[ft-devel] [PATCH] POSIX resource fork accessor in 2.3.8 is broken since CVS 2008-10-04

[mpsuzuki]

Hi all,

When I added a preliminary support for sfnt-wrapped PostScript
Type1 & CID-keyed font on 2008-10-04, I had broken
Mac_Read_sfnt_Resource() in src/base/ftobjs.c. So,
freetype-2.3.8 on non-MacOS platforms cannot load suitcase fonts
at present. I will fix CVS soon, but if you want separated patch,
please apply attached patch. This bug is filed at:

        https://savannah.nongnu.org/bugs/?25347

Regards,
mpsuzuki

--


Before all, Mac_Read_sfnt_Resource() tries to open PS Type1
or CID-keyed font in temporal sfnt stream, by calling
open_face_PS_from_sfnt_stream(), like this:
----------------------------------------------------------------
  static FT_Error
  Mac_Read_sfnt_Resource( FT_Library  library,
                          FT_Stream   stream,
                          FT_Long    *offsets,
                          FT_Long     resource_cnt,
                          FT_Long     face_index,
                          FT_Face    *aface )
  {

    ...

    flag_offset = offsets[face_index];
    error = FT_Stream_Seek( stream, flag_offset );
    if ( error )
      goto Exit;

    if ( FT_READ_LONG( rlen ) )
      goto Exit;
    if ( rlen == -1 )
      return FT_Err_Cannot_Open_Resource;

    error = open_face_PS_from_sfnt_stream( library,
                                           stream,
                                           face_index,
                                           0, NULL,
                                           aface );
----------------------------------------------------------------
If failed, whole of sfnt stream is copied to memory buffer, and
the buffer is passed to open_face_from_buffer() (and TrueType
face would be opened), like this.
----------------------------------------------------------------
    if ( !error )
      goto Exit;

    if ( FT_ALLOC( sfnt_data, (FT_Long)rlen ) )
      return error;
    error = FT_Stream_Read( stream, (FT_Byte *)sfnt_data, rlen );
    if ( error )
      goto Exit;

    is_cff = rlen > 4 && !ft_memcmp( sfnt_data, "OTTO", 4 );
    error = open_face_from_buffer( library,
                                   sfnt_data,
                                   rlen,
                                   face_index_in_resource,
                                   is_cff ? "cff" : "truetype",
                                   aface );
----------------------------------------------------------------
But, this copying of sfnt stream to memory buffer is not
exact. In some case (e.g. PS Type1 nor CID-keyed font is
not found), open_face_PS_from_sfnt_stream() returns without
restoring the position of the sfnt stream, like this:
----------------------------------------------------------------
  FT_LOCAL_DEF( FT_Error )
  open_face_PS_from_sfnt_stream( FT_Library     library,
                                 FT_Stream      stream,
                                 FT_Long        face_index,
                                 FT_Int         num_params,
                                 FT_Parameter  *params,
                                 FT_Face       *aface )
  {

    ...

    error = ft_lookup_PS_in_sfnt_stream( stream,
                                         face_index,
                                         &offset,
                                         &length,
                                         &is_sfnt_cid );
    if ( error )
      return error;
----------------------------------------------------------------
Thus, the copying of sfnt stream to memory buffer by
Mac_Read_sfnt_Resource() can make wrong image due to
unexpected position of sfnt stream.

The fix would be one of followings.

Fix 1) Improve open_face_PS_from_sfnt_stream() to restore
the position of sfnt stream always.

Fix 2) Improve Mac_Read_sfnt_Resource() to seek the sfnt
stream to correct position by itself, even if it is shifted
by open_face_PS_from_sfnt_stream().


Index: src/base/ftobjs.c
===================================================================
RCS file: /sources/freetype/freetype2/src/base/ftobjs.c,v
retrieving revision 1.318
diff -u -r1.318 ftobjs.c
--- src/base/ftobjs.c   13 Jan 2009 17:42:00 -0000      1.318
+++ src/base/ftobjs.c   16 Jan 2009 17:00:15 -0000
@@ -1417,7 +1417,7 @@
                                          &length,
                                          &is_sfnt_cid );
     if ( error )
-      return error;
+      goto Exit;
 
     if ( FT_Stream_Seek( stream, pos + offset ) )
       goto Exit;
@@ -1605,6 +1605,10 @@
     if ( !error )
       goto Exit;
 
+    /* rewind sfnt stream before open_face_PS_from_sfnt_stream() */
+    if ( FT_Stream_Seek( stream, flag_offset + 4 ) )
+      goto Exit;
+
     if ( FT_ALLOC( sfnt_data, (FT_Long)rlen ) )
       return error;
     error = FT_Stream_Read( stream, (FT_Byte *)sfnt_data, rlen );