Possible 26bit CLib issue

I’m not sure what the exact issue is here, but FTPc 1.56 running under RISC OS 3.11 fails to display the User choices menu with a recent Clib loaded.

I’ve gone back through the CLib builds I have to hand and the problem does not occur on CLib 6.04, but does on 6.07. I do not have 6.05 or 6.06 to narrow it to the specific build.

6.05 – no longer messes with the M32 flag in the abort handler (as it no longer means 26/32 bit, it means 32/64 bit and, well, that’s not how it’s done ;) ).

6.05 – two changes in rlib sprite stuff for Paint (this is RISC_OSLib).

6.06 – better support of scrollwheel requests in txtar (Edit, SrcEdit…; this also is RISC_OSLib).

6.07 – various changes because MSR returns bogus values for devices that don’t support ARM32 privileged mode.

Nothing there sounds particularly culpritish. I mean, I’d say the most likely would be the 6.07 stuff, except that it occurs in stubs in two places – _kernel_entrypoint and _kernel_moduleentry. Which are unlikely to make a random window vanish.

Here are 4 modules [withdrawn] to try out. As Rick says there’s not much happening around there that directly implicates menus.

Thanks Rob, the problem starts with 6.05.

I don’t suspect it’s a menu issue, my initial thought was something file related – C flag corruption on OS_GBPB perhaps? Hard to tell what’s going on without the FTPc source code.

Could be a hidden bug in FTPc for all I know!

Thanks Rob, the problem starts with 6.05.
I don’t suspect it’s a menu issue, my initial thought was something file related – C flag corruption on OS_GBPB perhaps? Hard to tell what’s going on without the FTPc source code.

I’ve been happily using FTPc 1.55 and SharedCLibrary 6.13 in a 26 bit config on a Risc PC without anything odd menus-wise. There were 4 key additions in 6.05 so I’ve built the 4 intermediates [withdrawn] to try. There’s really only 3 since one only affected header files, but might as well do all four for completeness.

I’m getting a 404 trying to download CLib2.zip

@Jon: I have just downloaded it ok … but the name is clibs2.zip (with an s)

Thanks, it’s 6.05c where the problem starts.

Thanks, it’s 6.05c where the problem starts.

OK, going on a hunch it might be the addition of aligned memory allocation I’ve narrowed it down a bit. The odd thing was the difference between a working and non working CLib was only in the allocation which corresponds to supervisor mode malloc or free which didn’t make much sense given FTPc is an application.

Then the penny dropped: it’s a toolbox application so the menus are handled by the Menu module which does run in supervisor mode, and that reminded me of something I’d seen on my travels that something about realloc was broken in RISC OS 3.10 and various things carry their own implementation.

That’s fine, except you can’t mix and match; either use your own for everything or use the C library for everything.

As a quick proof of concept I’ve changed the toolbox library to use the C library for everything. Now, the resulting Menu module [withdrawn] seems happy with FTPc again. Do you see that?

I’d seen on my travels that something about realloc was broken in RISC OS 3.10

Aha, did a lot of searching, and finally came across this in the library Blacklog.

Version: 4.44 Thu 20-Feb-92        ENevill                       

Bug fix:     _kernel_RMAextend previously freed the block it had just
             extended by falling through to _kernel_RMAfree.

So one doesn’t use realloc in module code on a 3.10 machine with the original CLib…

I have a suspicion that I ran into this myself a long long time ago, but since updated versions of CLib came regularly on the cover discs, it was easily worked around.

Now, the resulting Menu module seems happy with FTPc again. Do you see that?

I can confirm the revised Menu does indeed fix FTPc with the latest CLib.

Is your proof of concept something you can roll into PlingSystem without impacting current RO builds?

I can confirm the revised Menu does indeed fix FTPc with the latest CLib.
Is your proof of concept something you can roll into PlingSystem without impacting current RO builds?

What I couldn’t fathom is how it worked fine on a Risc PC (26 bit, same CLib, same version of FTPc) but not on RISC OS 3.10. Then I noticed some macro foo which revealed it wasn’t calling the well known ANSI functions but actually a Toolbox_Memory SWI. In turn that revealed that if a Dynamic Area call fails it falls back to the RMA and so that’s why it differs.

I think all that’s needed, based on Rick’s archaeology, is to check for 4.44 and call realloc directly. Anything with dynamic areas is already not taking that code path.

Searching, Menu and Window are the only two bits of the toolbox affected, so they’d both get fixed as a result, and the fix would apply to all uses (not PlingSystem specific).

Menu and Window are the only two bits of the toolbox affected, so they’d both get fixed as a result, and the fix would apply to all uses (not PlingSystem specific)

Aforementioned modules with proper fix applied. These should work fine regardless of CLib version and whether or not dynamic areas are available in 26 or 32 bit configs.

This problem appears to have resurfaced with Menu 0.41 from the latest PlingSystem. Rolling back to Menu 0.40 does get the FTPc User choices menu working again.

This problem appears to have resurfaced with Menu 0.41 from the latest PlingSystem. Rolling back to Menu 0.40 does get the FTPc User choices menu working again

The problem hasn’t resurfaced per-se, since I never submitted the changes. If you look 1 message earlier in the thread you’re replying to you’ll see a trio of modules waiting to be tested – but nobody’s mentioned testing them or told me if they worked.

If you look 1 message earlier in the thread you’re replying to you’ll see a trio of modules waiting to be tested – but nobody’s mentioned testing them or told me if they worked.

I confirmed your fix worked above:

I can confirm the revised Menu does indeed fix FTPc

I then assumed from your follow up message that the fix had been applied:

Aforementioned modules with proper fix applied

Would you like me to retest a patched Menu 0.41 so you can submit the change?

Aforementioned modules with proper fix applied

Ah, no, by “proper fix” I meant “fix done properly rather than hacking around at the Menu module”. 0 lines of Menu source code are changed as the root cause is in some shared memory management elsewhere. Subsequently you’ve been lured onto the rocks by the sight of a beautiful new version of Menu, but that’s actually unrelated work and purely coincidental.

Would you like me to retest a patched Menu 0.41 so you can submit the change?

For completeness I’ve rebuilt the trio of modules to test (same link) – please test those 3 together and if they look good I can submit the changes to ROOL.

please test those 3 together and if they look good I can submit the changes to ROOL

They look good to me, the FTPc menu is appearing with all three installed over a PlingSystem update from a few days ago.

Spoke too soon – just spotted a new issue with the patched Menu 0.41.

If you right click on a remote file and then try to bring up the sub-menu to rename it – the menu doesn’t appear.

If you right click on a remote file and then try to bring up the sub-menu to rename it – the menu doesn’t appear.

I think that’s a new/different bug introduced in 0.41 – it also doesn’t work on RISC OS 5; the top level menu just shimmers as though being opened/closed really quickly. Let’s just change one thing at once then, here are a trio with only the memory allocation changes.

here are a trio with only the memory allocation changes

Yes, they look good to me.