src/stylesheet.h: set uses_revert flag for shorthand properties

Take for example the list-style and list-style-type properties; the
former is a shorthand property that subsumes the latter. When the
list-style-type property is parsed, the "flags" variable has its
FLAG_REVERT bit set, and we call,

  css__stylesheet_style_appendOPV(result,
                                  CSS_PROP_LIST_STYLE_TYPE,
				  flags,
				  value);

which then sets the "uses_revert" bit on the stylesheet:

  if ((flags & (0x7 << 1)) == FLAG_REVERT) {
    style->sheet->uses_revert = true;
  }

In contrast, when list-style is parsed and a flag is found, we run

  error = css_stylesheet_style_flag_value(result,
                                          flag_value,
                                          CSS_PROP_LIST_STYLE_TYPE);

which immediately delegates to css__stylesheet_style_append() and
buildOPV() without checking if "uses_revert" needs to be set. This can
lead to segfault when we try to revert to a state that we have not
saved (Mantis bug 2854).

Adding a FLAG_REVERT check to css_stylesheet_style_flag_value() fixes
the issue for the shorthand properties listed in docs/Bytecode, most
(but not all) of which experienced the crash.

Closes: https://bugs.netsurf-browser.org/mantis/view.php?id=2854

0 files changed, 0 insertions, 0 deletions