src/shims/foreign_items/posix/linux.rs

   1 use crate::*;
   2 use rustc::mir;
   3
   4 impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
   5 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx> {
   6     fn emulate_foreign_item_by_name(
   7         &mut self,
   8         link_name: &str,
   9         args: &[OpTy<'tcx, Tag>],
  10         dest: PlaceTy<'tcx, Tag>,
  11         _ret: mir::BasicBlock,
  12     ) -> InterpResult<'tcx, bool> {
  13         let this = self.eval_context_mut();
  14
  15         match link_name {
  16             "__errno_location" => {
  17                 let errno_place = this.machine.last_error.unwrap();
  18                 this.write_scalar(errno_place.to_ref().to_scalar()?, dest)?;
  19             }
  20
  21             // File related shims
  22
  23             // The only reason this is not in the `posix` module is because the `macos` item has a
  24             // different name.
  25             "close" => {
  26                 let result = this.close(args[0])?;
  27                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  28             }
  29
  30             // Time related shims
  31
  32             // This is a POSIX function but it has only been tested on linux.
  33             "clock_gettime" => {
  34                 let result = this.clock_gettime(args[0], args[1])?;
  35                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  36             }
  37
  38             // Other shims
  39             "pthread_getattr_np" => {
  40                 this.write_null(dest)?;
  41             }
  42
  43             "syscall" => {
  44                 let sys_getrandom = this
  45                     .eval_path_scalar(&["libc", "SYS_getrandom"])?
  46                     .expect("Failed to get libc::SYS_getrandom")
  47                     .to_machine_usize(this)?;
  48
  49                 let sys_statx = this
  50                     .eval_path_scalar(&["libc", "SYS_statx"])?
  51                     .expect("Failed to get libc::SYS_statx")
  52                     .to_machine_usize(this)?;
  53
  54                 match this.read_scalar(args[0])?.to_machine_usize(this)? {
  55                     // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
  56                     // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
  57                     id if id == sys_getrandom => {
  58                         // The first argument is the syscall id,
  59                         // so skip over it.
  60                         getrandom(this, &args[1..], dest)?;
  61                     }
  62                     // `statx` is used by `libstd` to retrieve metadata information in `linux`
  63                     // instead of using `stat`,`lstat` or `fstat` as in the `macos` platform.
  64                     id if id == sys_statx => {
  65                         // The first argument is the syscall id,
  66                         // so skip over it.
  67                         let result = this.linux_statx(args[1], args[2], args[3], args[4], args[5])?;
  68                         this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  69                     }
  70                     id => throw_unsup_format!("miri does not support syscall ID {}", id),
  71                 }
  72             }
  73
  74             "getrandom" => {
  75                 getrandom(this, args, dest)?;
  76             }
  77
  78             "sched_getaffinity" => {
  79                 // Return an error; `num_cpus` then falls back to `sysconf`.
  80                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
  81             }
  82
  83             _ => throw_unsup_format!("can't call foreign function: {}", link_name),
  84         };
  85
  86         Ok(true)
  87     }
  88 }
  89
  90 // Shims the linux 'getrandom()' syscall.
  91 fn getrandom<'tcx>(
  92     this: &mut MiriEvalContext<'_, 'tcx>,
  93     args: &[OpTy<'tcx, Tag>],
  94     dest: PlaceTy<'tcx, Tag>,
  95 ) -> InterpResult<'tcx> {
  96     let ptr = this.read_scalar(args[0])?.not_undef()?;
  97     let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
  98
  99     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
 100     // neither of which have any effect on our current PRNG.
 101     let _flags = this.read_scalar(args[2])?.to_i32()?;
 102
 103     this.gen_random(ptr, len as usize)?;
 104     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 105     Ok(())
 106 }