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Work around Xlib 64-bit "specialness"

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When putting 32-bit properties into longs on 64-bit architectures,
XGetWindowProperty assumes the values are supposed to be signed, and
so it sign-extends values greater than 0x7fffffff. So if they *aren't*
supposed to be signed, we need to chop off the high bits ourselves.

(Most CARDINAL-valued properties only end up using small values
anyway, so it doesn't matter, but _NET_WM_WINDOW_OPACITY uses the full
range, and so was previously failing on 64-bit machines.)

https://bugzilla.gnome.org/show_bug.cgi?id=605678
This commit is contained in:
Dan Winship 2010-01-21 10:10:44 -05:00
parent 8d5ba7a6d7
commit 576417648a
1 changed files with 14 additions and 0 deletions
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14
src/core/xprops.c
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@ -264,6 +264,16 @@ cardinal_list_from_results (GetPropertyResults *results,
*n_cardinals_p = results->n_items; *n_cardinals_p = results->n_items;
results->prop = NULL; results->prop = NULL;
#if GLIB_SIZEOF_LONG == 8
/* Xlib sign-extends format=32 items, but we want them unsigned */
{
int i;
for (i = 0; i < *n_cardinals_p; i++)
(*cardinals_p)[i] = (*cardinals_p)[i] & 0xffffffff;
}
#endif
return TRUE; return TRUE;
} }
@ -608,6 +618,10 @@ cardinal_with_atom_type_from_results (GetPropertyResults *results,
return FALSE; return FALSE;
*cardinal_p = *(gulong*) results->prop; *cardinal_p = *(gulong*) results->prop;
#if GLIB_SIZEOF_LONG == 8
/* Xlib sign-extends format=32 items, but we want them unsigned */
*cardinal_p &= 0xffffffff;
#endif
XFree (results->prop); XFree (results->prop);
results->prop = NULL; results->prop = NULL;