otvgsub.c

winNT技术操作系统,国外开放的原代码和LIUX一样

/***************************************************************************/
/*                                                                         */
/*  otvgsub.c                                                              */
/*                                                                         */
/*    OpenType GSUB table validation (body).                               */
/*                                                                         */
/*  Copyright 2004, 2005 by                                                */
/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
/*                                                                         */
/*  This file is part of the FreeType project, and may only be used,       */
/*  modified, and distributed under the terms of the FreeType project      */
/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
/*  this file you indicate that you have read the license and              */
/*  understand and accept it fully.                                        */
/*                                                                         */
/***************************************************************************/


#include "otvalid.h"
#include "otvcommn.h"


  /*************************************************************************/
  /*                                                                       */
  /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
  /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
  /* messages during execution.                                            */
  /*                                                                       */
#undef  FT_COMPONENT
#define FT_COMPONENT  trace_otvgsub


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                  GSUB LOOKUP TYPE 1                           *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  /* uses valid->glyph_count */

  static void
  otv_SingleSubst_validate( FT_Bytes       table,
                            OTV_Validator  valid )
  {
    FT_Bytes  p = table;
    FT_UInt   SubstFormat;


    OTV_NAME_ENTER( "SingleSubst" );

    OTV_LIMIT_CHECK( 2 );
    SubstFormat = FT_NEXT_USHORT( p );

    OTV_TRACE(( " (format %d)\n", SubstFormat ));

    switch ( SubstFormat )
    {
    case 1:     /* SingleSubstFormat1 */
      {
        FT_Bytes  Coverage;
        FT_Int    DeltaGlyphID;
        FT_Long   idx;


        OTV_LIMIT_CHECK( 4 );
        Coverage     = table + FT_NEXT_USHORT( p );
        DeltaGlyphID = FT_NEXT_SHORT( p );

        otv_Coverage_validate( Coverage, valid );

        idx = otv_Coverage_get_first( Coverage ) + DeltaGlyphID;
        if ( idx < 0 )
          FT_INVALID_DATA;

        idx = otv_Coverage_get_last( Coverage ) + DeltaGlyphID;
        if ( (FT_UInt)idx >= valid->glyph_count )
          FT_INVALID_DATA;
      }
      break;

    case 2:     /* SingleSubstFormat2 */
      {
        FT_UInt  Coverage, GlyphCount;


        OTV_LIMIT_CHECK( 4 );
        Coverage   = FT_NEXT_USHORT( p );
        GlyphCount = FT_NEXT_USHORT( p );

        OTV_TRACE(( " (GlyphCount = %d)\n", GlyphCount ));

        otv_Coverage_validate( table + Coverage, valid );

        OTV_LIMIT_CHECK( GlyphCount * 2 );

        /* Substitute */
        for ( ; GlyphCount > 0; GlyphCount-- )
          if ( FT_NEXT_USHORT( p ) >= valid->glyph_count )
            FT_INVALID_DATA;
      }
      break;

    default:
      FT_INVALID_DATA;
    }

    OTV_EXIT;
  }


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                  GSUB LOOKUP TYPE 2                           *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  /* sets valid->extra1 (glyph count) */

  static void
  otv_MultipleSubst_validate( FT_Bytes       table,
                              OTV_Validator  valid )
  {
    FT_Bytes  p = table;
    FT_UInt   SubstFormat;


    OTV_NAME_ENTER( "MultipleSubst" );

    OTV_LIMIT_CHECK( 2 );
    SubstFormat = FT_NEXT_USHORT( p );

    OTV_TRACE(( " (format %d)\n", SubstFormat ));

    switch ( SubstFormat )
    {
    case 1:
      valid->extra1 = valid->glyph_count;
      OTV_NEST2( MultipleSubstFormat1, Sequence );
      OTV_RUN( table, valid );
      break;

    default:
      FT_INVALID_DATA;
    }

    OTV_EXIT;
  }


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                    GSUB LOOKUP TYPE 3                         *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  /* sets valid->extra1 (glyph count) */

  static void
  otv_AlternateSubst_validate( FT_Bytes       table,
                               OTV_Validator  valid )
  {
    FT_Bytes  p = table;
    FT_UInt   SubstFormat;


    OTV_NAME_ENTER( "AlternateSubst" );

    OTV_LIMIT_CHECK( 2 );
    SubstFormat = FT_NEXT_USHORT( p );

    OTV_TRACE(( " (format %d)\n", SubstFormat ));

    switch ( SubstFormat )
    {
    case 1:
      valid->extra1 = valid->glyph_count;
      OTV_NEST2( AlternateSubstFormat1, AlternateSet );
      OTV_RUN( table, valid );
      break;

    default:
      FT_INVALID_DATA;
    }

    OTV_EXIT;
  }


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                    GSUB LOOKUP TYPE 4                         *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

#define LigatureFunc  otv_Ligature_validate

  /* uses valid->glyph_count */

  static void
  otv_Ligature_validate( FT_Bytes       table,
                         OTV_Validator  valid )
  {
    FT_Bytes  p = table;
    FT_UInt   LigatureGlyph, CompCount;


    OTV_ENTER;

    OTV_LIMIT_CHECK( 4 );
    LigatureGlyph = FT_NEXT_USHORT( p );
    if ( LigatureGlyph >= valid->glyph_count )
      FT_INVALID_DATA;

    CompCount = FT_NEXT_USHORT( p );

    OTV_TRACE(( " (CompCount = %d)\n", CompCount ));

    if ( CompCount == 0 )
      FT_INVALID_DATA;

    CompCount--;

    OTV_LIMIT_CHECK( CompCount * 2 );     /* Component */

    /* no need to check the Component glyph indices */

    OTV_EXIT;
  }


  static void
  otv_LigatureSubst_validate( FT_Bytes       table,
                              OTV_Validator  valid )
  {
    FT_Bytes  p = table;
    FT_UInt   SubstFormat;


    OTV_NAME_ENTER( "LigatureSubst" );

    OTV_LIMIT_CHECK( 2 );
    SubstFormat = FT_NEXT_USHORT( p );

    OTV_TRACE(( " (format %d)\n", SubstFormat ));

    switch ( SubstFormat )
    {
    case 1:
      OTV_NEST3( LigatureSubstFormat1, LigatureSet, Ligature );
      OTV_RUN( table, valid );
      break;

    default:
      FT_INVALID_DATA;
    }

    OTV_EXIT;
  }


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                  GSUB LOOKUP TYPE 5                           *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  /* sets valid->extra1 (lookup count) */

  static void
  otv_ContextSubst_validate( FT_Bytes       table,
                             OTV_Validator  valid )
  {
    FT_Bytes  p = table;
    FT_UInt   SubstFormat;


    OTV_NAME_ENTER( "ContextSubst" );

    OTV_LIMIT_CHECK( 2 );
    SubstFormat = FT_NEXT_USHORT( p );

    OTV_TRACE(( " (format %d)\n", SubstFormat ));