diff --git a/src/libos/src/fs/mod.rs b/src/libos/src/fs/mod.rs
index d0c57b66..d845563e 100644
--- a/src/libos/src/fs/mod.rs
+++ b/src/libos/src/fs/mod.rs
@@ -35,24 +35,8 @@ pub fn do_open(path: &str, flags: u32, mode: u32) -> Result<FileDesc, Error> {
     let current_ref = process::get_current();
     let mut proc = current_ref.lock().unwrap();
 
-    let inode = if flags.contains(OpenFlags::CREATE) {
-        let (dir_path, file_name) = split_path(&path);
-        let dir_inode = proc.lookup_inode(dir_path)?;
-        match dir_inode.find(file_name) {
-            Ok(file_inode) => {
-                if flags.contains(OpenFlags::EXCLUSIVE) {
-                    return Err(Error::new(EEXIST, "file exists"));
-                }
-                file_inode
-            }
-            Err(FsError::EntryNotFound) => dir_inode.create(file_name, FileType::File, mode)?,
-            Err(e) => return Err(Error::from(e)),
-        }
-    } else {
-        proc.lookup_inode(&path)?
-    };
-
-    let file_ref: Arc<Box<File>> = Arc::new(Box::new(INodeFile::open(inode, flags.to_options())?));
+    let file = proc.open_file(path, flags, mode)?;
+    let file_ref: Arc<Box<File>> = Arc::new(Box::new(file));
 
     let fd = {
         let close_on_spawn = flags.contains(OpenFlags::CLOEXEC);
@@ -363,6 +347,28 @@ extern "C" {
 }
 
 impl Process {
+    /// Open a file on the process. But DO NOT add it to file table.
+    pub fn open_file(&self, path: &str, flags: OpenFlags, mode: u32) -> Result<INodeFile, Error> {
+        let inode = if flags.contains(OpenFlags::CREATE) {
+            let (dir_path, file_name) = split_path(&path);
+            let dir_inode = self.lookup_inode(dir_path)?;
+            match dir_inode.find(file_name) {
+                Ok(file_inode) => {
+                    if flags.contains(OpenFlags::EXCLUSIVE) {
+                        return Err(Error::new(EEXIST, "file exists"));
+                    }
+                    file_inode
+                }
+                Err(FsError::EntryNotFound) => dir_inode.create(file_name, FileType::File, mode)?,
+                Err(e) => return Err(Error::from(e)),
+            }
+        } else {
+            self.lookup_inode(&path)?
+        };
+        INodeFile::open(inode, flags.to_options())
+    }
+
+    /// Lookup INode from the cwd of the process
     pub fn lookup_inode(&self, path: &str) -> Result<Arc<INode>, Error> {
         debug!("lookup_inode: cwd: {:?}, path: {:?}", self.get_cwd(), path);
         if path.len() > 0 && path.as_bytes()[0] == b'/' {
diff --git a/src/libos/src/process/spawn/mod.rs b/src/libos/src/process/spawn/mod.rs
index ca218537..b8654c2f 100644
--- a/src/libos/src/process/spawn/mod.rs
+++ b/src/libos/src/process/spawn/mod.rs
@@ -1,7 +1,7 @@
 use xmas_elf::{ElfFile, header, program, sections};
 use xmas_elf::symbol_table::Entry;
 
-use fs::{File, FileDesc, FileTable, INodeExt, ROOT_INODE, StdinFile, StdoutFile};
+use fs::{File, FileDesc, FileTable, INodeExt, ROOT_INODE, StdinFile, StdoutFile, OpenFlags};
 use std::ffi::{CStr, CString};
 use std::path::Path;
 use std::sgxfs::SgxFile;
@@ -20,8 +20,14 @@ mod segment;
 
 #[derive(Debug)]
 pub enum FileAction {
-    // TODO: Add open action
-    // Open(...)
+    /// open(path, oflag, mode) had been called, and the returned file
+    /// descriptor, if not `fd`, had been changed to `fd`.
+    Open {
+        path: String,
+        mode: u32,
+        oflag: u32,
+        fd: FileDesc,
+    },
     Dup2(FileDesc, FileDesc),
     Close(FileDesc),
 }
@@ -92,14 +98,22 @@ fn init_files(parent_ref: &ProcessRef, file_actions: &[FileAction]) -> Result<Fi
         // Perform file actions to modify the cloned file table
         for file_action in file_actions {
             match file_action {
-                FileAction::Dup2(old_fd, new_fd) => {
-                    let file = cloned_file_table.get(*old_fd)?;
+                &FileAction::Open { ref path, mode, oflag, fd} => {
+                    let flags = OpenFlags::from_bits_truncate(oflag);
+                    let file = parent.open_file(path.as_str(), flags, mode)?;
+                    let file_ref: Arc<Box<File>> = Arc::new(Box::new(file));
+
+                    let close_on_spawn = flags.contains(OpenFlags::CLOEXEC);
+                    cloned_file_table.put_at(fd, file_ref, close_on_spawn);
+                }
+                &FileAction::Dup2(old_fd, new_fd) => {
+                    let file = cloned_file_table.get(old_fd)?;
                     if old_fd != new_fd {
-                        cloned_file_table.put_at(*new_fd, file, false);
+                        cloned_file_table.put_at(new_fd, file, false);
                     }
                 }
-                FileAction::Close(fd) => {
-                    cloned_file_table.del(*fd)?;
+                &FileAction::Close(fd) => {
+                    cloned_file_table.del(fd)?;
                 }
             }
         }
diff --git a/src/libos/src/syscall/mod.rs b/src/libos/src/syscall/mod.rs
index 0bea6239..6bc09dd8 100644
--- a/src/libos/src/syscall/mod.rs
+++ b/src/libos/src/syscall/mod.rs
@@ -283,7 +283,7 @@ pub struct FdOp {
     srcfd: u32,
     oflag: u32,
     mode: u32,
-    path: *const u8,
+    path: *const i8,
 }
 
 fn clone_file_actions_safely(fdop_ptr: *const FdOp) -> Result<Vec<FileAction>, Error> {
@@ -297,9 +297,12 @@ fn clone_file_actions_safely(fdop_ptr: *const FdOp) -> Result<Vec<FileAction>, E
         let file_action = match fdop.cmd {
             FDOP_CLOSE => FileAction::Close(fdop.fd),
             FDOP_DUP2 => FileAction::Dup2(fdop.srcfd, fdop.fd),
-            FDOP_OPEN => {
-                return errno!(EINVAL, "Not implemented");
-            }
+            FDOP_OPEN => FileAction::Open {
+                path: clone_cstring_safely(fdop.path)?.to_string_lossy().into_owned(),
+                mode: fdop.mode,
+                oflag: fdop.oflag,
+                fd: fdop.fd,
+            },
             _ => {
                 return errno!(EINVAL, "Unknown file action command");
             }