FT_Get_Glyph_Name(FT_Face face, FT_UInt glyph_index, FT_Pointer buffer, FT_UInt buffer_max );

FT_Face = face;
FT_Pointer = name;
FT_Get_Glyph_Name(face, 0, name, 45);

char name[100];
FT_Get_Glyph_Name(face, 0, (FT_Pointer) name, 100);
printf("Name : '%s'n", name);