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<p class="MsoNormal">Hi <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’m using 4.3.30 and I’m experiencing core dumps on some servers using the directory directive in hosts.cfg. The contents of my directory sometimes change and this sometimes leads to a core dump.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In hosts.cfg I have:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">directory /home/xymon/server/etc/include_xxxxx/xxxxx/<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">this directory contains one file per host which contain something like this:<o:p></o:p></p>
<p class="MsoNormal">0.0.0.0 a_unique_name # noconn NOCOLUMNS:conn,info,trends nonongreen<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">A cron job adds/removes files from this directory periodically, however, the directory should contain at least one file at all times.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">It’s been a long time since I did any C but I think I’ve been able to track this down a bit with gdb and --debug on xymond. Here’s some xymond debug output:<br>
<br>
<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.037113 File /home/xymon/server/etc/include_xxxxx/xxxxx//xxxxxxxxx new timestamp<o:p></o:p></p>
<p class="MsoNormal">16223 2021-11-03 12:08:45.037136 -> save_checkpoint<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.037218 Opening file /home/xymon/server/etc/hosts.cfg<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.040573 Opening file /home/xymon/server/etc/include_xxxxx/xxxxx//xxxxxxxxxx<br>
.. (opens all the files)<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047109 -> handle_dropnrename<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047128 -> posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047144 Posting message 13651 to 1 readers<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047155 <- posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047159 -> posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047168 Posting message 4683 to 1 readers<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047176 <- posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047179 -> posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047188 Posting message 1367 to 1 readers<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047195 <- posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047199 -> posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047207 Posting message 1905 to 1 readers<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047214 <- posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047218 -> posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047221 Dropping message - no readers<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047225 -> posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047228 Dropping message - no readers<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047232 -> posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047240 Posting message 785 to 1 readers<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047247 <- posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047251 -> posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047259 Posting message 6 to 1 readers<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047266 <- posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047269 -> posttochannel<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047273 Dropping message - no readers<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047287 -> free_log_t<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047300 <- free_log_t<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047308 <- handle_dropnrename<o:p></o:p></p>
<p class="MsoNormal">5315 2021-11-03 12:08:45.047312 -> handle_dropnrename<o:p></o:p></p>
<p class="MsoNormal">16223 2021-11-03 12:08:45.240284 <- save_checkpoint<o:p></o:p></p>
<p class="MsoNormal">2021-11-03 12:09:00.061085 Whoops ! Failed to send message (timeout)<o:p></o:p></p>
<p class="MsoNormal">2021-11-03 12:09:00.061303 -><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">On the last handle_dropnrename, the core dump occurs:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Program terminated with signal 6, Aborted.<o:p></o:p></p>
<p class="MsoNormal">#0 0x00007f39f751e387 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:55<o:p></o:p></p>
<p class="MsoNormal">55 return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig);<o:p></o:p></p>
<p class="MsoNormal">(gdb) bt<o:p></o:p></p>
<p class="MsoNormal">#0 0x00007f39f751e387 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:55<o:p></o:p></p>
<p class="MsoNormal">#1 0x00007f39f751fa78 in __GI_abort () at abort.c:90<o:p></o:p></p>
<p class="MsoNormal">#2 0x0000000000415f63 in sigsegv_handler (signum=<optimized out>) at sig.c:57<o:p></o:p></p>
<p class="MsoNormal">#3 <signal handler called><o:p></o:p></p>
<p class="MsoNormal">#4 __strlen_sse2_pminub () at ../sysdeps/x86_64/multiarch/strlen-sse2-pminub.S:38<o:p></o:p></p>
<p class="MsoNormal">#5 0x000000000040a5ac in handle_dropnrename (cmd=cmd@entry=CMD_DROPSTATE, sender=sender@entry=0x425e3c "xymond", hostname=0x0, n1=n1@entry=0x0, n2=n2@entry=0x0) at xymond.c:2511<o:p></o:p></p>
<p class="MsoNormal">#6 0x0000000000403eb1 in main (argc=<optimized out>, argv=<optimized out>) at xymond.c:5702<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What is interesting is that handle_dropnrename appears to be passed an empty hostname or null pointer if I understand gdb correctly.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In handle_dropnrename strlen is called on hostname and I think this causes the core dump? (xymond.c line 2511):<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> char *msgbuf = (char *)malloc(20 + strlen(hostname) + (n1 ? strlen(n1) : 0) + (n2 ? strlen(n2) : 0))<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I _<i>think</i>_ handle_dropnrename is being called around line 5700 of xymond.c:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> else if (hostinfo(hwalk->hostname) == NULL) {<o:p></o:p></p>
<p class="MsoNormal"> /* Remove all state info about this host. This will NOT remove files. */<o:p></o:p></p>
<p class="MsoNormal"> handle_dropnrename(CMD_DROPSTATE, "xymond", hwalk->hostname, NULL, NULL);<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What am I doing wrong <span style="font-family:"Segoe UI Emoji",sans-serif">
😊</span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-GB">Zak </span><span style="mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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