Handle backspace for k210/qemu platform && Add lots of user tests.

user/src/bin/usertests.rs

@@ -0,0 +1,40 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+static TESTS: &[&str] = &[
+    "exit\0",
+    "fantastic_text\0",
+    "forktest\0",
+    "forktest2\0",
+    "forktest_simple\0",
+    "hello_world\0",
+    "matrix\0",
+    "sleep\0",
+    "sleep_simple\0",
+    "stack_overflow\0",
+    "yield\0",
+];
+
+use user_lib::{exec, fork, waitpid};
+
+#[no_mangle]
+pub fn main() -> i32 {
+    for test in TESTS {
+        println!("Usertests: Running {}", test);
+        let pid = fork();
+        if pid == 0 {
+            exec(*test);
+            panic!("unreachable!");
+        } else {
+            let mut xstate: i32 = Default::default();
+            let wait_pid = waitpid(pid as usize, &mut xstate);
+            assert_eq!(pid, wait_pid);
+            println!("\x1b[32mUsertests: Test {} in Process {} exited with code {}\x1b[0m", test, pid, xstate);
+        }
+    }
+    println!("Usertests passed!");
+    0
+}