Refactor context list

kernel/syscall/fs.rs

@@ -1,5 +1,6 @@
 //! Filesystem syscalls
 
+use context;
 use scheme;
 
 use super::{Error, Result};
@@ -7,22 +8,32 @@ use super::{Error, Result};
 /// Read syscall
 pub fn read(fd: usize, buf: &mut [u8]) -> Result<usize> {
     println!("Read {}: {}", fd, buf.len());
-    if let Some(file) = unsafe { &mut ::context::CONTEXT }.files.get(fd) {
-        println!("{:?}", file);
-        Ok(0)
+    if let Some(context_lock) = context::contexts().get(&0) {
+        let context = context_lock.read();
+        if let Some(file) = context.files.get(fd) {
+            println!("{:?}", file);
+            Ok(0)
+        } else {
+            Err(Error::BadFile)
+        }
     } else {
-        Err(Error::BadFile)
+        Err(Error::NoProcess)
     }
 }
 
 /// Write syscall
 pub fn write(fd: usize, buf: &[u8]) -> Result<usize> {
     println!("Write {}: {}", fd, buf.len());
-    if let Some(file) = unsafe { &mut ::context::CONTEXT }.files.get(fd) {
-        println!("{:?}: {:?}", file, ::core::str::from_utf8(buf));
-        Ok(buf.len())
+    if let Some(context_lock) = context::contexts().get(&0) {
+        let context = context_lock.read();
+        if let Some(file) = context.files.get(fd) {
+            println!("{:?}: {:?}", file, ::core::str::from_utf8(buf));
+            Ok(buf.len())
+        } else {
+            Err(Error::BadFile)
+        }
     } else {
-        Err(Error::BadFile)
+        Err(Error::NoProcess)
     }
 }
 
@@ -46,13 +57,18 @@ pub fn open(path: &[u8], flags: usize) -> Result<usize> {
         }
     }?;
 
-    if let Some(fd) = unsafe { &mut ::context::CONTEXT }.add_file(::context::file::File {
-        scheme: 0,
-        number: file
-    }) {
-        Ok(fd)
+    if let Some(context_lock) = context::contexts().get(&0) {
+        let mut context = context_lock.write();
+        if let Some(fd) = context.add_file(::context::file::File {
+            scheme: 0,
+            number: file
+        }) {
+            Ok(fd)
+        } else {
+            Err(Error::TooManyFiles)
+        }
     } else {
-        Err(Error::TooManyFiles)
+        Err(Error::NoProcess)
     }
 }
 

kernel/syscall/mod.rs

@@ -53,6 +53,8 @@ pub enum Error {
     NotPermitted,
     /// No such file or directory
     NoEntry,
+    /// No such process
+    NoProcess,
     /// Bad file number
     BadFile,
     /// Invalid argument
@@ -70,6 +72,7 @@ impl From<Error> for usize {
         match err {
             Error::NotPermitted => 1,
             Error::NoEntry => 2,
+            Error::NoProcess => 3,
             Error::BadFile => 9,
             Error::InvalidValue => 22,
             Error::TooManyFiles => 24,