refactor: make Vnode::stat() return Stat

fs/macros/src/lib.rs

@@ -31,8 +31,8 @@ fn impl_inode_fn<T: ToTokens>(name: &str, behavior: T) -> ImplItem {
             }
         },
         "stat" => quote! {
-            fn stat(&mut self, _at: VnodeRef, _stat: &mut libsys::stat::Stat) ->
-                Result<(), libsys::error::Errno>
+            fn stat(&mut self, _at: VnodeRef) ->
+                Result<libsys::stat::Stat, libsys::error::Errno>
             {
                 #behavior
             }

fs/memfs/src/dir.rs

@@ -35,12 +35,13 @@ impl<A: BlockAllocator + Copy + 'static> VnodeImpl for DirInode<A> {
         Ok(())
     }
 
-    fn stat(&mut self, node: VnodeRef, stat: &mut Stat) -> Result<(), Errno> {
+    fn stat(&mut self, node: VnodeRef) -> Result<Stat, Errno> {
         let props = node.props();
-        stat.size = 0;
-        stat.blksize = 4096;
-        stat.mode = props.mode;
-        Ok(())
+        Ok(Stat {
+            size: 0,
+            blksize: 4096,
+            mode: props.mode
+        })
     }
 }
 

fs/memfs/src/file.rs

@@ -35,12 +35,13 @@ impl<'a, A: BlockAllocator + Copy + 'static> VnodeImpl for FileInode<'a, A> {
         Ok(self.data.size())
     }
 
-    fn stat(&mut self, node: VnodeRef, stat: &mut Stat) -> Result<(), Errno> {
+    fn stat(&mut self, node: VnodeRef) -> Result<Stat, Errno> {
         let props = node.props();
-        stat.size = self.data.size() as u64;
-        stat.blksize = 4096;
-        stat.mode = props.mode;
-        Ok(())
+        Ok(Stat {
+            size: self.data.size() as u64,
+            blksize: 4096,
+            mode: props.mode
+        })
     }
 }
 

fs/vfs/src/node.rs

@@ -82,7 +82,7 @@ pub trait VnodeImpl {
     ) -> Result<usize, Errno>;
 
     /// Retrieves file status
-    fn stat(&mut self, node: VnodeRef, stat: &mut Stat) -> Result<(), Errno>;
+    fn stat(&mut self, node: VnodeRef) -> Result<Stat, Errno>;
 
     /// Reports the size of this filesystem object in bytes
     fn size(&mut self, node: VnodeRef) -> Result<usize, Errno>;
@@ -451,9 +451,9 @@ impl Vnode {
     }
 
     /// Reports file status
-    pub fn stat(self: &VnodeRef, stat: &mut Stat) -> Result<(), Errno> {
+    pub fn stat(self: &VnodeRef) -> Result<Stat, Errno> {
         if let Some(ref mut data) = *self.data() {
-            data.stat(self.clone(), stat)
+            data.stat(self.clone())
         } else {
             Err(Errno::NotImplemented)
         }

kernel/src/syscall/mod.rs

@@ -107,7 +107,8 @@ pub fn syscall(num: SystemCall, args: &[usize]) -> Result<usize, Errno> {
 
             let proc = Process::current();
             let mut io = proc.io.lock();
-            find_at_node(&mut io, at_fd, filename, flags & AT_EMPTY_PATH != 0)?.stat(buf)?;
+            let stat = find_at_node(&mut io, at_fd, filename, flags & AT_EMPTY_PATH != 0)?.stat()?;
+            *buf = stat;
             Ok(0)
         }
         SystemCall::Ioctl => {