rsh: add rcp, remote copy program

kernel/driver/net/core/src/util/queue.rs

@@ -250,7 +250,7 @@ impl<T: GenericRxDescriptor> GenericRxRing<T> {
     ) -> Result<usize, Error> {
         let mut inner = self.inner.lock();
 
-        while head.map_or(true, |tail| tail != inner.rd) {
+        while head.is_none_or(|tail| tail != inner.rd) {
             let index = inner.rd % self.capacity;
 
             inner.entries.cache_flush_element(index, false);

kernel/libk/src/vfs/ioctx.rs

@@ -312,7 +312,8 @@ impl IoContext {
         let (dst_node, dst_name) = if let Ok(node) = self.find(dst_at.clone(), dst, false) {
             // There is a node with the destination name, but it's not a directory
             if !node.is_directory() {
-                return Err(Error::AlreadyExists);
+                node.parent().unlink_child(&node)?;
+                // return Err(Error::AlreadyExists);
             }
 
             // mv /a/b /c if /c exists -> move /a/b into /c with filename b
@@ -321,7 +322,7 @@ impl IoContext {
             // Otherwise try looking up a parent
             let node = self.find(dst_at, dst_parent, true)?;
             if !node.is_directory() {
-                return Err(Error::NotADirectory);
+                node.parent().unlink_child(&node)?;
             }
 
             // mv /a/b /c/d if /c/d doesn't exist -> move /a/b into /c with filename d