Merge lp:~mterry/lightdm/write-crash into lp:lightdm

[Michael Terry]

This crash was triggered by a false-negative when writing the xauthority. The error code path was run with a NULL error.

I believe I have found it, though I did not actually reproduce the crash. But code analysis led me to this.

g_output_stream_write returns -1 on error. A zero return isn't an error (though it will only be returned if the count argument is zero).

I suspect that for the user that hit this crash, some empty string was trying to be written.

[Robert Ancell (robert-ancell)]

Nice catch. Feel free to merge these changes directly in the future.

=== modified file 'src/xauthority.c'
--- src/xauthority.c	2011-07-25 11:40:18 +0000
+++ src/xauthority.c	2011-08-18 16:31:24 +0000
@@ -206,13 +206,13 @@
 
     data[0] = value >> 8;
     data[1] = value & 0xFF;
-    return g_output_stream_write (stream, data, 2, NULL, error);
+    return g_output_stream_write (stream, data, 2, NULL, error) >= 0;
 }
 
 static gboolean
 write_data (GOutputStream *stream, const guint8 *data, gsize data_length, GError **error)
 {
-    return g_output_stream_write (stream, data, data_length, NULL, error);
+    return g_output_stream_write (stream, data, data_length, NULL, error) >= 0;
 }
 
 static gboolean