Failure to create a GdkPixbufLoader for a specific MIME type doesn't
necessarily indicate an error. It is possible that the fallback code
would still be able to parse the image data. For example, Canon CR2 RAW
files have the MIME type image/x-canon-cr2. While we don't have a
loader for that specific MIME type, the TIFF loader can still parse the
data.

In case the fallback code failed to parse the image data, we get a
WARNING anyway:
  MateDesktop-WARNING **: Error creating thumbnail for ...

Having a log message to indicate that we are using the fallback code is
useful for debugging, but there is no need for the WARNING. It can be
extra noise and needlessly interferes with things like
G_DEBUG=fatal-warnings.

https://bugzilla.gnome.org/show_bug.cgi?id=762504

origin commit:
https://gitlab.gnome.org/GNOME/gnome-desktop/commit/7507254

We are seeing crashes in Fedora that point at the settings signal
handlers getting run after the thumbnail factory is finalized.
Explicitly disconnecting the handlers in finalize is the right
thing to do, anyway.

While we are at it, replace some of the cleanup code in finalize
with g_clear_pointer and g_clear_object, as suggested by Colin.

https://bugzilla.gnome.org/show_bug.cgi?id=761049
origin commit:
https://gitlab.gnome.org/GNOME/gnome-desktop/commit/f32c389

If a failed thumbnail is created because the pixbuf fail to save
(for instance if user is over quota) we should still try to rename
the temporary file that might have been created.
If not, the thumbnail will not be marked as failed, and thumbnailing
will be reattempted.

https://bugzilla.gnome.org/show_bug.cgi?id=728775

origin commit:
https://gitlab.gnome.org/GNOME/gnome-desktop/commit/54f68ab

"time_t" may not equal with "long", especiall 32-bit
platforms  resolved "Year 2038 problem".
There are no standard way to convert time_t from/to
string, but GLib2 using gint64 type as a time internally,
so it is reasonable to use gint64 for such purpose.

Fixes Clang static analyzer warning:

mate-thumbnail-pixbuf-utils.c:160:17: warning: Division by zero
                                *dest++ = r / n_pixels;
                                          ~~^~~~~~~~~~

Fixes Clang static analyzer warning:

mate-bg.c:2764:2: warning: Potential leak of memory pointed to by 'size'
        g_queue_push_tail (parser->stack, g_strdup (name));
        ^~~~~~~~~~~~~~~~~

Fixes Clang static analyzer warnings:

mate-rr-config.c:549:3: warning: Call to function 'strcpy' is insecure as it does not provide bounding of the memory buffer. Replace unbounded copy functions with analogous functions that support length arguments such as 'strlcpy'. CWE-119
                strcpy (output->priv->vendor, "???");
                ^~~~~~

mate-desktop-item.c:2118:2: warning: Call to function 'strcpy' is insecure as it does not provide bounding of the memory buffer. Replace unbounded copy functions with analogous functions that support length arguments such as 'strlcpy'. CWE-119
        strcpy (the_exec, exec);
        ^~~~~~

Fixes Clang static analyzer warning:

test-ditem.c:94:2: warning: Call to function 'strcat' is insecure as it does not provide bounding of the memory buffer. Replace unbounded copy functions with analogous functions that support length arguments such as 'strlcat'. CWE-119
        strcat (path, "/foo.desktop");
        ^~~~~~