[Libreoffice-bugs] [Bug 142391] New: Use binary image format 0x13 only when necessary, to allow compatibility with other suites

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=142391

            Bug ID: 142391
           Summary: Use binary image format 0x13 only when necessary, to
                    allow compatibility with other suites
           Product: LibreOffice
           Version: 5.0.3.2 release
          Hardware: All
                OS: All
            Status: UNCONFIRMED
          Keywords: difficultyInteresting, easyHack, skillCpp
          Severity: normal
          Priority: medium
         Component: BASIC
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: mikekaganski at hotmail.com
            Blocks: 107659

https://bz.apache.org/ooo/show_bug.cgi?id=64377 took great effort to assure
compatibility when using new large image (binary format 0x12 - see
basic/source/inc/filefmt.hxx). Every OOo, LO and AOO versions since 2006 can
use that format without problems. This had prepared grounds to finally start
using this binary format in ODF, allowing to remove the limitation of module
size in password-protected libraries.

However, LibreOffice now uses incompatible binary format 0x13, which was
introduced in version 5.0.3 and 5.1 in tdf#94617. Since 5.2 (tdf#87530), that
format is written into ODF. This makes the image unusable for any other suite.

The proposal here is only use binary format 0x13 when actually needed, i.e.
when there are methods starting at an offset that would overflow 16 bits, and
use format 0x12 in other cases. That would make the resulting binary compatible
with ~100% OOo derivatives used today *wherever possible* (and when there is
such a method that requires use of format 0x13, use of incompatible format
would be justified, since such a module would be impossible to use in those
versions/derivatives anyway).

The warning that appears when saving such a module should explicitly mention
compatibility issues.

See also tdf#92620.

The code pointers are in the related change
https://git.libreoffice.org/core/+/ddb45261590939d884ac2bcb1fd258de7b2370da
that introduced 0x13.


Referenced Bugs:

https://bugs.documentfoundation.org/show_bug.cgi?id=107659
[Bug 107659] [META] Macro bugs and enhancements
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