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