Simple filetest passed on qemu/k210.

user/Cargo.toml

@@ -7,4 +7,5 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-buddy_system_allocator = "0.6"
+buddy_system_allocator = "0.6"
+bitflags = "1.2.1"

user/src/bin/filetest_simple.rs

@@ -0,0 +1,38 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+use user_lib::{
+    open,
+    close,
+    read,
+    write,
+    OpenFlags,
+};
+
+#[no_mangle]
+pub fn main() -> i32 {
+    let test_str = "Hello, world!";
+    let filea = "filea\0";
+    let fd = open(filea, OpenFlags::CREATE | OpenFlags::WRONLY);
+    assert!(fd > 0);
+    let fd = fd as usize;
+    write(fd, test_str.as_bytes());
+    close(fd);
+
+    let fd = open(filea, OpenFlags::RDONLY);
+    assert!(fd > 0);
+    let fd = fd as usize;
+    let mut buffer = [0u8; 100];
+    let read_len = read(fd, &mut buffer) as usize;
+    close(fd);
+
+    assert_eq!(
+        test_str,
+        core::str::from_utf8(&buffer[..read_len]).unwrap(),
+    );
+    println!("file_test passed!");
+    0
+}

user/src/lib.rs

@@ -10,6 +10,8 @@ mod syscall;
 mod lang_items;
 
 extern crate alloc;
+#[macro_use]
+extern crate bitflags;
 
 use syscall::*;
 use buddy_system_allocator::LockedHeap;
@@ -42,6 +44,17 @@ fn main() -> i32 {
     panic!("Cannot find main!");
 }
 
+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 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) }

user/src/syscall.rs

@@ -1,3 +1,4 @@
+const SYSCALL_OPEN: usize = 56;
 const SYSCALL_CLOSE: usize = 57;
 const SYSCALL_PIPE: usize = 59;
 const SYSCALL_READ: usize = 63;
@@ -23,6 +24,10 @@ fn syscall(id: usize, args: [usize; 3]) -> isize {
     ret
 }
 
+pub fn sys_open(path: &str, flags: u32) -> isize {
+    syscall(SYSCALL_OPEN, [path.as_ptr() as usize, flags as usize, 0])
+}
+
 pub fn sys_close(fd: usize) -> isize {
     syscall(SYSCALL_CLOSE, [fd, 0, 0])
 }