diff --git a/.travis.yml b/.travis.yml
index 0f33674..3b2fc9c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,3 +1,3 @@
 language: rust
 rust:
-  - nightly
\ No newline at end of file
+  - nightly-2018-04-01
\ No newline at end of file
diff --git a/Cargo.toml b/Cargo.toml
index 43be0a7..f98dd4c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,4 +5,7 @@ authors = ["WangRunji <wangrunji0408@163.com>"]
 
 [dependencies]
 spin = "0.4"
-bit-set = "0.5"
\ No newline at end of file
+bit-set = "0.5"
+
+[features]
+ucore = []
\ No newline at end of file
diff --git a/src/c_interface.rs b/src/c_interface.rs
index 0b235fe..f9f01a9 100644
--- a/src/c_interface.rs
+++ b/src/c_interface.rs
@@ -1,5 +1,10 @@
 //! C Interfaces for ucore
 
+pub use self::allocator::UcoreAllocator;
+
+#[no_mangle]
+pub static SFS_INODE_OPS: INodeOps = INodeOps::from_rust_inode::<sfs::INode>();
+
 /// Abstract low-level file.
 ///
 /// Match struct `inode` in ucore `kern/fs/vfs/inode.h`
@@ -38,33 +43,127 @@ struct Stat {
     size: u32,
 }
 
-const S_IFMT : u32 = 070000;          // mask for type of file
-const S_IFREG: u32 = 010000;          // ordinary regular file
-const S_IFDIR: u32 = 020000;          // directory
-const S_IFLNK: u32 = 030000;          // symbolic link
-const S_IFCHR: u32 = 040000;          // character device
-const S_IFBLK: u32 = 050000;          // block device
+/// mask for type of file
+const S_IFMT: u32 = 070000;
+/// ordinary regular file
+const S_IFREG: u32 = 010000;
+/// directory
+const S_IFDIR: u32 = 020000;
+/// symbolic link
+const S_IFLNK: u32 = 030000;
+/// character device
+const S_IFCHR: u32 = 040000;
+/// block device
+const S_IFBLK: u32 = 050000;
 
 /// Abstract operations on a inode.
 ///
 /// Match struct `inode_ops` in ucore `kern/fs/vfs/inode.h`
 // TODO: Append docs from ucore
 #[repr(C)]
-struct INodeOps {
+pub struct INodeOps {
     magic: u64,
-    open: extern fn(*mut INode, flags: u32) -> i32,
-    close: extern fn(*mut INode) -> i32,
-    read: extern fn(*mut INode, *mut IoBuf) -> i32,
-    write: extern fn(*mut INode, *mut IoBuf) -> i32,
-    fstat: extern fn(*mut INode, *mut Stat) -> i32,
-    fsync: extern fn(*mut INode) -> i32,
-    namefile: extern fn(*mut INode, *mut IoBuf) -> i32,
-    getdirentry: extern fn(*mut INode, *mut IoBuf) -> i32,
-    reclaim: extern fn(*mut INode) -> i32,
-    gettype: extern fn(*mut INode, type_store: *mut u32) -> i32,
-    tryseek: extern fn(*mut INode, pos: i32) -> i32,
-    truncate: extern fn(*mut INode, len: i32) -> i32,
-    create: extern fn(*mut INode, name: *const u8, excl: bool, inode_store: *mut *mut INode) -> i32,
-    lookup: extern fn(*mut INode, path: *mut u8, inode_store: *mut *mut INode) -> i32,
-    ioctl: extern fn(*mut INode, op: i32, data: *mut u8) -> i32,
+    open: extern fn(*mut INode, flags: u32) -> ErrorCode,
+    close: extern fn(*mut INode) -> ErrorCode,
+    read: extern fn(*mut INode, *mut IoBuf) -> ErrorCode,
+    write: extern fn(*mut INode, *mut IoBuf) -> ErrorCode,
+    fstat: extern fn(*mut INode, *mut Stat) -> ErrorCode,
+    fsync: extern fn(*mut INode) -> ErrorCode,
+    namefile: extern fn(*mut INode, *mut IoBuf) -> ErrorCode,
+    getdirentry: extern fn(*mut INode, *mut IoBuf) -> ErrorCode,
+    reclaim: extern fn(*mut INode) -> ErrorCode,
+    gettype: extern fn(*mut INode, type_store: *mut u32) -> ErrorCode,
+    tryseek: extern fn(*mut INode, pos: i32) -> ErrorCode,
+    truncate: extern fn(*mut INode, len: i32) -> ErrorCode,
+    create: extern fn(*mut INode, name: *const u8, excl: bool, inode_store: *mut *mut INode) -> ErrorCode,
+    lookup: extern fn(*mut INode, path: *mut u8, inode_store: *mut *mut INode) -> ErrorCode,
+    ioctl: extern fn(*mut INode, op: i32, data: *mut u8) -> ErrorCode,
+}
+
+#[repr(i32)]
+#[derive(Debug)]
+pub enum ErrorCode {
+    Ok = 0,
+    Unimplemented = -1,
+}
+
+use vfs;
+use sfs;
+
+impl INodeOps {
+    const fn from_rust_inode<T: vfs::INode>() -> Self {
+        extern fn open(inode: *mut INode, flags: u32) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn close(inode: *mut INode) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn read(inode: *mut INode, buf: *mut IoBuf) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn write(inode: *mut INode, buf: *mut IoBuf) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn fstat(inode: *mut INode, stat: *mut Stat) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn fsync(inode: *mut INode) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn namefile(inode: *mut INode, buf: *mut IoBuf) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn getdirentry(inode: *mut INode, buf: *mut IoBuf) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn reclaim(inode: *mut INode) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn gettype(inode: *mut INode, type_store: *mut u32) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn tryseek(inode: *mut INode, pos: i32) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn truncate(inode: *mut INode, len: i32) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn create(inode: *mut INode, name: *const u8, excl: bool, inode_store: *mut *mut INode) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn lookup(inode: *mut INode, path: *mut u8, inode_store: *mut *mut INode) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        extern fn ioctl(inode: *mut INode, op: i32, data: *mut u8) -> ErrorCode {
+            ErrorCode::Unimplemented
+        }
+        INodeOps {
+            magic: 0x8c4ba476,
+            open, close, read, write, fstat, fsync, namefile, getdirentry,
+            reclaim, gettype, tryseek, truncate, create, lookup, ioctl,
+        }
+    }
+}
+
+mod allocator {
+    use alloc::heap::{Alloc, AllocErr, Layout};
+    use core::ptr::NonNull;
+
+    pub struct UcoreAllocator {
+        pub malloc: unsafe extern fn(size: usize) -> *mut u8,
+        pub free: unsafe extern fn(*mut u8),
+    }
+
+    unsafe impl<'a> Alloc for &'a UcoreAllocator {
+        unsafe fn alloc(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+            const NULL: *mut u8 = 0 as *mut u8;
+            match (self.malloc)(layout.size()) {
+                NULL => Err(AllocErr::Exhausted { request: layout }),
+                ptr => Ok(ptr),
+            }
+        }
+        unsafe fn dealloc(&mut self, ptr: *mut u8, layout: Layout) {
+            (self.free)(ptr);
+        }
+    }
 }
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
index d76f4dd..4e737d2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,19 +1,37 @@
 #![feature(alloc)]
 #![feature(const_fn)]
+#![cfg_attr(feature = "ucore", feature(allocator_api, global_allocator))]
 #![no_std]
 
 #[cfg(test)]
 #[macro_use]
 extern crate std;
-
 extern crate spin;
 extern crate alloc;
 extern crate bit_set;
 
+#[cfg(not(test))]
+macro_rules! eprintln {
+    () => ();
+    ($fmt:expr) => ();
+    ($fmt:expr, $($arg:tt)*) => ();
+}
+
 mod dirty;
 mod vfs;
 mod sfs;
 mod structs;
-mod c_interface;
+#[cfg(feature = "ucore")]
+pub mod c_interface;
 #[cfg(test)]
-mod tests;
\ No newline at end of file
+mod tests;
+
+#[cfg(feature = "ucore")]
+#[global_allocator]
+pub static UCORE_ALLOCATOR: c_interface::UcoreAllocator = {
+    extern {
+        fn kmalloc(size: usize) -> *mut u8;
+        fn kfree(ptr: *mut u8);
+    }
+    c_interface::UcoreAllocator{malloc: kmalloc, free: kfree}
+};
\ No newline at end of file