Rename helper function and apply comment suggestion

Author: tiif

src/shims/unix/fd.rs

@@ -142,7 +142,7 @@ impl FileDescription for io::Stdin {
             helpers::isolation_abort_error("`read` from stdin")?;
         }
         let result = Read::read(&mut { self }, &mut bytes);
-        ecx.read_byte_helper(ptr, bytes, result, dest)?;
+        ecx.return_read_bytes_and_count(ptr, bytes, result, dest)?;
         Ok(())
     }
 
@@ -172,7 +172,7 @@ impl FileDescription for io::Stdout {
         // the host -- there is no good in adding extra buffering
         // here.
         io::stdout().flush().unwrap();
-        ecx.write_byte_helper(result, dest)?;
+        ecx.return_written_byte_count_or_error(result, dest)?;
         Ok(())
     }
 
@@ -197,7 +197,7 @@ impl FileDescription for io::Stderr {
         // We allow writing to stderr even with isolation enabled.
         // No need to flush, stderr is not buffered.
         let result = Write::write(&mut { self }, bytes);
-        ecx.write_byte_helper(result, dest)?;
+        ecx.return_written_byte_count_or_error(result, dest)?;
         Ok(())
     }
 
@@ -225,7 +225,7 @@ impl FileDescription for NullOutput {
     ) -> InterpResult<'tcx> {
         // We just don't write anything, but report to the user that we did.
         let result = Ok(bytes.len());
-        ecx.write_byte_helper(result, dest)?;
+        ecx.return_written_byte_count_or_error(result, dest)?;
         Ok(())
     }
 }
@@ -644,8 +644,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         Ok(())
     }
 
-    /// This function either writes to the user supplied buffer and to dest place, or return error.
-    fn read_byte_helper(
+    /// This function either writes to the user supplied buffer and to dest place, or sets the
+    /// last libc error and writes -1 to dest.
+    fn return_read_bytes_and_count(
         &mut self,
         buf: Pointer,
         bytes: Vec<u8>,
@@ -671,8 +672,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         }
     }
 
-    /// This function either writes the number of written bytes to dest place or return error.
-    fn write_byte_helper(
+    /// This function writes the number of written bytes to dest place, or sets the
+    /// last libc error and writes -1 to dest.
+    fn return_written_byte_count_or_error(
         &mut self,
         result: io::Result<usize>,
         dest: &MPlaceTy<'tcx>,

src/shims/unix/fs.rs

@@ -42,7 +42,7 @@ impl FileDescription for FileHandle {
         assert!(communicate_allowed, "isolation should have prevented even opening a file");
         let mut bytes = vec![0; usize::try_from(len).unwrap()];
         let result = (&mut &self.file).read(&mut bytes);
-        ecx.read_byte_helper(ptr, bytes.to_vec(), result, dest)?;
+        ecx.return_read_bytes_and_count(ptr, bytes.to_vec(), result, dest)?;
         Ok(())
     }
 
@@ -56,7 +56,7 @@ impl FileDescription for FileHandle {
     ) -> InterpResult<'tcx> {
         assert!(communicate_allowed, "isolation should have prevented even opening a file");
         let result = (&mut &self.file).write(bytes);
-        ecx.write_byte_helper(result, dest)?;
+        ecx.return_written_byte_count_or_error(result, dest)?;
         Ok(())
     }
 
@@ -85,7 +85,7 @@ impl FileDescription for FileHandle {
             res
         };
         let result = f();
-        ecx.read_byte_helper(ptr, bytes.to_vec(), result, dest)?;
+        ecx.return_read_bytes_and_count(ptr, bytes.to_vec(), result, dest)?;
         Ok(())
     }
 
@@ -112,7 +112,7 @@ impl FileDescription for FileHandle {
             res
         };
         let result = f();
-        ecx.write_byte_helper(result, dest)?;
+        ecx.return_written_byte_count_or_error(result, dest)?;
         Ok(())
     }
 

src/shims/unix/linux/eventfd.rs

@@ -72,7 +72,7 @@ impl FileDescription for Event {
         // Check the size of slice, and return error only if the size of the slice < 8.
         if len < U64_ARRAY_SIZE.try_into().unwrap() {
             let result = Err(Error::from(ErrorKind::InvalidInput));
-            read_byte_helper_ev(&buf_place, None, result, dest, ecx)?;
+            return_read_bytes_and_count_ev(&buf_place, None, result, dest, ecx)?;
             return Ok(());
         }
 
@@ -81,7 +81,7 @@ impl FileDescription for Event {
         if counter == 0 {
             if self.is_nonblock {
                 let result = Err(Error::from(ErrorKind::WouldBlock));
-                read_byte_helper_ev(&buf_place, None, result, dest, ecx)?;
+                return_read_bytes_and_count_ev(&buf_place, None, result, dest, ecx)?;
                 return Ok(());
             } else {
                 //FIXME: blocking is not supported
@@ -91,7 +91,7 @@ impl FileDescription for Event {
             // Synchronize with all prior `write` calls to this FD.
             ecx.acquire_clock(&self.clock.borrow());
             let result = Ok(U64_ARRAY_SIZE);
-            read_byte_helper_ev(&buf_place, Some(counter), result, dest, ecx)?;
+            return_read_bytes_and_count_ev(&buf_place, Some(counter), result, dest, ecx)?;
             self.counter.set(0);
             // When any of the event happened, we check and update the status of all supported event
             // types for current file description.
@@ -124,7 +124,7 @@ impl FileDescription for Event {
         // Check the size of slice, and return error only if the size of the slice < 8.
         let Some(bytes) = bytes.first_chunk::<U64_ARRAY_SIZE>() else {
             let result = Err(Error::from(ErrorKind::InvalidInput));
-            ecx.write_byte_helper(result, dest)?;
+            ecx.return_written_byte_count_or_error(result, dest)?;
             return Ok(());
         };
         // Convert from bytes to int according to host endianness.
@@ -135,7 +135,7 @@ impl FileDescription for Event {
         // u64::MAX as input is invalid because the maximum value of counter is u64::MAX - 1.
         if num == u64::MAX {
             let result = Err(Error::from(ErrorKind::InvalidInput));
-            ecx.write_byte_helper(result, dest)?;
+            ecx.return_written_byte_count_or_error(result, dest)?;
             return Ok(());
         }
         // If the addition does not let the counter to exceed the maximum value, update the counter.
@@ -151,7 +151,7 @@ impl FileDescription for Event {
             None | Some(u64::MAX) => {
                 if self.is_nonblock {
                     let result = Err(Error::from(ErrorKind::WouldBlock));
-                    ecx.write_byte_helper(result, dest)?;
+                    ecx.return_written_byte_count_or_error(result, dest)?;
                     return Ok(());
                 } else {
                     //FIXME: blocking is not supported
@@ -164,7 +164,7 @@ impl FileDescription for Event {
         ecx.check_and_update_readiness(self_ref)?;
 
         let result = Ok(U64_ARRAY_SIZE);
-        ecx.write_byte_helper(result, dest)?;
+        ecx.return_written_byte_count_or_error(result, dest)?;
         Ok(())
     }
 }
@@ -231,8 +231,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
     }
 }
 
-/// This function either writes to the user supplied buffer and to dest place, or return error.
-fn read_byte_helper_ev<'tcx>(
+/// This function either writes to the user supplied buffer and to dest place, or sets the
+/// last libc error and writes -1 to dest. This is only used by eventfd.
+fn return_read_bytes_and_count_ev<'tcx>(
     buf_place: &MPlaceTy<'tcx>,
     read_val: Option<u64>,
     result: io::Result<usize>,

src/shims/unix/unnamed_socket.rs

@@ -137,7 +137,7 @@ impl FileDescription for AnonSocket {
         // Always succeed on read size 0.
         if request_byte_size == 0 {
             let result = Ok(0);
-            ecx.read_byte_helper(ptr, bytes.to_vec(), result, dest)?;
+            ecx.return_read_bytes_and_count(ptr, bytes.to_vec(), result, dest)?;
             return Ok(());
         }
 
@@ -152,7 +152,7 @@ impl FileDescription for AnonSocket {
                 // Socketpair with no peer and empty buffer.
                 // 0 bytes successfully read indicates end-of-file.
                 let result = Ok(0);
-                ecx.read_byte_helper(ptr, bytes.to_vec(), result, dest)?;
+                ecx.return_read_bytes_and_count(ptr, bytes.to_vec(), result, dest)?;
                 return Ok(());
             } else {
                 if self.is_nonblock {
@@ -162,7 +162,7 @@ impl FileDescription for AnonSocket {
                     // POSIX.1-2001 allows either error to be returned for this case.
                     // Since there is no ErrorKind for EAGAIN, WouldBlock is used.
                     let result = Err(Error::from(ErrorKind::WouldBlock));
-                    ecx.read_byte_helper(ptr, bytes.to_vec(), result, dest)?;
+                    ecx.return_read_bytes_and_count(ptr, bytes.to_vec(), result, dest)?;
                     return Ok(());
                 } else {
                     // Blocking socketpair with writer and empty buffer.
@@ -196,7 +196,7 @@ impl FileDescription for AnonSocket {
         }
 
         let result = Ok(actual_read_size);
-        ecx.read_byte_helper(ptr, bytes.to_vec(), result, dest)?;
+        ecx.return_read_bytes_and_count(ptr, bytes.to_vec(), result, dest)?;
         return Ok(());
     }
 
@@ -213,7 +213,7 @@ impl FileDescription for AnonSocket {
         // ("If count is zero and fd refers to a file other than a regular file, the results are not specified.")
         if write_size == 0 {
             let result = Ok(0);
-            ecx.write_byte_helper(result, dest)?;
+            ecx.return_written_byte_count_or_error(result, dest)?;
             return Ok(());
         }
 
@@ -222,7 +222,7 @@ impl FileDescription for AnonSocket {
             // If the upgrade from Weak to Rc fails, it indicates that all read ends have been
             // closed.
             let result = Err(Error::from(ErrorKind::BrokenPipe));
-            ecx.write_byte_helper(result, dest)?;
+            ecx.return_written_byte_count_or_error(result, dest)?;
             return Ok(());
         };
 
@@ -238,7 +238,7 @@ impl FileDescription for AnonSocket {
             if self.is_nonblock {
                 // Non-blocking socketpair with a full buffer.
                 let result = Err(Error::from(ErrorKind::WouldBlock));
-                ecx.write_byte_helper(result, dest)?;
+                ecx.return_written_byte_count_or_error(result, dest)?;
                 return Ok(());
             } else {
                 // Blocking socketpair with a full buffer.
@@ -261,7 +261,7 @@ impl FileDescription for AnonSocket {
         ecx.check_and_update_readiness(&peer_fd)?;
 
         let result = Ok(actual_write_size);
-        ecx.write_byte_helper(result, dest)?;
+        ecx.return_written_byte_count_or_error(result, dest)?;
         return Ok(());
     }
 }