[Libreoffice] making binfilter aka StarOffice FileFormat read-only

[Pierre-André Jacquod]

Hello,
these days, I have tried (and not really with full success) to
understand how binfilter works...

My goal: since it is an old legacy format, make StarOffice formats
read-only, and clean binfilter component of all code used for writing files.

Reason: with read-only, you will still be able to read your old files /
archive, but his will push the users to use a current / supported format
in case of change. So a less heavy software, use of well-maintained (see
minutes of tech steering call ... 2010.12.09)

After some code reading here a resume of my understanding. Thanks for
correcting, asking, challenging me. I hope I did not understand it too
wrongly.

An easy (and clean) possibility would be to change the filters defined
in binfilter as read-only filters (using as filter flag
SFX_FILTER_OPENREADONLY defined as 0x00010000L) This will make the
opening read-only. By this way, this is not possible any more to save
using these file formats.
(I have not yet found where this is set, but still searching)

Currently, I have simulated it locally adding in
libs-core/sfx2/source/bastyp/fltfnc.cxx: (almost at the end of the
function SfxFilterContainer::ReadSingleFilter_Impl )

if (nFormatVersion < SOFFICE_FILEFORMAT_60)
{
    pFilter->nFormatType = ( nFlags | SFX_FILTER_OPENREADONLY);
}

this is not a nice hack, but it demonstrates me that it works / how it
works.

This shows me:
a) it works. Yesss : -)

b) there are functions defined in libs-core and binfilter (sfx2 of
libs-core and sfx2 in binfilters) that are redundant. e.g
SFX_FILTER_OPENREADONLY (and other constant values) are defined in both
filters/binfilter/inc/bf_sfx2/docfilt.hxx
libs-core/sfx2/inc/sfx2/docfilt.hxx

c) it seems there are elements in the sfx2 of binfilter that are still
called, generated, but have no impact on the running system. For exemple
function SfxFilterContainer::ReadExternalFilters (in
binfilter/bf_sfx2/source/bastyp/sfx2_fltfnc.cxx) is still called,
produced me a lot of debug text, but the above mentionned code inserted
at the same place (as in libs-core but within his function) did not
produced any effect. So this function is still called, but its effects
are not taken into account.

d) So binfilter could be simplified if I take out all wrinting stuff,
and not needed section of code still called...

I noticed the following at SaveAs: all StarOffice format were still
available, but were producing an error at saving, since they are now by
me read-only... I did not find the place, but could someone hint me
where this is? Actually, I think the list of format displayed at Save or
SaveAs should contain only "not read-only" filters, something like this
in pseudo-code:

(if (filter.getFlags() && SFX_FILTER_OPENREADONLY) !=
SFX_FILTER_OPENREADONLY)
{ display this filter in save / saveas dialog}
(note: I also saw a function isReadOnly() or something like this that
could be called on filter objects, returning true / false. Is probably
even better...)

I do not think there are currently READONLY filters, but basically, I
think this is a bug not taking this flag into account. And so in one go
all problem solved in switching the binfilter to READ-ONLY. If someone
could help me for this part...

Finaly, at saving, this work like this:
(valid for StarOffice format... beware, other format, other paths)

SfxObjectShell::PreDoSaveAs_Impl(param) in libs-core
SfxObjectShell::SaveTo_Impl(param) for ExporTo in libs-core
SfxObjectShell::PreDoSaveAs_Impl(param)
SfxObjectShell::SaveTo_Impl(param) 2  in sfx2_objstor.cxx
SfxObjectShell::SaveAsOwnFormat( param) in sfx2_objstor.cxx
SfxObjectShell::SaveAs(param) in sfx2_objstor.cxx
SfxObjectShell::SaveInfoAndConfig_Impl(param2)
BasicManager::Store(param)
BasicManager::Store(param2)
BasicLibInfo::Store(param)
StgWriter::Write (param)
Sw3Writer::WriteStorage()
Sw3IO::SaveAs
Sw3IO::Save
ExportTo is finished and has returned

with the ExportTo function going "magically" to the binfilter module. I
did not understood what I read there, with the uno part...

Until (and with) the function BasicLibInfo::Store(param), this the
common part of binfilter for all modules. Then it splits to writer,
calc,...

At opening with read-write filter, some of these write functions are
called (for the lock file). With a read-only filter, this does not
happens. At opening, there is also the dark magic call (:- (  through
uno to go through the different filters one by one for generating them....


So how to go ahead?

Here I am asking you:
- is it OK to go ahead with this idea?
- should I make a feature/StarOffice-read-only branch ?
- could someone (help me) implement the sorting in order to ensure that
read-only filters are not available for Save / Save As?

Of course, if going ahead on this way, I will search the code in order
to find the right place for activating the SFX_FILTER_OPENREADONLY flag
as property for the filter, not using this hack....hopefully

Thanks for your feed-backs
Regards
Pierre-André