Update libstd. Add CWD and associated syscalls. Remove debugging

kernel/syscall/call.rs

@@ -19,6 +19,8 @@ pub enum Call {
     WaitPid = 7,
     /// Execute syscall
     Exec = 11,
+    /// Change working directory
+    ChDir = 12,
     /// Get process ID
     GetPid = 20,
     /// Duplicate file descriptor
@@ -30,12 +32,15 @@ pub enum Call {
     /// Clone process
     Clone = 120,
     /// Yield to scheduler
-    SchedYield = 158
+    SchedYield = 158,
+    /// Get process working directory
+    GetCwd = 183
 }
 
 /// Convert numbers to calls
 /// See http://syscalls.kernelgrok.com/
 impl Call {
+    //TODO: Return Option<Call>
     pub fn from(number: usize) -> Result<Call> {
         match number {
             1 => Ok(Call::Exit),
@@ -45,12 +50,14 @@ impl Call {
             6 => Ok(Call::Close),
             7 => Ok(Call::WaitPid),
             11 => Ok(Call::Exec),
+            12 => Ok(Call::ChDir),
             20 => Ok(Call::GetPid),
             41 => Ok(Call::Dup),
             45 => Ok(Call::Brk),
             110 => Ok(Call::Iopl),
             120 => Ok(Call::Clone),
             158 => Ok(Call::SchedYield),
+            183 => Ok(Call::GetCwd),
             _ => Err(Error::NoCall)
         }
     }