[newlib-cygwin] Cygwin: FIFO: simplify raw_read

[Ken Brown]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=5b2696cb83617234446f3f4a304573c6aa3125d3

commit 5b2696cb83617234446f3f4a304573c6aa3125d3
Author: Ken Brown <kbr...@cornell.edu>
Date:   Fri Jun 21 17:33:30 2019 -0400

    Cygwin: FIFO: simplify raw_read
    
    Call NtReadFile directly instead of calling fhandler_base::raw_read.
    In addition to being simpler, this gives us access to the return value
    from NtReadFile.

Diff:
---
 winsup/cygwin/fhandler_fifo.cc | 50 ++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index b96c4d5..b755544 100644
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -802,8 +802,6 @@ fhandler_fifo::check_listen_client_thread ()
 void __reg3
 fhandler_fifo::raw_read (void *in_ptr, size_t& len)
 {
-  size_t orig_len = len;
-
   /* Make sure the lct is running. */
   int res = check_listen_client_thread ();
   debug_printf ("lct status %d", res);
@@ -826,26 +824,40 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
       for (int i = 0; i < nhandlers; i++)
        if (fc_handler[i].state == fc_connected)
          {
-           len = orig_len;
-           fc_handler[i].fh->fhandler_base::raw_read (in_ptr, len);
-           ssize_t nread = (ssize_t) len;
-           if (nread > 0)
-             {
-               fifo_client_unlock ();
-               return;
-             }
-           /* If the pipe is empty, we  get nread == -1 with
-              ERROR_NO_DATA. */
-           else if (nread < 0 && GetLastError () != ERROR_NO_DATA)
-             {
-               fifo_client_unlock ();
-               goto errout;
-             }
-           else if (nread == 0)
-             /* Client has disconnected. */
+           NTSTATUS status;
+           IO_STATUS_BLOCK io;
+           size_t nbytes = 0;
+
+           status = NtReadFile (get_fc_handle (i), NULL, NULL, NULL,
+                                &io, in_ptr, len, NULL, NULL);
+           switch (status)
              {
+             case STATUS_SUCCESS:
+             case STATUS_BUFFER_OVERFLOW:
+               /* io.Information is supposedly valid. */
+               nbytes = io.Information;
+               if (nbytes > 0)
+                 {
+                   len = nbytes;
+                   fifo_client_unlock ();
+                   return;
+                 }
+               break;
+             case STATUS_PIPE_EMPTY:
+               break;
+             case STATUS_PIPE_BROKEN:
+               /* Client has disconnected.  Mark the client handler
+                  to be deleted when it's safe to do that. */
+               fc_handler[i].state = fc_invalid;
+               nconnected--;
+               break;
+             default:
+               debug_printf ("NtReadFile status %y", status);
+               __seterrno_from_nt_status (status);
                fc_handler[i].state = fc_invalid;
                nconnected--;
+               fifo_client_unlock ();
+               goto errout;
              }
          }
       fifo_client_unlock ();