On Jun 8, 2013, at 2:27 PM, Johan Dahlin <jo...@gnome.org> wrote: > If you run your program under valgrind, will it report any relevant errors? > > Remember to use the python supressions file, or you'll get a lot of > false positives.
I'm on OSX 10.8, which isn't well supported by Valgrind. It does have a pretty good built-in memory analyzer, and I find from that that the address causing the error (0x07a7b830 with malloc debugging turned on) is in a single 1K allocation block: MALLOC_TINY 07a00000-07b00000 [ 1024K 1024K 1024K] rw-/rwx SM=COW DefaultMallocZone_0x1bf000 It hasn't been scribbled: (gdb) x /32xw 0x07a7b800 0x7a7b800: 0x02989970 0x02f0ea20 0x00000000 0xaaaaaaaa 0x7a7b810: 0xa7b810b8 0xb2a6e907 0xaaaafaf4 0x030fd2fc 0x7a7b820: 0x02956a20 0x030fd2f0 0x07a7b810 0xaaaaaaaa 0x7a7b830: 0xa7b830b8 0xb286e907 0xaaaafaf4 0x00a6c26c 0x7a7b840: 0x02956a20 0x00a6c260 0x07a7b830 0xaaaaaaaa 0x7a7b850: 0x00000002 0x00000000 0x00000037 0x07a7b610 0x7a7b860: 0x002b7320 0x00000088 0x00000005 0x00000000 0x7a7b870: 0x00000000 0x02f8dd40 0x00000000 0x07a7b610 Looking a bit deeper into the assignment of the callback, though, it appears to me that the offset for the callback is a bit large: (gdb) up #1 0x02f0a02e in g_type_class_meta_marshal (closure=0x7a79d70, return_value=0x0, n_param_values=3, param_values=0xbfff8660, invocation_hint=0xbfff85e0, marshal_data=0x5c) at gclosure.c:970 970 closure->marshal (closure, (gdb) list 965 guint offset = GPOINTER_TO_UINT (marshal_data); 966 967 class = G_TYPE_INSTANCE_GET_CLASS (g_value_peek_pointer (param_values + 0), itype, GTypeClass); 968 callback = G_STRUCT_MEMBER (gpointer, class, offset); 969 if (callback) 970 closure->marshal (closure, 971 return_value, 972 n_param_values, param_values, 973 invocation_hint, 974 callback); I suspect that for some reason the marshal_data value (0x5c) is wrong; it would have been set in a call to g_signal_type_cclosure_new(), but I don't know how to find the right instance of that to probe the actual class struct and see what the offset really should be or if it's a pointer that's getting overwritten. Regards, John Ralls
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