[Devel] FT 2.1.2: CFF stack undeflow problem

[KANOU Hiroki]

I generated a pair of OpenType fonts which contains CFF outline. 
This font is converted from CID-Keyed PostScript font I made based
on the work of Yasuyuki Furukawa. 
(http://kappa.allnet.ne.jp/Kochi-CID/current/Kochi-Mincho.otf.bz2 and
 http://kappa.allnet.ne.jp/Kochi-CID/current/Kochi-Gothic.otf.bz2 )

When I tried to brouse with ftview in ft2demos-2.1.2, this error 
message was shown.
--------------------------------
% ftview 40 Kochi-Gothic.otf
could not find/open any font file
  error = 0x0006
--------------------------------

I noticed that Compact Font Format operators which appear in Private 
dictionaries can raise stack undeflow to FreeType. Giving dummy 
arguments to these operators or removing these operators from the font
make ftview work.

BlueValues                              6
OtherBlues                              7
FamilyBlues                             8
FamilyOtherBlues                9
StemSnapH                               12 12
StemSnapV                               12 13
and this entry in Top Dict will also be:
BaseFontBlend                   12 23

These operators take a delta encoded array as the argument, and
the array can be empty. Especially, BlueValues is mandatory in
private dict. `Adobe Type 1 Font Format' sais (p.37):

    The BlueValues array is requierd in the Private dicitonary. If no
    alignment zones are necessary, use an empty array for the value of
    BlueValues:

    /BlueValues [ ] def

On the other hand, BlueValues and/or other operators which take a 
delta as an argument have no default values and `The Compact Font
Format Specification' does NOT describe them as omissible when the
array is empty.

I think these operators can appear with no argument within CFF dicts.
At least, that fonts are installable to Windows NT 4.0 + ATM 4.1, 
Windows 2000 SP3 and Mac OS X 10.1.4 and seems to work fine.

KANOU Hiroki <address@hidden>