Further move the dest place to read_byte_helper

Author: tiif

src/shims/unix/fd.rs

@@ -582,8 +582,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 fd.pread(communicate, &mut bytes, offset, this)
             }
         };
-        let res = read_byte_helper(buf, bytes, result, this)?;
-        this.write_scalar(res, dest)?;
+        read_byte_helper(buf, bytes, result, dest, this)?;
         Ok(())
     }
 
@@ -625,8 +624,9 @@ fn read_byte_helper<'tcx>(
     buf: Pointer,
     bytes: Vec<u8>,
     result: InterpResult<'tcx, io::Result<usize>>,
+    dest: &MPlaceTy<'tcx>,
     ecx: &mut MiriInterpCx<'tcx>,
-) -> InterpResult<'tcx, Scalar> {
+) -> InterpResult<'tcx> {
     // `File::read` never returns a value larger than `count`, so this cannot fail.
     match result?.map(|c| i64::try_from(c).unwrap()) {
         // try to pass this the write_ptr inside write
@@ -639,11 +639,13 @@ fn read_byte_helper<'tcx>(
                 buf,
                 bytes[..usize::try_from(read_bytes).unwrap()].iter().copied(),
             )?;
-            Ok(Scalar::from_target_isize(read_bytes, ecx))
+            ecx.write_scalar(Scalar::from_target_isize(read_bytes, ecx), dest)?;
+            return Ok(());
         }
         Err(e) => {
             ecx.set_last_error_from_io_error(e)?;
-            Ok(Scalar::from_target_isize(-1, ecx))
+            ecx.write_scalar(Scalar::from_target_isize(-1, ecx), dest)?;
+            return Ok(());
         }
     }
 }