common/common.c: compareprocname(): Linux /proc/X/exe pseudo-symlink can end with "(deleted)"…

[jimklimov]

…if the program was removed or replaced, breaking detection that a PID describes a running copy of our program

Before this fix, the running process was not detected and signaled (e.g. for config reload):

:; ./server/upsd -DDDDDD -c reload
Network UPS Tools upsd 2.8.3.544.37-581+gbc306fb5a (development iteration after 2.8.3)
   0.000000     [D3] getprocname: /proc is an accessible directory, investigating
   0.000021     [D3] getprocname: located symlink for PID 3245141 at: /proc/3245141/exe
   0.000032     [D1] getprocname: determined process name for PID 3245141: /usr/local/ups/sbin/upsd (deleted)
   0.000037     [D1] compareprocname: did not find any match of program names for PID 3245141 of '/usr/local/ups/sbin/upsd (deleted)'=>'upsd (deleted)' and checked 'upsd'=>'upsd'
   0.000050     [D3] getprocname: /proc is an accessible directory, investigating
   0.000065     [D3] getprocname: located symlink for PID 3253997 at: /proc/3253997/exe
   0.000074     [D1] getprocname: determined process name for PID 3253997: /usr/local/src/nut-pve/server/upsd
   0.000079     [D1] compareprocname: did not find any match of program names for PID 3245141 of '/usr/local/ups/sbin/upsd (deleted)'=>'upsd (deleted)' and checked '/usr/local/src/nut-pve/server/upsd'=>'upsd'
   0.000083     [D1] sendsignalpid: ran at least one check, and all such checks found a process name for PID 3245141 and failed to match: found procname='/usr/local/ups/sbin/upsd (deleted)', expected progname='upsd' (res=0), current progname='/usr/local/src/nut-pve/server/upsd' (res=0)
   0.000086     Tried to signal PID 3245141 which exists but is not of expected program 'upsd' nor current '/usr/local/src/nut-pve/server/upsd'
   0.000090     [D1] Just failed to send signal, no daemon was running
   0.000093     Failed to signal the currently running daemon (if any)
   0.000095     Try 'systemctl reload nut-server.service' or add '-P $PID' argument

With this fix:

:; ./server/upsd -DDDDDD -c reload
Network UPS Tools upsd 2.8.3.544.1-545+gc504cc2f86 (development iteration after 2.8.3)
   0.000000     [D3] getprocname: /proc is an accessible directory, investigating
   0.000029     [D3] getprocname: located symlink for PID 3245141 at: /proc/3245141/exe
   0.000043     [D1] getprocname: determined process name for PID 3245141: /usr/local/ups/sbin/upsd (deleted)
   0.000051     [D2] compareprocname: re-evaluate the substring without a special tail: '/usr/local/ups/sbin/upsd (deleted)'=>'/usr/local/ups/sbin/upsd'
   0.000062     [D1] compareprocname: case-sensitive base name hit for PID 3245141 of '/usr/local/ups/sbin/upsd'=>'upsd' and checked 'upsd'=>'upsd'
   0.000066     [D1] compareprocname: original program file of running PID 3245141 named '/usr/local/ups/sbin/upsd (deleted)' was removed or replaced, but matches our 'upsd'
   0.000080     [D1] Signaled old daemon OK

journalctl>
Jul 16 23:16:22 pve nut-server[3245141]: mainloop: Interrupted system call
Jul 16 23:16:22 pve nut-server[3245141]: SIGHUP: reloading configuration
Jul 16 23:16:22 pve nut-server[3245141]: Applying DEBUG_MIN 6 from upsd.conf
...

[AppVeyorBot]

✅ Build nut 2.8.3.3367-master completed (commit d5698dc63a by @jimklimov)