[Geary] segfault when saving inline image from context menu

[Federico Bruni <fede inventati org>]

Hi folks

I'm using the latest master.
I can reproduce 100% of times a segfault when I right-click on an 
inline image and choose save as.
I've tested one message only so far.

This is the source message:

--Apple-Mail-EDB70D8C-44C0-42B3-9B1C-107DAD10615F
Content-Type: image/jpeg;
        name=image1.JPG;
        x-apple-part-url=B3DBC2FE-84E5-4976-BD5F-A7F6EF46610C
Content-Disposition: inline;
        filename=image1.JPG
Content-Transfer-Encoding: base64


And this is the backtrace:

(gdb) bt
#0  0x00000000004e08e1 in ___lambda37__g_simple_action_activate 
(param=<optimized out>, self=0xc83040) at 
/home/fede/src/geary/src/client/conversation-viewer/conversation-message.vala:323
#1  0x00000000004e08e1 in ___lambda37__g_simple_action_activate 
(_sender=<optimized out>, parameter=<optimized out>, self=0xc83040)
   at 
/home/fede/src/geary/src/client/conversation-viewer/conversation-message.vala:321
#2  0x00007ffff14e33e5 in g_closure_invoke () at 
/lib64/libgobject-2.0.so.0
#3  0x00007ffff14f5432 in signal_emit_unlocked_R () at 
/lib64/libgobject-2.0.so.0
#4  0x00007ffff14fe05f in g_signal_emit_valist () at 
/lib64/libgobject-2.0.so.0
#5  0x00007ffff14fe43f in g_signal_emit () at /lib64/libgobject-2.0.so.0
#6  0x00007ffff17da425 in g_simple_action_activate () at 
/lib64/libgio-2.0.so.0
#7  0x00007ffff2f1f54e in gtk_action_muxer_activate_action () at 
/lib64/libgtk-3.so.0
#8  0x00007ffff2f1f584 in gtk_action_muxer_activate_action () at 
/lib64/libgtk-3.so.0
#9  0x00007ffff306e356 in gtk_menu_tracker_item_activated () at 
/lib64/libgtk-3.so.0
#10 0x00007ffff14e33e5 in g_closure_invoke () at 
/lib64/libgobject-2.0.so.0
#11 0x00007ffff14f5432 in signal_emit_unlocked_R () at 
/lib64/libgobject-2.0.so.0
#12 0x00007ffff14fe05f in g_signal_emit_valist () at 
/lib64/libgobject-2.0.so.0
#13 0x00007ffff14fe43f in g_signal_emit () at /lib64/libgobject-2.0.so.0
#14 0x00007ffff3193dee in gtk_widget_activate () at /lib64/libgtk-3.so.0
#15 0x00007ffff306afb6 in gtk_menu_shell_activate_item () at 
/lib64/libgtk-3.so.0
#16 0x00007ffff306b2eb in gtk_menu_shell_button_release () at 
/lib64/libgtk-3.so.0
#17 0x00007ffff304f5e1 in _gtk_marshal_BOOLEAN__BOXEDv () at 
/lib64/libgtk-3.so.0
#18 0x00007ffff14e3614 in _g_closure_invoke_va () at 
/lib64/libgobject-2.0.so.0
#19 0x00007ffff14fd8b3 in g_signal_emit_valist () at 
/lib64/libgobject-2.0.so.0
#20 0x00007ffff14fe43f in g_signal_emit () at /lib64/libgobject-2.0.so.0
#21 0x00007ffff31919fc in gtk_widget_event_internal () at 
/lib64/libgtk-3.so.0
#22 0x00007ffff304c75e in propagate_event () at /lib64/libgtk-3.so.0
#23 0x00007ffff304e692 in gtk_main_do_event () at /lib64/libgtk-3.so.0
#24 0x00007ffff2b890c5 in _gdk_event_emit () at /lib64/libgdk-3.so.0
#25 0x00007ffff2bb60b2 in gdk_event_source_dispatch () at 
/lib64/libgdk-3.so.0
#26 0x00007ffff04b36ba in g_main_context_dispatch () at 
/lib64/libglib-2.0.so.0
#27 0x00007ffff04b3a70 in g_main_context_iterate.isra () at 
/lib64/libglib-2.0.so.0
#28 0x00007ffff04b3b1c in g_main_context_iteration () at 
/lib64/libglib-2.0.so.0
#29 0x00007ffff17d248d in g_application_run () at /lib64/libgio-2.0.so.0
#30 0x00000000004879ef in _vala_main (args=0x7fffffffde98, 
args_length1=1) at 
/home/fede/src/geary/src/client/application/main.vala:25
#31 0x00007ffff00c8731 in __libc_start_main () at /lib64/libc.so.6
#32 0x000000000046a6d9 in _start ()