[uniscribe] Fix buffer allocation
Email from Jonathan Kew:
My cygwin build kept aborting on certain test words when run with the
uniscribe backend. Turned out this was caused by a bug in the allocation
of scratch buffers in hb-uniscribe.cc.
Commit 2a17f9568d9724e045d2c1d660e007f3acd747d9 introduced a new line
ALLOCATE_ARRAY (SCRIPT_VISATTR, vis_attr, glyphs_size);
but it failed to account for this in the computation of glyphs_size
(the number of glyphs for which scratch buffer space is available),
with the result that the vis_clusters array ends up overrunning the
end of the scratch buffer and clobbering the beginning of the buffer's
info[].
AFAICS, the vis_attr array is not actually used, so the simple fix is
to remove the line that allocates it. (If/when we -do- need to use
vis_attr for something, we'll need to add another term to the earlier
calculation of glyphs_size.)
With this patch, the uniscribe backend runs reliably again.
JK
diff --git a/src/hb-uniscribe.cc b/src/hb-uniscribe.cc
index 2582ac6..4d27b9b 100644
--- a/src/hb-uniscribe.cc
+++ b/src/hb-uniscribe.cc
@@ -501,7 +501,6 @@
ALLOCATE_ARRAY (WORD, glyphs, glyphs_size);
ALLOCATE_ARRAY (SCRIPT_GLYPHPROP, glyph_props, glyphs_size);
- ALLOCATE_ARRAY (SCRIPT_VISATTR, vis_attr, glyphs_size);
ALLOCATE_ARRAY (int, advances, glyphs_size);
ALLOCATE_ARRAY (GOFFSET, offsets, glyphs_size);
ALLOCATE_ARRAY (uint32_t, vis_clusters, glyphs_size);
