1 files changed, 18 insertions, 7 deletions

diff --git a/winsup/cygwin/poll.cc b/winsup/cygwin/poll.cc
index 3c342adfd..ea86ab5aa 100644
--- a/winsup/cygwin/poll.cc
+++ b/winsup/cygwin/poll.cc
@@ -28,6 +28,7 @@ extern "C" int
 poll (struct pollfd *fds, nfds_t nfds, int timeout)
 {
   int max_fd = 0;
+  int invalid_fds = 0;
   fd_set *read_fds, *write_fds, *except_fds;
   struct timeval tv = { timeout / 1000, (timeout % 1000) * 1000 };
 
@@ -51,7 +52,6 @@ poll (struct pollfd *fds, nfds_t nfds, int timeout)
   memset (write_fds, 0, fds_size);
   memset (except_fds, 0, fds_size);
 
-  int invalid_fds = 0;
   for (unsigned int i = 0; i < nfds; ++i)
     {
       fds[i].revents = 0;
@@ -71,20 +71,31 @@ poll (struct pollfd *fds, nfds_t nfds, int timeout)
 	}
     }
 
-  if (invalid_fds)
-    return invalid_fds;
+  /* Invalid fds? */
+  if (invalid_fds > 0)
+    {
+      /* Only invalid fds?  Return. */
+      if ((nfds_t) invalid_fds == nfds)
+	return invalid_fds;
+      /* POSIX doesn't explicitely define this behaviour, but on Linux,
+	 the timeout is set to 0 if an error occurs, and POLLNVAL is one
+	 of these errors.  So, for Linux-compatibility's sake... */
+      tv.tv_sec = tv.tv_usec = 0;
+    }
 
   int ret = cygwin_select (max_fd + 1, read_fds, write_fds, except_fds,
 			   timeout < 0 ? NULL : &tv);
+  /* timeout, signal, whatever?  Return.  If invalid fds exist, return with
+     their number. */
   if (ret <= 0)
-    return ret;
+    return invalid_fds ?: ret;
 
   /* Set revents fields and count fds with non-zero revents fields for
      return value. */
   ret = 0;
   for (unsigned int i = 0; i < nfds; ++i)
     {
-      if (fds[i].fd >= 0)
+      if (fds[i].fd >= 0 && fds[i].revents != POLLNVAL)
 	{
 	  fhandler_socket *sock;
 
@@ -123,8 +134,8 @@ poll (struct pollfd *fds, nfds_t nfds, int timeout)
 	    ++ret;
 	}
     }
-
-  return ret;
+  /* Number of fds with event includes the invalid fds. */
+  return ret + invalid_fds;
 }
 
 extern "C" int