diff --git a/src/libos/src/fs/mod.rs b/src/libos/src/fs/mod.rs
index 8fe0777b..823149c5 100644
--- a/src/libos/src/fs/mod.rs
+++ b/src/libos/src/fs/mod.rs
@@ -248,9 +248,7 @@ pub fn do_dup3(old_fd: FileDesc, new_fd: FileDesc, flags: u32) -> Result<FileDes
 }
 
 pub fn do_sync() -> Result<(), Error> {
-    unsafe {
-        ocall_sync();
-    }
+    ROOT_INODE.fs().sync()?;
     Ok(())
 }
 
@@ -299,6 +297,21 @@ pub fn do_mkdir(path: &str, mode: usize) -> Result<(), Error> {
     Ok(())
 }
 
+pub fn do_rmdir(path: &str) -> Result<(), Error> {
+    let current_ref = process::get_current();
+    let current_process = current_ref.lock().unwrap();
+    info!("rmdir: path: {:?}", path);
+
+    let (dir_path, file_name) = split_path(&path);
+    let dir_inode = current_process.lookup_inode(dir_path)?;
+    let file_inode = dir_inode.find(file_name)?;
+    if file_inode.metadata()?.type_ != FileType::Dir {
+        return Err(Error::new(ENOTDIR, "rmdir on not directory"));
+    }
+    dir_inode.unlink(file_name)?;
+    Ok(())
+}
+
 pub fn do_link(oldpath: &str, newpath: &str) -> Result<(), Error> {
     let current_ref = process::get_current();
     let current_process = current_ref.lock().unwrap();
@@ -318,6 +331,10 @@ pub fn do_unlink(path: &str) -> Result<(), Error> {
 
     let (dir_path, file_name) = split_path(&path);
     let dir_inode = current_process.lookup_inode(dir_path)?;
+    let file_inode = dir_inode.find(file_name)?;
+    if file_inode.metadata()?.type_ == FileType::Dir {
+        return Err(Error::new(EISDIR, "unlink on directory"));
+    }
     dir_inode.unlink(file_name)?;
     Ok(())
 }
diff --git a/src/libos/src/syscall/mod.rs b/src/libos/src/syscall/mod.rs
index d0ae0340..4757baa1 100644
--- a/src/libos/src/syscall/mod.rs
+++ b/src/libos/src/syscall/mod.rs
@@ -52,6 +52,7 @@ pub extern "C" fn dispatch_syscall(
         SYS_CHDIR => do_chdir(arg0 as *mut i8),
         SYS_RENAME => do_rename(arg0 as *const i8, arg1 as *const i8),
         SYS_MKDIR => do_mkdir(arg0 as *const i8, arg1 as usize),
+        SYS_RMDIR => do_rmdir(arg0 as *const i8),
         SYS_LINK => do_link(arg0 as *const i8, arg1 as *const i8),
         SYS_UNLINK => do_unlink(arg0 as *const i8),
 
@@ -508,7 +509,7 @@ fn do_getcwd(buf: *mut u8, size: usize) -> Result<isize, Error> {
     }
     safe_buf[..cwd.len()].copy_from_slice(cwd.as_bytes());
     safe_buf[cwd.len()] = 0;
-    Ok(0)
+    Ok(buf as isize)
 }
 
 fn do_chdir(path: *const i8) -> Result<isize, Error> {
@@ -530,6 +531,12 @@ fn do_mkdir(path: *const i8, mode: usize) -> Result<isize, Error> {
     Ok(0)
 }
 
+fn do_rmdir(path: *const i8) -> Result<isize, Error> {
+    let path = clone_cstring_safely(path)?.to_string_lossy().into_owned();
+    fs::do_rmdir(&path)?;
+    Ok(0)
+}
+
 fn do_link(oldpath: *const i8, newpath: *const i8) -> Result<isize, Error> {
     let oldpath = clone_cstring_safely(oldpath)?.to_string_lossy().into_owned();
     let newpath = clone_cstring_safely(newpath)?.to_string_lossy().into_owned();