[pango/harfbuzz-ng] [GSUB] Fix context_length handling in Ligature too

[Behdad Esfahbod <behdad src gnome org>]

commit 6cc2d15e154deb656967e5bdff1e3bbe9130f368
Author: Behdad Esfahbod <behdad behdad org>
Date:   Mon May 18 04:21:53 2009 -0400

    [GSUB] Fix context_length handling in Ligature too
---
 pango/opentype/hb-ot-layout-gsub-private.h     |    9 ++++-----
 pango/opentype/hb-ot-layout-gsubgpos-private.h |    5 +++--
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/pango/opentype/hb-ot-layout-gsub-private.h b/pango/opentype/hb-ot-layout-gsub-private.h
index a65a351..9f0b0d8 100644
--- a/pango/opentype/hb-ot-layout-gsub-private.h
+++ b/pango/opentype/hb-ot-layout-gsub-private.h
@@ -318,14 +318,13 @@ struct Ligature {
 
     unsigned int i, j;
     unsigned int count = component.len;
-
-    if (HB_UNLIKELY (buffer->in_pos + count > buffer->in_length ||
-		     context_length < count))
-      return false; /* Not enough glyphs in input or context */
+    unsigned int end = MIN (buffer->in_length, buffer->in_pos + context_length);
+    if (HB_UNLIKELY (buffer->in_pos + count > end))
+      return false;
 
     for (i = 1, j = buffer->in_pos + 1; i < count; i++, j++) {
       while (!_hb_ot_layout_check_glyph_property (layout, IN_ITEM (j), lookup_flag, &property)) {
-	if (HB_UNLIKELY (j + count - i == buffer->in_length))
+	if (HB_UNLIKELY (j + count - i == end))
 	  return false;
 	j++;
       }
diff --git a/pango/opentype/hb-ot-layout-gsubgpos-private.h b/pango/opentype/hb-ot-layout-gsubgpos-private.h
index f5b900f..f9a1f6b 100644
--- a/pango/opentype/hb-ot-layout-gsubgpos-private.h
+++ b/pango/opentype/hb-ot-layout-gsubgpos-private.h
@@ -221,7 +221,7 @@ static inline bool context_lookup (LOOKUP_ARGS_DEF,
 {
   /* First guess */
   if (HB_UNLIKELY (buffer->in_pos + inputCount > buffer->in_length ||
-		   context_length < inputCount))
+		   inputCount > context_length))
     return false;
 
   return match_input (LOOKUP_ARGS,
@@ -435,7 +435,8 @@ static inline bool chain_context_lookup (LOOKUP_ARGS_DEF,
 {
   /* First guess */
   if (HB_UNLIKELY (buffer->out_pos < backtrackCount ||
-		   buffer->in_pos + inputCount + lookaheadCount > buffer->in_length))
+		   buffer->in_pos + inputCount + lookaheadCount > buffer->in_length ||
+		   inputCount + lookaheadCount > context_length))
     return false;
 
   unsigned int offset;