#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_TRUETYPE_TAGS_H
#include FT_INTERNAL_OBJECTS_H
#include FT_INTERNAL_STREAM_H
#include FT_SERVICE_SFNT_H
#include FT_SERVICE_TRUETYPE_GLYF_H

  static FT_Bool
  _tt_check_patents_in_range( FT_Stream  stream,
                              FT_ULong   size )
  {
    FT_Bool   result = 0;
    FT_Error  error;
    FT_Bytes  p, end;

    if ( FT_FRAME_ENTER(size) )
      return 0;

    p   = stream->cursor;
    end = p + size;

    while (p < end)
    {
      switch (p[0])
      {
      case 0x06:  /* SPvTL // */
      case 0x07:  /* SPvTL +  */
      case 0x08:  /* SFvTL // */
      case 0x09:  /* SFvTL +  */
      case 0x0A:  /* SPvFS */
      case 0x0B:  /* SFvFS */
        result = 1;
        goto Exit;

      case 0x40:
        if ( p+1 >= end )
          goto Exit;

        p += p[1] + 2;
        break;

      case 0x41:
        if ( p+1 >= end )
          goto Exit;

        p += p[1]*2 + 2;
        break;

      case 0x71:  /* DELTAP2 */
      case 0x72:  /* DELTAP3 */
      case 0x73:  /* DELTAC0 */
      case 0x74:  /* DELTAC1 */
      case 0x75:  /* DELTAC2 */
        result = 1;
        goto Exit;

      case 0xB0:
      case 0xB1:
      case 0xB2:
      case 0xB3:
      case 0xB4:
      case 0xB5:
      case 0xB6:
      case 0xB7:
        p += (p[0] - 0xB0) + 2;
        break;

      case 0xB8:
      case 0xB9:
      case 0xBA:
      case 0xBB:
      case 0xBC:
      case 0xBD:
      case 0xBE:
      case 0xBF:
        p += (p[0] - 0xB8) * 2 + 3;
        break;

      default:
        p += 1;
        break;
      }
    }

  Exit:
    FT_FRAME_EXIT();
    return result;
  }


  static FT_Bool
  _tt_check_patents_in_table( FT_Face   face,
                              FT_ULong  tag )
  {
    FT_Stream              stream = face->stream;
    FT_Error               error;
    FT_Service_SFNT_Table  service;
    FT_Bool                result = 0;

    FT_FACE_FIND_SERVICE( face, service, SFNT_TABLE );

    if (service)
    {
      FT_ULong  offset, size;

      error = service->table_info( face, tag, &offset, &size );
      if ( error                    ||
           FT_STREAM_SEEK( offset ) )
        goto Exit;

      result = _tt_check_patents_in_range( stream, size );
    }
  Exit:
    return result;
  }


  static FT_Bool
  _tt_face_check_patents( FT_Face  face )
  {
    FT_Stream  stream = face->stream;
    FT_UInt    gindex;
    FT_Error   error;
    FT_Bool    result;

    FT_Service_TTGlyf  service;

    result = _tt_check_patents_in_table( face, TTAG_fpgm );
    if (result)
      goto Exit;

    result = _tt_check_patents_in_table( face, TTAG_prep );
    if (result)
      goto Exit;

    FT_FACE_FIND_SERVICE( face, service, TT_GLYF );
    if (service == NULL)
      goto Exit;

    for (gindex = 0; gindex < (FT_UInt)face->num_glyphs; gindex++)
    {
      FT_ULong  offset, num_ins, size;
      FT_Int    num_contours;

      offset = service->get_location( face, gindex, &size );
      if (size == 0)
        continue;

      if ( FT_STREAM_SEEK(offset)      ||
           FT_READ_SHORT(num_contours) )
        continue;

      if (num_contours >= 0)  /* simple glyph */
      {
        if ( FT_STREAM_SKIP( 8 + num_contours*2 ) )
          continue;
      }
      else  /* compound glyph */
      {
        FT_Bool  has_instr = 0;

        if ( FT_STREAM_SKIP( 8 ) )
          continue;

        /* now read each component */
        for (;;)
        {
          FT_UInt  flags, toskip;

          if( FT_READ_USHORT(flags) )
            break;

          toskip = 2 + 1 + 1;

          if ((flags & (1 << 0)) != 0)  /* ARGS_ARE_WORDS */
            toskip += 2;

          if ((flags & (1 << 3)) != 0)  /* WE_HAVE_A_SCALE */
            toskip += 2;
          else if ((flags & (1 << 6)) != 0)  /* WE_HAVE_X_Y_SCALE */
            toskip += 4;
          else if ((flags & (1 << 7)) != 0)  /* WE_HAVE_A_2x2 */
            toskip += 8;

          if ((flags & (1 << 8)) != 0)  /* WE_HAVE_INSTRUCTIONS */
            has_instr = 1;

          if ( FT_STREAM_SKIP( toskip ) )
            goto NextGlyph;

          if ((flags & (1 << 5)) == 0)  /* MORE_COMPONENTS */
            break;
        }
        if (!has_instr)
          goto NextGlyph;
      }

      if ( FT_READ_USHORT(num_ins) )
        continue;

      result = _tt_check_patents_in_range( stream, num_ins );
      if (result)
        goto Exit;

    NextGlyph:
      ;
    }
  Exit:
    return result;
  }

  FT_EXPORT_DEF( FT_Bool )
  FT_Face_CheckTrueTypePatents( FT_Face   face )
  {
    FT_Bool  result = 0;

    if ( face && FT_IS_SFNT(face) )
    {
      result = _tt_face_check_patents( face );
    }
    return  result;
  }