[truetype] Updates for the forthcoming OpenType 1.9 standard (1/2).

This is in preparation for implementing `DeltaSetIndexMap` format 1, which
is used by `COLR` v1 tables, and which allows 32bit indices.

  https://docs.microsoft.com/en-us/typography/opentype/otspec190/delta/otvarcommonformats_delta.html

* src/truetype/ttgxvar.h (GX_DeltaSetIdxMapRec): Change type of `mapCount`
to `FT_ULong`.

* src/truetype/ttgxvar.c (ft_var_load_delta_set_index_mapping): Add argument
for passing the table size; update caller.
Implement new format.

2 files changed, 49 insertions, 19 deletions

diff --git a/src/truetype/ttgxvar.c b/src/truetype/ttgxvar.c
index 4fda29962..553e27d0c 100644
--- a/src/truetype/ttgxvar.c
+++ b/src/truetype/ttgxvar.c
@@ -664,37 +664,66 @@
   ft_var_load_delta_set_index_mapping( TT_Face            face,
                                        FT_ULong           offset,
                                        GX_DeltaSetIdxMap  map,
-                                       GX_ItemVarStore    itemStore )
+                                       GX_ItemVarStore    itemStore,
+                                       FT_ULong           table_len )
   {
     FT_Stream  stream = FT_FACE_STREAM( face );
     FT_Memory  memory = stream->memory;
 
-    FT_Error   error;
+    FT_Error  error;
 
-    FT_UShort  format;
-    FT_UInt    entrySize;
-    FT_UInt    innerBitCount;
-    FT_UInt    innerIndexMask;
-    FT_UInt    i, j;
+    FT_Byte   format;
+    FT_Byte   entryFormat;
+    FT_UInt   entrySize;
+    FT_UInt   innerBitCount;
+    FT_UInt   innerIndexMask;
+    FT_ULong  i;
+    FT_UInt   j;
 
 
-    if ( FT_STREAM_SEEK( offset )        ||
-         FT_READ_USHORT( format )        ||
-         FT_READ_USHORT( map->mapCount ) )
+    if ( FT_STREAM_SEEK( offset )    ||
+         FT_READ_BYTE( format )      ||
+         FT_READ_BYTE( entryFormat ) )
       goto Exit;
 
-    if ( format & 0xFFC0 )
+    if ( format == 0 )
+    {
+      if ( FT_READ_USHORT( map->mapCount ) )
+        goto Exit;
+    }
+    else if ( format == 1 ) /* new in OpenType 1.9 */
+    {
+      if ( FT_READ_ULONG( map->mapCount ) )
+        goto Exit;
+    }
+    else
     {
       FT_TRACE2(( "bad map format %d\n", format ));
       error = FT_THROW( Invalid_Table );
       goto Exit;
     }
 
+    if ( entryFormat & 0xC0 )
+    {
+      FT_TRACE2(( "bad entry format %d\n", format ));
+      error = FT_THROW( Invalid_Table );
+      goto Exit;
+    }
+
     /* bytes per entry: 1, 2, 3, or 4 */
-    entrySize      = ( ( format & 0x0030 ) >> 4 ) + 1;
-    innerBitCount  = ( format & 0x000F ) + 1;
+    entrySize      = ( ( entryFormat & 0x30 ) >> 4 ) + 1;
+    innerBitCount  = ( entryFormat & 0x0F ) + 1;
     innerIndexMask = ( 1 << innerBitCount ) - 1;
 
+    /* rough sanity check */
+    if ( map->mapCount * entrySize > table_len )
+    {
+      FT_TRACE1(( "ft_var_load_delta_set_index_mapping:"
+                  " invalid number of delta-set index mappings\n" ));
+      error = FT_THROW( Invalid_Table );
+      goto Exit;
+    }
+
     if ( FT_NEW_ARRAY( map->innerIndex, map->mapCount ) )
       goto Exit;
 
@@ -723,7 +752,7 @@
 
       if ( outerIndex >= itemStore->dataCount )
       {
-        FT_TRACE2(( "outerIndex[%d] == %d out of range\n",
+        FT_TRACE2(( "outerIndex[%ld] == %d out of range\n",
                     i,
                     outerIndex ));
         error = FT_THROW( Invalid_Table );
@@ -736,7 +765,7 @@
 
       if ( innerIndex >= itemStore->varData[outerIndex].itemCount )
       {
-        FT_TRACE2(( "innerIndex[%d] == %d out of range\n",
+        FT_TRACE2(( "innerIndex[%ld] == %d out of range\n",
                     i,
                     innerIndex ));
         error = FT_THROW( Invalid_Table );
@@ -861,7 +890,8 @@
                 face,
                 table_offset + widthMap_offset,
                 &table->widthMap,
-                &table->itemStore );
+                &table->itemStore,
+                table_len );
       if ( error )
         goto Exit;
     }
diff --git a/src/truetype/ttgxvar.h b/src/truetype/ttgxvar.h
index c58731951..ded9ea1d6 100644
--- a/src/truetype/ttgxvar.h
+++ b/src/truetype/ttgxvar.h
@@ -106,9 +106,9 @@ FT_BEGIN_HEADER
 
   typedef struct  GX_DeltaSetIdxMapRec_
   {
-    FT_UInt   mapCount;
-    FT_UInt*  outerIndex;             /* indices to item var data */
-    FT_UInt*  innerIndex;             /* indices to delta set     */
+    FT_ULong  mapCount;
+    FT_UInt*  outerIndex;               /* indices to item var data */
+    FT_UInt*  innerIndex;               /* indices to delta set     */
 
   } GX_DeltaSetIdxMapRec, *GX_DeltaSetIdxMap;