Cygwin: fhandler_fifo::raw_read: handle STATUS_PENDING

NtReadFile can return STATUS_PENDING occasionally even in non-blocking
mode.  Check for this and wait for NtReadFile to complete.  To avoid
code repetition, do this in a static helper function nt_read.

diff --git a/winsup/cygwin/fhandler_fifo.cc b/winsup/cygwin/fhandler_fifo.cc
index 489ba528c5ead7757ebddfd218b1fb23b249e8c9..34bd835aebb7ff6793ea68d7a0556a289e0f2582 100644 (file)
--- a/winsup/cygwin/fhandler_fifo.cc
+++ b/winsup/cygwin/fhandler_fifo.cc
@@ -1201,12 +1201,39 @@ fhandler_fifo::release_select_sem (const char *from)
     ReleaseSemaphore (select_sem, n_release, NULL);
 }
 
+/* Read from a non-blocking pipe and wait for completion. */
+static NTSTATUS
+nt_read (HANDLE h, HANDLE evt, PIO_STATUS_BLOCK pio, void *in_ptr, size_t& len)
+{
+  NTSTATUS status;
+
+  ResetEvent (evt);
+  status = NtReadFile (h, evt, NULL, NULL, pio, in_ptr, len, NULL, NULL);
+  if (status == STATUS_PENDING)
+    {
+      /* Very short-lived */
+      status = NtWaitForSingleObject (evt, FALSE, NULL);
+      if (NT_SUCCESS (status))
+       status = pio->Status;
+    }
+  return status;
+}
+
 void __reg3
 fhandler_fifo::raw_read (void *in_ptr, size_t& len)
 {
+  HANDLE evt;
+
   if (!len)
     return;
 
+  if (!(evt = CreateEvent (NULL, false, false, NULL)))
+    {
+      __seterrno ();
+      len = (size_t) -1;
+      return;
+    }
+
   while (1)
     {
       int nconnected = 0;
@@ -1244,17 +1271,15 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
          NTSTATUS status;
          IO_STATUS_BLOCK io;
 
-         status = NtReadFile (fc_handler[j].h, NULL, NULL, NULL,
-                              &io, in_ptr, len, NULL, NULL);
+         status = nt_read (fc_handler[j].h, evt, &io, in_ptr, len);
          switch (status)
            {
            case STATUS_SUCCESS:
            case STATUS_BUFFER_OVERFLOW:
-             /* io.Information is supposedly valid in latter case. */
              if (io.Information > 0)
                {
                  len = io.Information;
-                 goto out;
+                 goto unlock_out;
                }
              break;
            case STATUS_PIPE_EMPTY:
@@ -1265,7 +1290,7 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
              fc_handler[j].set_state (fc_disconnected);
              break;
            default:
-             debug_printf ("NtReadFile status %y", status);
+             debug_printf ("nt_read status %y", status);
              fc_handler[j].set_state (fc_error);
              break;
            }
@@ -1278,8 +1303,7 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
            NTSTATUS status;
            IO_STATUS_BLOCK io;
 
-           status = NtReadFile (fc_handler[i].h, NULL, NULL, NULL,
-                                &io, in_ptr, len, NULL, NULL);
+           status = nt_read (fc_handler[i].h, evt, &io, in_ptr, len);
            switch (status)
              {
              case STATUS_SUCCESS:
@@ -1290,7 +1314,7 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
                    if (j < nhandlers)
                      fc_handler[j].last_read = false;
                    fc_handler[i].last_read = true;
-                   goto out;
+                   goto unlock_out;
                  }
                break;
              case STATUS_PIPE_EMPTY:
@@ -1301,7 +1325,7 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
                fc_handler[i].set_state (fc_disconnected);
                break;
              default:
-               debug_printf ("NtReadFile status %y", status);
+               debug_printf ("nt_read status %y", status);
                fc_handler[i].set_state (fc_error);
                break;
              }
@@ -1315,8 +1339,7 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
            IO_STATUS_BLOCK io;
 
            nconnected++;
-           status = NtReadFile (fc_handler[i].h, NULL, NULL, NULL,
-                                &io, in_ptr, len, NULL, NULL);
+           status = nt_read (fc_handler[i].h, evt, &io, in_ptr, len);
            switch (status)
              {
              case STATUS_SUCCESS:
@@ -1327,7 +1350,7 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
                    if (j < nhandlers)
                      fc_handler[j].last_read = false;
                    fc_handler[i].last_read = true;
-                   goto out;
+                   goto unlock_out;
                  }
                break;
              case STATUS_PIPE_EMPTY:
@@ -1337,25 +1360,25 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
                nconnected--;
                break;
              default:
-               debug_printf ("NtReadFile status %y", status);
+               debug_printf ("nt_read status %y", status);
                fc_handler[i].set_state (fc_error);
                nconnected--;
                break;
              }
          }
-      fifo_client_unlock ();
       if (!nconnected && hit_eof ())
        {
-         reading_unlock ();
          len = 0;
-         return;
+         goto unlock_out;
        }
+      fifo_client_unlock ();
 maybe_retry:
       reading_unlock ();
       if (is_nonblocking ())
        {
          set_errno (EAGAIN);
-         goto errout;
+         len = (size_t) -1;
+         goto out;
        }
       else
        {
@@ -1370,7 +1393,8 @@ maybe_retry:
              else
                {
                  set_errno (EINTR);
-                 goto errout;
+                 len = (size_t) -1;
+                 goto out;
                }
            }
        }
@@ -1378,17 +1402,17 @@ maybe_retry:
       if (isclosed ())
        {
          set_errno (EBADF);
-         goto errout;
+         len = (size_t) -1;
+         goto out;
        }
     }
-errout:
-  len = (size_t) -1;
-  return;
-out:
+unlock_out:
   fifo_client_unlock ();
   reading_unlock ();
+out:
   if (select_sem)
     release_select_sem ("raw_read");
+  CloseHandle (evt);
 }
 
 int __reg2