Refactor File trait with default implementation

src/libos/src/fs/dev_null.rs

@@ -16,42 +16,6 @@ impl File for DevNull {
         Ok(bufs.iter().map(|buf| buf.len()).sum())
     }
 
-    fn read(&self, _buf: &mut [u8]) -> Result<usize> {
-        return_errno!(EINVAL, "device not support reads")
-    }
-
-    fn read_at(&self, _offset: usize, _buf: &mut [u8]) -> Result<usize> {
-        return_errno!(EINVAL, "device not support reads")
-    }
-
-    fn readv(&self, bufs: &mut [&mut [u8]]) -> Result<usize> {
-        return_errno!(EINVAL, "device not support reads")
-    }
-
-    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
-        return_errno!(EINVAL, "device not support seeks")
-    }
-
-    fn metadata(&self) -> Result<Metadata> {
-        unimplemented!()
-    }
-
-    fn set_len(&self, len: u64) -> Result<()> {
-        return_errno!(EINVAL, "device not support resizing")
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        Ok(())
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        Ok(())
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        return_errno!(ENOTDIR, "device is not a directory")
-    }
-
     fn as_any(&self) -> &Any {
         self
     }

src/libos/src/fs/dev_random.rs

@@ -41,42 +41,6 @@ impl File for DevRandom {
         Ok(total_nbytes)
     }
 
-    fn write(&self, _buf: &[u8]) -> Result<usize> {
-        return_errno!(EINVAL, "device not support writes")
-    }
-
-    fn write_at(&self, _offset: usize, _buf: &[u8]) -> Result<usize> {
-        return_errno!(EINVAL, "device not support writes")
-    }
-
-    fn writev(&self, bufs: &[&[u8]]) -> Result<usize> {
-        return_errno!(EINVAL, "device not support writes")
-    }
-
-    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
-        return_errno!(EINVAL, "device not support seeks")
-    }
-
-    fn metadata(&self) -> Result<Metadata> {
-        unimplemented!()
-    }
-
-    fn set_len(&self, len: u64) -> Result<()> {
-        return_errno!(EINVAL, "device not support resizing")
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        Ok(())
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        Ok(())
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        return_errno!(ENOTDIR, "device is not a directory")
-    }
-
     fn as_any(&self) -> &Any {
         self
     }

src/libos/src/fs/dev_zero.rs

@@ -23,42 +23,6 @@ impl File for DevZero {
         Ok(total_nbytes)
     }
 
-    fn write(&self, _buf: &[u8]) -> Result<usize> {
-        return_errno!(EINVAL, "device not support writes")
-    }
-
-    fn write_at(&self, _offset: usize, _buf: &[u8]) -> Result<usize> {
-        return_errno!(EINVAL, "device not support writes")
-    }
-
-    fn writev(&self, bufs: &[&[u8]]) -> Result<usize> {
-        return_errno!(EINVAL, "device not support writes")
-    }
-
-    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
-        return_errno!(EINVAL, "device not support seeks")
-    }
-
-    fn metadata(&self) -> Result<Metadata> {
-        unimplemented!()
-    }
-
-    fn set_len(&self, len: u64) -> Result<()> {
-        return_errno!(EINVAL, "device not support resizing")
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        Ok(())
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        Ok(())
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        return_errno!(ENOTDIR, "device is not a directory")
-    }
-
     fn as_any(&self) -> &Any {
         self
     }

src/libos/src/fs/file.rs

@@ -4,19 +4,69 @@ use std::borrow::BorrowMut;
 use std::fmt;
 use std::io::SeekFrom;
 
+macro_rules! return_op_unsupported_error {
+    ($op_name: expr, $errno: expr) => {{
+        let errno = $errno;
+        // FIXME: use the safe core::any::type_name when we upgrade to Rust 1.38 or above
+        let type_name = unsafe { core::intrinsics::type_name::<Self>() };
+        let op_name = $op_name;
+        let error = FileOpNotSupportedError::new(errno, type_name, op_name);
+        return_errno!(error)
+    }};
+    ($op_name: expr) => {{
+        return_op_unsupported_error!($op_name, ENOSYS)
+    }};
+}
+
 pub trait File: Debug + Sync + Send + Any {
-    fn read(&self, buf: &mut [u8]) -> Result<usize>;
+    fn read(&self, buf: &mut [u8]) -> Result<usize> {
-    fn write(&self, buf: &[u8]) -> Result<usize>;
+        return_op_unsupported_error!("read")
-    fn read_at(&self, offset: usize, buf: &mut [u8]) -> Result<usize>;
+    }
-    fn write_at(&self, offset: usize, buf: &[u8]) -> Result<usize>;
+
-    fn readv(&self, bufs: &mut [&mut [u8]]) -> Result<usize>;
+    fn write(&self, buf: &[u8]) -> Result<usize> {
-    fn writev(&self, bufs: &[&[u8]]) -> Result<usize>;
+        return_op_unsupported_error!("write")
-    fn seek(&self, pos: SeekFrom) -> Result<off_t>;
+    }
-    fn metadata(&self) -> Result<Metadata>;
+
-    fn set_len(&self, len: u64) -> Result<()>;
+    fn read_at(&self, offset: usize, buf: &mut [u8]) -> Result<usize> {
-    fn sync_all(&self) -> Result<()>;
+        return_op_unsupported_error!("read_at")
-    fn sync_data(&self) -> Result<()>;
+    }
-    fn read_entry(&self) -> Result<String>;
+
+    fn write_at(&self, offset: usize, buf: &[u8]) -> Result<usize> {
+        return_op_unsupported_error!("write_at")
+    }
+
+    fn readv(&self, bufs: &mut [&mut [u8]]) -> Result<usize> {
+        return_op_unsupported_error!("readv")
+    }
+
+    fn writev(&self, bufs: &[&[u8]]) -> Result<usize> {
+        return_op_unsupported_error!("writev")
+    }
+
+    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
+        return_op_unsupported_error!("seek")
+    }
+
+    fn metadata(&self) -> Result<Metadata> {
+        return_op_unsupported_error!("metadata")
+    }
+
+    fn set_len(&self, len: u64) -> Result<()> {
+        return_op_unsupported_error!("set_len")
+    }
+
+    fn read_entry(&self) -> Result<String> {
+        return_op_unsupported_error!("read_entry", ENOTDIR)
+    }
+
+    fn sync_all(&self) -> Result<()> {
+        Ok(())
+    }
+
+    fn sync_data(&self) -> Result<()> {
+        Ok(())
+    }
+
     fn as_any(&self) -> &Any;
 }
 
@@ -96,26 +146,6 @@ impl File for SgxFile {
         inner.seek(pos)
     }
 
-    fn metadata(&self) -> Result<Metadata> {
-        unimplemented!()
-    }
-
-    fn set_len(&self, len: u64) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        unimplemented!()
-    }
-
     fn as_any(&self) -> &Any {
         self
     }
@@ -296,27 +326,15 @@ impl StdoutFile {
 }
 
 impl File for StdoutFile {
-    fn read(&self, buf: &mut [u8]) -> Result<usize> {
-        return_errno!(EBADF, "Stdout does not support read")
-    }
-
     fn write(&self, buf: &[u8]) -> Result<usize> {
         let write_len = { self.inner.lock().write(buf).map_err(|e| errno!(e))? };
         Ok(write_len)
     }
 
-    fn read_at(&self, _offset: usize, buf: &mut [u8]) -> Result<usize> {
-        self.read(buf)
-    }
-
     fn write_at(&self, _offset: usize, buf: &[u8]) -> Result<usize> {
         self.write(buf)
     }
 
-    fn readv(&self, bufs: &mut [&mut [u8]]) -> Result<usize> {
-        return_errno!(EBADF, "Stdout does not support read")
-    }
-
     fn writev(&self, bufs: &[&[u8]]) -> Result<usize> {
         let mut guard = self.inner.lock();
         let mut total_bytes = 0;
@@ -341,10 +359,6 @@ impl File for StdoutFile {
         Ok(total_bytes)
     }
 
-    fn seek(&self, seek_pos: SeekFrom) -> Result<off_t> {
-        return_errno!(ESPIPE, "Stdout does not support seek")
-    }
-
     fn metadata(&self) -> Result<Metadata> {
         Ok(Metadata {
             dev: 0,
@@ -364,10 +378,6 @@ impl File for StdoutFile {
         })
     }
 
-    fn set_len(&self, _len: u64) -> Result<()> {
-        return_errno!(EINVAL, "Stdout does not support set_len")
-    }
-
     fn sync_all(&self) -> Result<()> {
         self.sync_data()
     }
@@ -377,10 +387,6 @@ impl File for StdoutFile {
         Ok(())
     }
 
-    fn read_entry(&self) -> Result<String> {
-        return_errno!(ENOTDIR, "Stdout does not support read_entry")
-    }
-
     fn as_any(&self) -> &Any {
         self
     }
@@ -413,18 +419,6 @@ impl File for StdinFile {
         Ok(read_len)
     }
 
-    fn write(&self, buf: &[u8]) -> Result<usize> {
-        return_errno!(EBADF, "Stdin does not support write")
-    }
-
-    fn read_at(&self, offset: usize, buf: &mut [u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn write_at(&self, offset: usize, buf: &[u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
     fn readv(&self, bufs: &mut [&mut [u8]]) -> Result<usize> {
         let mut guard = self.inner.lock();
         let mut total_bytes = 0;
@@ -449,14 +443,6 @@ impl File for StdinFile {
         Ok(total_bytes)
     }
 
-    fn writev(&self, bufs: &[&[u8]]) -> Result<usize> {
-        return_errno!(EBADF, "Stdin does not support write")
-    }
-
-    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
-        return_errno!(ESPIPE, "Stdin does not support seek")
-    }
-
     fn metadata(&self) -> Result<Metadata> {
         Ok(Metadata {
             dev: 0,
@@ -476,22 +462,6 @@ impl File for StdinFile {
         })
     }
 
-    fn set_len(&self, _len: u64) -> Result<()> {
-        return_errno!(EINVAL, "Stdin does not support set_len")
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        self.sync_data()
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        Ok(())
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        return_errno!(ENOTDIR, "Stdin does not support read_entry")
-    }
-
     fn as_any(&self) -> &Any {
         self
     }
@@ -505,3 +475,36 @@ impl Debug for StdinFile {
 
 unsafe impl Send for StdinFile {}
 unsafe impl Sync for StdinFile {}
+
+#[derive(Copy, Clone, Debug)]
+struct FileOpNotSupportedError {
+    errno: Errno,
+    type_name: &'static str,
+    op_name: &'static str,
+}
+
+impl FileOpNotSupportedError {
+    pub fn new(
+        errno: Errno,
+        type_name: &'static str,
+        op_name: &'static str,
+    ) -> FileOpNotSupportedError {
+        FileOpNotSupportedError {
+            errno,
+            type_name,
+            op_name,
+        }
+    }
+}
+
+impl fmt::Display for FileOpNotSupportedError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{} does not support {}", self.type_name, self.op_name)
+    }
+}
+
+impl ToErrno for FileOpNotSupportedError {
+    fn errno(&self) -> Errno {
+        self.errno
+    }
+}

src/libos/src/fs/io_multiplexing.rs

@@ -308,54 +308,6 @@ impl Drop for EpollFileInner {
 }
 
 impl File for EpollFile {
-    fn read(&self, buf: &mut [u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn write(&self, buf: &[u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn read_at(&self, offset: usize, buf: &mut [u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn write_at(&self, offset: usize, buf: &[u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn readv(&self, bufs: &mut [&mut [u8]]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn writev(&self, bufs: &[&[u8]]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
-        return_errno!(ESPIPE, "Epoll does not support seek")
-    }
-
-    fn metadata(&self) -> Result<Metadata> {
-        unimplemented!()
-    }
-
-    fn set_len(&self, len: u64) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        unimplemented!()
-    }
-
     fn as_any(&self) -> &Any {
         self
     }

src/libos/src/fs/pipe.rs

@@ -36,18 +36,6 @@ impl File for PipeReader {
         ringbuf.read(buf)
     }
 
-    fn write(&self, buf: &[u8]) -> Result<usize> {
-        return_errno!(EBADF, "PipeReader does not support write")
-    }
-
-    fn read_at(&self, offset: usize, buf: &mut [u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn write_at(&self, offset: usize, buf: &[u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
     fn readv(&self, bufs: &mut [&mut [u8]]) -> Result<usize> {
         let mut ringbuf = self.inner.lock().unwrap();
         let mut total_bytes = 0;
@@ -72,34 +60,6 @@ impl File for PipeReader {
         Ok(total_bytes)
     }
 
-    fn writev(&self, bufs: &[&[u8]]) -> Result<usize> {
-        return_errno!(EBADF, "PipeReader does not support write")
-    }
-
-    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
-        return_errno!(ESPIPE, "Pipe does not support seek")
-    }
-
-    fn metadata(&self) -> Result<Metadata> {
-        unimplemented!()
-    }
-
-    fn set_len(&self, len: u64) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        unimplemented!()
-    }
-
     fn as_any(&self) -> &Any {
         self
     }
@@ -114,25 +74,10 @@ pub struct PipeWriter {
 }
 
 impl File for PipeWriter {
-    fn read(&self, buf: &mut [u8]) -> Result<usize> {
-        return_errno!(EBADF, "PipeWriter does not support read")
-    }
-
     fn write(&self, buf: &[u8]) -> Result<usize> {
         let ringbuf = self.inner.lock().unwrap();
         ringbuf.write(buf)
     }
-    fn read_at(&self, offset: usize, buf: &mut [u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn write_at(&self, offset: usize, buf: &[u8]) -> Result<usize> {
-        unimplemented!()
-    }
-
-    fn readv(&self, bufs: &mut [&mut [u8]]) -> Result<usize> {
-        return_errno!(EBADF, "PipeWriter does not support read")
-    }
 
     fn writev(&self, bufs: &[&[u8]]) -> Result<usize> {
         let ringbuf = self.inner.lock().unwrap();
@@ -158,30 +103,10 @@ impl File for PipeWriter {
         Ok(total_bytes)
     }
 
-    fn seek(&self, seek_pos: SeekFrom) -> Result<off_t> {
+    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
         return_errno!(ESPIPE, "Pipe does not support seek")
     }
 
-    fn metadata(&self) -> Result<Metadata> {
-        unimplemented!()
-    }
-
-    fn set_len(&self, len: u64) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        unimplemented!()
-    }
-
     fn as_any(&self) -> &Any {
         self
     }

src/libos/src/fs/socket_file.rs

@@ -119,22 +119,6 @@ impl File for SocketFile {
         })
     }
 
-    fn set_len(&self, len: u64) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        unimplemented!()
-    }
-
     fn as_any(&self) -> &Any {
         self
     }

src/libos/src/fs/unix_socket.rs

@@ -59,10 +59,6 @@ impl File for UnixSocketFile {
         Ok(total_len)
     }
 
-    fn seek(&self, pos: SeekFrom) -> Result<off_t> {
-        return_errno!(ESPIPE, "UnixSocket does not support seek")
-    }
-
     fn metadata(&self) -> Result<Metadata> {
         Ok(Metadata {
             dev: 0,
@@ -82,22 +78,6 @@ impl File for UnixSocketFile {
         })
     }
 
-    fn set_len(&self, len: u64) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_all(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn sync_data(&self) -> Result<()> {
-        unimplemented!()
-    }
-
-    fn read_entry(&self) -> Result<String> {
-        unimplemented!()
-    }
-
     fn as_any(&self) -> &Any {
         self
     }