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 use syntax::symbol::sym;
   7
   8 use rand::RngCore;
   9
  10 use crate::*;
  11
  12 impl<'a, 'mir, 'tcx> EvalContextExt<'a, 'mir, 'tcx> for crate::MiriEvalContext<'a, 'mir, 'tcx> {}
  13 pub trait EvalContextExt<'a, 'mir, 'tcx: 'a + 'mir>: crate::MiriEvalContextExt<'a, 'mir, 'tcx> {
  14     fn find_fn(
  15         &mut self,
  16         instance: ty::Instance<'tcx>,
  17         args: &[OpTy<'tcx, Tag>],
  18         dest: Option<PlaceTy<'tcx, Tag>>,
  19         ret: Option<mir::BasicBlock>,
  20     ) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
  21         let this = self.eval_context_mut();
  22         trace!("eval_fn_call: {:#?}, {:?}", instance, dest.map(|place| *place));
  23
  24         // First, run the common hooks also supported by CTFE.
  25         if this.hook_fn(instance, args, dest)? {
  26             this.goto_block(ret)?;
  27             return Ok(None);
  28         }
  29         // There are some more lang items we want to hook that CTFE does not hook (yet).
  30         if this.tcx.lang_items().align_offset_fn() == Some(instance.def.def_id()) {
  31             // FIXME: return a real value in case the target allocation has an
  32             // alignment bigger than the one requested.
  33             let n = u128::max_value();
  34             let dest = dest.unwrap();
  35             let n = this.truncate(n, dest.layout);
  36             this.write_scalar(Scalar::from_uint(n, dest.layout.size), dest)?;
  37             this.goto_block(ret)?;
  38             return Ok(None);
  39         }
  40
  41         // Try to see if we can do something about foreign items.
  42         if this.tcx.is_foreign_item(instance.def_id()) {
  43             // An external function that we cannot find MIR for, but we can still run enough
  44             // of them to make miri viable.
  45             this.emulate_foreign_item(instance.def_id(), args, dest, ret)?;
  46             // `goto_block` already handled.
  47             return Ok(None);
  48         }
  49
  50         // Otherwise, load the MIR.
  51         Ok(Some(this.load_mir(instance.def)?))
  52     }
  53
  54     fn malloc(
  55         &mut self,
  56         size: u64,
  57         zero_init: bool,
  58     ) -> Scalar<Tag> {
  59         let this = self.eval_context_mut();
  60         let tcx = &{this.tcx.tcx};
  61         if size == 0 {
  62             Scalar::from_int(0, this.pointer_size())
  63         } else {
  64             let align = this.tcx.data_layout.pointer_align.abi;
  65             let ptr = this.memory_mut().allocate(Size::from_bytes(size), align, MiriMemoryKind::C.into());
  66             if zero_init {
  67                 // We just allocated this, the access cannot fail
  68                 this.memory_mut()
  69                     .get_mut(ptr.alloc_id).unwrap()
  70                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size)).unwrap();
  71             }
  72             Scalar::Ptr(ptr)
  73         }
  74     }
  75
  76     fn free(
  77         &mut self,
  78         ptr: Scalar<Tag>,
  79     ) -> InterpResult<'tcx> {
  80         let this = self.eval_context_mut();
  81         if !ptr.is_null_ptr(this) {
  82             this.memory_mut().deallocate(
  83                 ptr.to_ptr()?,
  84                 None,
  85                 MiriMemoryKind::C.into(),
  86             )?;
  87         }
  88         Ok(())
  89     }
  90
  91     fn realloc(
  92         &mut self,
  93         old_ptr: Scalar<Tag>,
  94         new_size: u64,
  95     ) -> InterpResult<'tcx, Scalar<Tag>> {
  96         let this = self.eval_context_mut();
  97         let align = this.tcx.data_layout.pointer_align.abi;
  98         if old_ptr.is_null_ptr(this) {
  99             if new_size == 0 {
 100                 Ok(Scalar::from_int(0, this.pointer_size()))
 101             } else {
 102                 let new_ptr = this.memory_mut().allocate(
 103                     Size::from_bytes(new_size),
 104                     align,
 105                     MiriMemoryKind::C.into()
 106                 );
 107                 Ok(Scalar::Ptr(new_ptr))
 108             }
 109         } else {
 110             let old_ptr = old_ptr.to_ptr()?;
 111             let memory = this.memory_mut();
 112             let old_size = Size::from_bytes(memory.get(old_ptr.alloc_id)?.bytes.len() as u64);
 113             if new_size == 0 {
 114                 memory.deallocate(
 115                     old_ptr,
 116                     Some((old_size, align)),
 117                     MiriMemoryKind::C.into(),
 118                 )?;
 119                 Ok(Scalar::from_int(0, this.pointer_size()))
 120             } else {
 121                 let new_ptr = memory.reallocate(
 122                     old_ptr,
 123                     old_size,
 124                     align,
 125                     Size::from_bytes(new_size),
 126                     align,
 127                     MiriMemoryKind::C.into(),
 128                 )?;
 129                 Ok(Scalar::Ptr(new_ptr))
 130             }
 131         }
 132     }
 133
 134     /// Emulates calling a foreign item, failing if the item is not supported.
 135     /// This function will handle `goto_block` if needed.
 136     fn emulate_foreign_item(
 137         &mut self,
 138         def_id: DefId,
 139         args: &[OpTy<'tcx, Tag>],
 140         dest: Option<PlaceTy<'tcx, Tag>>,
 141         ret: Option<mir::BasicBlock>,
 142     ) -> InterpResult<'tcx> {
 143         let this = self.eval_context_mut();
 144         let attrs = this.tcx.get_attrs(def_id);
 145         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
 146             Some(name) => name.as_str(),
 147             None => this.tcx.item_name(def_id).as_str(),
 148         };
 149         // Strip linker suffixes (seen on 32-bit macOS).
 150         let link_name = link_name.get().trim_end_matches("$UNIX2003");
 151         let tcx = &{this.tcx.tcx};
 152
 153         // First: functions that diverge.
 154         match link_name {
 155             "__rust_start_panic" | "panic_impl" => {
 156                 return err!(MachineError("the evaluated program panicked".to_string()));
 157             }
 158             "exit" | "ExitProcess" => {
 159                 // it's really u32 for ExitProcess, but we have to put it into the `Exit` error variant anyway
 160                 let code = this.read_scalar(args[0])?.to_i32()?;
 161                 return err!(Exit(code));
 162             }
 163             _ => if dest.is_none() {
 164                 return err!(Unimplemented(
 165                     format!("can't call diverging foreign function: {}", link_name),
 166                 ));
 167             }
 168         }
 169
 170         // Next: functions that assume a ret and dest.
 171         let dest = dest.expect("we already checked for a dest");
 172         let ret = ret.expect("dest is `Some` but ret is `None`");
 173         match link_name {
 174             "malloc" => {
 175                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 176                 let res = this.malloc(size, /*zero_init:*/ false);
 177                 this.write_scalar(res, dest)?;
 178             }
 179             "calloc" => {
 180                 let items = this.read_scalar(args[0])?.to_usize(this)?;
 181                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 182                 let size = items.checked_mul(len).ok_or_else(|| InterpError::Overflow(mir::BinOp::Mul))?;
 183                 let res = this.malloc(size, /*zero_init:*/ true);
 184                 this.write_scalar(res, dest)?;
 185             }
 186             "posix_memalign" => {
 187                 let ret = this.deref_operand(args[0])?;
 188                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 189                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 190                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 191                 if !align.is_power_of_two() {
 192                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 193                 }
 194                 if align < this.pointer_size().bytes() {
 195                     return err!(MachineError(format!(
 196                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 197                         align,
 198                     )));
 199                 }
 200                 if size == 0 {
 201                     this.write_null(ret.into())?;
 202                 } else {
 203                     let ptr = this.memory_mut().allocate(
 204                         Size::from_bytes(size),
 205                         Align::from_bytes(align).unwrap(),
 206                         MiriMemoryKind::C.into()
 207                     );
 208                     this.write_scalar(Scalar::Ptr(ptr), ret.into())?;
 209                 }
 210                 this.write_null(dest)?;
 211             }
 212             "free" => {
 213                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 214                 this.free(ptr)?;
 215             }
 216             "realloc" => {
 217                 let old_ptr = this.read_scalar(args[0])?.not_undef()?;
 218                 let new_size = this.read_scalar(args[1])?.to_usize(this)?;
 219                 let res = this.realloc(old_ptr, new_size)?;
 220                 this.write_scalar(res, dest)?;
 221             }
 222
 223             "__rust_alloc" => {
 224                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 225                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 226                 if size == 0 {
 227                     return err!(HeapAllocZeroBytes);
 228                 }
 229                 if !align.is_power_of_two() {
 230                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 231                 }
 232                 let ptr = this.memory_mut()
 233                     .allocate(
 234                         Size::from_bytes(size),
 235                         Align::from_bytes(align).unwrap(),
 236                         MiriMemoryKind::Rust.into()
 237                     );
 238                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 239             }
 240             "__rust_alloc_zeroed" => {
 241                 let size = this.read_scalar(args[0])?.to_usize(this)?;
 242                 let align = this.read_scalar(args[1])?.to_usize(this)?;
 243                 if size == 0 {
 244                     return err!(HeapAllocZeroBytes);
 245                 }
 246                 if !align.is_power_of_two() {
 247                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 248                 }
 249                 let ptr = this.memory_mut()
 250                     .allocate(
 251                         Size::from_bytes(size),
 252                         Align::from_bytes(align).unwrap(),
 253                         MiriMemoryKind::Rust.into()
 254                     );
 255                 this.memory_mut()
 256                     .get_mut(ptr.alloc_id)?
 257                     .write_repeat(tcx, ptr, 0, Size::from_bytes(size))?;
 258                 this.write_scalar(Scalar::Ptr(ptr), dest)?;
 259             }
 260             "__rust_dealloc" => {
 261                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 262                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 263                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 264                 if old_size == 0 {
 265                     return err!(HeapAllocZeroBytes);
 266                 }
 267                 if !align.is_power_of_two() {
 268                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 269                 }
 270                 this.memory_mut().deallocate(
 271                     ptr,
 272                     Some((Size::from_bytes(old_size), Align::from_bytes(align).unwrap())),
 273                     MiriMemoryKind::Rust.into(),
 274                 )?;
 275             }
 276             "__rust_realloc" => {
 277                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 278                 let old_size = this.read_scalar(args[1])?.to_usize(this)?;
 279                 let align = this.read_scalar(args[2])?.to_usize(this)?;
 280                 let new_size = this.read_scalar(args[3])?.to_usize(this)?;
 281                 if old_size == 0 || new_size == 0 {
 282                     return err!(HeapAllocZeroBytes);
 283                 }
 284                 if !align.is_power_of_two() {
 285                     return err!(HeapAllocNonPowerOfTwoAlignment(align));
 286                 }
 287                 let new_ptr = this.memory_mut().reallocate(
 288                     ptr,
 289                     Size::from_bytes(old_size),
 290                     Align::from_bytes(align).unwrap(),
 291                     Size::from_bytes(new_size),
 292                     Align::from_bytes(align).unwrap(),
 293                     MiriMemoryKind::Rust.into(),
 294                 )?;
 295                 this.write_scalar(Scalar::Ptr(new_ptr), dest)?;
 296             }
 297
 298             "syscall" => {
 299                 let sys_getrandom = this.eval_path_scalar(&["libc", "SYS_getrandom"])?
 300                     .expect("Failed to get libc::SYS_getrandom")
 301                     .to_usize(this)?;
 302
 303                 // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
 304                 // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
 305                 match this.read_scalar(args[0])?.to_usize(this)? {
 306                     id if id == sys_getrandom => {
 307                         let ptr = this.read_scalar(args[1])?.not_undef()?;
 308                         let len = this.read_scalar(args[2])?.to_usize(this)?;
 309
 310                         // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 311                         // neither of which have any effect on our current PRNG
 312                         let _flags = this.read_scalar(args[3])?.to_i32()?;
 313
 314                         gen_random(this, len as usize, ptr)?;
 315                         this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 316                     }
 317                     id => {
 318                         return err!(Unimplemented(
 319                             format!("miri does not support syscall ID {}", id),
 320                         ))
 321                     }
 322                 }
 323             }
 324
 325             "dlsym" => {
 326                 let _handle = this.read_scalar(args[0])?;
 327                 let symbol = this.read_scalar(args[1])?.to_ptr()?;
 328                 let symbol_name = this.memory().get(symbol.alloc_id)?.read_c_str(tcx, symbol)?;
 329                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 330                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 331                 return err!(Unimplemented(format!(
 332                     "miri does not support dynamically loading libraries (requested symbol: {})",
 333                     symbol_name
 334                 )));
 335             }
 336
 337             "__rust_maybe_catch_panic" => {
 338                 // fn __rust_maybe_catch_panic(
 339                 //     f: fn(*mut u8),
 340                 //     data: *mut u8,
 341                 //     data_ptr: *mut usize,
 342                 //     vtable_ptr: *mut usize,
 343                 // ) -> u32
 344                 // We abort on panic, so not much is going on here, but we still have to call the closure.
 345                 let f = this.read_scalar(args[0])?.to_ptr()?;
 346                 let data = this.read_scalar(args[1])?.not_undef()?;
 347                 let f_instance = this.memory().get_fn(f)?;
 348                 this.write_null(dest)?;
 349                 trace!("__rust_maybe_catch_panic: {:?}", f_instance);
 350
 351                 // Now we make a function call.
 352                 // TODO: consider making this reusable? `InterpretCx::step` does something similar
 353                 // for the TLS destructors, and of course `eval_main`.
 354                 let mir = this.load_mir(f_instance.def)?;
 355                 let ret_place = MPlaceTy::dangling(this.layout_of(this.tcx.mk_unit())?, this).into();
 356                 this.push_stack_frame(
 357                     f_instance,
 358                     mir.span,
 359                     mir,
 360                     Some(ret_place),
 361                     // Directly return to caller.
 362                     StackPopCleanup::Goto(Some(ret)),
 363                 )?;
 364                 let mut args = this.frame().body.args_iter();
 365
 366                 let arg_local = args.next().ok_or_else(||
 367                     InterpError::AbiViolation(
 368                         "Argument to __rust_maybe_catch_panic does not take enough arguments."
 369                             .to_owned(),
 370                     ),
 371                 )?;
 372                 let arg_dest = this.eval_place(&mir::Place::Base(mir::PlaceBase::Local(arg_local)))?;
 373                 this.write_scalar(data, arg_dest)?;
 374
 375                 assert!(args.next().is_none(), "__rust_maybe_catch_panic argument has more arguments than expected");
 376
 377                 // We ourselves will return `0`, eventually (because we will not return if we paniced).
 378                 this.write_null(dest)?;
 379
 380                 // Don't fall through, we do *not* want to `goto_block`!
 381                 return Ok(());
 382             }
 383
 384             "memcmp" => {
 385                 let left = this.read_scalar(args[0])?.not_undef()?;
 386                 let right = this.read_scalar(args[1])?.not_undef()?;
 387                 let n = Size::from_bytes(this.read_scalar(args[2])?.to_usize(this)?);
 388
 389                 let result = {
 390                     let left_bytes = this.memory().read_bytes(left, n)?;
 391                     let right_bytes = this.memory().read_bytes(right, n)?;
 392
 393                     use std::cmp::Ordering::*;
 394                     match left_bytes.cmp(right_bytes) {
 395                         Less => -1i32,
 396                         Equal => 0,
 397                         Greater => 1,
 398                     }
 399                 };
 400
 401                 this.write_scalar(
 402                     Scalar::from_int(result, Size::from_bits(32)),
 403                     dest,
 404                 )?;
 405             }
 406
 407             "memrchr" => {
 408                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 409                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 410                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 411                 if let Some(idx) = this.memory().read_bytes(ptr, Size::from_bytes(num))?
 412                     .iter().rev().position(|&c| c == val)
 413                 {
 414                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 415                     this.write_scalar(new_ptr, dest)?;
 416                 } else {
 417                     this.write_null(dest)?;
 418                 }
 419             }
 420
 421             "memchr" => {
 422                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 423                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 424                 let num = this.read_scalar(args[2])?.to_usize(this)?;
 425                 let idx = this
 426                     .memory()
 427                     .read_bytes(ptr, Size::from_bytes(num))?
 428                     .iter()
 429                     .position(|&c| c == val);
 430                 if let Some(idx) = idx {
 431                     let new_ptr = ptr.ptr_offset(Size::from_bytes(idx as u64), this)?;
 432                     this.write_scalar(new_ptr, dest)?;
 433                 } else {
 434                     this.write_null(dest)?;
 435                 }
 436             }
 437
 438             "getenv" => {
 439                 let result = {
 440                     let name_ptr = this.read_scalar(args[0])?.to_ptr()?;
 441                     let name = this.memory().get(name_ptr.alloc_id)?.read_c_str(tcx, name_ptr)?;
 442                     match this.machine.env_vars.get(name) {
 443                         Some(&var) => Scalar::Ptr(var),
 444                         None => Scalar::ptr_null(&*this.tcx),
 445                     }
 446                 };
 447                 this.write_scalar(result, dest)?;
 448             }
 449
 450             "unsetenv" => {
 451                 let mut success = None;
 452                 {
 453                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 454                     if !name_ptr.is_null_ptr(this) {
 455                         let name_ptr = name_ptr.to_ptr()?;
 456                         let name = this
 457                             .memory()
 458                             .get(name_ptr.alloc_id)?
 459                             .read_c_str(tcx, name_ptr)?
 460                             .to_owned();
 461                         if !name.is_empty() && !name.contains(&b'=') {
 462                             success = Some(this.machine.env_vars.remove(&name));
 463                         }
 464                     }
 465                 }
 466                 if let Some(old) = success {
 467                     if let Some(var) = old {
 468                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 469                     }
 470                     this.write_null(dest)?;
 471                 } else {
 472                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 473                 }
 474             }
 475
 476             "setenv" => {
 477                 let mut new = None;
 478                 {
 479                     let name_ptr = this.read_scalar(args[0])?.not_undef()?;
 480                     let value_ptr = this.read_scalar(args[1])?.to_ptr()?;
 481                     let value = this.memory().get(value_ptr.alloc_id)?.read_c_str(tcx, value_ptr)?;
 482                     if !name_ptr.is_null_ptr(this) {
 483                         let name_ptr = name_ptr.to_ptr()?;
 484                         let name = this.memory().get(name_ptr.alloc_id)?.read_c_str(tcx, name_ptr)?;
 485                         if !name.is_empty() && !name.contains(&b'=') {
 486                             new = Some((name.to_owned(), value.to_owned()));
 487                         }
 488                     }
 489                 }
 490                 if let Some((name, value)) = new {
 491                     // `+1` for the null terminator.
 492                     let value_copy = this.memory_mut().allocate(
 493                         Size::from_bytes((value.len() + 1) as u64),
 494                         Align::from_bytes(1).unwrap(),
 495                         MiriMemoryKind::Env.into(),
 496                     );
 497                     {
 498                         let alloc = this.memory_mut().get_mut(value_copy.alloc_id)?;
 499                         alloc.write_bytes(tcx, value_copy, &value)?;
 500                         let trailing_zero_ptr = value_copy.offset(
 501                             Size::from_bytes(value.len() as u64),
 502                             tcx,
 503                         )?;
 504                         alloc.write_bytes(tcx, trailing_zero_ptr, &[0])?;
 505                     }
 506                     if let Some(var) = this.machine.env_vars.insert(
 507                         name.to_owned(),
 508                         value_copy,
 509                     )
 510                     {
 511                         this.memory_mut().deallocate(var, None, MiriMemoryKind::Env.into())?;
 512                     }
 513                     this.write_null(dest)?;
 514                 } else {
 515                     this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
 516                 }
 517             }
 518
 519             "write" => {
 520                 let fd = this.read_scalar(args[0])?.to_i32()?;
 521                 let buf = this.read_scalar(args[1])?.not_undef()?;
 522                 let n = this.read_scalar(args[2])?.to_usize(&*this.tcx)?;
 523                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
 524                 let result = if fd == 1 || fd == 2 {
 525                     // stdout/stderr
 526                     use std::io::{self, Write};
 527
 528                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(n))?;
 529                     // We need to flush to make sure this actually appears on the screen
 530                     let res = if fd == 1 {
 531                         // Stdout is buffered, flush to make sure it appears on the screen.
 532                         // This is the write() syscall of the interpreted program, we want it
 533                         // to correspond to a write() syscall on the host -- there is no good
 534                         // in adding extra buffering here.
 535                         let res = io::stdout().write(buf_cont);
 536                         io::stdout().flush().unwrap();
 537                         res
 538                     } else {
 539                         // No need to flush, stderr is not buffered.
 540                         io::stderr().write(buf_cont)
 541                     };
 542                     match res {
 543                         Ok(n) => n as i64,
 544                         Err(_) => -1,
 545                     }
 546                 } else {
 547                     eprintln!("Miri: Ignored output to FD {}", fd);
 548                     // Pretend it all went well.
 549                     n as i64
 550                 };
 551                 // Now, `result` is the value we return back to the program.
 552                 this.write_scalar(
 553                     Scalar::from_int(result, dest.layout.size),
 554                     dest,
 555                 )?;
 556             }
 557
 558             "strlen" => {
 559                 let ptr = this.read_scalar(args[0])?.to_ptr()?;
 560                 let n = this.memory().get(ptr.alloc_id)?.read_c_str(tcx, ptr)?.len();
 561                 this.write_scalar(Scalar::from_uint(n as u64, dest.layout.size), dest)?;
 562             }
 563
 564             // Some things needed for `sys::thread` initialization to go through.
 565             "signal" | "sigaction" | "sigaltstack" => {
 566                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 567             }
 568
 569             "sysconf" => {
 570                 let name = this.read_scalar(args[0])?.to_i32()?;
 571
 572                 trace!("sysconf() called with name {}", name);
 573                 // Cache the sysconf integers via Miri's global cache.
 574                 let paths = &[
 575                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(4096, dest.layout.size)),
 576                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 577                     (&["libc", "_SC_NPROCESSORS_ONLN"], Scalar::from_int(1, dest.layout.size)),
 578                 ];
 579                 let mut result = None;
 580                 for &(path, path_value) in paths {
 581                     if let Some(val) = this.eval_path_scalar(path)? {
 582                         let val = val.to_i32()?;
 583                         if val == name {
 584                             result = Some(path_value);
 585                             break;
 586                         }
 587
 588                     }
 589                 }
 590                 if let Some(result) = result {
 591                     this.write_scalar(result, dest)?;
 592                 } else {
 593                     return err!(Unimplemented(
 594                         format!("Unimplemented sysconf name: {}", name),
 595                     ));
 596                 }
 597             }
 598
 599             "isatty" => {
 600                 this.write_null(dest)?;
 601             }
 602
 603             // Hook pthread calls that go to the thread-local storage memory subsystem.
 604             "pthread_key_create" => {
 605                 let key_ptr = this.read_scalar(args[0])?.to_ptr()?;
 606
 607                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 608                 let dtor = match this.read_scalar(args[1])?.not_undef()? {
 609                     Scalar::Ptr(dtor_ptr) => Some(this.memory().get_fn(dtor_ptr)?),
 610                     Scalar::Raw { data: 0, size } => {
 611                         // NULL pointer
 612                         assert_eq!(size as u64, this.memory().pointer_size().bytes());
 613                         None
 614                     },
 615                     Scalar::Raw { .. } => return err!(ReadBytesAsPointer),
 616                 };
 617
 618                 // Figure out how large a pthread TLS key actually is.
 619                 // This is `libc::pthread_key_t`.
 620                 let key_type = args[0].layout.ty
 621                     .builtin_deref(true)
 622                     .ok_or_else(|| InterpError::AbiViolation("wrong signature used for `pthread_key_create`: first argument must be a raw pointer.".to_owned()))?
 623                     .ty;
 624                 let key_layout = this.layout_of(key_type)?;
 625
 626                 // Create key and write it into the memory where `key_ptr` wants it.
 627                 let key = this.machine.tls.create_tls_key(dtor, tcx) as u128;
 628                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128) {
 629                     return err!(OutOfTls);
 630                 }
 631
 632                 this.memory().check_align(key_ptr.into(), key_layout.align.abi)?;
 633                 this.memory_mut().get_mut(key_ptr.alloc_id)?.write_scalar(
 634                     tcx,
 635                     key_ptr,
 636                     Scalar::from_uint(key, key_layout.size).into(),
 637                     key_layout.size,
 638                 )?;
 639
 640                 // Return success (`0`).
 641                 this.write_null(dest)?;
 642             }
 643             "pthread_key_delete" => {
 644                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 645                 this.machine.tls.delete_tls_key(key)?;
 646                 // Return success (0)
 647                 this.write_null(dest)?;
 648             }
 649             "pthread_getspecific" => {
 650                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 651                 let ptr = this.machine.tls.load_tls(key)?;
 652                 this.write_scalar(ptr, dest)?;
 653             }
 654             "pthread_setspecific" => {
 655                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 656                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 657                 this.machine.tls.store_tls(key, new_ptr)?;
 658
 659                 // Return success (`0`).
 660                 this.write_null(dest)?;
 661             }
 662
 663             // Determine stack base address.
 664             "pthread_attr_init" | "pthread_attr_destroy" | "pthread_attr_get_np" |
 665             "pthread_getattr_np" | "pthread_self" | "pthread_get_stacksize_np" => {
 666                 this.write_null(dest)?;
 667             }
 668             "pthread_attr_getstack" => {
 669                 // Second argument is where we are supposed to write the stack size.
 670                 let ptr = this.deref_operand(args[1])?;
 671                 // Just any address.
 672                 let stack_addr = Scalar::from_int(0x80000, args[1].layout.size);
 673                 this.write_scalar(stack_addr, ptr.into())?;
 674                 // Return success (`0`).
 675                 this.write_null(dest)?;
 676             }
 677             "pthread_get_stackaddr_np" => {
 678                 // Just any address.
 679                 let stack_addr = Scalar::from_int(0x80000, dest.layout.size);
 680                 this.write_scalar(stack_addr, dest)?;
 681             }
 682
 683             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 684             "pthread_mutexattr_init" | "pthread_mutexattr_settype" | "pthread_mutex_init" |
 685             "pthread_mutexattr_destroy" | "pthread_mutex_lock" | "pthread_mutex_unlock" |
 686             "pthread_mutex_destroy" | "pthread_rwlock_rdlock" | "pthread_rwlock_unlock" |
 687             "pthread_rwlock_wrlock" | "pthread_rwlock_destroy" | "pthread_condattr_init" |
 688             "pthread_condattr_setclock" | "pthread_cond_init" | "pthread_condattr_destroy" |
 689             "pthread_cond_destroy" => {
 690                 this.write_null(dest)?;
 691             }
 692
 693             // We don't support fork so we don't have to do anything for atfork.
 694             "pthread_atfork" => {
 695                 this.write_null(dest)?;
 696             }
 697
 698             "mmap" => {
 699                 // 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.
 700                 let addr = this.read_scalar(args[0])?.not_undef()?;
 701                 this.write_scalar(addr, dest)?;
 702             }
 703             "mprotect" => {
 704                 this.write_null(dest)?;
 705             }
 706
 707             // macOS API stubs.
 708             "_tlv_atexit" => {
 709                 // FIXME: register the destructor.
 710             },
 711             "_NSGetArgc" => {
 712                 this.write_scalar(Scalar::Ptr(this.machine.argc.unwrap()), dest)?;
 713             },
 714             "_NSGetArgv" => {
 715                 this.write_scalar(Scalar::Ptr(this.machine.argv.unwrap()), dest)?;
 716             },
 717             "SecRandomCopyBytes" => {
 718                 let len = this.read_scalar(args[1])?.to_usize(this)?;
 719                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 720                 gen_random(this, len as usize, ptr)?;
 721                 this.write_null(dest)?;
 722             }
 723
 724             // Windows API stubs.
 725             // HANDLE = isize
 726             // DWORD = ULONG = u32
 727             // BOOL = i32
 728             "GetProcessHeap" => {
 729                 // Just fake a HANDLE
 730                 this.write_scalar(Scalar::from_int(1, this.pointer_size()), dest)?;
 731             }
 732             "HeapAlloc" => {
 733                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 734                 let flags = this.read_scalar(args[1])?.to_u32()?;
 735                 let size = this.read_scalar(args[2])?.to_usize(this)?;
 736                 let zero_init = (flags & 0x00000008) != 0; // HEAP_ZERO_MEMORY
 737                 let res = this.malloc(size, zero_init);
 738                 this.write_scalar(res, dest)?;
 739             }
 740             "HeapFree" => {
 741                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 742                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 743                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 744                 this.free(ptr)?;
 745                 this.write_scalar(Scalar::from_int(1, Size::from_bytes(4)), dest)?;
 746             }
 747             "HeapReAlloc" => {
 748                 let _handle = this.read_scalar(args[0])?.to_isize(this)?;
 749                 let _flags = this.read_scalar(args[1])?.to_u32()?;
 750                 let ptr = this.read_scalar(args[2])?.not_undef()?;
 751                 let size = this.read_scalar(args[3])?.to_usize(this)?;
 752                 let res = this.realloc(ptr, size)?;
 753                 this.write_scalar(res, dest)?;
 754             }
 755
 756             "SetLastError" => {
 757                 let err = this.read_scalar(args[0])?.to_u32()?;
 758                 this.machine.last_error = err;
 759             }
 760             "GetLastError" => {
 761                 this.write_scalar(Scalar::from_u32(this.machine.last_error), dest)?;
 762             }
 763
 764             "AddVectoredExceptionHandler" => {
 765                 // Any non zero value works for the stdlib. This is just used for stack overflows anyway.
 766                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 767             },
 768             "InitializeCriticalSection" |
 769             "EnterCriticalSection" |
 770             "LeaveCriticalSection" |
 771             "DeleteCriticalSection" => {
 772                 // Nothing to do, not even a return value.
 773             },
 774             "GetModuleHandleW" |
 775             "GetProcAddress" |
 776             "TryEnterCriticalSection" |
 777             "GetConsoleScreenBufferInfo" |
 778             "SetConsoleTextAttribute" => {
 779                 // Pretend these do not exist / nothing happened, by returning zero.
 780                 this.write_null(dest)?;
 781             },
 782             "GetSystemInfo" => {
 783                 let system_info = this.deref_operand(args[0])?;
 784                 let system_info_ptr = system_info.ptr.to_ptr()?;
 785                 // Initialize with `0`.
 786                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 787                     .write_repeat(tcx, system_info_ptr, 0, system_info.layout.size)?;
 788                 // Set number of processors to `1`.
 789                 let dword_size = Size::from_bytes(4);
 790                 let offset = 2*dword_size + 3*tcx.pointer_size();
 791                 this.memory_mut().get_mut(system_info_ptr.alloc_id)?
 792                     .write_scalar(
 793                         tcx,
 794                         system_info_ptr.offset(offset, tcx)?,
 795                         Scalar::from_int(1, dword_size).into(),
 796                         dword_size,
 797                     )?;
 798             }
 799
 800             "TlsAlloc" => {
 801                 // This just creates a key; Windows does not natively support TLS destructors.
 802
 803                 // Create key and return it.
 804                 let key = this.machine.tls.create_tls_key(None, tcx) as u128;
 805
 806                 // Figure out how large a TLS key actually is. This is `c::DWORD`.
 807                 if dest.layout.size.bits() < 128
 808                         && key >= (1u128 << dest.layout.size.bits() as u128) {
 809                     return err!(OutOfTls);
 810                 }
 811                 this.write_scalar(Scalar::from_uint(key, dest.layout.size), dest)?;
 812             }
 813             "TlsGetValue" => {
 814                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 815                 let ptr = this.machine.tls.load_tls(key)?;
 816                 this.write_scalar(ptr, dest)?;
 817             }
 818             "TlsSetValue" => {
 819                 let key = this.read_scalar(args[0])?.to_u32()? as u128;
 820                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 821                 this.machine.tls.store_tls(key, new_ptr)?;
 822
 823                 // Return success (`1`).
 824                 this.write_scalar(Scalar::from_int(1, dest.layout.size), dest)?;
 825             }
 826             "GetStdHandle" => {
 827                 let which = this.read_scalar(args[0])?.to_i32()?;
 828                 // We just make this the identity function, so we know later in `WriteFile`
 829                 // which one it is.
 830                 this.write_scalar(Scalar::from_int(which, this.pointer_size()), dest)?;
 831             }
 832             "WriteFile" => {
 833                 let handle = this.read_scalar(args[0])?.to_isize(this)?;
 834                 let buf = this.read_scalar(args[1])?.not_undef()?;
 835                 let n = this.read_scalar(args[2])?.to_u32()?;
 836                 let written_place = this.deref_operand(args[3])?;
 837                 // Spec says to always write `0` first.
 838                 this.write_null(written_place.into())?;
 839                 let written = if handle == -11 || handle == -12 {
 840                     // stdout/stderr
 841                     use std::io::{self, Write};
 842
 843                     let buf_cont = this.memory().read_bytes(buf, Size::from_bytes(u64::from(n)))?;
 844                     let res = if handle == -11 {
 845                         io::stdout().write(buf_cont)
 846                     } else {
 847                         io::stderr().write(buf_cont)
 848                     };
 849                     res.ok().map(|n| n as u32)
 850                 } else {
 851                     eprintln!("Miri: Ignored output to handle {}", handle);
 852                     // Pretend it all went well.
 853                     Some(n)
 854                 };
 855                 // If there was no error, write back how much was written.
 856                 if let Some(n) = written {
 857                     this.write_scalar(Scalar::from_u32(n), written_place.into())?;
 858                 }
 859                 // Return whether this was a success.
 860                 this.write_scalar(
 861                     Scalar::from_int(if written.is_some() { 1 } else { 0 }, dest.layout.size),
 862                     dest,
 863                 )?;
 864             }
 865             "GetConsoleMode" => {
 866                 // Everything is a pipe.
 867                 this.write_null(dest)?;
 868             }
 869             "GetEnvironmentVariableW" => {
 870                 // This is not the env var you are looking for.
 871                 this.machine.last_error = 203; // ERROR_ENVVAR_NOT_FOUND
 872                 this.write_null(dest)?;
 873             }
 874             "GetCommandLineW" => {
 875                 this.write_scalar(Scalar::Ptr(this.machine.cmd_line.unwrap()), dest)?;
 876             }
 877             // The actual name of 'RtlGenRandom'
 878             "SystemFunction036" => {
 879                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 880                 let len = this.read_scalar(args[1])?.to_u32()?;
 881                 gen_random(this, len as usize, ptr)?;
 882                 this.write_scalar(Scalar::from_bool(true), dest)?;
 883             }
 884
 885             // We can't execute anything else.
 886             _ => {
 887                 return err!(Unimplemented(
 888                     format!("can't call foreign function: {}", link_name),
 889                 ));
 890             }
 891         }
 892
 893         this.goto_block(Some(ret))?;
 894         this.dump_place(*dest);
 895         Ok(())
 896     }
 897
 898     fn write_null(&mut self, dest: PlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
 899         self.eval_context_mut().write_scalar(Scalar::from_int(0, dest.layout.size), dest)
 900     }
 901
 902     /// Evaluates the scalar at the specified path. Returns Some(val)
 903     /// if the path could be resolved, and None otherwise
 904     fn eval_path_scalar(&mut self, path: &[&str]) -> InterpResult<'tcx, Option<ScalarMaybeUndef<Tag>>> {
 905         let this = self.eval_context_mut();
 906         if let Ok(instance) = this.resolve_path(path) {
 907             let cid = GlobalId {
 908                 instance,
 909                 promoted: None,
 910             };
 911             let const_val = this.const_eval_raw(cid)?;
 912             let const_val = this.read_scalar(const_val.into())?;
 913             return Ok(Some(const_val));
 914         }
 915         return Ok(None);
 916     }
 917 }
 918
 919 fn gen_random<'a, 'mir, 'tcx>(
 920     this: &mut MiriEvalContext<'a, 'mir, 'tcx>,
 921     len: usize,
 922     dest: Scalar<Tag>,
 923 ) -> InterpResult<'tcx>  {
 924     if len == 0 {
 925         // Nothing to do
 926         return Ok(());
 927     }
 928     let ptr = dest.to_ptr()?;
 929
 930     let data = match &mut this.machine.rng {
 931         Some(rng) => {
 932             let mut data = vec![0; len];
 933             rng.fill_bytes(&mut data);
 934             data
 935         }
 936         None => {
 937             return err!(Unimplemented(
 938                 "miri does not support gathering system entropy in deterministic mode!
 939                 Use '-Zmiri-seed=<seed>' to enable random number generation.
 940                 WARNING: Miri does *not* generate cryptographically secure entropy -
 941                 do not use Miri to run any program that needs secure random number generation".to_owned(),
 942             ));
 943         }
 944     };
 945     let tcx = &{this.tcx.tcx};
 946     this.memory_mut().get_mut(ptr.alloc_id)?
 947         .write_bytes(tcx, ptr, &data)
 948 }