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             "close" => {
  23                 let result = this.close(args[0])?;
  24                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  25             }
  26
  27             // Time related shims
  28
  29             // This is a POSIX function but it has only been tested on linux.
  30             "clock_gettime" => {
  31                 let result = this.clock_gettime(args[0], args[1])?;
  32                 this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  33             }
  34
  35             // Other shims
  36             "pthread_getattr_np" => {
  37                 this.write_null(dest)?;
  38             }
  39
  40             "syscall" => {
  41                 let sys_getrandom = this
  42                     .eval_path_scalar(&["libc", "SYS_getrandom"])?
  43                     .expect("Failed to get libc::SYS_getrandom")
  44                     .to_machine_usize(this)?;
  45
  46                 let sys_statx = this
  47                     .eval_path_scalar(&["libc", "SYS_statx"])?
  48                     .expect("Failed to get libc::SYS_statx")
  49                     .to_machine_usize(this)?;
  50
  51                 match this.read_scalar(args[0])?.to_machine_usize(this)? {
  52                     // `libc::syscall(NR_GETRANDOM, buf.as_mut_ptr(), buf.len(), GRND_NONBLOCK)`
  53                     // is called if a `HashMap` is created the regular way (e.g. HashMap<K, V>).
  54                     id if id == sys_getrandom => {
  55                         // The first argument is the syscall id,
  56                         // so skip over it.
  57                         getrandom(this, &args[1..], dest)?;
  58                     }
  59                     id if id == sys_statx => {
  60                         // The first argument is the syscall id,
  61                         // so skip over it.
  62                         let result = this.linux_statx(args[1], args[2], args[3], args[4], args[5])?;
  63                         this.write_scalar(Scalar::from_int(result, dest.layout.size), dest)?;
  64                     }
  65                     id => throw_unsup_format!("miri does not support syscall ID {}", id),
  66                 }
  67             }
  68
  69             "getrandom" => {
  70                 getrandom(this, args, dest)?;
  71             }
  72
  73             "sched_getaffinity" => {
  74                 // Return an error; `num_cpus` then falls back to `sysconf`.
  75                 this.write_scalar(Scalar::from_int(-1, dest.layout.size), dest)?;
  76             }
  77
  78             _ => throw_unsup_format!("can't call foreign function: {}", link_name),
  79         };
  80
  81         Ok(true)
  82     }
  83 }
  84
  85 // Shims the linux 'getrandom()' syscall.
  86 fn getrandom<'tcx>(
  87     this: &mut MiriEvalContext<'_, 'tcx>,
  88     args: &[OpTy<'tcx, Tag>],
  89     dest: PlaceTy<'tcx, Tag>,
  90 ) -> InterpResult<'tcx> {
  91     let ptr = this.read_scalar(args[0])?.not_undef()?;
  92     let len = this.read_scalar(args[1])?.to_machine_usize(this)?;
  93
  94     // The only supported flags are GRND_RANDOM and GRND_NONBLOCK,
  95     // neither of which have any effect on our current PRNG.
  96     let _flags = this.read_scalar(args[2])?.to_i32()?;
  97
  98     this.gen_random(ptr, len as usize)?;
  99     this.write_scalar(Scalar::from_uint(len, dest.layout.size), dest)?;
 100     Ok(())
 101 }