Re: Crash with --enable-checking and some glyphs

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> But what about the font?  We don't use the above for it->descent, at
> least not directly.  So where in the code did it->descent get
> negative?

(gdb) p font->descent
$14 = 2
(gdb) print boff
$15 = 3

I think it has to be from here:

      if (it->char_to_display != '\n' && it->char_to_display != '\t')
        {
          it->nglyphs = 1;

          if (it->override_ascent >= 0)
            {
              it->ascent = it->override_ascent;
              it->descent = it->override_descent;
              boff = it->override_boff;
            }
          else
            {
              it->ascent = FONT_BASE (font) + boff;
              it->descent = FONT_DESCENT (font) - boff;
            }

And boff is 3 because of:

      boff = font->baseline_offset;
      if (font->vertical_centering)
        boff = VCENTER_BASELINE_OFFSET (font, it->f) - boff;

(gdb) print font->vertical_centering 
$17 = true


And we don't apply these sanity checks in this case:

                      /* These limitations are enforced by an
                         assertion near the end of this function.  */
                      if (it->ascent < 0)
                        it->ascent = 0;
                      if (it->descent < 0)
                        it->descent = 0;


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