misc/libfreetype/src/otvalid/otvgpos.c
changeset 5172 88f2e05288ba
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/misc/libfreetype/src/otvalid/otvgpos.c	Mon Apr 25 01:46:54 2011 +0200
@@ -0,0 +1,1017 @@
+/***************************************************************************/
+/*                                                                         */
+/*  otvgpos.c                                                              */
+/*                                                                         */
+/*    OpenType GPOS table validation (body).                               */
+/*                                                                         */
+/*  Copyright 2002, 2004, 2005, 2006, 2007, 2008 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"
+#include "otvgpos.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_otvgpos
+
+
+  static void
+  otv_Anchor_validate( FT_Bytes       table,
+                       OTV_Validator  valid );
+
+  static void
+  otv_MarkArray_validate( FT_Bytes       table,
+                          OTV_Validator  valid );
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                      UTILITY FUNCTIONS                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+#define BaseArrayFunc       otv_x_sxy
+#define LigatureAttachFunc  otv_x_sxy
+#define Mark2ArrayFunc      otv_x_sxy
+
+  /* uses valid->extra1 (counter)                             */
+  /* uses valid->extra2 (boolean to handle NULL anchor field) */
+
+  static void
+  otv_x_sxy( FT_Bytes       table,
+             OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   Count, count1, table_size;
+
+
+    OTV_ENTER;
+
+    OTV_LIMIT_CHECK( 2 );
+
+    Count = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (Count = %d)\n", Count ));
+
+    OTV_LIMIT_CHECK( Count * valid->extra1 * 2 );
+
+    table_size = Count * valid->extra1 * 2 + 2;
+
+    for ( ; Count > 0; Count-- )
+      for ( count1 = valid->extra1; count1 > 0; count1-- )
+      {
+        OTV_OPTIONAL_TABLE( anchor_offset );
+
+
+        OTV_OPTIONAL_OFFSET( anchor_offset );
+
+        if ( valid->extra2 )
+        {
+          OTV_SIZE_CHECK( anchor_offset );
+          if ( anchor_offset )
+            otv_Anchor_validate( table + anchor_offset, valid );
+        }
+        else
+          otv_Anchor_validate( table + anchor_offset, valid );
+      }
+
+    OTV_EXIT;
+  }
+
+
+#define MarkBasePosFormat1Func  otv_u_O_O_u_O_O
+#define MarkLigPosFormat1Func   otv_u_O_O_u_O_O
+#define MarkMarkPosFormat1Func  otv_u_O_O_u_O_O
+
+  /* sets valid->extra1 (class count) */
+
+  static void
+  otv_u_O_O_u_O_O( FT_Bytes       table,
+                   OTV_Validator  valid )
+  {
+    FT_Bytes           p = table;
+    FT_UInt            Coverage1, Coverage2, ClassCount;
+    FT_UInt            Array1, Array2;
+    OTV_Validate_Func  func;
+
+
+    OTV_ENTER;
+
+    p += 2;     /* skip PosFormat */
+
+    OTV_LIMIT_CHECK( 10 );
+    Coverage1  = FT_NEXT_USHORT( p );
+    Coverage2  = FT_NEXT_USHORT( p );
+    ClassCount = FT_NEXT_USHORT( p );
+    Array1     = FT_NEXT_USHORT( p );
+    Array2     = FT_NEXT_USHORT( p );
+
+    otv_Coverage_validate( table + Coverage1, valid, -1 );
+    otv_Coverage_validate( table + Coverage2, valid, -1 );
+
+    otv_MarkArray_validate( table + Array1, valid );
+
+    valid->nesting_level++;
+    func          = valid->func[valid->nesting_level];
+    valid->extra1 = ClassCount;
+
+    func( table + Array2, valid );
+
+    valid->nesting_level--;
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                        VALUE RECORDS                          *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  static FT_UInt
+  otv_value_length( FT_UInt  format )
+  {
+    FT_UInt  count;
+
+
+    count = ( ( format & 0xAA ) >> 1 ) + ( format & 0x55 );
+    count = ( ( count  & 0xCC ) >> 2 ) + ( count  & 0x33 );
+    count = ( ( count  & 0xF0 ) >> 4 ) + ( count  & 0x0F );
+
+    return count * 2;
+  }
+
+
+  /* uses valid->extra3 (pointer to base table) */
+
+  static void
+  otv_ValueRecord_validate( FT_Bytes       table,
+                            FT_UInt        format,
+                            OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   count;
+
+#ifdef FT_DEBUG_LEVEL_TRACE
+    FT_Int    loop;
+    FT_ULong  res = 0;
+
+
+    OTV_NAME_ENTER( "ValueRecord" );
+
+    /* display `format' in dual representation */
+    for ( loop = 7; loop >= 0; loop-- )
+    {
+      res <<= 4;
+      res  += ( format >> loop ) & 1;
+    }
+
+    OTV_TRACE(( " (format 0b%08lx)\n", res ));
+#endif
+
+    if ( format >= 0x100 )
+      FT_INVALID_FORMAT;
+
+    for ( count = 4; count > 0; count-- )
+    {
+      if ( format & 1 )
+      {
+        /* XPlacement, YPlacement, XAdvance, YAdvance */
+        OTV_LIMIT_CHECK( 2 );
+        p += 2;
+      }
+
+      format >>= 1;
+    }
+
+    for ( count = 4; count > 0; count-- )
+    {
+      if ( format & 1 )
+      {
+        FT_PtrDist  table_size;
+
+        OTV_OPTIONAL_TABLE( device );
+
+
+        /* XPlaDevice, YPlaDevice, XAdvDevice, YAdvDevice */
+        OTV_LIMIT_CHECK( 2 );
+        OTV_OPTIONAL_OFFSET( device );
+
+        /* XXX: this value is usually too small, especially if the current */
+        /* ValueRecord is part of an array -- getting the correct table    */
+        /* size is probably not worth the trouble                          */
+
+        table_size = p - valid->extra3;
+
+        OTV_SIZE_CHECK( device );
+        if ( device )
+          otv_Device_validate( valid->extra3 + device, valid );
+      }
+      format >>= 1;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                           ANCHORS                             *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  static void
+  otv_Anchor_validate( FT_Bytes       table,
+                       OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   AnchorFormat;
+
+
+    OTV_NAME_ENTER( "Anchor");
+
+    OTV_LIMIT_CHECK( 6 );
+    AnchorFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", AnchorFormat ));
+
+    p += 4;     /* skip XCoordinate and YCoordinate */
+
+    switch ( AnchorFormat )
+    {
+    case 1:
+      break;
+
+    case 2:
+      OTV_LIMIT_CHECK( 2 );  /* AnchorPoint */
+      break;
+
+    case 3:
+      {
+        FT_UInt   table_size;
+
+        OTV_OPTIONAL_TABLE( XDeviceTable );
+        OTV_OPTIONAL_TABLE( YDeviceTable );
+
+
+        OTV_LIMIT_CHECK( 4 );
+        OTV_OPTIONAL_OFFSET( XDeviceTable );
+        OTV_OPTIONAL_OFFSET( YDeviceTable );
+
+        table_size = 6 + 4;
+
+        OTV_SIZE_CHECK( XDeviceTable );
+        if ( XDeviceTable )
+          otv_Device_validate( table + XDeviceTable, valid );
+
+        OTV_SIZE_CHECK( YDeviceTable );
+        if ( YDeviceTable )
+          otv_Device_validate( table + YDeviceTable, valid );
+      }
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                         MARK ARRAYS                           *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  static void
+  otv_MarkArray_validate( FT_Bytes       table,
+                          OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   MarkCount;
+
+
+    OTV_NAME_ENTER( "MarkArray" );
+
+    OTV_LIMIT_CHECK( 2 );
+    MarkCount = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (MarkCount = %d)\n", MarkCount ));
+
+    OTV_LIMIT_CHECK( MarkCount * 4 );
+
+    /* MarkRecord */
+    for ( ; MarkCount > 0; MarkCount-- )
+    {
+      p += 2;   /* skip Class */
+      /* MarkAnchor */
+      otv_Anchor_validate( table + FT_NEXT_USHORT( p ), valid );
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     GPOS LOOKUP TYPE 1                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  /* sets valid->extra3 (pointer to base table) */
+
+  static void
+  otv_SinglePos_validate( FT_Bytes       table,
+                          OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   PosFormat;
+
+
+    OTV_NAME_ENTER( "SinglePos" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PosFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", PosFormat ));
+
+    valid->extra3 = table;
+
+    switch ( PosFormat )
+    {
+    case 1:     /* SinglePosFormat1 */
+      {
+        FT_UInt  Coverage, ValueFormat;
+
+
+        OTV_LIMIT_CHECK( 4 );
+        Coverage    = FT_NEXT_USHORT( p );
+        ValueFormat = FT_NEXT_USHORT( p );
+
+        otv_Coverage_validate( table + Coverage, valid, -1 );
+        otv_ValueRecord_validate( p, ValueFormat, valid ); /* Value */
+      }
+      break;
+
+    case 2:     /* SinglePosFormat2 */
+      {
+        FT_UInt  Coverage, ValueFormat, ValueCount, len_value;
+
+
+        OTV_LIMIT_CHECK( 6 );
+        Coverage    = FT_NEXT_USHORT( p );
+        ValueFormat = FT_NEXT_USHORT( p );
+        ValueCount  = FT_NEXT_USHORT( p );
+
+        OTV_TRACE(( " (ValueCount = %d)\n", ValueCount ));
+
+        len_value = otv_value_length( ValueFormat );
+
+        otv_Coverage_validate( table + Coverage, valid, ValueCount );
+
+        OTV_LIMIT_CHECK( ValueCount * len_value );
+
+        /* Value */
+        for ( ; ValueCount > 0; ValueCount-- )
+        {
+          otv_ValueRecord_validate( p, ValueFormat, valid );
+          p += len_value;
+        }
+      }
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     GPOS LOOKUP TYPE 2                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  static void
+  otv_PairSet_validate( FT_Bytes       table,
+                        FT_UInt        format1,
+                        FT_UInt        format2,
+                        OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   value_len1, value_len2, PairValueCount;
+
+
+    OTV_NAME_ENTER( "PairSet" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PairValueCount = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (PairValueCount = %d)\n", PairValueCount ));
+
+    value_len1 = otv_value_length( format1 );
+    value_len2 = otv_value_length( format2 );
+
+    OTV_LIMIT_CHECK( PairValueCount * ( value_len1 + value_len2 + 2 ) );
+
+    /* PairValueRecord */
+    for ( ; PairValueCount > 0; PairValueCount-- )
+    {
+      p += 2;       /* skip SecondGlyph */
+
+      if ( format1 )
+        otv_ValueRecord_validate( p, format1, valid ); /* Value1 */
+      p += value_len1;
+
+      if ( format2 )
+        otv_ValueRecord_validate( p, format2, valid ); /* Value2 */
+      p += value_len2;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /* sets valid->extra3 (pointer to base table) */
+
+  static void
+  otv_PairPos_validate( FT_Bytes       table,
+                        OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   PosFormat;
+
+
+    OTV_NAME_ENTER( "PairPos" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PosFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", PosFormat ));
+
+    valid->extra3 = table;
+
+    switch ( PosFormat )
+    {
+    case 1:     /* PairPosFormat1 */
+      {
+        FT_UInt  Coverage, ValueFormat1, ValueFormat2, PairSetCount;
+
+
+        OTV_LIMIT_CHECK( 8 );
+        Coverage     = FT_NEXT_USHORT( p );
+        ValueFormat1 = FT_NEXT_USHORT( p );
+        ValueFormat2 = FT_NEXT_USHORT( p );
+        PairSetCount = FT_NEXT_USHORT( p );
+
+        OTV_TRACE(( " (PairSetCount = %d)\n", PairSetCount ));
+
+        otv_Coverage_validate( table + Coverage, valid, -1 );
+
+        OTV_LIMIT_CHECK( PairSetCount * 2 );
+
+        /* PairSetOffset */
+        for ( ; PairSetCount > 0; PairSetCount-- )
+          otv_PairSet_validate( table + FT_NEXT_USHORT( p ),
+                                ValueFormat1, ValueFormat2, valid );
+      }
+      break;
+
+    case 2:     /* PairPosFormat2 */
+      {
+        FT_UInt  Coverage, ValueFormat1, ValueFormat2, ClassDef1, ClassDef2;
+        FT_UInt  ClassCount1, ClassCount2, len_value1, len_value2, count;
+
+
+        OTV_LIMIT_CHECK( 14 );
+        Coverage     = FT_NEXT_USHORT( p );
+        ValueFormat1 = FT_NEXT_USHORT( p );
+        ValueFormat2 = FT_NEXT_USHORT( p );
+        ClassDef1    = FT_NEXT_USHORT( p );
+        ClassDef2    = FT_NEXT_USHORT( p );
+        ClassCount1  = FT_NEXT_USHORT( p );
+        ClassCount2  = FT_NEXT_USHORT( p );
+
+        OTV_TRACE(( " (ClassCount1 = %d)\n", ClassCount1 ));
+        OTV_TRACE(( " (ClassCount2 = %d)\n", ClassCount2 ));
+
+        len_value1 = otv_value_length( ValueFormat1 );
+        len_value2 = otv_value_length( ValueFormat2 );
+
+        otv_Coverage_validate( table + Coverage, valid, -1 );
+        otv_ClassDef_validate( table + ClassDef1, valid );
+        otv_ClassDef_validate( table + ClassDef2, valid );
+
+        OTV_LIMIT_CHECK( ClassCount1 * ClassCount2 *
+                     ( len_value1 + len_value2 ) );
+
+        /* Class1Record */
+        for ( ; ClassCount1 > 0; ClassCount1-- )
+        {
+          /* Class2Record */
+          for ( count = ClassCount2; count > 0; count-- )
+          {
+            if ( ValueFormat1 )
+              /* Value1 */
+              otv_ValueRecord_validate( p, ValueFormat1, valid );
+            p += len_value1;
+
+            if ( ValueFormat2 )
+              /* Value2 */
+              otv_ValueRecord_validate( p, ValueFormat2, valid );
+            p += len_value2;
+          }
+        }
+      }
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     GPOS LOOKUP TYPE 3                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  static void
+  otv_CursivePos_validate( FT_Bytes       table,
+                           OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   PosFormat;
+
+
+    OTV_NAME_ENTER( "CursivePos" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PosFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", PosFormat ));
+
+    switch ( PosFormat )
+    {
+    case 1:     /* CursivePosFormat1 */
+      {
+        FT_UInt   table_size;
+        FT_UInt   Coverage, EntryExitCount;
+
+        OTV_OPTIONAL_TABLE( EntryAnchor );
+        OTV_OPTIONAL_TABLE( ExitAnchor  );
+
+
+        OTV_LIMIT_CHECK( 4 );
+        Coverage       = FT_NEXT_USHORT( p );
+        EntryExitCount = FT_NEXT_USHORT( p );
+
+        OTV_TRACE(( " (EntryExitCount = %d)\n", EntryExitCount ));
+
+        otv_Coverage_validate( table + Coverage, valid, EntryExitCount );
+
+        OTV_LIMIT_CHECK( EntryExitCount * 4 );
+
+        table_size = EntryExitCount * 4 + 4;
+
+        /* EntryExitRecord */
+        for ( ; EntryExitCount > 0; EntryExitCount-- )
+        {
+          OTV_OPTIONAL_OFFSET( EntryAnchor );
+          OTV_OPTIONAL_OFFSET( ExitAnchor  );
+
+          OTV_SIZE_CHECK( EntryAnchor );
+          if ( EntryAnchor )
+            otv_Anchor_validate( table + EntryAnchor, valid );
+
+          OTV_SIZE_CHECK( ExitAnchor );
+          if ( ExitAnchor )
+            otv_Anchor_validate( table + ExitAnchor, valid );
+        }
+      }
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     GPOS LOOKUP TYPE 4                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  /* UNDOCUMENTED (in OpenType 1.5):              */
+  /* BaseRecord tables can contain NULL pointers. */
+
+  /* sets valid->extra2 (1) */
+
+  static void
+  otv_MarkBasePos_validate( FT_Bytes       table,
+                            OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   PosFormat;
+
+
+    OTV_NAME_ENTER( "MarkBasePos" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PosFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", PosFormat ));
+
+    switch ( PosFormat )
+    {
+    case 1:
+      valid->extra2 = 1;
+      OTV_NEST2( MarkBasePosFormat1, BaseArray );
+      OTV_RUN( table, valid );
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     GPOS LOOKUP TYPE 5                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  /* sets valid->extra2 (1) */
+
+  static void
+  otv_MarkLigPos_validate( FT_Bytes       table,
+                           OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   PosFormat;
+
+
+    OTV_NAME_ENTER( "MarkLigPos" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PosFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", PosFormat ));
+
+    switch ( PosFormat )
+    {
+    case 1:
+      valid->extra2 = 1;
+      OTV_NEST3( MarkLigPosFormat1, LigatureArray, LigatureAttach );
+      OTV_RUN( table, valid );
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     GPOS LOOKUP TYPE 6                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  /* sets valid->extra2 (0) */
+
+  static void
+  otv_MarkMarkPos_validate( FT_Bytes       table,
+                            OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   PosFormat;
+
+
+    OTV_NAME_ENTER( "MarkMarkPos" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PosFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", PosFormat ));
+
+    switch ( PosFormat )
+    {
+    case 1:
+      valid->extra2 = 0;
+      OTV_NEST2( MarkMarkPosFormat1, Mark2Array );
+      OTV_RUN( table, valid );
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     GPOS LOOKUP TYPE 7                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  /* sets valid->extra1 (lookup count) */
+
+  static void
+  otv_ContextPos_validate( FT_Bytes       table,
+                           OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   PosFormat;
+
+
+    OTV_NAME_ENTER( "ContextPos" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PosFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", PosFormat ));
+
+    switch ( PosFormat )
+    {
+    case 1:
+      /* no need to check glyph indices/classes used as input for these */
+      /* context rules since even invalid glyph indices/classes return  */
+      /* meaningful results                                             */
+
+      valid->extra1 = valid->lookup_count;
+      OTV_NEST3( ContextPosFormat1, PosRuleSet, PosRule );
+      OTV_RUN( table, valid );
+      break;
+
+    case 2:
+      /* no need to check glyph indices/classes used as input for these */
+      /* context rules since even invalid glyph indices/classes return  */
+      /* meaningful results                                             */
+
+      OTV_NEST3( ContextPosFormat2, PosClassSet, PosClassRule );
+      OTV_RUN( table, valid );
+      break;
+
+    case 3:
+      OTV_NEST1( ContextPosFormat3 );
+      OTV_RUN( table, valid );
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     GPOS LOOKUP TYPE 8                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  /* sets valid->extra1 (lookup count) */
+
+  static void
+  otv_ChainContextPos_validate( FT_Bytes       table,
+                                OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   PosFormat;
+
+
+    OTV_NAME_ENTER( "ChainContextPos" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PosFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", PosFormat ));
+
+    switch ( PosFormat )
+    {
+    case 1:
+      /* no need to check glyph indices/classes used as input for these */
+      /* context rules since even invalid glyph indices/classes return  */
+      /* meaningful results                                             */
+
+      valid->extra1 = valid->lookup_count;
+      OTV_NEST3( ChainContextPosFormat1,
+                 ChainPosRuleSet, ChainPosRule );
+      OTV_RUN( table, valid );
+      break;
+
+    case 2:
+      /* no need to check glyph indices/classes used as input for these */
+      /* context rules since even invalid glyph indices/classes return  */
+      /* meaningful results                                             */
+
+      OTV_NEST3( ChainContextPosFormat2,
+                 ChainPosClassSet, ChainPosClassRule );
+      OTV_RUN( table, valid );
+      break;
+
+    case 3:
+      OTV_NEST1( ChainContextPosFormat3 );
+      OTV_RUN( table, valid );
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                     GPOS LOOKUP TYPE 9                        *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  /* uses valid->type_funcs */
+
+  static void
+  otv_ExtensionPos_validate( FT_Bytes       table,
+                             OTV_Validator  valid )
+  {
+    FT_Bytes  p = table;
+    FT_UInt   PosFormat;
+
+
+    OTV_NAME_ENTER( "ExtensionPos" );
+
+    OTV_LIMIT_CHECK( 2 );
+    PosFormat = FT_NEXT_USHORT( p );
+
+    OTV_TRACE(( " (format %d)\n", PosFormat ));
+
+    switch ( PosFormat )
+    {
+    case 1:     /* ExtensionPosFormat1 */
+      {
+        FT_UInt            ExtensionLookupType;
+        FT_ULong           ExtensionOffset;
+        OTV_Validate_Func  validate;
+
+
+        OTV_LIMIT_CHECK( 6 );
+        ExtensionLookupType = FT_NEXT_USHORT( p );
+        ExtensionOffset     = FT_NEXT_ULONG( p );
+
+        if ( ExtensionLookupType == 0 || ExtensionLookupType >= 9 )
+          FT_INVALID_DATA;
+
+        validate = valid->type_funcs[ExtensionLookupType - 1];
+        validate( table + ExtensionOffset, valid );
+      }
+      break;
+
+    default:
+      FT_INVALID_FORMAT;
+    }
+
+    OTV_EXIT;
+  }
+
+
+  static const OTV_Validate_Func  otv_gpos_validate_funcs[9] =
+  {
+    otv_SinglePos_validate,
+    otv_PairPos_validate,
+    otv_CursivePos_validate,
+    otv_MarkBasePos_validate,
+    otv_MarkLigPos_validate,
+    otv_MarkMarkPos_validate,
+    otv_ContextPos_validate,
+    otv_ChainContextPos_validate,
+    otv_ExtensionPos_validate
+  };
+
+
+  /* sets valid->type_count */
+  /* sets valid->type_funcs */
+
+  FT_LOCAL_DEF( void )
+  otv_GPOS_subtable_validate( FT_Bytes       table,
+                              OTV_Validator  valid )
+  {
+    valid->type_count = 9;
+    valid->type_funcs = (OTV_Validate_Func*)otv_gpos_validate_funcs;
+
+    otv_Lookup_validate( table, valid );
+  }
+
+
+  /*************************************************************************/
+  /*************************************************************************/
+  /*****                                                               *****/
+  /*****                          GPOS TABLE                           *****/
+  /*****                                                               *****/
+  /*************************************************************************/
+  /*************************************************************************/
+
+  /* sets valid->glyph_count */
+
+  FT_LOCAL_DEF( void )
+  otv_GPOS_validate( FT_Bytes      table,
+                     FT_UInt       glyph_count,
+                     FT_Validator  ftvalid )
+  {
+    OTV_ValidatorRec  validrec;
+    OTV_Validator     valid = &validrec;
+    FT_Bytes          p     = table;
+    FT_UInt           ScriptList, FeatureList, LookupList;
+
+
+    valid->root = ftvalid;
+
+    FT_TRACE3(( "validating GPOS table\n" ));
+    OTV_INIT;
+
+    OTV_LIMIT_CHECK( 10 );
+
+    if ( FT_NEXT_ULONG( p ) != 0x10000UL )      /* Version */
+      FT_INVALID_FORMAT;
+
+    ScriptList  = FT_NEXT_USHORT( p );
+    FeatureList = FT_NEXT_USHORT( p );
+    LookupList  = FT_NEXT_USHORT( p );
+
+    valid->type_count  = 9;
+    valid->type_funcs  = (OTV_Validate_Func*)otv_gpos_validate_funcs;
+    valid->glyph_count = glyph_count;
+
+    otv_LookupList_validate( table + LookupList,
+                             valid );
+    otv_FeatureList_validate( table + FeatureList, table + LookupList,
+                              valid );
+    otv_ScriptList_validate( table + ScriptList, table + FeatureList,
+                             valid );
+
+    FT_TRACE4(( "\n" ));
+  }
+
+
+/* END */