src/fn_call.rs

   1 use rustc::ty;
   2 use rustc::ty::layout::{Align, LayoutOf, Size};
   3 use rustc::hir::def_id::DefId;
   4 use rustc::mir;
   5 use syntax::attr;
   6
   7 use crate::*;
   8
   9 impl<'a, 'mir, 'tcx> EvalContextExt<'a, 'mir, 'tcx> for crate::MiriEvalContext<'a, 'mir, 'tcx> {}
  10 pub trait EvalContextExt<'a, 'mir, 'tcx: 'a + 'mir>: crate::MiriEvalContextExt<'a, 'mir, 'tcx> {
  11     fn find_fn(
  12         &mut self,
  13         instance: ty::Instance<'tcx>,
  14         args: &[OpTy<'tcx, Borrow>],
  15         dest: Option<PlaceTy<'tcx, Borrow>>,
  16         ret: Option<mir::BasicBlock>,
  17     ) -> EvalResult<'tcx, Option<&'mir mir::Mir<'tcx>>> {
  18         let this = self.eval_context_mut();
  19         trace!("eval_fn_call: {:#?}, {:?}", instance, dest.map(|place| *place));
  20
  21         // First, run the common hooks also supported by CTFE.
  22         if this.hook_fn(instance, args, dest)? {
  23             this.goto_block(ret)?;
  24             return Ok(None);
  25         }
  26         // There are some more lang items we want to hook that CTFE does not hook (yet).
  27         if this.tcx.lang_items().align_offset_fn() == Some(instance.def.def_id()) {
  28             // FIXME: return a real value in case the target allocation has an
  29             // alignment bigger than the one requested.
  30             let n = u128::max_value();
  31             let dest = dest.unwrap();
  32             let n = this.truncate(n, dest.layout);
  33             this.write_scalar(Scalar::from_uint(n, dest.layout.size), dest)?;
  34             this.goto_block(ret)?;
  35             return Ok(None);
  36         }
  37
  38         // Try to see if we can do something about foreign items.
  39         if this.tcx.is_foreign_item(instance.def_id()) {
  40             // An external function that we cannot find MIR for, but we can still run enough
  41             // of them to make miri viable.
  42             this.emulate_foreign_item(instance.def_id(), args, dest, ret)?;
  43             // `goto_block` already handled.
  44             return Ok(None);
  45         }
  46
  47         // Otherwise, load the MIR.
  48         Ok(Some(this.load_mir(instance.def)?))
  49     }
  50
  51     /// Emulates calling a foreign item, failing if the item is not supported.
  52     /// This function will handle `goto_block` if needed.
  53     fn emulate_foreign_item(
  54         &mut self,
  55         def_id: DefId,
  56         args: &[OpTy<'tcx, Borrow>],
  57         dest: Option<PlaceTy<'tcx, Borrow>>,
  58         ret: Option<mir::BasicBlock>,
  59     ) -> EvalResult<'tcx> {
  60         let this = self.eval_context_mut();
  61         let attrs = this.tcx.get_attrs(def_id);
  62         let link_name = match attr::first_attr_value_str_by_name(&attrs, "link_name") {
  63             Some(name) => name.as_str().get(),
  64             None => this.tcx.item_name(def_id).as_str().get(),
  65         };
  66         // Strip linker suffixes (seen on 32-bit macOS).
  67         let link_name = link_name.trim_end_matches("$UNIX2003");
  68         let tcx = &{this.tcx.tcx};
  69
  70         // First: functions that could diverge.
  71         match link_name {
  72             "__rust_start_panic" | "panic_impl" => {
  73                 return err!(MachineError("the evaluated program panicked".to_string()));
  74             }
  75             _ => if dest.is_none() {
  76                 return err!(Unimplemented(
  77                     format!("can't call diverging foreign function: {}", link_name),
  78                 ));
  79             }
  80         }
  81
  82         // Next: functions that assume a ret and dest.
  83         let dest = dest.expect("we already checked for a dest");
  84         let ret = ret.expect("dest is `Some` but ret is `None`");
  85         match link_name {
  86             "malloc" => {
  87                 let size = this.read_scalar(args[0])?.to_usize(this)?;
  88                 if size == 0 {
  89                     this.write_null(dest)?;
  90                 } else {
  91                     let align = this.tcx.data_layout.pointer_align.abi;
  92                     let ptr = this.memory_mut().allocate(Size::from_bytes(size), align, MiriMemoryKind::C.into());
  93                     this.write_scalar(Scalar::Ptr(ptr.with_default_tag()), dest)?;
  94                 }
  95             }
  96             "posix_memalign" => {
  97                 let ret = this.deref_operand(args[0])?;
  98                 let align = this.read_scalar(args[1])?.to_usize(this)?;
  99                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 100                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 101                 if !align.is_power_of_two() {
 102                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 103                 }
 104                 if align < this.pointer_size().bytes() {
 105                     return err!(MachineError(format!(
 106                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 107                         align,
 108                     )));
 109                 }
 110                 if size == 0 {
 111                     this.write_null(ret.into())?;
 112                 } else {
 113                     let ptr = this.memory_mut().allocate(
 114                         Size::from_bytes(size),
 115                         Align::from_bytes(align).unwrap(),
 116                         MiriMemoryKind::C.into()
 117                     );
 118                     this.write_scalar(Scalar::Ptr(ptr.with_default_tag()), ret.into())?;
 119                 }
 120                 this.write_null(dest)?;
 121             }
 122
 123             "free" => {
 124                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 125                 if !ptr.is_null_ptr(this) {
 126                     this.memory_mut().deallocate(
 127                         ptr.to_ptr()?,
 128                         None,
 129                         MiriMemoryKind::C.into(),
 130                     )?;
 131                 }
 132             }
 133
 134             "__rust_alloc" => {
 135                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 136                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 137                 if size == 0 {
 138                     return err!(HeapAllocZeroBytes);
 139                 }
 140                 if !align.is_power_of_two() {
 141                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 142                 }
 143                 let ptr = this.memory_mut()
 144                     .allocate(
 145                         Size::from_bytes(size),
 146                         Align::from_bytes(align).unwrap(),
 147                         MiriMemoryKind::Rust.into()
 148                     )
 149                     .with_default_tag();
 150                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 151             }
 152             "__rust_alloc_zeroed" => {
 153                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 154                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 155                 if size == 0 {
 156                     return err!(HeapAllocZeroBytes);
 157                 }
 158                 if !align.is_power_of_two() {
 159                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 160                 }
 161                 let ptr = this.memory_mut()
 162                     .allocate(
 163                         Size::from_bytes(size),
 164                         Align::from_bytes(align).unwrap(),
 165                         MiriMemoryKind::Rust.into()
 166                     )
 167                     .with_default_tag();
 168                 this.memory_mut()
 169                     .get_mut(ptr.alloc_id)?
 170                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size))?;
 171                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 172             }
 173             "__rust_dealloc" => {
 174                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 175                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 176                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 177                 if old_size == 0 {
 178                     return err!(HeapAllocZeroBytes);
 179                 }
 180                 if !align.is_power_of_two() {
 181                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 182                 }
 183                 this.memory_mut().deallocate(
 184                     ptr,
 185                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 186                     MiriMemoryKind::Rust.into(),
 187                 )?;
 188             }
 189             "__rust_realloc" => {
 190                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 191                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 192                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 193                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 194                 if old_size == 0 || new_size == 0 {
 195                     return err!(HeapAllocZeroBytes);
 196                 }
 197                 if !align.is_power_of_two() {
 198                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 199                 }
 200                 let new_ptr = this.memory_mut().reallocate(
 201                     ptr,
 202                     Size::from_bytes(old_size),
 203                     Align::from_bytes(align).unwrap(),
 204                     Size::from_bytes(new_size),
 205                     Align::from_bytes(align).unwrap(),
 206                     MiriMemoryKind::Rust.into(),
 207                 )?;
 208                 this.write_scalar(Scalar::Ptr(new_ptr.with_default_tag()), dest)?;
 209             }
 210
 211             "syscall" => {
 212                 // TODO: read `syscall` IDs like `sysconf` IDs and
 213                 // figure out some way to actually process some of them.
 214                 //
 215                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 216                 // is called if a `HashMap` is created the regular way.
 217                 match this.read_scalar(args[0])?.to_usize(this)? {
 218                     318 | 511 => {
 219                         return err!(Unimplemented(
 220                             "miri does not support random number generators".to_owned(),
 221                         ))
 222                     }
 223                     id => {
 224                         return err!(Unimplemented(
 225                             format!("miri does not support syscall ID {}", id),
 226                         ))
 227                     }
 228                 }
 229             }
 230
 231             "dlsym" => {
 232                 let _handle = this.read_scalar(args[0])?;
 233                 let symbol = this.read_scalar(args[1])?.to_ptr()?;
 234                 let symbol_name = this.memory().get(symbol.alloc_id)?.read_c_str(tcx, symbol)?;
 235                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 236                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 237                 return err!(Unimplemented(format!(
 238                     "miri does not support dynamically loading libraries (requested symbol: {})",
 239                     symbol_name
 240                 )));
 241             }
 242
 243             "__rust_maybe_catch_panic" => {
 244                 // fn __rust_maybe_catch_panic(
 245                 //     f: fn(*mut u8),
 246                 //     data: *mut u8,
 247                 //     data_ptr: *mut usize,
 248                 //     vtable_ptr: *mut usize,
 249                 // ) -> u32
 250                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 251                 let f = this.read_scalar(args[0])?.to_ptr()?;
 252                 let data = this.read_scalar(args[1])?.not_undef()?;
 253                 let f_instance = this.memory().get_fn(f)?;
 254                 this.write_null(dest)?;
 255                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 256
 257                 // Now we make a function call.
 258                 // TODO: consider making this reusable? `InterpretCx::step` does something similar
 259                 // for the TLS destructors, and of course `eval_main`.
 260                 let mir = this.load_mir(f_instance.def)?;
 261                 let ret_place = MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 262                 this.push_stack_frame(
 263                     f_instance,
 264                     mir.span,
 265                     mir,
 266                     Some(ret_place),
 267                     // Directly return to caller.
 268                     StackPopCleanup::Goto(Some(ret)),
 269                 )?;
 270                 let mut args = this.frame().mir.args_iter();
 271
 272                 let arg_local = args.next().ok_or_else(||
 273                     InterpError::AbiViolation(
 274                         "Argument to __rust_maybe_catch_panic does not take enough arguments."
 275                             .to_owned(),
 276                     ),
 277                 )?;
 278                 let arg_dest = this.eval_place(&mir::Place::Base(mir::PlaceBase::Local(arg_local)))?;
 279                 this.write_scalar(data, arg_dest)?;
 280
 281                 assert!(args.next().is_none(), "__rust_maybe_catch_panic argument has more arguments than expected");
 282
 283                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 284                 this.write_null(dest)?;
 285
 286                 // Don't fall through, we do *not* want to `goto_block`!
 287                 return Ok(());
 288             }
 289
 290             "memcmp" => {
 291                 let left = this.read_scalar(args[0])?.not_undef()?;
 292                 let right = this.read_scalar(args[1])?.not_undef()?;
 293                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 294
 295                 let result = {
 296                     let left_bytes = this.memory().read_bytes(left, n)?;
 297                     let right_bytes = this.memory().read_bytes(right, n)?;
 298
 299                     use std::cmp::Ordering::*;
 300                     match left_bytes.cmp(right_bytes) {
 301                         Less => -1i32,
 302                         Equal => 0,
 303                         Greater => 1,
 304                     }
 305                 };
 306
 307                 this.write_scalar(
 308                     Scalar::from_int(result, Size::from_bits(32)),
 309                     dest,
 310                 )?;
 311             }
 312
 313             "memrchr" => {
 314                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 315                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 316                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 317                 if let Some(idx) = this.memory().read_bytes(ptr, Size::from_bytes(num))?
 318                     .iter().rev().position(|&c| c == val)
 319                 {
 320                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 321                     this.write_scalar(new_ptr, dest)?;
 322                 } else {
 323                     this.write_null(dest)?;
 324                 }
 325             }
 326
 327             "memchr" => {
 328                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 329                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 330                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 331                 let idx = this
 332                     .memory()
 333                     .read_bytes(ptr, Size::from_bytes(num))?
 334                     .iter()
 335                     .position(|&c| c == val);
 336                 if let Some(idx) = idx {
 337                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 338                     this.write_scalar(new_ptr, dest)?;
 339                 } else {
 340                     this.write_null(dest)?;
 341                 }
 342             }
 343
 344             "getenv" => {
 345                 let result = {
 346                     let name_ptr = this.read_scalar(args[0])?.to_ptr()?;
 347                     let name = this.memory().get(name_ptr.alloc_id)?.read_c_str(tcx, name_ptr)?;
 348                     match this.machine.env_vars.get(name) {
 349                         Some(&var) => Scalar::Ptr(var),
 350                         None => Scalar::ptr_null(&*this.tcx),
 351                     }
 352                 };
 353                 this.write_scalar(result, dest)?;
 354             }
 355
 356             "unsetenv" => {
 357                 let mut success = None;
 358                 {
 359                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 360                     if !name_ptr.is_null_ptr(this) {
 361                         let name_ptr = name_ptr.to_ptr()?;
 362                         let name = this
 363                             .memory()
 364                             .get(name_ptr.alloc_id)?
 365                             .read_c_str(tcx, name_ptr)?
 366                             .to_owned();
 367                         if !name.is_empty() && !name.contains(&b'=') {
 368                             success = Some(this.machine.env_vars.remove(&name));
 369                         }
 370                     }
 371                 }
 372                 if let Some(old) = success {
 373                     if let Some(var) = old {
 374                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 375                     }
 376                     this.write_null(dest)?;
 377                 } else {
 378                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 379                 }
 380             }
 381
 382             "setenv" => {
 383                 let mut new = None;
 384                 {
 385                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 386                     let value_ptr = this.read_scalar(args[1])?.to_ptr()?;
 387                     let value = this.memory().get(value_ptr.alloc_id)?.read_c_str(tcx, value_ptr)?;
 388                     if !name_ptr.is_null_ptr(this) {
 389                         let name_ptr = name_ptr.to_ptr()?;
 390                         let name = this.memory().get(name_ptr.alloc_id)?.read_c_str(tcx, name_ptr)?;
 391                         if !name.is_empty() && !name.contains(&b'=') {
 392                             new = Some((name.to_owned(), value.to_owned()));
 393                         }
 394                     }
 395                 }
 396                 if let Some((name, value)) = new {
 397                     // `+1` for the null terminator.
 398                     let value_copy = this.memory_mut().allocate(
 399                         Size::from_bytes((value.len() + 1) as u64),
 400                         Align::from_bytes(1).unwrap(),
 401                         MiriMemoryKind::Env.into(),
 402                     ).with_default_tag();
 403                     {
 404                         let alloc = this.memory_mut().get_mut(value_copy.alloc_id)?;
 405                         alloc.write_bytes(tcx, value_copy, &value)?;
 406                         let trailing_zero_ptr = value_copy.offset(
 407                             Size::from_bytes(value.len() as u64),
 408                             tcx,
 409                         )?;
 410                         alloc.write_bytes(tcx, trailing_zero_ptr, &[0])?;
 411                     }
 412                     if let Some(var) = this.machine.env_vars.insert(
 413                         name.to_owned(),
 414                         value_copy,
 415                     )
 416                     {
 417                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 418                     }
 419                     this.write_null(dest)?;
 420                 } else {
 421                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 422                 }
 423             }
 424
 425             "write" => {
 426                 let fd = this.read_scalar(args[0])?.to_i32()?;
 427                 let buf = this.read_scalar(args[1])?.not_undef()?;
 428                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 429                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 430                 let result = if fd == 1 || fd == 2 {
 431                     // stdout/stderr
 432                     use std::io::{self, Write};
 433
 434                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 435                     // We need to flush to make sure this actually appears on the screen
 436                     let res = if fd == 1 {
 437                         // Stdout is buffered, flush to make sure it appears on the screen.
 438                         // This is the write() syscall of the interpreted program, we want it
 439                         // to correspond to a write() syscall on the host -- there is no good
 440                         // in adding extra buffering here.
 441                         let res = io::stdout().write(buf_cont);
 442                         io::stdout().flush().unwrap();
 443                         res
 444                     } else {
 445                         // No need to flush, stderr is not buffered.
 446                         io::stderr().write(buf_cont)
 447                     };
 448                     match res {
 449                         Ok(n) => n as i64,
 450                         Err(_) => -1,
 451                     }
 452                 } else {
 453                     eprintln!("Miri: Ignored output to FD {}", fd);
 454                     // Pretend it all went well.
 455                     n as i64
 456                 };
 457                 // Now, `result` is the value we return back to the program.
 458                 this.write_scalar(
 459                     Scalar::from_int(result, dest.layout.size),
 460                     dest,
 461                 )?;
 462             }
 463
 464             "strlen" => {
 465                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 466                 let n = this.memory().get(ptr.alloc_id)?.read_c_str(tcx, ptr)?.len();
 467                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 468             }
 469
 470             // Some things needed for `sys::thread` initialization to go through.
 471             "signal" | "sigaction" | "sigaltstack" => {
 472                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 473             }
 474
 475             "sysconf" => {
 476                 let name = this.read_scalar(args[0])?.to_i32()?;
 477
 478                 trace!("sysconf() called with name {}", name);
 479                 // Cache the sysconf integers via Miri's global cache.
 480                 let paths = &[
 481                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(4096, dest.layout.size)),
 482                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 483                     (&["libc", "_SC_NPROCESSORS_ONLN"], Scalar::from_int(1, dest.layout.size)),
 484                 ];
 485                 let mut result = None;
 486                 for &(path, path_value) in paths {
 487                     if let Ok(instance) = this.resolve_path(path) {
 488                         let cid = GlobalId {
 489                             instance,
 490                             promoted: None,
 491                         };
 492                         let const_val = this.const_eval_raw(cid)?;
 493                         let const_val = this.read_scalar(const_val.into())?;
 494                         let value = const_val.to_i32()?;
 495                         if value == name {
 496                             result = Some(path_value);
 497                             break;
 498                         }
 499                     }
 500                 }
 501                 if let Some(result) = result {
 502                     this.write_scalar(result, dest)?;
 503                 } else {
 504                     return err!(Unimplemented(
 505                         format!("Unimplemented sysconf name: {}", name),
 506                     ));
 507                 }
 508             }
 509
 510             "isatty" => {
 511                 this.write_null(dest)?;
 512             }
 513
 514             // Hook pthread calls that go to the thread-local storage memory subsystem.
 515             "pthread_key_create" => {
 516                 let key_ptr = this.read_scalar(args[0])?.to_ptr()?;
 517
 518                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 519                 let dtor = match this.read_scalar(args[1])?.not_undef()? {
 520                     Scalar::Ptr(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?),
 521                     Scalar::Bits { bits: 0, size } => {
 522                         assert_eq!(size as u64, this.memory().pointer_size().bytes());
 523                         None
 524                     },
 525                     Scalar::Bits { .. } => return err!(ReadBytesAsPointer),
 526                 };
 527
 528                 // Figure out how large a pthread TLS key actually is.
 529                 // This is `libc::pthread_key_t`.
 530                 let key_type = args[0].layout.ty
 531                     .builtin_deref(true)
 532                     .ok_or_else(|| InterpError::AbiViolation("wrong signature used for `pthread_key_create`: first argument must be a raw pointer.".to_owned()))?
 533                     .ty;
 534                 let key_layout = this.layout_of(key_type)?;
 535
 536                 // Create key and write it into the memory where `key_ptr` wants it.
 537                 let key = this.machine.tls.create_tls_key(dtor, tcx) as u128;
 538                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128) {
 539                     return err!(OutOfTls);
 540                 }
 541
 542                 this.memory().check_align(key_ptr.into(), key_layout.align.abi)?;
 543                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 544                     tcx,
 545                     key_ptr,
 546                     Scalar::from_uint(key, key_layout.size).into(),
 547                     key_layout.size,
 548                 )?;
 549
 550                 // Return success (`0`).
 551                 this.write_null(dest)?;
 552             }
 553             "pthread_key_delete" => {
 554                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 555                 this.machine.tls.delete_tls_key(key)?;
 556                 // Return success (0)
 557                 this.write_null(dest)?;
 558             }
 559             "pthread_getspecific" => {
 560                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 561                 let ptr = this.machine.tls.load_tls(key)?;
 562                 this.write_scalar(ptr, dest)?;
 563             }
 564             "pthread_setspecific" => {
 565                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 566                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 567                 this.machine.tls.store_tls(key, new_ptr)?;
 568
 569                 // Return success (`0`).
 570                 this.write_null(dest)?;
 571             }
 572
 573             // Determine stack base address.
 574             "pthread_attr_init" | "pthread_attr_destroy" | "pthread_attr_get_np" |
 575             "pthread_getattr_np" | "pthread_self" | "pthread_get_stacksize_np" => {
 576                 this.write_null(dest)?;
 577             }
 578             "pthread_attr_getstack" => {
 579                 // Second argument is where we are supposed to write the stack size.
 580                 let ptr = this.deref_operand(args[1])?;
 581                 // Just any address.
 582                 let stack_addr = Scalar::from_int(0x80000, args[1].layout.size);
 583                 this.write_scalar(stack_addr, ptr.into())?;
 584                 // Return success (`0`).
 585                 this.write_null(dest)?;
 586             }
 587             "pthread_get_stackaddr_np" => {
 588                 // Just any address.
 589                 let stack_addr = Scalar::from_int(0x80000, dest.layout.size);
 590                 this.write_scalar(stack_addr, dest)?;
 591             }
 592
 593             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 594             "pthread_mutexattr_init" | "pthread_mutexattr_settype" | "pthread_mutex_init" |
 595             "pthread_mutexattr_destroy" | "pthread_mutex_lock" | "pthread_mutex_unlock" |
 596             "pthread_mutex_destroy" | "pthread_rwlock_rdlock" | "pthread_rwlock_unlock" |
 597             "pthread_rwlock_wrlock" | "pthread_rwlock_destroy" | "pthread_condattr_init" |
 598             "pthread_condattr_setclock" | "pthread_cond_init" | "pthread_condattr_destroy" |
 599             "pthread_cond_destroy" => {
 600                 this.write_null(dest)?;
 601             }
 602
 603             "mmap" => {
 604                 // 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.
 605                 let addr = this.read_scalar(args[0])?.not_undef()?;
 606                 this.write_scalar(addr, dest)?;
 607             }
 608             "mprotect" => {
 609                 this.write_null(dest)?;
 610             }
 611
 612             // macOS API stubs.
 613             "_tlv_atexit" => {
 614                 // FIXME: register the destructor.
 615             },
 616             "_NSGetArgc" => {
 617                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 618             },
 619             "_NSGetArgv" => {
 620                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 621             },
 622
 623             // Windows API stubs.
 624             "SetLastError" => {
 625                 let err = this.read_scalar(args[0])?.to_u32()?;
 626                 this.machine.last_error = err;
 627             }
 628             "GetLastError" => {
 629                 this.write_scalar(Scalar::from_uint(this.machine.last_error, Size::from_bits(32)), dest)?;
 630             }
 631
 632             "AddVectoredExceptionHandler" => {
 633                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 634                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 635             },
 636             "InitializeCriticalSection" |
 637             "EnterCriticalSection" |
 638             "LeaveCriticalSection" |
 639             "DeleteCriticalSection" => {
 640                 // Nothing to do, not even a return value.
 641             },
 642             "GetModuleHandleW" |
 643             "GetProcAddress" |
 644             "TryEnterCriticalSection" |
 645             "GetConsoleScreenBufferInfo" |
 646             "SetConsoleTextAttribute" => {
 647                 // Pretend these do not exist / nothing happened, by returning zero.
 648                 this.write_null(dest)?;
 649             },
 650             "GetSystemInfo" => {
 651                 let system_info = this.deref_operand(args[0])?;
 652                 let system_info_ptr = system_info.ptr.to_ptr()?;
 653                 // Initialize with `0`.
 654                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 655                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 656                 // Set number of processors to `1`.
 657                 let dword_size = Size::from_bytes(4);
 658                 let offset = 2*dword_size + 3*tcx.pointer_size();
 659                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 660                     .write_scalar(
 661                         tcx,
 662                         system_info_ptr.offset(offset, tcx)?,
 663                         Scalar::from_int(1, dword_size).into(),
 664                         dword_size,
 665                     )?;
 666             }
 667
 668             "TlsAlloc" => {
 669                 // This just creates a key; Windows does not natively support TLS destructors.
 670
 671                 // Create key and return it.
 672                 let key = this.machine.tls.create_tls_key(None, tcx) as u128;
 673
 674                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 675                 if dest.layout.size.bits() < 128
 676                         && key >= (1u128 << dest.layout.size.bits() as u128) {
 677                     return err!(OutOfTls);
 678                 }
 679                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 680             }
 681             "TlsGetValue" => {
 682                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 683                 let ptr = this.machine.tls.load_tls(key)?;
 684                 this.write_scalar(ptr, dest)?;
 685             }
 686             "TlsSetValue" => {
 687                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 688                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 689                 this.machine.tls.store_tls(key, new_ptr)?;
 690
 691                 // Return success (`1`).
 692                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 693             }
 694             "GetStdHandle" => {
 695                 let which = this.read_scalar(args[0])?.to_i32()?;
 696                 // We just make this the identity function, so we know later in `WriteFile`
 697                 // which one it is.
 698                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 699             }
 700             "WriteFile" => {
 701                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 702                 let buf = this.read_scalar(args[1])?.not_undef()?;
 703                 let n = this.read_scalar(args[2])?.to_u32()?;
 704                 let written_place = this.deref_operand(args[3])?;
 705                 // Spec says to always write `0` first.
 706                 this.write_null(written_place.into())?;
 707                 let written = if handle == -11 || handle == -12 {
 708                     // stdout/stderr
 709                     use std::io::{self, Write};
 710
 711                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 712                     let res = if handle == -11 {
 713                         io::stdout().write(buf_cont)
 714                     } else {
 715                         io::stderr().write(buf_cont)
 716                     };
 717                     res.ok().map(|n| n as u32)
 718                 } else {
 719                     eprintln!("Miri: Ignored output to handle {}", handle);
 720                     // Pretend it all went well.
 721                     Some(n)
 722                 };
 723                 // If there was no error, write back how much was written.
 724                 if let Some(n) = written {
 725                     this.write_scalar(Scalar::from_uint(n, Size::from_bits(32)), written_place.into())?;
 726                 }
 727                 // Return whether this was a success.
 728                 this.write_scalar(
 729                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 730                     dest,
 731                 )?;
 732             }
 733             "GetConsoleMode" => {
 734                 // Everything is a pipe.
 735                 this.write_null(dest)?;
 736             }
 737             "GetEnvironmentVariableW" => {
 738                 // This is not the env var you are looking for.
 739                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 740                 this.write_null(dest)?;
 741             }
 742             "GetCommandLineW" => {
 743                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 744             }
 745
 746             // We can't execute anything else.
 747             _ => {
 748                 return err!(Unimplemented(
 749                     format!("can't call foreign function: {}", link_name),
 750                 ));
 751             }
 752         }
 753
 754         this.goto_block(Some(ret))?;
 755         this.dump_place(*dest);
 756         Ok(())
 757     }
 758
 759     fn write_null(&mut self, dest: PlaceTy<'tcx, Borrow>) -> EvalResult<'tcx> {
 760         self.eval_context_mut().write_scalar(Scalar::from_int(0, dest.layout.size), dest)
 761     }
 762 }