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