Re: [ft-devel] [FYI] Re: Getting pathname from FT_Face (patch for future discussion)

[mpsuzuki]

On Sun, 14 Mar 2010 21:19:44 -0400
Behdad Esfahbod <address@hidden> wrote:

>On 03/11/2010 02:47 AM, address@hidden wrote:
>> Attached (get-stream-info.diff) is a revised patch with
>> a feature to get the info about the origin of the memory
>> in FT_Stream object, which is inspired by recent discussion
>> with Behdad about mprotect() to the buffer in FT_Stream
>> object. Sample code (get-stream-info.c) invokes the new APIs
>> FT_Get_MemInfo_From_Stream() and FT_Get_Path_From_Stream()
>> then shows results, aslike:
>
>Thanks!  Looks interesting.  I don't see the mmap() in there though.
>What am I missing?

I'm sorry for poor description, you missed nothing.
get-stream-info.c does not invoke mmap() by itself,
it reports if FT_Face->stream->base is allocated by
mmap(), ft_alloc(), static buffer (for Amiga).
If it is mmap()ed, it should be read only.
If it is ft_alloc()ed, it can be modified without
changing font file.

>Otherwise, looks like something I can use, yes.

Thanks. Considering with another comment from you
on my idea restricting memory allocation methods
in FT_Face object creation, I have to switch "this"
direction.

>On 03/13/2010 06:53 AM, Werner LEMBERG wrote:
>>
>> Very nice!  If Behdad thinks this is useful just add it to the git
>> repository.  Shall we control this by an FT_CONFIG_OPTION_XXX macro?
>
>I'd rather it be enalbed unconditionally.

Indeed. I guess, Fontconfig, Cairo, HarfBuzz, Pango
and GTK+ developers don't want to make their softwares
dependent with FreeType2 under non-default configuration.
Maybe, it is expected that new feature is available in
widely distributed libfreetype binaries on free Unix-like
systems.

Werner, except of the code size, do you have any concern
about my patch? I will post about the code size evaluation.

# One of my concern (except of the code size) is that APIs
# like FT_Get_Path_From_Stream() is a bad idea from the
# viewpoint of software design, and it can encourage badly-
# designed FT2 clients. FT_Get_MemInfo_From_Stream() might
# not be so bad, but it could conflict with the philosophy of
# the encapsulation of FT_Stream.

Regards,
mpsuzuki