fix(io): read_exact should use the capacity

Author: Berrysoft

compio-buf/src/io_buf.rs

@@ -594,7 +594,7 @@ pub trait SetBufInit {
     ///
     /// # Safety
     ///
-    /// `len` should be less or equal than `buf_capacity() - buf_len()`.
+    /// `len` should be less or equal than `buf_capacity()`.
     unsafe fn set_buf_init(&mut self, len: usize);
 }
 

compio-io/src/read/ext.rs

@@ -147,7 +147,7 @@ pub trait AsyncReadExt: AsyncRead {
 
     /// Read the exact number of bytes required to fill the buf.
     async fn read_exact<T: IoBufMut>(&mut self, mut buf: T) -> BufResult<usize, T> {
-        loop_read_exact!(buf, buf.buf_capacity() - buf.buf_len(), read, loop self.read(buf.slice(read..)));
+        loop_read_exact!(buf, buf.buf_capacity(), read, loop self.read(buf.slice(read..)));
     }
 
     /// Read all bytes until underlying reader reaches `EOF`.
@@ -221,7 +221,7 @@ pub trait AsyncReadAtExt: AsyncReadAt {
     async fn read_exact_at<T: IoBufMut>(&self, mut buf: T, pos: u64) -> BufResult<usize, T> {
         loop_read_exact!(
             buf,
-            buf.buf_capacity() - buf.buf_len(),
+            buf.buf_capacity(),
             read,
             loop self.read_at(buf.slice(read..), pos + read as u64)
         );

compio-io/tests/io.rs

@@ -220,7 +220,7 @@ impl AsyncReadAt for RepeatOne {
 async fn read_exact() {
     let mut src = RepeatOne(114);
 
-    let (len, buf) = src.read_exact(Vec::with_capacity(5)).await.unwrap();
+    let (len, buf) = src.read_exact(vec![0; 5]).await.unwrap();
     assert_eq!(len, 5);
     assert_eq!(buf, [114; 5]);