Support v10 CFF2 fonts

remove string index, font index
top dict follows header, but has no index
font dict in FDArray, but skip FDSelect when there's only one font dict

src/cff/cffload.c

@@ -726,6 +726,10 @@
   {
     FT_Byte  fd = 0;
 
+    /* if there is no FDSelect, return zero               */
+    /* Note: CFF2 with just one Font Dict has no FDSelect */
+    if ( fdselect->data == NULL )
+      goto Exit;
 
     switch ( fdselect->format )
     {
@@ -779,6 +783,7 @@
       ;
     }
 
+  Exit:
     return fd;
   }
 
@@ -1505,14 +1510,27 @@
     top->cid_ordering        = 0xFFFFU;
     top->cid_font_name       = 0xFFFFU;
 
-    error = cff_index_access_element( idx, font_index, &dict, &dict_len );
+    if ( idx->count )   /* count is nonzero for a real index */
+      error = cff_index_access_element( idx, font_index, &dict, &dict_len );
+    else
+    {
+      /* cff2 has a fake top dict index. simulate cff_index_access_element */
+      /* Note: macros implicitly use "stream" and set "error"              */
+      if ( !FT_STREAM_SEEK( idx->data_offset ) )
+        FT_FRAME_EXTRACT( idx->data_size, dict );
+      dict_len = idx->data_size;
+    }
     if ( !error )
     {
       FT_TRACE4(( " top dictionary:\n" ));
       error = cff_parser_run( &parser, dict, dict + dict_len );
     }
 
-    cff_index_forget_element( idx, &dict );
+    /* clean up regardless of error */
+    if ( idx->count )
+      cff_index_forget_element( idx, &dict );
+    else
+      FT_FRAME_RELEASE( dict );
 
     if ( error )
       goto Exit;
@@ -1624,6 +1642,7 @@
 
     font->stream = stream;
     font->memory = memory;
+    font->cff2   = cff2;
     dict         = &font->top_font.font_dict;
     base_offset  = FT_STREAM_POS();
 
@@ -1634,7 +1653,7 @@
     /* check format */
     if ( font->version_major != ( cff2 ? 2 : 1 ) ||
          font->header_size      < 4 ||
-         font->absolute_offsize > 4 )
+         ( !cff2 && font->absolute_offsize > 4 ) )
     {
       FT_TRACE2(( "  not a CFF font header\n" ));
       error = FT_THROW( Unknown_File_Format );
@@ -1645,10 +1664,31 @@
     if ( FT_STREAM_SKIP( font->header_size - 4 ) )
       goto Exit;
 
-    /* read the name, top dict, string and global subrs index */
-    /* CFF2 does not contain a name index */
-    if ( ( !cff2 && FT_SET_ERROR( cff_index_init( &font->name_index,
-                                       stream, 0 ) ) )                     ||
+    if ( cff2 )
+    {
+      /* For CFF2, the top dict data immediately follow the header */
+      /* and the length is stored in the header offSize field      */
+      /* there is no index for it.                                 */
+      /* use the font_dict_index to save the current position and  */
+      /* length of data, but leave count at zero as an indicator   */
+      FT_ZERO( &font->font_dict_index );
+      font->font_dict_index.data_offset = FT_STREAM_POS();
+      font->font_dict_index.data_size = font->absolute_offsize;
+
+      /* skip the top dict data for now, we'll parse it later      */
+      if ( FT_STREAM_SKIP( font->absolute_offsize ) )
+        goto Exit;
+
+      /* next, read the global subrs index                         */
+      if ( FT_SET_ERROR( cff_index_init( &font->global_subrs_index,
+                                       stream, 1 ) ) )
+        goto Exit;
+    }
+    else
+    {
+      /* for CFF, read the name, top dict, string and global subrs index */
+      if ( FT_SET_ERROR( cff_index_init( &font->name_index,
+                                       stream, 0 ) )                       ||
          FT_SET_ERROR( cff_index_init( &font->font_dict_index,
                                        stream, 0 ) )                       ||
          FT_SET_ERROR( cff_index_init( &string_index,
@@ -1659,7 +1699,8 @@
                                                &font->strings,
                                                &font->string_pool,
                                                &font->string_pool_size ) ) )
-      goto Exit;
+        goto Exit;
+    }
 
     font->num_strings = string_index.count;
 
@@ -1716,8 +1757,9 @@
     if ( error )
       goto Exit;
 
-    /* now, check for a CID font */
-    if ( dict->cid_registry != 0xFFFFU )
+    /* now, check for a CID or CFF2 font */
+    if ( dict->cid_registry != 0xFFFFU ||
+         cff2 )
     {
       CFF_IndexRec  fd_index;
       CFF_SubFont   sub = NULL;
@@ -1760,6 +1802,8 @@
       }
 
       /* now load the FD Select array */
+      /* CFF2 omits FDSelect if there's only one FD */
+      if ( !cff2 || fd_index.count > 1 )
       error = CFF_Load_FD_Select( &font->fd_select,
                                   font->charstrings_index.count,
                                   stream,
@@ -1847,7 +1891,7 @@
     cff_index_done( &font->charstrings_index );
 
     /* release font dictionaries, but only if working with */
-    /* a CID keyed CFF font                                */
+    /* a CID keyed CFF font or a CFF2 font                 */
     if ( font->num_subfonts > 0 )
     {
       for ( idx = 0; idx < font->num_subfonts; idx++ )

src/cff/cfftypes.h

@@ -269,8 +269,9 @@ FT_BEGIN_HEADER
     FT_Byte          version_major;
     FT_Byte          version_minor;
     FT_Byte          header_size;
-    FT_Byte          absolute_offsize;
+    FT_Byte          absolute_offsize;  /* cff2_top_dict_length */
 
+    FT_Bool          cff2;
 
     CFF_IndexRec     name_index;
     CFF_IndexRec     top_dict_index;