Add context and file structs

kernel/syscall/fs.rs

@@ -1,6 +1,6 @@
 //! Filesystem syscalls
 
-use super::Result;
+use super::{Error, Result};
 
 /// Read syscall
 pub fn read(fd: usize, buf: &mut [u8]) -> Result<usize> {
@@ -11,13 +11,25 @@ pub fn read(fd: usize, buf: &mut [u8]) -> Result<usize> {
 /// Write syscall
 pub fn write(fd: usize, buf: &[u8]) -> Result<usize> {
     println!("Write {}: {}", fd, buf.len());
-    Ok(0)
+    if let Some(file) = unsafe { &mut ::context::CONTEXT }.files.get(fd) {
+        println!("{:?}: {:?}", file, ::core::str::from_utf8(buf));
+        Ok(buf.len())
+    } else {
+        Err(Error::BadFile)
+    }
 }
 
 /// Open syscall
 pub fn open(path: &[u8], flags: usize) -> Result<usize> {
     println!("Open {:?}: {:X}", ::core::str::from_utf8(path), flags);
-    Ok(0)
+    if let Some(fd) = unsafe { &mut ::context::CONTEXT }.add_file(::context::file::File {
+        scheme: 0,
+        number: 0
+    }) {
+        Ok(fd)
+    } else {
+        Err(Error::TooManyFiles)
+    }
 }
 
 /// Close syscall