[glib] gpollableoutputstream: document side effects of WOULD_BLOCK on D/TLS

[Philip Withnall <pwithnall src gnome org>]

commit 1a991548988619350631713120a31c381fa8fa91
Author: Ignacio Casal Quinteiro <qignacio amazon com>
Date:   Wed Jan 24 11:31:52 2018 +0100

    gpollableoutputstream: document side effects of WOULD_BLOCK on D/TLS
    
    If the underlying transport is D/TLS the same data and data length
    is required to be sent on the next iteration when a WOULD_BLOCK
    happens. This is due to the fact that gnutls or openssl keep
    an internal state for the data.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=792862

 gio/gpollableoutputstream.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gio/gpollableoutputstream.c b/gio/gpollableoutputstream.c
index 9bd6b8c..40c649f 100644
--- a/gio/gpollableoutputstream.c
+++ b/gio/gpollableoutputstream.c
@@ -178,6 +178,9 @@ g_pollable_output_stream_default_write_nonblocking (GPollableOutputStream  *stre
  * may happen if you call this method after a source triggers due
  * to having been cancelled.
  *
+ * Also note that if %G_IO_ERROR_WOULD_BLOCK is returned some underlying
+ * transports like D/TLS require that you send the same @buffer and @count.
+ *
  * Virtual: write_nonblocking
  * Returns: the number of bytes written, or -1 on error (including
  *   %G_IO_ERROR_WOULD_BLOCK).