src/shims/foreign_items/posix.rs

   1 mod linux;
   2 mod macos;
   3
   4 use std::convert::TryFrom;
   5
   6 use log::trace;
   7
   8 use crate::*;
   9 use rustc_index::vec::Idx;
  10 use rustc_middle::mir;
  11 use rustc_target::abi::{Align, LayoutOf, Size};
  12
  13 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
  14 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
  15     fn emulate_foreign_item_by_name(
  16         &mut self,
  17         link_name: &str,
  18         args: &[OpTy<'tcx, Tag>],
  19         dest: PlaceTy<'tcx, Tag>,
  20         ret: mir::BasicBlock,
  21     ) -> InterpResult<'tcx, bool> {
  22         let this = self.eval_context_mut();
  23
  24         match link_name {
  25             // Environment related shims
  26             "getenv" => {
  27                 let result = this.getenv(args[0])?;
  28                 this.write_scalar(result, dest)?;
  29             }
  30             "unsetenv" => {
  31                 let result = this.unsetenv(args[0])?;
  32                 this.write_scalar(Scalar::from_i32(result), dest)?;
  33             }
  34             "setenv" => {
  35                 let result = this.setenv(args[0], args[1])?;
  36                 this.write_scalar(Scalar::from_i32(result), dest)?;
  37             }
  38             "getcwd" => {
  39                 let result = this.getcwd(args[0], args[1])?;
  40                 this.write_scalar(result, dest)?;
  41             }
  42             "chdir" => {
  43                 let result = this.chdir(args[0])?;
  44                 this.write_scalar(Scalar::from_i32(result), dest)?;
  45             }
  46
  47             // File related shims
  48             "open" | "open64" => {
  49                 let result = this.open(args[0], args[1])?;
  50                 this.write_scalar(Scalar::from_i32(result), dest)?;
  51             }
  52             "fcntl" => {
  53                 let result = this.fcntl(args[0], args[1], args.get(2).cloned())?;
  54                 this.write_scalar(Scalar::from_i32(result), dest)?;
  55             }
  56             "read" => {
  57                 let result = this.read(args[0], args[1], args[2])?;
  58                 this.write_scalar(Scalar::from_machine_isize(result, this), dest)?;
  59             }
  60             "write" => {
  61                 let fd = this.read_scalar(args[0])?.to_i32()?;
  62                 let buf = this.read_scalar(args[1])?.not_undef()?;
  63                 let n = this.read_scalar(args[2])?.to_machine_usize(this)?;
  64                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
  65                 let result = if fd == 1 || fd == 2 {
  66                     // stdout/stderr
  67                     use std::io::{self, Write};
  68
  69                     let buf_cont = this.memory.read_bytes(buf, Size::from_bytes(n))?;
  70                     // We need to flush to make sure this actually appears on the screen
  71                     let res = if fd == 1 {
  72                         // Stdout is buffered, flush to make sure it appears on the screen.
  73                         // This is the write() syscall of the interpreted program, we want it
  74                         // to correspond to a write() syscall on the host -- there is no good
  75                         // in adding extra buffering here.
  76                         let res = io::stdout().write(buf_cont);
  77                         io::stdout().flush().unwrap();
  78                         res
  79                     } else {
  80                         // No need to flush, stderr is not buffered.
  81                         io::stderr().write(buf_cont)
  82                     };
  83                     match res {
  84                         Ok(n) => i64::try_from(n).unwrap(),
  85                         Err(_) => -1,
  86                     }
  87                 } else {
  88                     this.write(args[0], args[1], args[2])?
  89                 };
  90                 // Now, `result` is the value we return back to the program.
  91                 this.write_scalar(Scalar::from_machine_isize(result, this), dest)?;
  92             }
  93             "unlink" => {
  94                 let result = this.unlink(args[0])?;
  95                 this.write_scalar(Scalar::from_i32(result), dest)?;
  96             }
  97             "symlink" => {
  98                 let result = this.symlink(args[0], args[1])?;
  99                 this.write_scalar(Scalar::from_i32(result), dest)?;
 100             }
 101             "rename" => {
 102                 let result = this.rename(args[0], args[1])?;
 103                 this.write_scalar(Scalar::from_i32(result), dest)?;
 104             }
 105             "mkdir" => {
 106                 let result = this.mkdir(args[0], args[1])?;
 107                 this.write_scalar(Scalar::from_i32(result), dest)?;
 108             }
 109             "rmdir" => {
 110                 let result = this.rmdir(args[0])?;
 111                 this.write_scalar(Scalar::from_i32(result), dest)?;
 112             }
 113             "closedir" => {
 114                 let result = this.closedir(args[0])?;
 115                 this.write_scalar(Scalar::from_i32(result), dest)?;
 116             }
 117             "lseek" | "lseek64" => {
 118                 let result = this.lseek64(args[0], args[1], args[2])?;
 119                 // "lseek" is only used on macOS which is 64bit-only, so `i64` always works.
 120                 this.write_scalar(Scalar::from_i64(result), dest)?;
 121             }
 122
 123             // Allocation
 124             "posix_memalign" => {
 125                 let ret = this.deref_operand(args[0])?;
 126                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 127                 let size = this.read_scalar(args[2])?.to_machine_usize(this)?;
 128                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 129                 if !align.is_power_of_two() {
 130                     throw_ub_format!("posix_memalign: alignment must be a power of two, but is {}", align);
 131                 }
 132                 if align < this.pointer_size().bytes() {
 133                     throw_ub_format!(
 134                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 135                         align,
 136                     );
 137                 }
 138
 139                 if size == 0 {
 140                     this.write_null(ret.into())?;
 141                 } else {
 142                     let ptr = this.memory.allocate(
 143                         Size::from_bytes(size),
 144                         Align::from_bytes(align).unwrap(),
 145                         MiriMemoryKind::C.into(),
 146                     );
 147                     this.write_scalar(ptr, ret.into())?;
 148                 }
 149                 this.write_null(dest)?;
 150             }
 151
 152             // Dynamic symbol loading
 153             "dlsym" => {
 154                 let _handle = this.read_scalar(args[0])?;
 155                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 156                 let symbol_name = this.memory.read_c_str(symbol)?;
 157                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 158                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 159                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 160                     let ptr = this.memory.create_fn_alloc(FnVal::Other(dlsym));
 161                     this.write_scalar(Scalar::from(ptr), dest)?;
 162                 } else {
 163                     this.write_null(dest)?;
 164                 }
 165             }
 166
 167             // Querying system information
 168             "sysconf" => {
 169                 let name = this.read_scalar(args[0])?.to_i32()?;
 170
 171                 let sysconfs = &[
 172                     ("_SC_PAGESIZE", Scalar::from_int(PAGE_SIZE, this.pointer_size())),
 173                     ("_SC_NPROCESSORS_ONLN", Scalar::from_int(NUM_CPUS, this.pointer_size())),
 174                 ];
 175                 let mut result = None;
 176                 for &(sysconf_name, value) in sysconfs {
 177                     let sysconf_name = this.eval_libc_i32(sysconf_name)?;
 178                     if sysconf_name == name {
 179                         result = Some(value);
 180                         break;
 181                     }
 182                 }
 183                 if let Some(result) = result {
 184                     this.write_scalar(result, dest)?;
 185                 } else {
 186                     throw_unsup_format!("unimplemented sysconf name: {}", name)
 187                 }
 188             }
 189
 190             // Thread-local storage
 191             "pthread_key_create" => {
 192                 let key_place = this.deref_operand(args[0])?;
 193
 194                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 195                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 196                     Some(dtor_ptr) => Some(this.memory.get_fn(dtor_ptr)?.as_instance()?),
 197                     None => None,
 198                 };
 199
 200                 // Figure out how large a pthread TLS key actually is.
 201                 // To this end, deref the argument type. This is `libc::pthread_key_t`.
 202                 let key_type = args[0].layout.ty
 203                     .builtin_deref(true)
 204                     .ok_or_else(|| err_ub_format!(
 205                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 206                     ))?
 207                     .ty;
 208                 let key_layout = this.layout_of(key_type)?;
 209
 210                 // Create key and write it into the memory where `key_ptr` wants it.
 211                 let key = this.machine.tls.create_tls_key(dtor, key_layout.size)?;
 212                 this.write_scalar(Scalar::from_uint(key, key_layout.size), key_place.into())?;
 213
 214                 // Return success (`0`).
 215                 this.write_null(dest)?;
 216             }
 217             "pthread_key_delete" => {
 218                 let key = this.force_bits(this.read_scalar(args[0])?.not_undef()?, args[0].layout.size)?;
 219                 this.machine.tls.delete_tls_key(key)?;
 220                 // Return success (0)
 221                 this.write_null(dest)?;
 222             }
 223             "pthread_getspecific" => {
 224                 let key = this.force_bits(this.read_scalar(args[0])?.not_undef()?, args[0].layout.size)?;
 225                 let active_thread = this.get_active_thread()?;
 226                 let ptr = this.machine.tls.load_tls(key, active_thread, this)?;
 227                 this.write_scalar(ptr, dest)?;
 228             }
 229             "pthread_setspecific" => {
 230                 let key = this.force_bits(this.read_scalar(args[0])?.not_undef()?, args[0].layout.size)?;
 231                 let active_thread = this.get_active_thread()?;
 232                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 233                 this.machine.tls.store_tls(key, active_thread, this.test_null(new_ptr)?)?;
 234
 235                 // Return success (`0`).
 236                 this.write_null(dest)?;
 237             }
 238
 239             // Synchronization primitives
 240             "pthread_mutexattr_init" => {
 241                 let result = this.pthread_mutexattr_init(args[0])?;
 242                 this.write_scalar(Scalar::from_i32(result), dest)?;
 243             }
 244             "pthread_mutexattr_settype" => {
 245                 let result = this.pthread_mutexattr_settype(args[0], args[1])?;
 246                 this.write_scalar(Scalar::from_i32(result), dest)?;
 247             }
 248             "pthread_mutexattr_destroy" => {
 249                 let result = this.pthread_mutexattr_destroy(args[0])?;
 250                 this.write_scalar(Scalar::from_i32(result), dest)?;
 251             }
 252             "pthread_mutex_init" => {
 253                 let result = this.pthread_mutex_init(args[0], args[1])?;
 254                 this.write_scalar(Scalar::from_i32(result), dest)?;
 255             }
 256             "pthread_mutex_lock" => {
 257                 let result = this.pthread_mutex_lock(args[0])?;
 258                 this.write_scalar(Scalar::from_i32(result), dest)?;
 259             }
 260             "pthread_mutex_trylock" => {
 261                 let result = this.pthread_mutex_trylock(args[0])?;
 262                 this.write_scalar(Scalar::from_i32(result), dest)?;
 263             }
 264             "pthread_mutex_unlock" => {
 265                 let result = this.pthread_mutex_unlock(args[0])?;
 266                 this.write_scalar(Scalar::from_i32(result), dest)?;
 267             }
 268             "pthread_mutex_destroy" => {
 269                 let result = this.pthread_mutex_destroy(args[0])?;
 270                 this.write_scalar(Scalar::from_i32(result), dest)?;
 271             }
 272             "pthread_rwlock_rdlock" => {
 273                 let result = this.pthread_rwlock_rdlock(args[0])?;
 274                 this.write_scalar(Scalar::from_i32(result), dest)?;
 275             }
 276             "pthread_rwlock_tryrdlock" => {
 277                 let result = this.pthread_rwlock_tryrdlock(args[0])?;
 278                 this.write_scalar(Scalar::from_i32(result), dest)?;
 279             }
 280             "pthread_rwlock_wrlock" => {
 281                 let result = this.pthread_rwlock_wrlock(args[0])?;
 282                 this.write_scalar(Scalar::from_i32(result), dest)?;
 283             }
 284             "pthread_rwlock_trywrlock" => {
 285                 let result = this.pthread_rwlock_trywrlock(args[0])?;
 286                 this.write_scalar(Scalar::from_i32(result), dest)?;
 287             }
 288             "pthread_rwlock_unlock" => {
 289                 let result = this.pthread_rwlock_unlock(args[0])?;
 290                 this.write_scalar(Scalar::from_i32(result), dest)?;
 291             }
 292             "pthread_rwlock_destroy" => {
 293                 let result = this.pthread_rwlock_destroy(args[0])?;
 294                 this.write_scalar(Scalar::from_i32(result), dest)?;
 295             }
 296
 297             // Miscellaneous
 298             "isatty" => {
 299                 let _fd = this.read_scalar(args[0])?.to_i32()?;
 300                 // "returns 1 if fd is an open file descriptor referring to a terminal; otherwise 0 is returned, and errno is set to indicate the error"
 301                 // FIXME: we just say nothing is a terminal.
 302                 let enotty = this.eval_libc("ENOTTY")?;
 303                 this.set_last_error(enotty)?;
 304                 this.write_null(dest)?;
 305             }
 306             "pthread_atfork" => {
 307                 let _prepare = this.read_scalar(args[0])?.not_undef()?;
 308                 let _parent = this.read_scalar(args[1])?.not_undef()?;
 309                 let _child = this.read_scalar(args[1])?.not_undef()?;
 310                 // We do not support forking, so there is nothing to do here.
 311                 this.write_null(dest)?;
 312             }
 313             "sched_yield" => {
 314                 this.write_null(dest)?;
 315             }
 316
 317             // Threading
 318             "pthread_create" => {
 319                 println!("WARNING: The thread support is experimental. \
 320                           For example, Miri does not detect data races yet.");
 321                 assert_eq!(args.len(), 4);
 322                 let func = args[2];
 323                 let fn_ptr = this.read_scalar(func)?.not_undef()?;
 324                 let fn_val = this.memory.get_fn(fn_ptr)?;
 325                 let instance = match fn_val {
 326                     rustc_mir::interpret::FnVal::Instance(instance) => instance,
 327                     _ => unreachable!(),
 328                 };
 329                 let thread_info_place = this.deref_operand(args[0])?;
 330                 let thread_info_type = args[0].layout.ty
 331                     .builtin_deref(true)
 332                     .ok_or_else(|| err_ub_format!(
 333                         "wrong signature used for `pthread_create`: first argument must be a raw pointer."
 334                     ))?
 335                     .ty;
 336                 let thread_info_layout = this.layout_of(thread_info_type)?;
 337                 let func_arg = match *args[3] {
 338                     rustc_mir::interpret::Operand::Immediate(immediate) => immediate,
 339                     _ => unreachable!(),
 340                 };
 341                 let func_args = [func_arg];
 342                 let ret_place =
 343                     this.allocate(this.layout_of(this.tcx.types.usize)?, MiriMemoryKind::Machine.into());
 344                 let new_thread_id = this.create_thread()?;
 345                 let old_thread_id = this.set_active_thread(new_thread_id)?;
 346                 this.call_function(
 347                     instance,
 348                     &func_args[..],
 349                     Some(ret_place.into()),
 350                     StackPopCleanup::None { cleanup: true },
 351                 )?;
 352                 this.set_active_thread(old_thread_id)?;
 353                 this.write_scalar(
 354                     Scalar::from_uint(new_thread_id.index() as u128, thread_info_layout.size),
 355                     thread_info_place.into(),
 356                 )?;
 357
 358                 // Return success (`0`).
 359                 this.write_null(dest)?;
 360             }
 361             "pthread_join" => {
 362                 assert_eq!(args.len(), 2);
 363                 assert!(
 364                     this.is_null(this.read_scalar(args[1])?.not_undef()?)?,
 365                     "Miri supports pthread_join only with retval==NULL"
 366                 );
 367                 let thread = this.read_scalar(args[0])?.not_undef()?.to_machine_usize(this)?;
 368                 this.join_thread(thread.into())?;
 369
 370                 // Return success (`0`).
 371                 this.write_null(dest)?;
 372             }
 373             "pthread_detach" => {
 374                 let thread = this.read_scalar(args[0])?.not_undef()?.to_machine_usize(this)?;
 375                 this.detach_thread(thread.into())?;
 376
 377                 // Return success (`0`).
 378                 this.write_null(dest)?;
 379             }
 380
 381             "pthread_attr_getguardsize" => {
 382                 assert_eq!(args.len(), 2);
 383
 384                 let guard_size = this.deref_operand(args[1])?;
 385                 let guard_size_type = args[1].layout.ty
 386                     .builtin_deref(true)
 387                     .ok_or_else(|| err_ub_format!(
 388                         "wrong signature used for `pthread_attr_getguardsize`: first argument must be a raw pointer."
 389                     ))?
 390                     .ty;
 391                 let guard_size_layout = this.layout_of(guard_size_type)?;
 392                 this.write_scalar(Scalar::from_uint(crate::PAGE_SIZE, guard_size_layout.size), guard_size.into())?;
 393
 394                 // Return success (`0`).
 395                 this.write_null(dest)?;
 396             }
 397
 398             "prctl" => {
 399                 let option = this.read_scalar(args[0])?.not_undef()?.to_i32()?;
 400                 assert_eq!(option, 0xf, "Miri supports only PR_SET_NAME");
 401
 402                 // Return success (`0`).
 403                 this.write_null(dest)?;
 404             }
 405
 406             // Incomplete shims that we "stub out" just to get pre-main initialziation code to work.
 407             // These shims are enabled only when the caller is in the standard library.
 408             | "pthread_attr_init"
 409             | "pthread_attr_destroy"
 410             | "pthread_self"
 411             | "pthread_attr_setstacksize"
 412             | "pthread_condattr_init"
 413             | "pthread_condattr_setclock"
 414             | "pthread_cond_init"
 415             | "pthread_condattr_destroy"
 416             | "pthread_cond_destroy" if this.frame().instance.to_string().starts_with("std::sys::unix::")
 417             => {
 418                 this.write_null(dest)?;
 419             }
 420
 421             | "signal"
 422             | "sigaction"
 423             | "sigaltstack"
 424             | "mprotect" if this.frame().instance.to_string().starts_with("std::sys::unix::")
 425             => {
 426                 this.write_null(dest)?;
 427             }
 428
 429             // Platform-specific shims
 430             _ => {
 431                 match this.tcx.sess.target.target.target_os.as_str() {
 432                     "linux" => return linux::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest, ret),
 433                     "macos" => return macos::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest, ret),
 434                     _ => unreachable!(),
 435                 }
 436             }
 437         };
 438
 439         Ok(true)
 440     }
 441 }