[glib/glib-2-30] GDataInputStream: don't segfault on async line reads

[Matthias Clasen <matthiasc src gnome org>]

commit 14ddbfc62ad793b010e33648d840924d590add87
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Mon Feb 13 16:41:20 2012 +0100

    GDataInputStream: don't segfault on async line reads
    
    If an async line read fails, it returns NULL. In that case, we
    must return NULL before validating the line, or we segfault.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=658484

 gio/gdatainputstream.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gio/gdatainputstream.c b/gio/gdatainputstream.c
index d5dd2fd..ea26aeb 100644
--- a/gio/gdatainputstream.c
+++ b/gio/gdatainputstream.c
@@ -1284,6 +1284,9 @@ g_data_input_stream_read_line_finish_utf8 (GDataInputStream  *stream,
   gchar *res;
 
   res = g_data_input_stream_read_line_finish (stream, result, length, error);
+  if (!res)
+    return NULL;
+
   if (!g_utf8_validate (res, -1, NULL))
     {
       g_set_error_literal (error, G_CONVERT_ERROR,