Fix cat && add count_lines

user/src/bin/cat.rs

@@ -21,7 +21,7 @@ pub fn main(argc: usize, argv: &[&str]) -> i32 {
         if size == 0 {
             break;
         }
-        println!("{}", core::str::from_utf8(&buf[..size]).unwrap());
+        print!("{}", core::str::from_utf8(&buf[..size]).unwrap());
     }
     close(fd);
     0

user/src/bin/count_lines.rs

@@ -0,0 +1,30 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+use user_lib::read;
+
+#[no_mangle]
+pub fn main(_argc: usize, _argv: &[&str]) -> i32 {
+    let mut buf = [0u8; 256];
+    let mut lines = 0usize;
+    let mut total_size = 0usize;
+    loop {
+        let len = read(0, &mut buf) as usize;
+        if len == 0 {
+            break;
+        }
+        total_size += len;
+        let string = core::str::from_utf8(&buf[..len]).unwrap();
+        lines += string
+            .chars()
+            .fold(0, |acc, c| acc + if c == '\n' { 1 } else { 0 });
+    }
+    if total_size > 0 {
+        lines += 1;
+    }
+    println!("{}", lines);
+    0
+}