X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=src%2Fhelpers.rs;h=f7be3de8e481227ba2d0077d757ec4d146bf9822;hb=cf9340113efcf5c7bea4a143f42c8ea47da4550e;hp=351a6e7e54a6f002ec05c9373ae8c28805e8f254;hpb=fe9056ee77f9a6804ec6ca7e0471bfe8e250cfb5;p=rust.git

diff --git a/src/helpers.rs b/src/helpers.rs
index 351a6e7e54a..f7be3de8e48 100644
--- a/src/helpers.rs
+++ b/src/helpers.rs
@@ -1,7 +1,12 @@
-use std::mem;
+use std::{mem, iter};
+use std::ffi::{OsStr, OsString};
 
-use rustc::ty::{self, layout::{self, Size, Align}};
 use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX};
+use rustc::mir;
+use rustc::ty::{
+    self,
+    layout::{self, LayoutOf, Size, TyLayout},
+};
 
 use rand::RngCore;
 
@@ -41,7 +46,7 @@ fn resolve_path(&self, path: &[&str]) -> InterpResult<'tcx, ty::Instance<'tcx>>
             })
             .ok_or_else(|| {
                 let path = path.iter().map(|&s| s.to_owned()).collect();
-                InterpError::PathNotFound(path).into()
+                err_unsup!(PathNotFound(path)).into()
             })
     }
 
@@ -53,7 +58,7 @@ fn write_null(&mut self, dest: PlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
     /// Test if this immediate equals 0.
     fn is_null(&self, val: Scalar<Tag>) -> InterpResult<'tcx, bool> {
         let this = self.eval_context_ref();
-        let null = Scalar::from_int(0, this.memory().pointer_size());
+        let null = Scalar::from_int(0, this.memory.pointer_size());
         this.ptr_eq(val, null)
     }
 
@@ -67,38 +72,42 @@ fn test_null(&self, val: Scalar<Tag>) -> InterpResult<'tcx, Option<Scalar<Tag>>>
         })
     }
 
+    /// Get the `Place` for a local
+    fn local_place(&mut self, local: mir::Local) -> InterpResult<'tcx, PlaceTy<'tcx, Tag>> {
+        let this = self.eval_context_mut();
+        let place = mir::Place { base: mir::PlaceBase::Local(local), projection: Box::new([]) };
+        this.eval_place(&place)
+    }
+
     /// Generate some random bytes, and write them to `dest`.
     fn gen_random(
         &mut self,
-        len: usize,
         ptr: Scalar<Tag>,
+        len: usize,
     ) -> InterpResult<'tcx>  {
+        // Some programs pass in a null pointer and a length of 0
+        // to their platform's random-generation function (e.g. getrandom())
+        // on Linux. For compatibility with these programs, we don't perform
+        // any additional checks - it's okay if the pointer is invalid,
+        // since we wouldn't actually be writing to it.
+        if len == 0 {
+            return Ok(());
+        }
         let this = self.eval_context_mut();
 
-        let ptr = match this.memory().check_ptr_access(ptr, Size::from_bytes(len as u64), Align::from_bytes(1).unwrap())? {
-            Some(ptr) => ptr,
-            None => return Ok(()), // zero-sized access
-        };
+        let mut data = vec![0; len];
 
-        let data = match &mut this.memory_mut().extra.rng {
-            Some(rng) => {
-                let mut rng = rng.borrow_mut();
-                let mut data = vec![0; len];
-                rng.fill_bytes(&mut data);
-                data
-            }
-            None => {
-                return err!(Unimplemented(
-                    "miri does not support gathering system entropy in deterministic mode!
-                    Use '-Zmiri-seed=<seed>' to enable random number generation.
-                    WARNING: Miri does *not* generate cryptographically secure entropy -
-                    do not use Miri to run any program that needs secure random number generation".to_owned(),
-                ));
-            }
-        };
-        let tcx = &{this.tcx.tcx};
-        this.memory_mut().get_mut(ptr.alloc_id)?
-            .write_bytes(tcx, ptr, &data)
+        if this.machine.communicate {
+            // Fill the buffer using the host's rng.
+            getrandom::getrandom(&mut data)
+                .map_err(|err| err_unsup_format!("getrandom failed: {}", err))?;
+        }
+        else {
+            let rng = this.memory.extra.rng.get_mut();
+            rng.fill_bytes(&mut data);
+        }
+
+        this.memory.write_bytes(ptr, data.iter().copied())
     }
 
     /// Visits the memory covered by `place`, sensitive to freezing: the 3rd parameter
@@ -199,7 +208,7 @@ fn ecx(&self) -> &MiriEvalContext<'mir, 'tcx> {
             fn visit_value(&mut self, v: MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx>
             {
                 trace!("UnsafeCellVisitor: {:?} {:?}", *v, v.layout.ty);
-                let is_unsafe_cell = match v.layout.ty.sty {
+                let is_unsafe_cell = match v.layout.ty.kind {
                     ty::Adt(adt, _) => Some(adt.did) == self.ecx.tcx.lang_items().unsafe_cell_type(),
                     _ => false,
                 };
@@ -210,8 +219,26 @@ fn visit_value(&mut self, v: MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx>
                     // This is `Freeze`, there cannot be an `UnsafeCell`
                     Ok(())
                 } else {
-                    // Proceed further
-                    self.walk_value(v)
+                    // We want to not actually read from memory for this visit. So, before
+                    // walking this value, we have to make sure it is not a
+                    // `Variants::Multiple`.
+                    match v.layout.variants {
+                        layout::Variants::Multiple { .. } => {
+                            // A multi-variant enum, or generator, or so.
+                            // Treat this like a union: without reading from memory,
+                            // we cannot determine the variant we are in. Reading from
+                            // memory would be subject to Stacked Borrows rules, leading
+                            // to all sorts of "funny" recursion.
+                            // We only end up here if the type is *not* freeze, so we just call the
+                            // `UnsafeCell` action.
+                            (self.unsafe_cell_action)(v)
+                        }
+                        layout::Variants::Single { .. } => {
+                            // Proceed further, try to find where exactly that `UnsafeCell`
+                            // is hiding.
+                            self.walk_value(v)
+                        }
+                    }
                 }
             }
 
@@ -261,4 +288,175 @@ fn visit_primitive(&mut self, _v: MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx>
             }
         }
     }
+
+    /// Helper function to get a `libc` constant as a `Scalar`.
+    fn eval_libc(&mut self, name: &str) -> InterpResult<'tcx, Scalar<Tag>> {
+        self.eval_context_mut()
+            .eval_path_scalar(&["libc", name])?
+            .ok_or_else(|| err_unsup_format!("Path libc::{} cannot be resolved.", name))?
+            .not_undef()
+    }
+
+    /// Helper function to get a `libc` constant as an `i32`.
+    fn eval_libc_i32(&mut self, name: &str) -> InterpResult<'tcx, i32> {
+        self.eval_libc(name)?.to_i32()
+    }
+
+    /// Helper function to get the `TyLayout` of a `libc` type
+    fn libc_ty_layout(&mut self, name: &str) -> InterpResult<'tcx, TyLayout<'tcx>> {
+        let this = self.eval_context_mut();
+        let ty = this.resolve_path(&["libc", name])?.ty(*this.tcx);
+        this.layout_of(ty)
+    }
+
+    // Writes several `ImmTy`s contiguosly into memory. This is useful when you have to pack
+    // different values into a struct.
+    fn write_packed_immediates(
+        &mut self,
+        place: &MPlaceTy<'tcx, Tag>,
+        imms: &[ImmTy<'tcx, Tag>],
+    ) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+
+        let mut offset = Size::from_bytes(0);
+
+        for &imm in imms {
+            this.write_immediate_to_mplace(
+                *imm,
+                place.offset(offset, None, imm.layout, &*this.tcx)?,
+            )?;
+            offset += imm.layout.size;
+        }
+        Ok(())
+    }
+
+    /// Helper function used inside the shims of foreign functions to check that isolation is
+    /// disabled. It returns an error using the `name` of the foreign function if this is not the
+    /// case.
+    fn check_no_isolation(&mut self, name: &str) -> InterpResult<'tcx> {
+        if !self.eval_context_mut().machine.communicate {
+            throw_unsup_format!("`{}` not available when isolation is enabled. Pass the flag `-Zmiri-disable-isolation` to disable it.", name)
+        }
+        Ok(())
+    }
+
+    /// Sets the last error variable.
+    fn set_last_error(&mut self, scalar: Scalar<Tag>) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+        let errno_place = this.machine.last_error.unwrap();
+        this.write_scalar(scalar, errno_place.into())
+    }
+
+    /// Gets the last error variable.
+    fn get_last_error(&mut self) -> InterpResult<'tcx, Scalar<Tag>> {
+        let this = self.eval_context_mut();
+        let errno_place = this.machine.last_error.unwrap();
+        this.read_scalar(errno_place.into())?.not_undef()
+    }
+
+    /// Sets the last OS error using a `std::io::Error`. This function tries to produce the most
+    /// similar OS error from the `std::io::ErrorKind` and sets it as the last OS error.
+    fn set_last_error_from_io_error(&mut self, e: std::io::Error) -> InterpResult<'tcx> {
+        use std::io::ErrorKind::*;
+        let this = self.eval_context_mut();
+        let target = &this.tcx.tcx.sess.target.target;
+        let last_error = if target.options.target_family == Some("unix".to_owned()) {
+            this.eval_libc(match e.kind() {
+                ConnectionRefused => "ECONNREFUSED",
+                ConnectionReset => "ECONNRESET",
+                PermissionDenied => "EPERM",
+                BrokenPipe => "EPIPE",
+                NotConnected => "ENOTCONN",
+                ConnectionAborted => "ECONNABORTED",
+                AddrNotAvailable => "EADDRNOTAVAIL",
+                AddrInUse => "EADDRINUSE",
+                NotFound => "ENOENT",
+                Interrupted => "EINTR",
+                InvalidInput => "EINVAL",
+                TimedOut => "ETIMEDOUT",
+                AlreadyExists => "EEXIST",
+                WouldBlock => "EWOULDBLOCK",
+                _ => throw_unsup_format!("The {} error cannot be transformed into a raw os error", e)
+            })?
+        } else {
+            // FIXME: we have to implement the windows' equivalent of this.
+            throw_unsup_format!("Setting the last OS error from an io::Error is unsupported for {}.", target.target_os)
+        };
+        this.set_last_error(last_error)
+    }
+
+    /// Helper function that consumes an `std::io::Result<T>` and returns an
+    /// `InterpResult<'tcx,T>::Ok` instead. In case the result is an error, this function returns
+    /// `Ok(-1)` and sets the last OS error accordingly.
+    ///
+    /// This function uses `T: From<i32>` instead of `i32` directly because some IO related
+    /// functions return different integer types (like `read`, that returns an `i64`)
+    fn try_unwrap_io_result<T: From<i32>>(
+        &mut self,
+        result: std::io::Result<T>,
+    ) -> InterpResult<'tcx, T> {
+        match result {
+            Ok(ok) => Ok(ok),
+            Err(e) => {
+                self.eval_context_mut().set_last_error_from_io_error(e)?;
+                Ok((-1).into())
+            }
+        }
+    }
+
+    /// Helper function to read an OsString from a null-terminated sequence of bytes, which is what
+    /// the Unix APIs usually handle.
+    fn read_os_string_from_c_string(&mut self, scalar: Scalar<Tag>) -> InterpResult<'tcx, OsString> {
+        let bytes = self.eval_context_mut().memory.read_c_str(scalar)?;
+        Ok(bytes_to_os_str(bytes)?.into())
+    }
+
+    /// Helper function to write an OsStr as a null-terminated sequence of bytes, which is what
+    /// the Unix APIs usually handle. This function returns `Ok(false)` without trying to write if
+    /// `size` is not large enough to fit the contents of `os_string` plus a null terminator. It
+    /// returns `Ok(true)` if the writing process was successful.
+    fn write_os_str_to_c_string(
+        &mut self,
+        os_str: &OsStr,
+        scalar: Scalar<Tag>,
+        size: u64
+    ) -> InterpResult<'tcx, bool> {
+        let bytes = os_str_to_bytes(os_str)?;
+        // If `size` is smaller or equal than `bytes.len()`, writing `bytes` plus the required null
+        // terminator to memory using the `ptr` pointer would cause an overflow.
+        if size <= bytes.len() as u64 {
+            return Ok(false);
+        }
+        // FIXME: We should use `Iterator::chain` instead when rust-lang/rust#65704 lands.
+        self.eval_context_mut().memory.write_bytes(scalar, bytes.iter().copied().chain(iter::once(0u8)))?;
+        Ok(true)
+    }
+}
+
+#[cfg(target_os = "unix")]
+fn os_str_to_bytes<'tcx, 'a>(os_str: &'a OsStr) -> InterpResult<'tcx, &'a [u8]> {
+    std::os::unix::ffi::OsStringExt::into_bytes(os_str)
+}
+
+#[cfg(target_os = "unix")]
+fn bytes_to_os_str<'tcx, 'a>(bytes: &'a[u8]) -> InterpResult<'tcx, &'a OsStr> {
+    Ok(std::os::unix::ffi::OsStringExt::from_bytes(bytes))
+}
+
+// On non-unix platforms the best we can do to transform bytes from/to OS strings is to do the
+// intermediate transformation into strings. Which invalidates non-utf8 paths that are actually
+// valid.
+#[cfg(not(target_os = "unix"))]
+fn os_str_to_bytes<'tcx, 'a>(os_str: &'a OsStr) -> InterpResult<'tcx, &'a [u8]> {
+    os_str
+        .to_str()
+        .map(|s| s.as_bytes())
+        .ok_or_else(|| err_unsup_format!("{:?} is not a valid utf-8 string", os_str).into())
+}
+
+#[cfg(not(target_os = "unix"))]
+fn bytes_to_os_str<'tcx, 'a>(bytes: &'a[u8]) -> InterpResult<'tcx, &'a OsStr> {
+    let s = std::str::from_utf8(bytes)
+        .map_err(|_| err_unsup_format!("{:?} is not a valid utf-8 string", bytes))?;
+    Ok(&OsStr::new(s))
 }