[lug] A head scratcher for your weekend

Sun May 20 17:46:41 MDT 2018

I've tried strace. It did show something wierd, were it found the 
library, and then kept searching other locations for it till it failed. 
I also symlinked it from the last location it searched, but it still 
failed with a file not found. I don't see any smoking gun here:
openat(AT_FDCWD, "/usr/lib/libQt5Core.so.5", O_RDONLY|O_CLOEXEC) = 3
read(3, 
"\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0 at g\t\0\0\0\0\0"..., 832) 
= 832
lseek(3, 5167904, SEEK_SET)             = 5167904
read(3, 
"\4\0\0\0\20\0\0\0\1\0\0\0GNU\0\0\0\0\0\3\0\0\0\21\0\0\0\0\0\0\0", 32) = 32
close(3)                                = 0
writev(2, [{iov_base="programs/mythbackend/mythbackend", iov_len=32}, 
{iov_base=": ", iov_len=2}, {iov_base="error while loading shared 
libra"..., iov_len=36}, {iov_base=": ", iov_len=2}, 
{iov_base="libQt5Core.so.5", iov_len=15}, {iov_base=": ", iov_len=2}, 
{iov_base="cannot open shared object file", iov_len=30}, {iov_base=": ", 
iov_len=2}, {iov_base="No such file or directory", iov_len=25}, 
{iov_base="\n", iov_len=1}], 10) = 147
exit_group(127)                         = ?
+++ exited with 127 +++

Isn't ltrace for running processes, or am I mistaken?

At this point I'm backing things up and looking at reloading the system.
-Matt

On 05/20/2018 05:08 PM, Davide Del Vento wrote:
> Have you tried strace and/or ltrace? Lots of output you'll need to
> sift (grep) through, but you should be able to get some more clues if
> not the solution...
> 
> On Sun, May 20, 2018 at 7:43 AM, Matt Bidwell <mbidwell at gmail.com> wrote:
>> Shouldn't be, but it got me to thinking about Apparmor. So I disabled that
>> in grub and rebooted. Unfortunately, still no progress. -Matt
>>
>> On 05/19/2018 08:36 PM, stimits at comcast.net wrote:
>>>
>>> Maybe SElinux?
>>> ----- Original Message -----
>>> From: Matt Bidwell <mbidwell at gmail.com>
>>> To: lug at lug.boulder.co.us
>>> Sent: Sat, 19 May 2018 22:26:11 -0000 (UTC)
>>> Subject: Re: [lug] A head scratcher for your weekend
>>> Unfortunatly they both appear to be 64bit and there only is one version
>>> of libQt5Core.
>>> # file /usr/bin/mythbackend
>>> /usr/bin/mythbackend: ELF 64-bit LSB pie executable x86-64, version 1
>>> (GNU/Linux), dynamically linked, interpreter
>>> /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0,
>>> BuildID[sha1]=293e8e4f8ef60e3a1d9a0133b50070cc837d008c, stripped
>>> # file /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.10.1
>>> /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.10.1: ELF 64-bit LSB shared
>>> object x86-64, version 1 (GNU/Linux), dynamically linked, interpreter
>>> /lib64/ld-linux-x86-64.so.2,
>>> BuildID[sha1]=29089e33a2458624bd5d495a5698237fedaa2a91, for GNU/Linux
>>> 3.17.0, stripped
>>>
>>> LD_LIBRARY_PATH was low hanging fruit that I already checked out
>>> leaving...
>>> RPATH and RUNPATH which I'm less sure how to hunt down.
>>> #readelf --dynamic /usr/bin/mythbackend | grep PATH
>>> returns nothing but web examples show me that I should get both a hit on
>>> RPATH and RUNPATH.
>>> Thanks for the response.
>>> On 05/19/2018 06:29 AM, Davide Del Vento wrote:
>>>   > Often a 32 vs 64 bit causes this problem. Try
>>>   >
>>>   > file /usr/bin/mythbackend
>>>   >
>>>   > file /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.10.1
>>>   >
>>>   > and make sure they are both 64 bit (assuming that the directory name
>>>   > for libQt5Core.so is correct).
>>>   >
>>>   > Also check LD_LIBRARY_PATH, RPATH, RUNPATH and /etc/ld.so.conf and
>>>   > make sure there isn't another location with higher priority than
>>>   > /usr/lib/x86_64-linux-gnu/ containing a file called libQt5Core.so.5
>>>   > (which again, could have 32/64 bit mismatch or be a broken link or
>>>   > something).
>>>   >
>>>   > HTH
>>>   > Davide
>>>   >
>>>   > On Sat, May 19, 2018 at 5:28 AM, Matt Bidwell <mbidwell at gmail.com>
>>> wrote:
>>>   >> Library is installed, program can find other libraries in that
>>> directory.
>>>   >> Reinstalling or downgrading either the package or the library didn't
>>> fix
>>>   >> it.... What could have happened to my system?
>>>   >> # ls -alh /usr/lib/x86_64-linux-gnu/libQt5Core.so.5*
>>>   >> lrwxrwxrwx 1 root root 20 May 12 07:03
>>>   >> /usr/lib/x86_64-linux-gnu/libQt5Core.so.5 -> libQt5Core.so.5.10.1
>>>   >> lrwxrwxrwx 1 root root 20 May 12 07:03
>>>   >> /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.10 -> libQt5Core.so.5.10.1
>>>   >> -rw-r--r-- 1 root root 5.0M May 12 07:03
>>>   >> /usr/lib/x86_64-linux-gnu/libQt5Core.so.5.10.1
>>>   >>
>>>   >> ldd /usr/bin/mythbackend
>>>   >> ...
>>>   >> libQt5Script.so.5 => /usr/lib/x86_64-linux-gnu/libQt5Script.so.5
>>>   >> (0x00007f4eb42f8000)
>>>   >> libQt5Core.so.5 => not found
>>>   >> libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0
>>>   >> (0x00007f4eb40d8000)
>>>   >> ...
>>>   >>
>>>   >> This is very perplexing.
>>>   >> _______________________________________________
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>>>
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>>
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> _______________________________________________
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