer_size().bytes() {
 220                     throw_ub_format!(
 221                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 222                         align,
 223                     );
 224                 }
 225
 226                 if size == 0 {
 227                     this.write_null(ret.into())?;
 228                 } else {
 229                     let ptr = this.memory.allocate(
 230                         Size::from_bytes(size),
 231                         Align::from_bytes(align).unwrap(),
 232                         MiriMemoryKind::C.into(),
 233                     );
 234                     this.write_scalar(ptr, ret.into())?;
 235                 }
 236                 this.write_null(dest)?;
 237             }
 238             "free" => {
 239                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 240                 this.free(ptr, MiriMemoryKind::C)?;
 241             }
 242             "realloc" => {
 243                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 244                 let new_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 245                 let res = this.realloc(old_ptr, new_size, MiriMemoryKind::C)?;
 246                 this.write_scalar(res, dest)?;
 247             }
 248
 249             "__rust_alloc" => {
 250                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 251                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 252                 if size == 0 {
 253                     throw_unsup!(HeapAllocZeroBytes);
 254                 }
 255                 if !align.is_power_of_two() {
 256                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 257                 }
 258                 let ptr = this.memory.allocate(
 259                     Size::from_bytes(size),
 260                     Align::from_bytes(align).unwrap(),
 261                     MiriMemoryKind::Rust.into(),
 262                 );
 263                 this.write_scalar(ptr, dest)?;
 264             }
 265             "__rust_alloc_zeroed" => {
 266                 let size = this.read_scalar(args[0])?.to_machine_usize(this)?;
 267                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 268                 if size == 0 {
 269                     throw_unsup!(HeapAllocZeroBytes);
 270                 }
 271                 if !align.is_power_of_two() {
 272                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 273                 }
 274                 let ptr = this.memory.allocate(
 275                     Size::from_bytes(size),
 276                     Align::from_bytes(align).unwrap(),
 277                     MiriMemoryKind::Rust.into(),
 278                 );
 279                 // We just allocated this, the access is definitely in-bounds.
 280                 this.memory.write_bytes(ptr.into(), iter::repeat(0u8).take(size as usize)).unwrap();
 281                 this.write_scalar(ptr, dest)?;
 282             }
 283             "__rust_dealloc" => {
 284                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 285                 let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 286                 let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
 287                 if old_size == 0 {
 288                     throw_unsup!(HeapAllocZeroBytes);
 289                 }
 290                 if !align.is_power_of_two() {
 291                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 292                 }
 293                 let ptr = this.force_ptr(ptr)?;
 294                 this.memory.deallocate(
 295                     ptr,
 296                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 297                     MiriMemoryKind::Rust.into(),
 298                 )?;
 299             }
 300             "__rust_realloc" => {
 301                 let old_size = this.read_scalar(args[1])?.to_machine_usize(this)?;
 302                 let align = this.read_scalar(args[2])?.to_machine_usize(this)?;
 303                 let new_size = this.read_scalar(args[3])?.to_machine_usize(this)?;
 304                 if old_size == 0 || new_size == 0 {
 305                     throw_unsup!(HeapAllocZeroBytes);
 306                 }
 307                 if !align.is_power_of_two() {
 308                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 309                 }
 310                 let ptr = this.force_ptr(this.read_scalar(args[0])?.not_undef()?)?;
 311                 let align = Align::from_bytes(align).unwrap();
 312                 let new_ptr = this.memory.reallocate(
 313                     ptr,
 314                     Some((Size::from_bytes(old_size), align)),
 315                     Size::from_bytes(new_size),
 316                     align,
 317                     MiriMemoryKind::Rust.into(),
 318                 )?;
 319                 this.write_scalar(new_ptr, dest)?;
 320             }
 321
 322             "syscall" => {
 323                 let sys_getrandom = this
 324                     .eval_path_scalar(&["libc", "SYS_getrandom"])?
 325                     .expect("Failed to get libc::SYS_getrandom")
 326                     .to_machine_usize(this)?;
 327
 328                 let sys_statx = this
 329                     .eval_path_scalar(&["libc", "SYS_statx"])?
 330                     .expect("Failed to get libc::SYS_statx")
 331                     .to_machine_usize(this)?;
 332
 333                 match this.read_scalar(args[0])?.to_machine_usize(this)? {
 334                     // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 335                     // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 336                     id if id == sys_getrandom => {
 337                         // The first argument is the syscall id,
 338                         // so skip over it.
 339                         linux_getrandom(this, &args[1..], dest)?;
 340                     }
 341                     id if id == sys_statx => {
 342                         // The first argument is the syscall id,
 343                         // so skip over it.
 344                         let result = this.statx(args[1], args[2], args[3], args[4], args[5])?;
 345                         this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 346                     }
 347                     id => throw_unsup_format!("miri does not support syscall ID {}", id),
 348                 }
 349             }
 350
 351             "getrandom" => {
 352                 linux_getrandom(this, args, dest)?;
 353             }
 354
 355             "dlsym" => {
 356                 let _handle = this.read_scalar(args[0])?;
 357                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 358                 let symbol_name = this.memory.read_c_str(symbol)?;
 359                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 360                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 361                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 362                     let ptr = this.memory.create_fn_alloc(FnVal::Other(dlsym));
 363                     this.write_scalar(Scalar::from(ptr), dest)?;
 364                 } else {
 365                     this.write_null(dest)?;
 366                 }
 367             }
 368
 369             "memcmp" => {
 370                 let left = this.read_scalar(args[0])?.not_undef()?;
 371                 let right = this.read_scalar(args[1])?.not_undef()?;
 372                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_machine_usize(this)?);
 373
 374                 let result = {
 375                     let left_bytes = this.memory.read_bytes(left, n)?;
 376                     let right_bytes = this.memory.read_bytes(right, n)?;
 377
 378                     use std::cmp::Ordering::*;
 379                     match left_bytes.cmp(right_bytes) {
 380                         Less => -1i32,
 381                         Equal => 0,
 382                         Greater => 1,
 383                     }
 384                 };
 385
 386                 this.write_scalar(Scalar::from_int(result, Size::from_bits(32)), dest)?;
 387             }
 388
 389             "memrchr" => {
 390                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 391                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 392                 let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
 393                 if let Some(idx) = this
 394                     .memory
 395                     .read_bytes(ptr, Size::from_bytes(num))?
 396                     .iter()
 397                     .rev()
 398                     .position(|&c| c == val)
 399                 {
 400                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 401                     this.write_scalar(new_ptr, dest)?;
 402                 } else {
 403                     this.write_null(dest)?;
 404                 }
 405             }
 406
 407             "memchr" => {
 408                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 409                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 410                 let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
 411                 let idx = this
 412                     .memory
 413                     .read_bytes(ptr, Size::from_bytes(num))?
 414                     .iter()
 415                     .position(|&c| c == val);
 416                 if let Some(idx) = idx {
 417                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 418                     this.write_scalar(new_ptr, dest)?;
 419                 } else {
 420                     this.write_null(dest)?;
 421                 }
 422             }
 423
 424
 425             "rename" => {
 426                 let result = this.rename(args[0], args[1])?;
 427                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
 428             }
 429
 430             "strlen" => {
 431                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 432                 let n = this.memory.read_c_str(ptr)?.len();
 433                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 434             }
 435
 436             // math functions
 437             | "cbrtf"
 438             | "coshf"
 439             | "sinhf"
 440             | "tanf"
 441             | "acosf"
 442             | "asinf"
 443             | "atanf"
 444             => {
 445                 // FIXME: Using host floats.
 446                 let f = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 447                 let f = match link_name {
 448                     "cbrtf" => f.cbrt(),
 449                     "coshf" => f.cosh(),
 450                     "sinhf" => f.sinh(),
 451                     "tanf" => f.tan(),
 452                     "acosf" => f.acos(),
 453                     "asinf" => f.asin(),
 454                     "atanf" => f.atan(),
 455                     _ => bug!(),
 456                 };
 457                 this.write_scalar(Scalar::from_u32(f.to_bits()), dest)?;
 458             }
 459             // underscore case for windows
 460             | "_hypotf"
 461             | "hypotf"
 462             | "atan2f"
 463             => {
 464                 // FIXME: Using host floats.
 465                 let f1 = f32::from_bits(this.read_scalar(args[0])?.to_u32()?);
 466                 let f2 = f32::from_bits(this.read_scalar(args[1])?.to_u32()?);
 467                 let n = match link_name {
 468                     "_hypotf" | "hypotf" => f1.hypot(f2),
 469                     "atan2f" => f1.atan2(f2),
 470                     _ => bug!(),
 471                 };
 472                 this.write_scalar(Scalar::from_u32(n.to_bits()), dest)?;
 473             }
 474
 475             | "cbrt"
 476             | "cosh"
 477             | "sinh"
 478             | "tan"
 479             | "acos"
 480             | "asin"
 481             | "atan"
 482             => {
 483                 // FIXME: Using host floats.
 484                 let f = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 485                 let f = match link_name {
 486                     "cbrt" => f.cbrt(),
 487                     "cosh" => f.cosh(),
 488                     "sinh" => f.sinh(),
 489                     "tan" => f.tan(),
 490                     "acos" => f.acos(),
 491                     "asin" => f.asin(),
 492                     "atan" => f.atan(),
 493                     _ => bug!(),
 494                 };
 495                 this.write_scalar(Scalar::from_u64(f.to_bits()), dest)?;
 496             }
 497             // underscore case for windows, here and below
 498             // (see https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/floating-point-primitives?view=vs-2019)
 499             | "_hypot"
 500             | "hypot"
 501             | "atan2"
 502             => {
 503                 // FIXME: Using host floats.
 504                 let f1 = f64::from_bits(this.read_scalar(args[0])?.to_u64()?);
 505                 let f2 = f64::from_bits(this.read_scalar(args[1])?.to_u64()?);
 506                 let n = match link_name {
 507                     "_hypot" | "hypot" => f1.hypot(f2),
 508                     "atan2" => f1.atan2(f2),
 509                     _ => bug!(),
 510                 };
 511                 this.write_scalar(Scalar::from_u64(n.to_bits()), dest)?;
 512             }
 513             // For radix-2 (binary) systems, `ldexp` and `scalbn` are the same.
 514             | "_ldexp"
 515             | "ldexp"
 516             | "scalbn"
 517             => {
 518                 let x = this.read_scalar(args[0])?.to_f64()?;
 519                 let exp = this.read_scalar(args[1])?.to_i32()?;
 520
 521                 // Saturating cast to i16. Even those are outside the valid exponent range to
 522                 // `scalbn` below will do its over/underflow handling.
 523                 let exp = if exp > i16::max_value() as i32 {
 524                     i16::max_value()
 525                 } else if exp < i16::min_value() as i32 {
 526                     i16::min_value()
 527                 } else {
 528                     exp.try_into().unwrap()
 529                 };
 530
 531                 let res = x.scalbn(exp);
 532                 this.write_scalar(Scalar::from_f64(res), dest)?;
 533             }
 534
 535             // Some things needed for `sys::thread` initialization to go through.
 536             | "signal"
 537             | "sigaction"
 538             | "sigaltstack"
 539             => {
 540                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 541             }
 542
 543             "sysconf" => {
 544                 let name = this.read_scalar(args[0])?.to_i32()?;
 545
 546                 trace!("sysconf() called with name {}", name);
 547                 // TODO: Cache the sysconf integers via Miri's global cache.
 548                 let paths = &[
 549                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(PAGE_SIZE, dest.layout.size)),
 550                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 551                     (
 552                         &["libc", "_SC_NPROCESSORS_ONLN"],
 553                         Scalar::from_int(NUM_CPUS, dest.layout.size),
 554                     ),
 555                 ];
 556                 let mut result = None;
 557                 for &(path, path_value) in paths {
 558                     if let Some(val) = this.eval_path_scalar(path)? {
 559                         let val = val.to_i32()?;
 560                         if val == name {
 561                             result = Some(path_value);
 562                             break;
 563                         }
 564                     }
 565                 }
 566                 if let Some(result) = result {
 567                     this.write_scalar(result, dest)?;
 568                 } else {
 569                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 570                 }
 571             }
 572
 573             "sched_getaffinity" => {
 574                 // Return an error; `num_cpus` then falls back to `sysconf`.
 575                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 576             }
 577
 578             "isatty" => {
 579                 this.write_null(dest)?;
 580             }
 581
 582             // Hook pthread calls that go to the thread-local storage memory subsystem.
 583             "pthread_key_create" => {
 584                 let key_place = this.deref_operand(args[0])?;
 585
 586                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 587                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 588                     Some(dtor_ptr) => Some(this.memory.get_fn(dtor_ptr)?.as_instance()?),
 589                     None => None,
 590                 };
 591
 592                 // Figure out how large a pthread TLS key actually is.
 593                 // This is `libc::pthread_key_t`.
 594                 let key_type = args[0].layout.ty
 595                     .builtin_deref(true)
 596                     .ok_or_else(|| err_ub_format!(
 597                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 598                     ))?
 599                     .ty;
 600                 let key_layout = this.layout_of(key_type)?;
 601
 602                 // Create key and write it into the memory where `key_ptr` wants it.
 603                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 604                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128)
 605                 {
 606                     throw_unsup!(OutOfTls);
 607                 }
 608
 609                 this.write_scalar(Scalar::from_uint(key, key_layout.size), key_place.into())?;
 610
 611                 // Return success (`0`).
 612                 this.write_null(dest)?;
 613             }
 614             "pthread_key_delete" => {
 615                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 616                 this.machine.tls.delete_tls_key(key)?;
 617                 // Return success (0)
 618                 this.write_null(dest)?;
 619             }
 620             "pthread_getspecific" => {
 621                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 622                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 623                 this.write_scalar(ptr, dest)?;
 624             }
 625             "pthread_setspecific" => {
 626                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 627                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 628                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 629
 630                 // Return success (`0`).
 631                 this.write_null(dest)?;
 632             }
 633
 634             // Stack size/address stuff.
 635             | "pthread_attr_init"
 636             | "pthread_attr_destroy"
 637             | "pthread_self"
 638             | "pthread_attr_setstacksize" => {
 639                 this.write_null(dest)?;
 640             }
 641             "pthread_attr_getstack" => {
 642                 let addr_place = this.deref_operand(args[1])?;
 643                 let size_place = this.deref_operand(args[2])?;
 644
 645                 this.write_scalar(
 646                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 647                     addr_place.into(),
 648                 )?;
 649                 this.write_scalar(
 650                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 651                     size_place.into(),
 652                 )?;
 653
 654                 // Return success (`0`).
 655                 this.write_null(dest)?;
 656             }
 657
 658             // We don't support threading. (Also for Windows.)
 659             | "pthread_create"
 660             | "CreateThread"
 661             => {
 662                 throw_unsup_format!("Miri does not support threading");
 663             }
 664
 665             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 666             | "pthread_mutexattr_init"
 667             | "pthread_mutexattr_settype"
 668             | "pthread_mutex_init"
 669             | "pthread_mutexattr_destroy"
 670             | "pthread_mutex_lock"
 671             | "pthread_mutex_unlock"
 672             | "pthread_mutex_destroy"
 673             | "pthread_rwlock_rdlock"
 674             | "pthread_rwlock_unlock"
 675             | "pthread_rwlock_wrlock"
 676             | "pthread_rwlock_destroy"
 677             | "pthread_condattr_init"
 678             | "pthread_condattr_setclock"
 679             | "pthread_cond_init"
 680             | "pthread_condattr_destroy"
 681             | "pthread_cond_destroy"
 682             => {
 683                 this.write_null(dest)?;
 684             }
 685
 686             // We don't support fork so we don't have to do anything for atfork.
 687             "pthread_atfork" => {
 688                 this.write_null(dest)?;
 689             }
 690
 691             "posix_fadvise" => {
 692                 // fadvise is only informational, we can ignore it.
 693                 this.write_null(dest)?;
 694             }
 695
 696             "mmap" => {
 697                 // 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.
 698                 let addr = this.read_scalar(args[0])?.not_undef()?;
 699                 this.write_scalar(addr, dest)?;
 700             }
 701             "mprotect" => {
 702                 this.write_null(dest)?;
 703             }
 704
 705             // macOS API stubs.
 706             | "pthread_attr_get_np"
 707             | "pthread_getattr_np"
 708             => {
 709                 this.write_null(dest)?;
 710             }
 711             "pthread_get_stackaddr_np" => {
 712                 let stack_addr = Scalar::from_uint(STACK_ADDR, dest.layout.size);
 713                 this.write_scalar(stack_addr, dest)?;
 714             }
 715             "pthread_get_stacksize_np" => {
 716                 let stack_size = Scalar::from_uint(STACK_SIZE, dest.layout.size);
 717                 this.write_scalar(stack_size, dest)?;
 718             }
 719             "_tlv_atexit" => {
 720                 // FIXME: register the destructor.
 721             }
 722             "_NSGetArgc" => {
 723                 this.write_scalar(this.machine.argc.expect("machine must be initialized"), dest)?;
 724             }
 725             "_NSGetArgv" => {
 726                 this.write_scalar(this.machine.argv.expect("machine must be initialized"), dest)?;
 727             }
 728             "SecRandomCopyBytes" => {
 729                 let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 730                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 731                 this.gen_random(ptr, len as usize)?;
 732                 this.write_null(dest)?;
 733             }
 734
 735             // Windows API stubs.
 736             // HANDLE = isize
 737             // DWORD = ULONG = u32
 738             // BOOL = i32
 739             "GetProcessHeap" => {
 740                 // Just fake a HANDLE
 741                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 742             }
 743             "HeapAlloc" => {
 744                 let _handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 745                 let flags = this.read_scalar(args[1])?.to_u32()?;
 746                 let size = this.read_scalar(args[2])?.to_machine_usize(this)?;
 747                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 748                 let res = this.malloc(size, zero_init, MiriMemoryKind::WinHeap);
 749                 this.write_scalar(res, dest)?;
 750             }
 751             "HeapFree" => {
 752                 let _handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 753                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 754                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 755                 this.free(ptr, MiriMemoryKind::WinHeap)?;
 756                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 757             }
 758             "HeapReAlloc" => {
 759                 let _handle = this.read_scalar(args[0])?.to_machine_isize(this)?;
 760                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 761                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 762                 let size = this.read_scalar(args[3])?.to_machine_usize(this)?;
 763                 let res = this.realloc(ptr, size, MiriMemoryKind::WinHeap)?;
 764                 this.write_scalar(res, dest)?;
 765             }
 766
 767             "SetLastError" => {
 768                 this.set_last_error(this.read_scalar(args[0])?.not_undef()?)?;
 769             }
 770             "GetLastError" => {
 771                 let last_error = this.get_last_error()?;
 772                 this.write_scalar(last_error, dest)?;
 773             }
 774
 775             "AddVectoredExceptionHandler" => {
 776                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 777                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 778             }
 779
 780             | "InitializeCriticalSection"
 781             | "EnterCriticalSection"
 782             | "LeaveCriticalSection"
 783             | "DeleteCriticalSection"
 784             => {
 785                 // Nothing to do, not even a return value.
 786             }
 787
 788             | "GetModuleHandleW"
 789             | "GetProcAddress"
 790             | "TryEnterCriticalSection"
 791             | "GetConsoleScreenBufferInfo"
 792             | "SetConsoleTextAttribute"
 793             => {
 794                 // Pretend these do not exist / nothing happened, by returning zero.
 795                 this.write_null(dest)?;
 796             }
 797
 798             "GetSystemInfo" => {
 799                 let system_info = this.deref_operand(args[0])?;
 800                 // Initialize with `0`.
 801                 this.memory.write_bytes(
 802                     system_info.ptr,
 803                     iter::repeat(0u8).take(system_info.layout.size.bytes() as usize),
 804                 )?;
 805                 // Set number of processors.
 806                 let dword_size = Size::from_bytes(4);
 807                 let num_cpus = this.mplace_field(system_info, 6)?;
 808                 this.write_scalar(Scalar::from_int(NUM_CPUS, dword_size), num_cpus.into())?;
 809             }
 810
 811             "TlsAlloc" => {
 812                 // This just creates a key; Windows does not natively support TLS destructors.
 813
 814                 // Create key and return it.
 815                 let key = this.machine.tls.create_tls_key(None) as u128;
 816
 817                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 818                 if dest.layout.size.bits() < 128
 819                     && key >= (1u128 << dest.layout.size.bits() as u128)
 820                 {
 821                     throw_unsup!(OutOfTls);
 822                 }
 823                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 824             }
 825             "TlsGetValue" => {
 826                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 827                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 828                 this.write_scalar(ptr, dest)?;
 829             }
 830             "TlsSetValue" => {
 831                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 832                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 833                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 834
 835                 // Return success (`1`).
 836                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 837             }
 838             "GetStdHandle" => {
 839                 let which = this.read_scalar(args[0])?.to_i32()?;
 840                 // We just make this the identity function, so we know later in `WriteFile`
 841                 // which one it is.
 842                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 843             }
 844             "GetConsoleMode" => {
 845                 // Everything is a pipe.
 846                 this.write_null(dest)?;
 847             }
 848             "GetCommandLineW" => {
 849                 this.write_scalar(
 850                     this.machine.cmd_line.expect("machine must be initialized"),
 851                     dest,
 852                 )?;
 853             }
 854             // The actual name of 'RtlGenRandom'
 855             "SystemFunction036" => {
 856                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 857                 let len = this.read_scalar(args[1])?.to_u32()?;
 858                 this.gen_random(ptr, len as usize)?;
 859                 this.write_scalar(Scalar::from_bool(true), dest)?;
 860             }
 861
 862             _ => match this.tcx.sess.target.target.target_os.to_lowercase().as_str() {
 863                 "linux" | "macos" => posix::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest)?,
 864                 "windows" => windows::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest)?,
 865                 target => throw_unsup_format!("The {} target platform is not supported", target),
 866             }
 867         };
 868
 869         Ok(())
 870     }
 871
 872     /// Evaluates the scalar at the specified path. Returns Some(val)
 873     /// if the path could be resolved, and None otherwise
 874     fn eval_path_scalar(
 875         &mut self,
 876         path: &[&str],
 877     ) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 878         let this = self.eval_context_mut();
 879         if let Ok(instance) = this.resolve_path(path) {
 880             let cid = GlobalId { instance, promoted: None };
 881             let const_val = this.const_eval_raw(cid)?;
 882             let const_val = this.read_scalar(const_val.into())?;
 883             return Ok(Some(const_val));
 884         }
 885         return Ok(None);
 886     }
 887 }
 888
 889 // Shims the linux 'getrandom()' syscall.
 890 fn linux_getrandom<'tcx>(
 891     this: &mut MiriEvalContext<'_, 'tcx>,
 892     args: &[OpTy<'tcx, Tag>],
 893     dest: PlaceTy<'tcx, Tag>,
 894 ) -> InterpResult<'tcx> {
 895     let ptr = this.read_scalar(args[0])?.not_undef()?;
 896     let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 897
 898     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 899     // neither of which have any effect on our current PRNG.
 900     let _flags = this.read_scalar(args[2])?.to_i32()?;
 901
 902     this.gen_random(ptr, len as usize)?;
 903     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 904     Ok(())
 905 }