src/shims/foreign_items/posix.rs

   1 mod linux;
   2 mod macos;
   3
   4 use crate::*;
   5 use rustc::ty::layout::{Align, LayoutOf, Size};
   6
   7 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
   8 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
   9     fn emulate_foreign_item_by_name(
  10         &mut self,
  11         link_name: &str,
  12         args: &[OpTy<'tcx, Tag>],
  13         dest: PlaceTy<'tcx, Tag>,
  14     ) -> InterpResult<'tcx> {
  15         let this = self.eval_context_mut();
  16         let tcx = &{ this.tcx.tcx };
  17
  18         match link_name {
  19             // Environment related shims
  20             "getenv" => {
  21                 let result = this.getenv(args[0])?;
  22                 this.write_scalar(result, dest)?;
  23             }
  24
  25             "unsetenv" => {
  26                 let result = this.unsetenv(args[0])?;
  27                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  28             }
  29
  30             "setenv" => {
  31                 let result = this.setenv(args[0], args[1])?;
  32                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  33             }
  34
  35             "getcwd" => {
  36                 let result = this.getcwd(args[0], args[1])?;
  37                 this.write_scalar(result, dest)?;
  38             }
  39
  40             "chdir" => {
  41                 let result = this.chdir(args[0])?;
  42                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  43             }
  44
  45             // File related shims
  46             "fcntl" => {
  47                 let result = this.fcntl(args[0], args[1], args.get(2).cloned())?;
  48                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  49             }
  50
  51             "read" => {
  52                 let result = this.read(args[0], args[1], args[2])?;
  53                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  54             }
  55
  56             "write" => {
  57                 let fd = this.read_scalar(args[0])?.to_i32()?;
  58                 let buf = this.read_scalar(args[1])?.not_undef()?;
  59                 let n = this.read_scalar(args[2])?.to_machine_usize(tcx)?;
  60                 trace!("Called write({:?}, {:?}, {:?})", fd, buf, n);
  61                 let result = if fd == 1 || fd == 2 {
  62                     // stdout/stderr
  63                     use std::io::{self, Write};
  64
  65                     let buf_cont = this.memory.read_bytes(buf, Size::from_bytes(n))?;
  66                     // We need to flush to make sure this actually appears on the screen
  67                     let res = if fd == 1 {
  68                         // Stdout is buffered, flush to make sure it appears on the screen.
  69                         // This is the write() syscall of the interpreted program, we want it
  70                         // to correspond to a write() syscall on the host -- there is no good
  71                         // in adding extra buffering here.
  72                         let res = io::stdout().write(buf_cont);
  73                         io::stdout().flush().unwrap();
  74                         res
  75                     } else {
  76                         // No need to flush, stderr is not buffered.
  77                         io::stderr().write(buf_cont)
  78                     };
  79                     match res {
  80                         Ok(n) => n as i64,
  81                         Err(_) => -1,
  82                     }
  83                 } else {
  84                     this.write(args[0], args[1], args[2])?
  85                 };
  86                 // Now, `result` is the value we return back to the program.
  87                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  88             }
  89
  90             "unlink" => {
  91                 let result = this.unlink(args[0])?;
  92                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  93             }
  94
  95             "symlink" => {
  96                 let result = this.symlink(args[0], args[1])?;
  97                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  98             }
  99
 100             "posix_memalign" => {
 101                 let ret = this.deref_operand(args[0])?;
 102                 let align = this.read_scalar(args[1])?.to_machine_usize(this)?;
 103                 let size = this.read_scalar(args[2])?.to_machine_usize(this)?;
 104                 // Align must be power of 2, and also at least ptr-sized (POSIX rules).
 105                 if !align.is_power_of_two() {
 106                     throw_unsup!(HeapAllocNonPowerOfTwoAlignment(align));
 107                 }
 108                 if align < this.pointer_size().bytes() {
 109                     throw_ub_format!(
 110                         "posix_memalign: alignment must be at least the size of a pointer, but is {}",
 111                         align,
 112                     );
 113                 }
 114
 115                 if size == 0 {
 116                     this.write_null(ret.into())?;
 117                 } else {
 118                     let ptr = this.memory.allocate(
 119                         Size::from_bytes(size),
 120                         Align::from_bytes(align).unwrap(),
 121                         MiriMemoryKind::C.into(),
 122                     );
 123                     this.write_scalar(ptr, ret.into())?;
 124                 }
 125                 this.write_null(dest)?;
 126             }
 127
 128             "dlsym" => {
 129                 let _handle = this.read_scalar(args[0])?;
 130                 let symbol = this.read_scalar(args[1])?.not_undef()?;
 131                 let symbol_name = this.memory.read_c_str(symbol)?;
 132                 let err = format!("bad c unicode symbol: {:?}", symbol_name);
 133                 let symbol_name = ::std::str::from_utf8(symbol_name).unwrap_or(&err);
 134                 if let Some(dlsym) = Dlsym::from_str(symbol_name)? {
 135                     let ptr = this.memory.create_fn_alloc(FnVal::Other(dlsym));
 136                     this.write_scalar(Scalar::from(ptr), dest)?;
 137                 } else {
 138                     this.write_null(dest)?;
 139                 }
 140             }
 141
 142             "memrchr" => {
 143                 let ptr = this.read_scalar(args[0])?.not_undef()?;
 144                 let val = this.read_scalar(args[1])?.to_i32()? as u8;
 145                 let num = this.read_scalar(args[2])?.to_machine_usize(this)?;
 146                 if let Some(idx) = this
 147                     .memory
 148                     .read_bytes(ptr, Size::from_bytes(num))?
 149                     .iter()
 150                     .rev()
 151                     .position(|&c| c == val)
 152                 {
 153                     let new_ptr = ptr.ptr_offset(Size::from_bytes(num - idx as u64 - 1), this)?;
 154                     this.write_scalar(new_ptr, dest)?;
 155                 } else {
 156                     this.write_null(dest)?;
 157                 }
 158             }
 159
 160             // Hook pthread calls that go to the thread-local storage memory subsystem.
 161             "pthread_key_create" => {
 162                 let key_place = this.deref_operand(args[0])?;
 163
 164                 // Extract the function type out of the signature (that seems easier than constructing it ourselves).
 165                 let dtor = match this.test_null(this.read_scalar(args[1])?.not_undef()?)? {
 166                     Some(dtor_ptr) => Some(this.memory.get_fn(dtor_ptr)?.as_instance()?),
 167                     None => None,
 168                 };
 169
 170                 // Figure out how large a pthread TLS key actually is.
 171                 // This is `libc::pthread_key_t`.
 172                 let key_type = args[0].layout.ty
 173                     .builtin_deref(true)
 174                     .ok_or_else(|| err_ub_format!(
 175                         "wrong signature used for `pthread_key_create`: first argument must be a raw pointer."
 176                     ))?
 177                     .ty;
 178                 let key_layout = this.layout_of(key_type)?;
 179
 180                 // Create key and write it into the memory where `key_ptr` wants it.
 181                 let key = this.machine.tls.create_tls_key(dtor) as u128;
 182                 if key_layout.size.bits() < 128 && key >= (1u128 << key_layout.size.bits() as u128)
 183                 {
 184                     throw_unsup!(OutOfTls);
 185                 }
 186
 187                 this.write_scalar(Scalar::from_uint(key, key_layout.size), key_place.into())?;
 188
 189                 // Return success (`0`).
 190                 this.write_null(dest)?;
 191             }
 192             "pthread_key_delete" => {
 193                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 194                 this.machine.tls.delete_tls_key(key)?;
 195                 // Return success (0)
 196                 this.write_null(dest)?;
 197             }
 198             "pthread_getspecific" => {
 199                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 200                 let ptr = this.machine.tls.load_tls(key, tcx)?;
 201                 this.write_scalar(ptr, dest)?;
 202             }
 203             "pthread_setspecific" => {
 204                 let key = this.read_scalar(args[0])?.to_bits(args[0].layout.size)?;
 205                 let new_ptr = this.read_scalar(args[1])?.not_undef()?;
 206                 this.machine.tls.store_tls(key, this.test_null(new_ptr)?)?;
 207
 208                 // Return success (`0`).
 209                 this.write_null(dest)?;
 210             }
 211
 212             // Stack size/address stuff.
 213             | "pthread_attr_init"
 214             | "pthread_attr_destroy"
 215             | "pthread_self"
 216             | "pthread_attr_setstacksize" => {
 217                 this.write_null(dest)?;
 218             }
 219             "pthread_attr_getstack" => {
 220                 let addr_place = this.deref_operand(args[1])?;
 221                 let size_place = this.deref_operand(args[2])?;
 222
 223                 this.write_scalar(
 224                     Scalar::from_uint(STACK_ADDR, addr_place.layout.size),
 225                     addr_place.into(),
 226                 )?;
 227                 this.write_scalar(
 228                     Scalar::from_uint(STACK_SIZE, size_place.layout.size),
 229                     size_place.into(),
 230                 )?;
 231
 232                 // Return success (`0`).
 233                 this.write_null(dest)?;
 234             }
 235
 236             // We don't support threading. (Also for Windows.)
 237             | "pthread_create"
 238             | "CreateThread"
 239             => {
 240                 throw_unsup_format!("Miri does not support threading");
 241             }
 242
 243             // Stub out calls for condvar, mutex and rwlock, to just return `0`.
 244             | "pthread_mutexattr_init"
 245             | "pthread_mutexattr_settype"
 246             | "pthread_mutex_init"
 247             | "pthread_mutexattr_destroy"
 248             | "pthread_mutex_lock"
 249             | "pthread_mutex_unlock"
 250             | "pthread_mutex_destroy"
 251             | "pthread_rwlock_rdlock"
 252             | "pthread_rwlock_unlock"
 253             | "pthread_rwlock_wrlock"
 254             | "pthread_rwlock_destroy"
 255             | "pthread_condattr_init"
 256             | "pthread_condattr_setclock"
 257             | "pthread_cond_init"
 258             | "pthread_condattr_destroy"
 259             | "pthread_cond_destroy"
 260             => {
 261                 this.write_null(dest)?;
 262             }
 263
 264             // We don't support fork so we don't have to do anything for atfork.
 265             "pthread_atfork" => {
 266                 this.write_null(dest)?;
 267             }
 268
 269             // Some things needed for `sys::thread` initialization to go through.
 270             | "signal"
 271             | "sigaction"
 272             | "sigaltstack"
 273             => {
 274                 this.write_scalar(Scalar::from_int(0, dest.layout.size), dest)?;
 275             }
 276
 277             "sysconf" => {
 278                 let name = this.read_scalar(args[0])?.to_i32()?;
 279
 280                 trace!("sysconf() called with name {}", name);
 281                 // TODO: Cache the sysconf integers via Miri's global cache.
 282                 let paths = &[
 283                     (&["libc", "_SC_PAGESIZE"], Scalar::from_int(PAGE_SIZE, dest.layout.size)),
 284                     (&["libc", "_SC_GETPW_R_SIZE_MAX"], Scalar::from_int(-1, dest.layout.size)),
 285                     (
 286                         &["libc", "_SC_NPROCESSORS_ONLN"],
 287                         Scalar::from_int(NUM_CPUS, dest.layout.size),
 288                     ),
 289                 ];
 290                 let mut result = None;
 291                 for &(path, path_value) in paths {
 292                     if let Some(val) = this.eval_path_scalar(path)? {
 293                         let val = val.to_i32()?;
 294                         if val == name {
 295                             result = Some(path_value);
 296                             break;
 297                         }
 298                     }
 299                 }
 300                 if let Some(result) = result {
 301                     this.write_scalar(result, dest)?;
 302                 } else {
 303                     throw_unsup_format!("Unimplemented sysconf name: {}", name)
 304                 }
 305             }
 306
 307             "isatty" => {
 308                 this.write_null(dest)?;
 309             }
 310
 311             "posix_fadvise" => {
 312                 // fadvise is only informational, we can ignore it.
 313                 this.write_null(dest)?;
 314             }
 315
 316             "mmap" => {
 317                 // 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.
 318                 let addr = this.read_scalar(args[0])?.not_undef()?;
 319                 this.write_scalar(addr, dest)?;
 320             }
 321
 322             "mprotect" => {
 323                 this.write_null(dest)?;
 324             }
 325
 326             _ => {
 327                 match this.tcx.sess.target.target.target_os.to_lowercase().as_str() {
 328                     "linux" => linux::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest)?,
 329                     "macos" => macos::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest)?,
 330                     _ => unreachable!(),
 331                 }
 332             }
 333         };
 334
 335         Ok(())
 336     }
 337 }
 338
 339 // Shims the posix 'getrandom()' syscall.
 340 fn getrandom<'tcx>(
 341     this: &mut MiriEvalContext<'_, 'tcx>,
 342     args: &[OpTy<'tcx, Tag>],
 343     dest: PlaceTy<'tcx, Tag>,
 344 ) -> InterpResult<'tcx> {
 345     let ptr = this.read_scalar(args[0])?.not_undef()?;
 346     let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
 347
 348     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 349     // neither of which have any effect on our current PRNG.
 350     let _flags = this.read_scalar(args[2])?.to_i32()?;
 351
 352     this.gen_random(ptr, len as usize)?;
 353     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 354     Ok(())
 355 }