[Pacemaker] reliable way to cib SEGFAULT -- how is cibadmin -Q --xpath supposed to work?

[Andrew Beekhof]

On Wed, Jun 3, 2009 at 6:10 PM, Lars Ellenberg
<lars.ellenberg at linbit.com> wrote:
>
> current mercurial pacemaker stable-1.0
>
> do
> cibadmin -Q --xpath //@id
> and watch your cib segfault:
> WARN: Managed /usr/lib/heartbeat/cib process 15295 killed by signal 11 [SIGSEGV - Segmentation violation]

crap :-(

try something like:

 cibadmin -Q --xpath '//nvpair[@id="something"]'

>
> :)
>
> (gdb) bt
> #0  0x40280a8b in xmlAddChild () from /usr/lib/libxml2.so.2
> #1  0x40031828 in add_node_copy (parent=0x80b6c10, src_node=0x8101720) at xml.c:266
> #2  0x40051c64 in cib_process_xpath (op=0x806a068 "cib_query", options=2, section=0x80ffe68 "//@id", req=0x8115bf0, input=0x0, existing_cib=0x8115d98, result_cib=0xbfd1d198, answer=0xbfd1d19c) at cib_ops.c:938
> #3  0x4004ebb4 in cib_process_query (op=0x806a068 "cib_query", options=2, section=0x80ffe68 "//@id", req=0x8115bf0, input=0x0, existing_cib=0x8115d98, result_cib=0xbfd1d198, answer=0xbfd1d19c) at cib_ops.c:49
> #4  0x400531c1 in cib_perform_op (op=0x806a068 "cib_query", call_options=2, fn=0x805c8d4, is_query=1, section=0x80ffe68 "//@id", req=0x8115bf0, input=0x0, manage_counters=0, config_changed=0xbfd1d188, current_cib=0x8115d98, result_cib=0xbfd1d198, diff=0x0, output=0xbfd1d19c)
>    at cib_utils.c:539
>
> blah blah.
>
> problem: the result is an attribute node, and gets added to the properties
> field of the querry-result node on first match,
> the next match will segfault out somewhere.
>
> for only one match, I simply get an empty answer from cibadmin, no segfault.
>
> now, why do I want to do that.
> lets say I have the IP, and want to know the xml id of the IPaddr2 primitive
> that handles this IP.
>
> (yes, of course, you are right.  actually I do not care about the IPaddr2, but
>  want to deduce the master id from a given drbd resource name.
>  but lets stay with the IP example for now.)
>
> cibadmin -Q --xpath '//primitive[@type="IPaddr2" and instance_attributes/nvpair [@name = "ip" and @value="10.0.0.1"]]'
>
> fine.  I can sed the id out from there.
> but I'd like to just do
> cibadmin -Q --xpath '//primitive[@type="IPaddr2" and instance_attributes/nvpair [@name = "ip" and @value="10.0.0.1"]]/@id'
> (which, unfortunately, is empty).
>
> according to xmllint, my xpath query is correct, however:
>
> cat > tmp.xml <<___
> <cib>
>  <configuration>
>    <resources>
>      <primitive class="ocf" id="ip_try3" provider="heartbeat" type="IPaddr2">
>        <instance_attributes id="ip_try3-instance_attributes">
>          <nvpair id="ip_try3-instance_attributes-ip" name="ip" value="10.0.0.1"/>
>        </instance_attributes>
>      </primitive>
>    </resources>
>  </configuration>
> </cib>
> ___
>
>
> xmllint --shell tmp.xml <<<'ls //@id'
> / > ls //@id
> tan        7 ip_try3
> t--       27 ip_try3-instance_attributes
> t--       30 ip_try3-instance_attributes-ip
> / >
>
> xmllint --shell tmp.xml <<<'ls //primitive[@type="IPaddr2" and instance_attributes/nvpair[@name = "ip" and @value="10.0.0.1"]]/@id'
> / > ls //primitive[@type="IPaddr2" and instance_attributes/nvpair[@name = "ip" and @value="10.0.0.1"]]/@id
> tan        7 ip_try3
> / >
>
> --
> : Lars Ellenberg
> : LINBIT | Your Way to High Availability
> : DRBD/HA support and consulting http://www.linbit.com
>
> DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
>
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>



-- 
-- Andrew