diff --git a/src/lib.rs b/src/lib.rs
index cb86c85..e56f5f4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,6 +6,7 @@ use std::{
     io::{self, Write, Error, ErrorKind},
     path::{Path, PathBuf},
     process::Command,
+    time::SystemTime,
 };
 
 pub const DEFAULT_BUF_SIZE: usize = 8 * 1024;
@@ -222,3 +223,49 @@ pub fn extract_package_and_wait(dir: &str, file_name: &str) -> io::Result<()> {
     run_command_and_wait(&mut cmd)
 }
 
+pub fn copy_io<R: ?Sized, W: ?Sized>(reader: &mut R, writer: &mut W, total: i64) -> io::Result<u64>
+        where R: io::Read, W: io::Write {
+    // let mut written = 0u64;
+    // let written_cell = RefCell::new(written);
+    let start = SystemTime::now();
+    let written = copy_io_callback(reader, writer, total, &|total, written, _len| {
+       // let mut written_borrowed = written_cell.borrow_mut();
+        //written_cell.replace_with(|&mut old_written| old_written + len as u64);
+        let cost = SystemTime::now().duration_since(start.clone()).unwrap().as_secs();
+        let mut download_speed = "-".to_string();
+        if cost > 0 {
+            download_speed = format!("{}/s", get_display_size((written / cost) as i64));
+        }
+        if total > 0 {
+            print_lastline(&format!("Downloading, Total: {}, Downloaded: {}, Speed: {}", 
+                get_display_size(total),
+                get_display_size(written as i64),
+                download_speed));
+        } else {
+            print_lastline(&format!("Downloading, Downloaded: {}, Speed: {}", 
+                get_display_size(written as i64),
+                download_speed));
+        }
+    });
+    println!();
+    written
+}
+
+pub fn copy_io_callback<R: ?Sized, W: ?Sized, FCallback>(reader: &mut R, writer: &mut W, total: i64, callback: &FCallback) -> io::Result<u64>
+        where R: io::Read,
+              W: io::Write,
+              FCallback: Fn(i64, u64, usize) -> () {
+    let mut written = 0u64;
+    let mut buf: [u8; DEFAULT_BUF_SIZE] = [0u8; DEFAULT_BUF_SIZE];
+    loop {
+        let len = match reader.read(&mut buf) {
+            Ok(0) => return Ok(written),
+            Ok(len) => len,
+            Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
+            Err(e) => return Err(e),
+        };
+        writer.write_all(&buf[..len])?;
+        written += len as u64;
+        callback(total, written, len);
+    }
+}