Write to des place in write_byte_helper

Author: tiif

src/shims/unix/fd.rs

@@ -621,8 +621,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             this.write_scalar(Scalar::from_target_isize(res, this), dest)?;
             return Ok(());
         };
-        let res = write_byte_helper(offset, fd, bytes, communicate, this)?;
-        this.write_scalar(res, dest)?;
+        write_byte_helper(offset, fd, bytes, communicate, dest, this)?;
         Ok(())
     }
 
@@ -665,20 +664,25 @@ fn write_byte_helper<'tcx>(
     fd: FileDescriptionRef,
     bytes: Vec<u8>,
     communicate: bool,
+    dest: &MPlaceTy<'tcx>,
     ecx: &mut MiriInterpCx<'tcx>,
-) -> InterpResult<'tcx, Scalar> {
+) -> InterpResult<'tcx> {
     let result = match offset {
         None => fd.write(&fd, communicate, &bytes, ecx),
         Some(offset) => {
             let Ok(offset) = u64::try_from(offset) else {
                 let einval = ecx.eval_libc("EINVAL");
                 ecx.set_last_error(einval)?;
-                return Ok(Scalar::from_target_isize(-1, ecx));
+                let res = Scalar::from_target_isize(-1, ecx);
+                ecx.write_scalar(res, dest)?;
+                return Ok(());
             };
             fd.pwrite(communicate, &bytes, offset, ecx)
         }
     };
+    // Write the result to the dest place.
     let result = result?.map(|c| i64::try_from(c).unwrap());
-    let res = ecx.try_unwrap_io_result(result)?;
-    Ok(Scalar::from_target_isize(res, ecx))
+    let res = Scalar::from_target_isize(ecx.try_unwrap_io_result(result)?, ecx);
+    ecx.write_scalar(res, dest)?;
+    return Ok(());
 }