diff --git a/kernel/syscall/fs.rs b/kernel/syscall/fs.rs
index 91c36e4..1552f25 100644
--- a/kernel/syscall/fs.rs
+++ b/kernel/syscall/fs.rs
@@ -2,9 +2,45 @@
 
 use context;
 use scheme;
-use syscall::data::Stat;
+use syscall::data::{Packet, Stat};
 use syscall::error::*;
 
+pub fn file_op(a: usize, fd: usize, c: usize, d: usize) -> Result<usize> {
+    let file = {
+        let contexts = context::contexts();
+        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
+        let context = context_lock.read();
+        let file = context.get_file(fd).ok_or(Error::new(EBADF))?;
+        file
+    };
+
+    let scheme = {
+        let schemes = scheme::schemes();
+        let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
+        scheme.clone()
+    };
+
+    let mut packet = Packet {
+        id: 0,
+        a: a,
+        b: file.number,
+        c: c,
+        d: d
+    };
+
+    scheme.handle(&mut packet);
+
+    Error::demux(packet.a)
+}
+
+pub fn file_op_slice(a: usize, fd: usize, slice: &[u8]) -> Result<usize> {
+    file_op(a, fd, slice.as_ptr() as usize, slice.len())
+}
+
+pub fn file_op_mut_slice(a: usize, fd: usize, slice: &mut [u8]) -> Result<usize> {
+    file_op(a, fd, slice.as_mut_ptr() as usize, slice.len())
+}
+
 /// Change the current working directory
 pub fn chdir(path: &[u8]) -> Result<usize> {
     let contexts = context::contexts();
@@ -92,12 +128,22 @@ pub fn dup(fd: usize) -> Result<usize> {
         file
     };
 
-    let scheme = {
-        let schemes = scheme::schemes();
-        let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
-        scheme.clone()
-    };
-    scheme.dup(file.number)
+    let file_id = {
+        let scheme = {
+            let schemes = scheme::schemes();
+            let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
+            scheme.clone()
+        };
+        scheme.dup(file.number)
+    }?;
+
+    let contexts = context::contexts();
+    let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
+    let context = context_lock.read();
+    context.add_file(::context::file::File {
+        scheme: file.scheme,
+        number: file_id
+    }).ok_or(Error::new(EMFILE))
 }
 
 /// Register events for file
@@ -119,129 +165,3 @@ pub fn fevent(fd: usize, flags: usize) -> Result<usize> {
     context::event::register(fd, file.scheme, file.number);
     Ok(0)
 }
-
-/// Get the canonical path of the file
-pub fn fpath(fd: usize, buf: &mut [u8]) -> Result<usize> {
-    let file = {
-        let contexts = context::contexts();
-        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
-        let context = context_lock.read();
-        let file = context.get_file(fd).ok_or(Error::new(EBADF))?;
-        file
-    };
-
-    let scheme = {
-        let schemes = scheme::schemes();
-        let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
-        scheme.clone()
-    };
-    scheme.fpath(file.number, buf)
-}
-
-/// Get information about the file
-pub fn fstat(fd: usize, stat: &mut Stat) -> Result<usize> {
-    let file = {
-        let contexts = context::contexts();
-        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
-        let context = context_lock.read();
-        let file = context.get_file(fd).ok_or(Error::new(EBADF))?;
-        file
-    };
-
-    let scheme = {
-        let schemes = scheme::schemes();
-        let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
-        scheme.clone()
-    };
-    scheme.fstat(file.number, stat)
-}
-
-/// Sync the file descriptor
-pub fn fsync(fd: usize) -> Result<usize> {
-    let file = {
-        let contexts = context::contexts();
-        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
-        let context = context_lock.read();
-        let file = context.get_file(fd).ok_or(Error::new(EBADF))?;
-        file
-    };
-
-    let scheme = {
-        let schemes = scheme::schemes();
-        let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
-        scheme.clone()
-    };
-    scheme.fsync(file.number)
-}
-
-/// Truncate the file descriptor
-pub fn ftruncate(fd: usize, len: usize) -> Result<usize> {
-    let file = {
-        let contexts = context::contexts();
-        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
-        let context = context_lock.read();
-        let file = context.get_file(fd).ok_or(Error::new(EBADF))?;
-        file
-    };
-
-    let scheme = {
-        let schemes = scheme::schemes();
-        let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
-        scheme.clone()
-    };
-    scheme.ftruncate(file.number, len)
-}
-
-/// Seek to an offset
-pub fn lseek(fd: usize, pos: usize, whence: usize) -> Result<usize> {
-    let file = {
-        let contexts = context::contexts();
-        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
-        let context = context_lock.read();
-        let file = context.get_file(fd).ok_or(Error::new(EBADF))?;
-        file
-    };
-
-    let scheme = {
-        let schemes = scheme::schemes();
-        let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
-        scheme.clone()
-    };
-    scheme.seek(file.number, pos, whence)
-}
-
-/// Read syscall
-pub fn read(fd: usize, buf: &mut [u8]) -> Result<usize> {
-    let file = {
-        let contexts = context::contexts();
-        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
-        let context = context_lock.read();
-        let file = context.get_file(fd).ok_or(Error::new(EBADF))?;
-        file
-    };
-
-    let scheme = {
-        let schemes = scheme::schemes();
-        let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
-        scheme.clone()
-    };
-    scheme.read(file.number, buf)
-}
-
-/// Write syscall
-pub fn write(fd: usize, buf: &[u8]) -> Result<usize> {
-    let file = {
-        let contexts = context::contexts();
-        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
-        let context = context_lock.read();
-        let file = context.get_file(fd).ok_or(Error::new(EBADF))?;
-        file
-    };
-
-    let scheme = {
-        let schemes = scheme::schemes();
-        let scheme = schemes.get(file.scheme).ok_or(Error::new(EBADF))?;
-        scheme.clone()
-    };
-    scheme.write(file.number, buf)
-}
diff --git a/kernel/syscall/mod.rs b/kernel/syscall/mod.rs
index 1bb5a56..3edecf9 100644
--- a/kernel/syscall/mod.rs
+++ b/kernel/syscall/mod.rs
@@ -8,7 +8,6 @@ pub use self::fs::*;
 pub use self::process::*;
 pub use self::validate::*;
 
-use self::data::Stat;
 use self::error::{Error, Result, ENOSYS};
 use self::number::*;
 
@@ -25,33 +24,35 @@ pub mod validate;
 pub extern fn syscall(a: usize, b: usize, c: usize, d: usize, e: usize, f: usize, stack: usize) -> usize {
     #[inline(always)]
     fn inner(a: usize, b: usize, c: usize, d: usize, e: usize, _f: usize, stack: usize) -> Result<usize> {
-        match a {
-            SYS_EXIT => exit(b),
-            SYS_READ => read(b, validate_slice_mut(c as *mut u8, d)?),
-            SYS_WRITE => write(b, validate_slice(c as *const u8, d)?),
-            SYS_OPEN => open(validate_slice(b as *const u8, c)?, d),
-            SYS_CLOSE => close(b),
-            SYS_WAITPID => waitpid(b, c, d),
-            SYS_EXECVE => exec(validate_slice(b as *const u8, c)?, validate_slice(d as *const [usize; 2], e)?),
-            SYS_CHDIR => chdir(validate_slice(b as *const u8, c)?),
-            SYS_LSEEK => lseek(b, c, d),
-            SYS_GETPID => getpid(),
-            SYS_FSTAT => fstat(b, &mut validate_slice_mut(c as *mut Stat, 1)?[0]),
-            SYS_DUP => dup(b),
-            SYS_BRK => brk(b),
-            SYS_FTRUNCATE => ftruncate(b, c),
-            SYS_IOPL => iopl(b),
-            SYS_FSYNC => fsync(b),
-            SYS_CLONE => clone(b, stack),
-            SYS_YIELD => sched_yield(),
-            SYS_GETCWD => getcwd(validate_slice_mut(b as *mut u8, c)?),
-            SYS_FEVENT => fevent(b, c),
-            SYS_FPATH => fpath(b, validate_slice_mut(c as *mut u8, d)?),
-            SYS_PHYSMAP => physmap(b, c, d),
-            SYS_PHYSUNMAP => physunmap(b),
-            _ => {
-                println!("Unknown syscall {}", a);
-                Err(Error::new(ENOSYS))
+        match a & SYS_CLASS {
+            SYS_CLASS_FILE => match a & SYS_ARG {
+                SYS_ARG_SLICE => file_op_slice(a, b, validate_slice(c as *const u8, d)?),
+                SYS_ARG_MSLICE => file_op_mut_slice(a, b, validate_slice_mut(c as *mut u8, d)?),
+                _ => match a {
+                    SYS_CLOSE => close(b),
+                    SYS_DUP => dup(b),
+                    SYS_FEVENT => fevent(b, c),
+                    _ => file_op(a, b, c, d)
+                }
+            },
+            SYS_CLASS_PATH => match a {
+                SYS_OPEN => open(validate_slice(b as *const u8, c)?, d),
+                _ => unreachable!()
+            },
+            _ => match a {
+                SYS_EXIT => exit(b),
+                SYS_WAITPID => waitpid(b, c, d),
+                SYS_EXECVE => exec(validate_slice(b as *const u8, c)?, validate_slice(d as *const [usize; 2], e)?),
+                SYS_CHDIR => chdir(validate_slice(b as *const u8, c)?),
+                SYS_GETPID => getpid(),
+                SYS_BRK => brk(b),
+                SYS_IOPL => iopl(b),
+                SYS_CLONE => clone(b, stack),
+                SYS_YIELD => sched_yield(),
+                SYS_GETCWD => getcwd(validate_slice_mut(b as *mut u8, c)?),
+                SYS_PHYSMAP => physmap(b, c, d),
+                SYS_PHYSUNMAP => physunmap(b),
+                _ => Err(Error::new(ENOSYS))
             }
         }
     }
diff --git a/kernel/syscall/process.rs b/kernel/syscall/process.rs
index 5150b95..4877503 100644
--- a/kernel/syscall/process.rs
+++ b/kernel/syscall/process.rs
@@ -395,7 +395,7 @@ pub fn exec(path: &[u8], arg_ptrs: &[[usize; 2]]) -> Result<usize> {
         let mut data = vec![];
         loop {
             let mut buf = [0; 16384];
-            let count = syscall::read(file, &mut buf)?;
+            let count = syscall::file_op_mut_slice(syscall::number::SYS_READ, file, &mut buf)?;
             if count > 0 {
                 data.extend_from_slice(&buf[..count]);
             } else {
diff --git a/syscall/src/lib.rs b/syscall/src/lib.rs
index 2f4ea89..9e3968a 100644
--- a/syscall/src/lib.rs
+++ b/syscall/src/lib.rs
@@ -8,6 +8,8 @@ pub use self::flag::*;
 pub use self::number::*;
 pub use self::scheme::*;
 
+use core::mem;
+
 #[cfg(target_arch = "x86")]
 #[path="x86.rs"]
 mod arch;
@@ -67,7 +69,7 @@ pub fn fpath(fd: usize, buf: &mut [u8]) -> Result<usize> {
 }
 
 pub fn fstat(fd: usize, stat: &mut Stat) -> Result<usize> {
-    unsafe { syscall2(SYS_FSTAT, fd, stat as *mut Stat as usize) }
+    unsafe { syscall3(SYS_FSTAT, fd, stat as *mut Stat as usize, mem::size_of::<Stat>()) }
 }
 
 pub fn fsync(fd: usize) -> Result<usize> {
diff --git a/syscall/src/number.rs b/syscall/src/number.rs
index c0f341c..5378172 100644
--- a/syscall/src/number.rs
+++ b/syscall/src/number.rs
@@ -1,31 +1,45 @@
-pub const SYS_BRK: usize = 45;
-pub const SYS_CHDIR: usize = 12;
-pub const SYS_CLONE: usize = 120;
-pub const SYS_CLOSE: usize = 6;
-pub const SYS_CLOCK_GETTIME: usize = 265;
-pub const SYS_DUP: usize = 41;
-pub const SYS_EXECVE: usize = 11;
-pub const SYS_EXIT: usize = 1;
-pub const SYS_FEVENT: usize = 927;
-pub const SYS_FPATH: usize = 928;
-pub const SYS_FSTAT: usize = 28;
-pub const SYS_FSYNC: usize = 118;
-pub const SYS_FTRUNCATE: usize = 93;
-pub const SYS_FUTEX: usize = 240;
-pub const SYS_GETCWD: usize = 183;
-pub const SYS_GETPID: usize = 20;
-pub const SYS_IOPL: usize = 110;
-pub const SYS_LINK: usize = 9;
-pub const SYS_LSEEK: usize = 19;
-pub const SYS_MKDIR: usize = 39;
-pub const SYS_NANOSLEEP: usize = 162;
-pub const SYS_OPEN: usize = 5;
-pub const SYS_PHYSMAP: usize = 945;
-pub const SYS_PHYSUNMAP: usize = 946;
-pub const SYS_PIPE2: usize = 331;
-pub const SYS_READ: usize = 3;
-pub const SYS_RMDIR: usize = 84;
-pub const SYS_UNLINK: usize = 10;
-pub const SYS_WAITPID: usize = 7;
-pub const SYS_WRITE: usize = 4;
-pub const SYS_YIELD: usize = 158;
+pub const SYS_CLASS: usize =    0xF000_0000;
+pub const SYS_CLASS_PATH: usize=0x1000_0000;
+pub const SYS_CLASS_FILE: usize=0x2000_0000;
+
+pub const SYS_ARG: usize =      0x0F00_0000;
+pub const SYS_ARG_SLICE: usize =0x0100_0000;
+pub const SYS_ARG_MSLICE: usize=0x0200_0000;
+pub const SYS_ARG_PATH: usize = 0x0300_0000;
+
+pub const SYS_RET: usize =      0x00F0_0000;
+pub const SYS_RET_FILE: usize = 0x0010_0000;
+
+pub const SYS_LINK: usize =     SYS_CLASS_PATH | SYS_ARG_PATH | 9;
+pub const SYS_OPEN: usize =     SYS_CLASS_PATH | SYS_RET_FILE | 5;
+pub const SYS_MKDIR: usize =    SYS_CLASS_PATH | 39;
+pub const SYS_RMDIR: usize =    SYS_CLASS_PATH | 84;
+pub const SYS_UNLINK: usize =   SYS_CLASS_PATH | 10;
+
+pub const SYS_CLOSE: usize =    SYS_CLASS_FILE | 6;
+pub const SYS_DUP: usize =      SYS_CLASS_FILE | SYS_RET_FILE | 41;
+pub const SYS_READ: usize =     SYS_CLASS_FILE | SYS_ARG_MSLICE | 3;
+pub const SYS_WRITE: usize =    SYS_CLASS_FILE | SYS_ARG_SLICE | 4;
+pub const SYS_FEVENT: usize =   SYS_CLASS_FILE | 927;
+pub const SYS_LSEEK: usize =    SYS_CLASS_FILE | 19;
+pub const SYS_FPATH: usize =    SYS_CLASS_FILE | SYS_ARG_MSLICE | 928;
+pub const SYS_FSTAT: usize =    SYS_CLASS_FILE | SYS_ARG_MSLICE | 28;
+pub const SYS_FSYNC: usize =    SYS_CLASS_FILE | 118;
+pub const SYS_FTRUNCATE: usize =SYS_CLASS_FILE | 93;
+
+pub const SYS_BRK: usize =      45;
+pub const SYS_CHDIR: usize =    12;
+pub const SYS_CLOCK_GETTIME: usize =  265;
+pub const SYS_CLONE: usize =    120;
+pub const SYS_EXECVE: usize =   11;
+pub const SYS_EXIT: usize =     1;
+pub const SYS_FUTEX: usize =    240;
+pub const SYS_GETCWD: usize =   183;
+pub const SYS_GETPID: usize =   20;
+pub const SYS_IOPL: usize =     110;
+pub const SYS_NANOSLEEP: usize =162;
+pub const SYS_PHYSMAP: usize =  945;
+pub const SYS_PHYSUNMAP: usize =946;
+pub const SYS_PIPE2: usize =    331;
+pub const SYS_WAITPID: usize =  7;
+pub const SYS_YIELD: usize =    158;