updates from ch9

user/src/file.rs

@@ -0,0 +1,30 @@
+use super::*;
+
+bitflags! {
+    pub struct OpenFlags: u32 {
+        const RDONLY = 0;
+        const WRONLY = 1 << 0;
+        const RDWR = 1 << 1;
+        const CREATE = 1 << 9;
+        const TRUNC = 1 << 10;
+    }
+}
+
+pub fn dup(fd: usize) -> isize {
+    sys_dup(fd)
+}
+pub fn open(path: &str, flags: OpenFlags) -> isize {
+    sys_open(path, flags.bits)
+}
+pub fn close(fd: usize) -> isize {
+    sys_close(fd)
+}
+pub fn pipe(pipe_fd: &mut [usize]) -> isize {
+    sys_pipe(pipe_fd)
+}
+pub fn read(fd: usize, buf: &mut [u8]) -> isize {
+    sys_read(fd, buf)
+}
+pub fn write(fd: usize, buf: &[u8]) -> isize {
+    sys_write(fd, buf)
+}