The library "libotf" provides the following facilites.

    o Read Open Type Layout Tables from OTF file.  Currently these
      tables are supported; head, name, cmap, GDEF, GSUB, and GPOS.

    o Convert a Unicode character sequence to a glyph code sequence by
      using the above tables.

WWW: http://tsukuba.m17n.org/libotf/