Use new helper in eventfd

Author: tiif

src/shims/unix/linux/eventfd.rs

@@ -1,7 +1,7 @@
 //! Linux `eventfd` implementation.
 use std::cell::{Cell, RefCell};
 use std::io;
-use std::io::{Error, ErrorKind};
+use std::io::ErrorKind;
 
 use crate::concurrency::VClock;
 use crate::shims::unix::fd::FileDescriptionRef;
@@ -66,9 +66,7 @@ impl FileDescription for Event {
         let ty = ecx.machine.layouts.u64;
         // Check the size of slice, and return error only if the size of the slice < 8.
         if len < ty.size.bytes_usize() {
-            ecx.set_last_error_from_io_error(Error::from(ErrorKind::InvalidInput))?;
-            ecx.write_int(-1, dest)?;
-            return Ok(());
+            return ecx.set_last_error_and_return(ErrorKind::InvalidInput, dest);
         }
 
         // eventfd read at the size of u64.
@@ -78,9 +76,7 @@ impl FileDescription for Event {
         let counter = self.counter.get();
         if counter == 0 {
             if self.is_nonblock {
-                ecx.set_last_error_from_io_error(Error::from(ErrorKind::WouldBlock))?;
-                ecx.write_int(-1, dest)?;
-                return Ok(());
+                return ecx.set_last_error_and_return(ErrorKind::WouldBlock, dest);
             }
 
             throw_unsup_format!("eventfd: blocking is unsupported");