update failure messages

src/shims/unix/fs/epoll.rs

@@ -13,39 +13,38 @@ pub struct Epoll;
 
 impl FileDescriptor for Epoll {
     fn as_file_handle<'tcx>(&self) -> InterpResult<'tcx, &FileHandle> {
-        throw_unsup_format!("stderr and stdout cannot be used as FileHandle");
+        throw_unsup_format!("epoll file descriptors cannot be used as FileHandle");
     }
 
     fn read<'tcx>(
         &mut self,
         _communicate_allowed: bool,
         _bytes: &mut [u8],
     ) -> InterpResult<'tcx, io::Result<usize>> {
-        throw_unsup_format!("cannot read from stderr or stdout");
+        throw_unsup_format!("cannot read from epoll file descriptors");
     }
 
     fn write<'tcx>(
         &self,
         _communicate_allowed: bool,
-        bytes: &[u8],
+        _bytes: &[u8],
     ) -> InterpResult<'tcx, io::Result<usize>> {
-        // We just don't write anything, but report to the user that we did.
-        Ok(Ok(bytes.len()))
+        throw_unsup_format!("cannot write from epoll file descriptors");
     }
 
     fn seek<'tcx>(
         &mut self,
         _communicate_allowed: bool,
         _offset: SeekFrom,
     ) -> InterpResult<'tcx, io::Result<u64>> {
-        throw_unsup_format!("cannot seek on stderr or stdout");
+        throw_unsup_format!("cannot seek on epoll file descriptors");
     }
 
     fn close<'tcx>(
         self: Box<Self>,
         _communicate_allowed: bool,
     ) -> InterpResult<'tcx, io::Result<i32>> {
-        throw_unsup_format!("stderr and stdout cannot be closed");
+        throw_unsup_format!("epoll file descriptors cannot be closed");
     }
 
     fn dup<'tcx>(&mut self) -> io::Result<Box<dyn FileDescriptor>> {

src/shims/unix/fs/event.rs

@@ -13,39 +13,38 @@ pub struct Event;
 
 impl FileDescriptor for Event {
     fn as_file_handle<'tcx>(&self) -> InterpResult<'tcx, &FileHandle> {
-        throw_unsup_format!("stderr and stdout cannot be used as FileHandle");
+        throw_unsup_format!("event file descriptors cannot be used as FileHandle");
     }
 
     fn read<'tcx>(
         &mut self,
         _communicate_allowed: bool,
         _bytes: &mut [u8],
     ) -> InterpResult<'tcx, io::Result<usize>> {
-        throw_unsup_format!("cannot read from stderr or stdout");
+        throw_unsup_format!("cannot read event file descriptors");
     }
 
     fn write<'tcx>(
         &self,
         _communicate_allowed: bool,
-        bytes: &[u8],
+        _bytes: &[u8],
     ) -> InterpResult<'tcx, io::Result<usize>> {
-        // We just don't write anything, but report to the user that we did.
-        Ok(Ok(bytes.len()))
+        throw_unsup_format!("cannot write event file descriptors");
     }
 
     fn seek<'tcx>(
         &mut self,
         _communicate_allowed: bool,
         _offset: SeekFrom,
     ) -> InterpResult<'tcx, io::Result<u64>> {
-        throw_unsup_format!("cannot seek on stderr or stdout");
+        throw_unsup_format!("cannot seek on event file descriptors");
     }
 
     fn close<'tcx>(
         self: Box<Self>,
         _communicate_allowed: bool,
     ) -> InterpResult<'tcx, io::Result<i32>> {
-        throw_unsup_format!("stderr and stdout cannot be closed");
+        throw_unsup_format!("event file descriptors cannot be closed");
     }
 
     fn dup<'tcx>(&mut self) -> io::Result<Box<dyn FileDescriptor>> {

tests/fail/crates/tokio_mvp.rs

@@ -1,5 +1,5 @@
 //@compile-flags: -Zmiri-disable-isolation
-//@error-pattern: unsupported operation: stderr and stdout cannot be closed
+//@error-pattern: unsupported operation: event file descriptors cannot be closed
 //@normalize-stderr-test: "   = note: inside .*\n" -> ""
 //@only-target-linux: the errors differ too much between platforms
 

tests/fail/crates/tokio_mvp.stderr

@@ -1,8 +1,8 @@
-error: unsupported operation: stderr and stdout cannot be closed
+error: unsupported operation: event file descriptors cannot be closed
   --> RUSTLIB/std/src/os/fd/owned.rs:LL:CC
    |
 LL |             let _ = libc::close(self.fd);
-   |                     ^^^^^^^^^^^^^^^^^^^^ stderr and stdout cannot be closed
+   |                     ^^^^^^^^^^^^^^^^^^^^ event file descriptors cannot be closed
    |
    = help: this is likely not a bug in the program; it indicates that the program performed an operation that the interpreter does not support
    = note: backtrace: