[Bug 82373] Re: segfault in gnome-keyboard-properties

[hggdh]

OK, I accept it. The only issue I have is that I have never programmed
under GTK, so I am not willing to write a patch on this.

Nevertheless, I can -- and did -- debug the application, and this is
what I see:

hggdh at xango:/usr/src/src/gnome-control-center/control-center-2.17.90/capplets/keyboard$ gdb /usr/src/src/gnome-control-center/control-center-2.17.90/capplets/keyboard/.libs/lt-gnome-keyboard-properties
GNU gdb 6.6-debian
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This GDB was configured as "x86_64-linux-gnu"...
Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) run
Starting program: /usr/src/src/gnome-control-center/control-center-2.17.90/capplets/keyboard/.libs/lt-gnome-keyboard-properties 
[Thread debugging using libthread_db enabled]
[New Thread 47079464161120 (LWP 29427)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 47079464161120 (LWP 29427)]
def_group_in_gconf_changed (client=<value optimized out>, cnxn_id=<value optimized out>, entry=<value optimized out>, dialog=0x629100) at gnome-keyboard-properties-xkblt.c:128
128             if (value->type == GCONF_VALUE_INT) {
(gdb) backtrace
#0  def_group_in_gconf_changed (client=<value optimized out>, cnxn_id=<value optimized out>, entry=<value optimized out>, dialog=0x629100)
    at gnome-keyboard-properties-xkblt.c:128
#1  0x000000000040a60f in xkb_layouts_fill_selected_tree (dialog=0x629100) at gnome-keyboard-properties-xkblt.c:417
#2  0x0000000000408b2d in setup_xkb_tabs (dialog=0x629100, changeset=0x0) at gnome-keyboard-properties-xkb.c:179
#3  0x00000000004084a7 in main (argc=<value optimized out>, argv=<value optimized out>) at gnome-keyboard-properties.c:172
(gdb) list
123                                 guint cnxn_id,
124                                 GConfEntry * entry, GladeXML * dialog)
125     {
126             GConfValue *value = gconf_entry_get_value (entry);
127
128             if (value->type == GCONF_VALUE_INT) {
129                     GtkWidget *tree_view = WID ("xkb_layouts_selected");
130                     GtkTreeModel *model =
131                         GTK_TREE_MODEL (gtk_tree_view_get_model
132                                         (GTK_TREE_VIEW (tree_view)));
(gdb) backtrace
#0  def_group_in_gconf_changed (client=<value optimized out>, cnxn_id=<value optimized out>, entry=<value optimized out>, dialog=0x629100)
    at gnome-keyboard-properties-xkblt.c:128
#1  0x000000000040a60f in xkb_layouts_fill_selected_tree (dialog=0x629100) at gnome-keyboard-properties-xkblt.c:417
#2  0x0000000000408b2d in setup_xkb_tabs (dialog=0x629100, changeset=0x0) at gnome-keyboard-properties-xkb.c:179
#3  0x00000000004084a7 in main (argc=<value optimized out>, argv=<value optimized out>) at gnome-keyboard-properties.c:172
(gdb) list 123
118             gtk_tree_path_free (chpath);
119     }
120
121     static void
122     def_group_in_gconf_changed (GConfClient * client,
123                                 guint cnxn_id,
124                                 GConfEntry * entry, GladeXML * dialog)
125     {
126             GConfValue *value = gconf_entry_get_value (entry);
127
(gdb) list
128             if (value->type == GCONF_VALUE_INT) {
129                     GtkWidget *tree_view = WID ("xkb_layouts_selected");
130                     GtkTreeModel *model =
131                         GTK_TREE_MODEL (gtk_tree_view_get_model
132                                         (GTK_TREE_VIEW (tree_view)));
133                     GtkTreeIter iter;
134                     int counter = 0;
135                     default_group = gconf_value_get_int (value);
136                     if (gtk_tree_model_get_iter_first (model, &iter)) {
137                             do {
(gdb) break 123
Breakpoint 1 at 0x409b00: file gnome-keyboard-properties-xkblt.c, line 123.
(gdb) run
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /usr/src/src/gnome-control-center/control-center-2.17.90/capplets/keyboard/.libs/lt-gnome-keyboard-properties 
[Thread debugging using libthread_db enabled]
[New Thread 47910289698656 (LWP 29596)]
[Switching to Thread 47910289698656 (LWP 29596)]

Breakpoint 1, def_group_in_gconf_changed (client=0x64c0c0, cnxn_id=4294967295, entry=0x8c12e0, dialog=0x629100) at gnome-keyboard-properties-xkblt.c:125
125     {
(gdb) next
126             GConfValue *value = gconf_entry_get_value (entry);
(gdb) next
128             if (value->type == GCONF_VALUE_INT) {
(gdb) next

Program received signal SIGSEGV, Segmentation fault.
def_group_in_gconf_changed (client=<value optimized out>, cnxn_id=<value optimized out>, entry=<value optimized out>, dialog=0x629100) at gnome-keyboard-properties-xkblt.c:128
128             if (value->type == GCONF_VALUE_INT) {
(gdb) inspect value
$1 = (GConfValue *) 0x0
(gdb) 
hggdh at xango:/usr/src/src/gnome-control-center/control-center-2.17.90/capplets/keyboard$ 

So, we segfaulted while testing 'value->type', and it makes sense, since
'value' is NULL.

Looking down on the code, the call to 'def_group_in_gconf_changed' is
being make in 'xkb_layouts_fill_selected_tree()'. There we see this:

        gce = gconf_client_get_entry (xkb_gconf_client,
                                      GKBD_DESKTOP_CONFIG_KEY_DEFAULT_GROUP,
                                      NULL, TRUE, &err);
        if (err == NULL) {
                def_group_in_gconf_changed (xkb_gconf_client, -1, gce,
                                            dialog);


and gce is the 'value' being passed above, and 'err' *is* NULL.

Now it is out of my depth.

-- 
segfault in gnome-keyboard-properties
https://launchpad.net/bugs/82373