On Tue, Mar 20, 2018 at 02:05:28PM -0700, Steve Langasek wrote:
> On Tue, Mar 20, 2018 at 11:59:28AM +0200, Peter Pentchev wrote:
> > Unfortunately, this patch is not moving in the right direction.  These
> > tests preload a library that is built as part of the mbuffer build that
> > intercepts open() and write() calls (among others) and simulates
> > changing tape devices; basically it splits the mbuffer output into
> > several files.  This is the reason why on amd64 there are many
> > output-test4.* and output-test5.* files - there should not be a single
> > output-test4 file, there should be output-test4.000001 and so on files.
> > So the test failure means that the tapetest.so object is not being
> > preloaded correctly or that it fails to intercept the necessary libc
> > calls.
> 
> > Sounds like I'll need to spin up a couple of VMs and see what's what.
> 
> > Thanks again for your work on this and Debian and Ubuntu in general!
> 
> Ah, ok.  Now that I understand the purpose, I can see why it's broken:
> 
> $ objdump -T /usr/lib/arm-linux-gnueabihf/mbuffer/tapetest.so |grep open
> 00000780 g    DF .text  000000e4  Base        open
> 0001100c g    DO .bss   00000004  Base        opencount
> $ objdump -T /usr/bin/mbuffer |grep open
> 00000000      DF *UND*  00000000  GLIBC_2.4   open64
> 00000000      DF *UND*  00000000  GLIBC_2.7   __open64_2
> $
> 
> mbuffer is quite reasonably built with LFS support on all archs, which means
> that, on 32-bit architectures in particular, the shim for open() does not
> match the actual function called by mbuffer.

Yep, this was my first suspicion; thanks for confirming it!  I'll try to
come up with a fix soon.

> So the tapetest shim is broken on these architectures.  My patch is
> definitely the wrong way to fix this, but if 'tapetest' is indeed simply a
> test library, I don't think I have broken the mbuffer package in Ubuntu by
> (effectively) skipping this test.

Right, sorry that I forgot to mention this.  Yes, if mbuffer passes
the other tests, it is highly unlikely that it's broken.

G'luck,
Peter

-- 
Peter Pentchev  r...@ringlet.net r...@freebsd.org p...@storpool.com
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