handling ERROR_MORE_DATA does not notify read event

Author: dswij

src/sys/windows/named_pipe.rs

@@ -565,10 +565,9 @@ impl<'a> Read for &'a NamedPipe {
                 Ok(n)
             }
 
-            // Schedule another read with a bigger buffer
-            e @ State::InsufficientBufferSize(..) => {
-                state.read = e;
-                Inner::schedule_read(&self.inner, &mut state, None);
+            // We scheduled another read with a bigger buffer after the first read (see `read_done`)
+            // This is not possible in theory, just like `State::None` case, but return would block for now.
+            State::InsufficientBufferSize(..) => {
                 Err(would_block())
             }
 
@@ -723,10 +722,11 @@ impl Inner {
     /// scheduled.
     fn schedule_read(me: &Arc<Inner>, io: &mut Io, events: Option<&mut Vec<Event>>) -> bool {
         // Check to see if a read is already scheduled/completed
+
         let mut buf = match mem::replace(&mut io.read, State::None) {
             State::None => me.get_buffer(),
             State::InsufficientBufferSize(mut buf, rem) => {
-                buf.reserve(rem);
+                buf.reserve_exact(rem);
                 buf
             }
             e @ _ => {
@@ -735,11 +735,12 @@ impl Inner {
             }
         };
 
+
         // Allocate a buffer and schedule the read.
         let e = unsafe {
             let overlapped = me.read.as_ptr() as *mut _;
             let slice = slice::from_raw_parts_mut(buf.as_mut_ptr(), buf.capacity());
-            me.read_overlapped(slice, overlapped)
+            me.read_overlapped(&mut slice[buf.len()..], overlapped)
         };
         match e {
             // See `NamedPipe::connect` above for the rationale behind `forget`
@@ -910,6 +911,8 @@ fn read_done(status: &OVERLAPPED_ENTRY, events: Option<&mut Vec<Event>>) {
                     Ok(rem) => {
                         buf.set_len(status.bytes_transferred() as usize);
                         io.read = State::InsufficientBufferSize(buf, rem);
+                        Inner::schedule_read(&me, &mut io, None);
+                        return;
                     }
                     Err(e) => {
                         io.read = State::Err(e);