kc3-lang/harfbuzz/src/hb-ot-color-colr-table.hh

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• Hash : 10642b3f
  Author :
  Date : 2018-09-15T19:43:33
  

  Disallow null-enabled offsets to unsized structures...
  
  ...like UnsizedArrayOf<>.
  
  This fixes a class of crasher bugs, mostly with color and AAT tables.  We
  cannot use nullable offsets to varsized data that does not declare min_size,
  because it's nost safe to use our fixed-size null pool for types that have
  their size external.  So, use non_null'able offsets for these.
  
  A further enhancement would be to make use of min_size in Null<> itself.
  Will try that after.
  

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• src/hb-ot-color-colr-table.hh

• /*
   * Copyright © 2018  Ebrahim Byagowi
   *
   *  This is part of HarfBuzz, a text shaping library.
   *
   * Permission is hereby granted, without written agreement and without
   * license or royalty fees, to use, copy, modify, and distribute this
   * software and its documentation for any purpose, provided that the
   * above copyright notice and the following two paragraphs appear in
   * all copies of this software.
   *
   * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
   * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
   * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
   * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
   * DAMAGE.
   *
   * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
   * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
   * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
   * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
   * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
   */
  
  #ifndef HB_OT_COLOR_COLR_TABLE_HH
  #define HB_OT_COLOR_COLR_TABLE_HH
  
  #include "hb-open-type.hh"
  
  /*
   * COLR -- Color
   * https://docs.microsoft.com/en-us/typography/opentype/spec/colr
   */
  #define HB_OT_TAG_COLR HB_TAG('C','O','L','R')
  
  
  namespace OT {
  
  
  struct LayerRecord
  {
    friend struct COLR;
  
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (c->check_struct (this));
    }
  
    protected:
    GlyphID	glyphid;	/* Glyph ID of layer glyph */
    HBUINT16	colorIdx;	/* Index value to use with a selected color palette */
    public:
    DEFINE_SIZE_STATIC (4);
  };
  
  struct BaseGlyphRecord
  {
    friend struct COLR;
  
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (likely (c->check_struct (this)));
    }
  
    inline int cmp (hb_codepoint_t g) const {
      return g < glyphid ? -1 : g > glyphid ? 1 : 0;
    }
  
    protected:
    GlyphID	glyphid;	/* Glyph ID of reference glyph */
    HBUINT16	firstLayerIdx;	/* Index to the layer record */
    HBUINT16	numLayers;	/* Number of color layers associated with this glyph */
    public:
    DEFINE_SIZE_STATIC (6);
  };
  
  static int compare_bgr (const void *pa, const void *pb)
  {
    const hb_codepoint_t *a = (const hb_codepoint_t *) pa;
    const BaseGlyphRecord *b = (const BaseGlyphRecord *) pb;
    return b->cmp (*a);
  }
  
  struct COLR
  {
    static const hb_tag_t tableTag = HB_OT_TAG_COLR;
  
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (likely (c->check_struct (this) &&
  			  (this+baseGlyphsZ).sanitize (c, numBaseGlyphs) &&
  			  (this+layersZ).sanitize (c, numLayers)));
    }
  
    inline bool get_base_glyph_record (hb_codepoint_t glyph_id,
  				     unsigned int *first_layer /* OUT */,
  				     unsigned int *num_layers /* OUT */) const
    {
      const BaseGlyphRecord* record;
      record = (BaseGlyphRecord *) bsearch (&glyph_id, &(this+baseGlyphsZ), numBaseGlyphs,
  					  sizeof (BaseGlyphRecord), compare_bgr);
      if (unlikely (!record))
        return false;
  
      *first_layer = record->firstLayerIdx;
      *num_layers = record->numLayers;
      return true;
    }
  
    inline bool get_layer_record (unsigned int record,
  				hb_codepoint_t *glyph_id /* OUT */,
  				unsigned int *palette_index /* OUT */) const
    {
      if (unlikely (record >= numLayers))
      {
        *glyph_id = 0;
        *palette_index = 0xFFFF;
        return false;
      }
      const LayerRecord &layer = (this+layersZ)[record];
      *glyph_id = layer.glyphid;
      *palette_index = layer.colorIdx;
      return true;
    }
  
    protected:
    HBUINT16	version;	/* Table version number */
    HBUINT16	numBaseGlyphs;	/* Number of Base Glyph Records */
    LOffsetTo<UnsizedArrayOf<BaseGlyphRecord>, false>
  		baseGlyphsZ;	/* Offset to Base Glyph records. */
    LOffsetTo<UnsizedArrayOf<LayerRecord>, false>
  		layersZ;	/* Offset to Layer Records */
    HBUINT16	numLayers;	/* Number of Layer Records */
    public:
    DEFINE_SIZE_STATIC (14);
  };
  
  } /* namespace OT */
  
  
  #endif /* HB_OT_COLOR_COLR_TABLE_HH */
  

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