Organize context module

kernel/context/context.rs

@@ -0,0 +1,87 @@
+use alloc::boxed::Box;
+use collections::Vec;
+
+use arch;
+use super::file::File;
+use super::memory::Memory;
+
+/// A context, which identifies either a process or a thread
+#[derive(Debug)]
+pub struct Context {
+    /// The ID of this context
+    pub id: usize,
+    //TODO: Status enum
+    /// Running or not
+    pub running: bool,
+    /// Blocked or not
+    pub blocked: bool,
+    /// Exited or not`
+    pub exited: bool,
+    /// The architecture specific context
+    pub arch: arch::context::Context,
+    /// Kernel stack
+    pub kstack: Option<Box<[u8]>>,
+    /// Executable image
+    pub image: Vec<Memory>,
+    /// User heap
+    pub heap: Option<Memory>,
+    /// User stack
+    pub stack: Option<Memory>,
+    /// The open files in the scheme
+    pub files: Vec<Option<File>>
+}
+
+impl Context {
+    /// Create a new context
+    pub fn new(id: usize) -> Context {
+        Context {
+            id: id,
+            running: false,
+            blocked: true,
+            exited: false,
+            arch: arch::context::Context::new(),
+            kstack: None,
+            image: Vec::new(),
+            heap: None,
+            stack: None,
+            files: Vec::new()
+        }
+    }
+
+    /// Add a file to the lowest available slot.
+    /// Return the file descriptor number or None if no slot was found
+    pub fn add_file(&mut self, file: File) -> Option<usize> {
+        for (i, mut file_option) in self.files.iter_mut().enumerate() {
+            if file_option.is_none() {
+                *file_option = Some(file);
+                return Some(i);
+            }
+        }
+        let len = self.files.len();
+        if len < super::CONTEXT_MAX_FILES {
+            self.files.push(Some(file));
+            Some(len)
+        } else {
+            None
+        }
+    }
+
+    /// Get a file
+    pub fn get_file(&self, i: usize) -> Option<File> {
+        if i < self.files.len() {
+            self.files[i]
+        } else {
+            None
+        }
+    }
+
+    /// Remove a file
+    // TODO: adjust files vector to smaller size if possible
+    pub fn remove_file(&mut self, i: usize) -> Option<File> {
+        if i < self.files.len() {
+            self.files[i].take()
+        } else {
+            None
+        }
+    }
+}