Marc Fournier [Mon, 1 Dec 2014 08:07:30 +0000 (09:07 +0100)]
cpu: remove legacy assignment to undefiend variable
This finishes up the cleanup done by
f7100301fa. It also fixes #828
(build error on Mac OS).
Many thanks to @njh for pointing that out !
Marc Fournier [Mon, 24 Nov 2014 08:18:44 +0000 (09:18 +0100)]
Merge branch 'collectd-4.10' into collectd-5.3
Marc Fournier [Wed, 19 Nov 2014 16:49:30 +0000 (17:49 +0100)]
Revert "Let snmp_synch_response deal with PDU freeing"
This reverts commit
e767dc103a142e1c57800f06a9c384f21a48aef5.
The proper fix to this issue is in the collectd-4.10 branch. See also
79e90bba.
Marc Fournier [Wed, 19 Nov 2014 16:54:09 +0000 (17:54 +0100)]
snmp: avoid freeing req under normal operation
Equivalent patch to
79e90bba5, to avoid issue #804 introduced while
fixing #610.
Pierre-Yves Ritschard [Wed, 19 Nov 2014 15:00:54 +0000 (16:00 +0100)]
Let snmp_synch_response deal with PDU freeing
When reading from tables, upon errors the PDUs sent are already
freed by snmp_synch_response since they are right after
snmp_send is called.
This commit syncs collectd's approach with other occurences of
snmp_synch_response calls.
There might be a few corner cases where we leak PDUs, but it
is unclear how to check for those since we would need to
have an indication that snmp_send was never called, which
as far as I can tell is not possible.
The potential for failure in snmp_send is rather low and will
be easily spotted though, since when crafting invalid PDUs
snmp send will constantly fail and since valid configurations
can never leak memory.
This fixes #804
Pierre-Yves Ritschard [Sat, 15 Nov 2014 14:45:00 +0000 (15:45 +0100)]
Merge pull request #796 from mfournier/write_redis-colon-mistake
write_redis: re-add colon dropped in
b7984797 + manpage
Bjørn Nordbø [Wed, 12 Nov 2014 11:27:43 +0000 (12:27 +0100)]
Link aggregation.so to libm.so
Conflicts:
src/Makefile.am
Pierre-Yves Ritschard [Tue, 11 Nov 2014 18:39:58 +0000 (19:39 +0100)]
Merge pull request #765 from tokkee/sh/write-err
Use the complain mechanism to report write failures.
Vincent Bernat [Fri, 7 Nov 2014 14:20:22 +0000 (15:20 +0100)]
network: don't enable gcrypt thread callbacks when gcrypt recent enough
From `gcrypt.h`:
> NOTE: Since Libgcrypt 1.6 the thread callbacks are not anymore used.
> However we keep it to allow for some source code compatibility if used
> in the standard way.
Otherwise, we get a deprecation warning which is turned into an error:
```
CC libcollectdclient_la-network_buffer.lo
../../../src/libcollectdclient/network_buffer.c:58:15: error: 'gcry_thread_cbs' is deprecated (declared at /usr/include/gcrypt.h:213) [-Werror=deprecated-declarations]
GCRY_THREAD_OPTION_PTHREAD_IMPL;
```
Fixes: #632
Marc Fournier [Tue, 11 Nov 2014 10:39:40 +0000 (11:39 +0100)]
add write_redis to manpage
Marc Fournier [Sat, 8 Nov 2014 23:16:11 +0000 (00:16 +0100)]
write_redis: re-add colon dropped in
b7984797
When running
f3706b0b87, the following command gets sent to redis:
"ZADD" "collectd/hostname/entropy/entropy" "
1415487432.000000" "
1415487432:932"
Meaning the value actually stored, and later returned by redis is:
"<timstamp>:<value>".
b7984797 accidentally dropped the comma separating the timestamp and the
value, which leads the plugin to store a somewhat confusing value in
redis:
"ZADD" "collectd/hostname/entropy/entropy" "
1415487432.000000" "
1415487432932"
Pierre-Yves Ritschard [Tue, 4 Nov 2014 16:41:38 +0000 (17:41 +0100)]
Merge pull request #764 from tokkee/sh/collectd-5.3
write_graphite plugin: Improved error reporting when connecting to the server.
Katelyn Perry [Mon, 3 Nov 2014 23:11:14 +0000 (17:11 -0600)]
fix grammar in plugin loading error message
"cause for this problem are" => "cause for this problem is"
Marc Fournier [Tue, 24 Jun 2014 15:47:08 +0000 (17:47 +0200)]
logfile: avoid total silence in case of a misconfiguration
Basically the same patch that was applied to syslog.c in
84c38056
Marc Fournier [Tue, 24 Jun 2014 15:48:26 +0000 (17:48 +0200)]
correct typo in error message
Wilfried Goesgens [Sat, 7 Jun 2014 10:01:32 +0000 (12:01 +0200)]
Syslog: if we can't find the loglevel specified by the configuration string default to 'info' and warn about the unknown configuration option. no way to make syslog totaly silent anymore.
Sebastian Harl [Sun, 19 Oct 2014 18:25:50 +0000 (20:25 +0200)]
Use the complain mechanism to report write failures.
This ensures that we don't spam the log for each submitted value. Instead, an
exponential backup is used to report permanent errors starting at one message
per second.
Sebastian Harl [Sun, 19 Oct 2014 16:22:09 +0000 (18:22 +0200)]
write_graphite plugin: Improved error reporting when connecting to the server.
Scott Sanders [Fri, 19 Sep 2014 14:31:18 +0000 (10:31 -0400)]
Bit shift right by 8 to get return code from exit status
Pull-Request: #741
Signed-off-by: Florian Forster <octo@collectd.org>
Florian Forster [Wed, 17 Sep 2014 06:24:57 +0000 (08:24 +0200)]
cpu plugin: Remove temperature code for Mac OS X.
This code would throw an error for some systems, because the temperature
couldn't be read. Since the plugin still works in general, this was very
confusing to users. Becaus the temperature, even when read sucessfully, was
never dispatched, remove the code entirely. We might want to add this back to
the apple_sensors plugin eventually.
Fixes: #22
Florian Forster [Wed, 17 Sep 2014 05:41:38 +0000 (07:41 +0200)]
swap plugin: Make "cached" optional under Linux.
This is the smallest possible fix for OpenVZ, where cached is not available.
master has a more complete fix which should be used going forward.
Fixes: #733
Vladimir Smirnov [Wed, 10 Sep 2014 19:08:50 +0000 (21:08 +0200)]
Fix typo in if caluse
Fixes #729
Signed-off-by: Florian Forster <octo@collectd.org>
Florian Forster [Wed, 10 Sep 2014 14:54:26 +0000 (16:54 +0200)]
src/common.c: Fix strstripnewline().
Because the length of the string was decremented too late, the function
would actually overwrite the trailing null byte instead of the newline.
Marc Fournier [Mon, 8 Sep 2014 14:59:30 +0000 (16:59 +0200)]
RPM specfile: enable netlink plugin on RHEL > 5
Marc Fournier [Mon, 8 Sep 2014 14:42:14 +0000 (16:42 +0200)]
RPM specfile: fix bogus dates
modern rpmbuild versions appear to be more strict on this point.
Marc Fournier [Mon, 8 Sep 2014 14:41:21 +0000 (16:41 +0200)]
RPM specfile: support for RHEL7
Marc Fournier [Mon, 8 Sep 2014 12:12:51 +0000 (14:12 +0200)]
RPM specfile: add missing %files section for modbus plugin
complement to
a781eb2c5
Marc Fournier [Mon, 8 Sep 2014 10:26:55 +0000 (12:26 +0200)]
RPM specfile: remove duplicate modbus block
Florian Forster [Sat, 6 Sep 2014 08:58:45 +0000 (10:58 +0200)]
network plugin: Improve client connecting behavior.
This moves the socket creation logic so it's called from
networt_send_buffer_plain(). This allows us to recover after network
failures or when collectd was started before the network was available.
Fixes: #627
Florian Forster [Wed, 3 Sep 2014 07:10:00 +0000 (09:10 +0200)]
src/utils_match.[ch]: Implement match_value_reset().
This is called from the curl and memcachec plugins. Previously, gauge
average, minimum and maximum values were calculated since the start of
the daemon, rather than per-interval. This is not the documented
functionality.
Fixes: #663
Florian Forster [Wed, 3 Sep 2014 05:39:27 +0000 (07:39 +0200)]
curl plugin: Use the utility functions for config handling.
Florian Forster [Tue, 2 Sep 2014 17:51:37 +0000 (19:51 +0200)]
Merge remote-tracking branch 'github/collectd-5.3' into collectd-5.3
Florian Forster [Tue, 2 Sep 2014 17:50:47 +0000 (19:50 +0200)]
src/meta_data.c: If the meta_data_t is empty, avoid calling malloc(0).
Florian Forster [Tue, 2 Sep 2014 17:49:11 +0000 (19:49 +0200)]
src/utils_format_json.c: Handle empty meta_data_t gracefully.
Previously, `meta != NULL` and `keys_num == 0` was possible and would
result in "{}", which is not valid JSON.
Fixes: 716
Florian Forster [Tue, 2 Sep 2014 17:48:10 +0000 (19:48 +0200)]
python plugin: Don't create empty meta_data_t objects.
Fixes: #716
Florian Forster [Tue, 2 Sep 2014 14:54:07 +0000 (16:54 +0200)]
src/utils_rrdcreate.c: Free "args".
Thanks to Yves Mettier for pointing this out!
Fixes: #661
Marc Fournier [Fri, 29 Aug 2014 15:20:57 +0000 (17:20 +0200)]
RPM specfile: update changelog without incrementing release number
Florian Forster [Thu, 28 Aug 2014 18:55:45 +0000 (20:55 +0200)]
GenericJMXConfConnection: Remove unused imports.
Florian Forster [Thu, 28 Aug 2014 18:41:25 +0000 (20:41 +0200)]
java plugin: Make sure cjni_thread_detach() is called on all paths.
Each call to cjni_thread_attach() much be accompanied by
a call to cjni_thread_detach(). Some error handling cases were missing
the call, potentially locking the plugin up.
Kevin Bowling [Thu, 14 Aug 2014 09:30:45 +0000 (02:30 -0700)]
EL <6 provide perl-ExtUtils-Embed with base perl
Conflicts:
contrib/redhat/collectd.spec
Florian Forster [Mon, 18 Aug 2014 07:58:34 +0000 (09:58 +0200)]
collectd.conf: Fix default packet size of the network plugin.
Fixes: #710
Florian Forster [Mon, 18 Aug 2014 07:33:29 +0000 (09:33 +0200)]
Merge branch 'collectd-4.10' into collectd-5.3
Arthur Marble [Sun, 17 Aug 2014 22:34:04 +0000 (17:34 -0500)]
curl_xml plugin: Fixed tautological pointer comparison error.
Fixes: http://bugs.debian.org/758481
Signed-off-by: Florian Forster <octo@collectd.org>
Marc Fournier [Wed, 13 Aug 2014 07:09:14 +0000 (09:09 +0200)]
collectd.conf(5): add detail & example about multi-instance filterchain targets
Marc Fournier [Fri, 8 Aug 2014 13:55:10 +0000 (15:55 +0200)]
snmp: free snmp_pdu struct allocated by snmp_pdu_create()
This should fix the leak reported in issue #610.
Marc Fournier [Thu, 7 Aug 2014 12:32:47 +0000 (14:32 +0200)]
Merge pull request #689 from ymettier/ym/cd53_fix_tcpconns_inet_diag
Fix for 'linux/inet_diag.h: No such file or directory'
Marc Fournier [Wed, 6 Aug 2014 14:59:21 +0000 (16:59 +0200)]
RedHat RPM spec: add modbus plugin
... now that EPEL6 provides libmodbus
Yves Mettier [Mon, 4 Aug 2014 12:01:01 +0000 (14:01 +0200)]
Fix for 'linux/inet_diag.h: No such file or directory'
Marc Fournier [Mon, 4 Aug 2014 11:37:09 +0000 (13:37 +0200)]
fix: use DOUBLE_TO_CDTIME_T() to match input type
... as strtod() returns a double not a time_t.
Follow-up to
7d1d59fb to match what
ada80db25 does (currently in
master) and avoid a merge conflict.
KOMEDA Shinji [Wed, 30 Jul 2014 08:56:07 +0000 (17:56 +0900)]
mistake, SAVE_LIBS="$LIBS" is correct.
KOMEDA Shinji [Wed, 25 Jun 2014 13:34:15 +0000 (22:34 +0900)]
patch required to build oracle plugin, collectd-5.4.0 (#653)
Pierre-Yves Ritschard [Mon, 28 Jul 2014 20:48:17 +0000 (22:48 +0200)]
Merge pull request #579 from mfournier/libiptc-ldflags
link iptables plugin against flags from pkg-config
Sebastian Harl [Sun, 27 Jul 2014 12:15:23 +0000 (14:15 +0200)]
utils_vl_lookup: Fixed a race when creating user objects.
This could cause multiple aggregation instances to be created in the
aggregation plugin when first writing data to the plugin. This, in turn, led
to "value too old" warnings because subsequently all data was submitted twice.
Thanks to @faxm0dem for reporting this in GH #535.
Manuel Luis Sanmartín Rozada [Thu, 19 Jun 2014 14:37:15 +0000 (16:37 +0200)]
Plugin exec: change notification time to integer.
Acording to collectd-exec.5 NOTIFICATION DATA FORMAT: time is epoch, i. e. as seconds since 1970-01-01 00:00:00 UTC.
Manuel Luis Sanmartín Rozada [Thu, 19 Jun 2014 17:14:53 +0000 (19:14 +0200)]
cmd PUTNOTIF time option: handle double values.
Conflicts:
src/utils_cmd_putnotif.c
Manuel Luis Sanmartín Rozada [Thu, 19 Jun 2014 13:14:02 +0000 (15:14 +0200)]
Plugin java: fix notification time conversion to cdtime_t.
Manuel Luis Sanmartín Rozada [Thu, 19 Jun 2014 14:50:48 +0000 (16:50 +0200)]
Plugin threshold: time is not set in missing notifications.
Marc Fournier [Tue, 24 Jun 2014 15:09:08 +0000 (17:09 +0200)]
manpage: document 2 missing options to amqp plugin section
Marc Fournier [Mon, 23 Jun 2014 16:00:01 +0000 (18:00 +0200)]
add missing backticks which broke the build
Marc Fournier [Mon, 23 Jun 2014 14:47:20 +0000 (16:47 +0200)]
write_riemann: coding style consistency
Make the style in line with
50d1b34d6 (from master) and avoid later
merge conflict.
Lauri Tirkkonen [Thu, 22 May 2014 11:05:40 +0000 (14:05 +0300)]
don't assume pkg-config is in PATH
Wilfried Goesgens [Thu, 5 Jun 2014 18:04:13 +0000 (20:04 +0200)]
Configparser: when we alocate an empty list, we also need to reset the counter; else we will trip over this later.
This fixes https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=750440
txaj [Mon, 28 Apr 2014 16:28:41 +0000 (11:28 -0500)]
Add DeleteSocket option in synopsis of manpage
Signed-off-by: Florian Forster <octo@collectd.org>
Marc Fournier [Tue, 1 Apr 2014 22:22:34 +0000 (00:22 +0200)]
add brackets to the list of characters graphite chokes on
Pierre-Yves Ritschard [Fri, 24 Jan 2014 15:49:22 +0000 (16:49 +0100)]
Graphite deals poorly with metric names containing quotes.
Sanitize graphite metrics with our own escaping function,
better suited for this use-case than the one in `utils_parse_option`
Adrian Miron [Sat, 8 Mar 2014 16:56:11 +0000 (18:56 +0200)]
fix for #477: Notification time gone wrong
Sub-second time handling was added in collectd 5.0.0. This adds support
for this to the target_notification plugin, which got missed out at the
time.
Joel Uckelman [Tue, 4 Mar 2014 11:07:04 +0000 (12:07 +0100)]
Updated Color to match DataSources and DSName for single-series graphs.
Justin Burnham [Thu, 6 Mar 2014 06:36:21 +0000 (22:36 -0800)]
Fix missed change from int to double for interval
Marc Fournier [Sat, 29 Mar 2014 12:37:36 +0000 (13:37 +0100)]
indent wh_init() to be consistent with the rest of the file
Jeremy Katz [Mon, 27 Jan 2014 01:43:19 +0000 (20:43 -0500)]
Call curl_global_init() in _init of plugins using curl
Need to call curl_global_init() or curl_easy_init() during init
for plugins when we're still running single threaded. This
updates the remaining ones
Marc Fournier [Mon, 10 Mar 2014 20:28:36 +0000 (21:28 +0100)]
link iptables plugin against flags from pkg-config
This solves issue #326 for ubuntu versions >= 13.10
John-John Tedro [Tue, 17 Sep 2013 13:40:13 +0000 (15:40 +0200)]
write_riemann plugin: Receive acknowledge message when using TCP.
Not receiving an acknowledge message when communicating with riemann over TCP
will cause the riemann instance to eventually hang for extended periods of time
because of resource exhaustion.
Took the time to reaorganize the riemann_send function to simplify locking.
Matthias Urlichs [Wed, 5 Feb 2014 09:49:24 +0000 (10:49 +0100)]
Please free strings *after* printing them ;-)
Signed-off-by: Florian Forster <octo@collectd.org>
Marc Fournier [Thu, 23 Jan 2014 13:18:08 +0000 (14:18 +0100)]
Merge remote-tracking branch 'origin/collectd-4.10' into collectd-5.3
Marc Fournier [Thu, 23 Jan 2014 13:17:25 +0000 (14:17 +0100)]
Merge remote-tracking branch 'origin/pr/490' into collectd-5.3
Sebastian Harl [Wed, 22 Jan 2014 12:34:30 +0000 (13:34 +0100)]
configure: Fixed linker options when checking for amqp_tcp_socket_new.
This fixes the check when using GCC's --as-needed which fails when options are
not specified in the right order. Libraries (-l options) have to be specified
after any source files. autoconf does the right thing when using $LIBS for
that case rather than $LDFLAGS.
Sebastian Harl [Wed, 22 Jan 2014 12:29:53 +0000 (13:29 +0100)]
amqp plugin: Don't use C++ style comments.
Sebastian Harl [Wed, 22 Jan 2014 12:27:30 +0000 (04:27 -0800)]
Merge pull request #2 from mfournier/amqp-symbol_lookup
amqp: fix symbol lookup error with librabbitmq >= 0.4.0
Marc Fournier [Tue, 21 Jan 2014 09:24:53 +0000 (10:24 +0100)]
amqp: fix symbol lookup error with librabbitmq >= 0.4.0
amqp_socket_close() which we were using isn't exported anymore.
See https://github.com/alanxz/rabbitmq-c/commit/
bdda7ab
amqp_destroy_connection() implicitly closes the socket, so we don't need
to bother about this if using librabbitmq >= 0.4.0
credits to @tokkee for figuring that out !
Marc Fournier [Wed, 15 Jan 2014 23:30:42 +0000 (00:30 +0100)]
network: comment libgcrypt initalization process
Florian Forster [Wed, 15 Jan 2014 22:47:33 +0000 (23:47 +0100)]
apache plugin: Call curl_global_init() from the init function.
This is a shot in the dark in trying to address #513. By calling this
from an init() callback, I hope to be initializing the curl and gcrypt
libraries before collectd becomes multi-threaded, avoiding the problems
described in the issue.
Chris Lundquist [Wed, 15 Jan 2014 02:33:13 +0000 (18:33 -0800)]
[network] set_thread_cbs so we initialize the right threading mode in gcry_check_version
Signed-off-by: Florian Forster <octo@collectd.org>
Sebastian Harl [Mon, 13 Jan 2014 14:46:43 +0000 (15:46 +0100)]
amqp plugin: Fixed compilation when using rabbitmq-c < 0.4.
Thanks to Marc Fournier for noticing!
Marc Fournier [Wed, 8 Jan 2014 17:24:27 +0000 (18:24 +0100)]
Merge branch 'collectd-4.10' into collectd-5.3
Marc Fournier [Wed, 8 Jan 2014 17:05:40 +0000 (18:05 +0100)]
Revert "curl_xml.c: avoid using uninitalized variable in error message"
This reverts commit
bbbf37d55a3959951604c4be482e9a705a0f86d9.
A different fix for this problem was commited to the collectd-5.4 branch
(
8327ee64) and conflicts with this patch. Also, initializing url the
same way as
8327ee64 does it, to avoid a merge conflict.
Marc Fournier [Tue, 7 Jan 2014 15:06:10 +0000 (16:06 +0100)]
interface.c: FreeBSD-10 support
Quoting @trtrmitya in github issue #506 : "[...] it is broken on
FreeBSD-10, in which getifaddrs() returns not only link level stats for
a particular interface, but also entries for each IP configured on that
interface. As a result if_submit() is called several times for each
interface, which results in incorrect data being logged.
I am attaching a patch which fixes a problem on FreeBSD (9/10), but it
should work for every *BSD because [...] the getifaddrs implementation
first appeared in BSDi BSD/OS."
Many thanks to @trtrmitya for providing the patch !
Marc Fournier [Tue, 7 Jan 2014 10:30:59 +0000 (11:30 +0100)]
curl_xml.c: avoid using uninitalized variable in error message
Thanks to @trtrmitya for reporting this. Fixes GH#507
Sebastian Harl [Sun, 22 Dec 2013 12:59:44 +0000 (13:59 +0100)]
curl plugin: Fixed a segfault when using <Match> without an Instance.
Thanks to Alexander Golovko for reporting this in
http://bugs.debian.org/732701
Sebastian Harl [Sat, 23 Nov 2013 14:54:26 +0000 (15:54 +0100)]
amqp plugin: Added support for rabbitmq-c 0.4.x.
Upstream introduced a new socket interface and deprecated the old one. This
leads to compiler errors when using GCC and -Werror.
Rainer Müller [Wed, 27 Feb 2013 18:46:41 +0000 (19:46 +0100)]
collection3: Fix data source names
Data sources were renamed in
6c1415d, but the data source names for some
of these entries still referenced the old data sources.
Rainer Müller [Sun, 10 Nov 2013 02:51:40 +0000 (03:51 +0100)]
Link to IOKit using -framework
The libIOKit.dylib symlink no longer exists in OS X 10.9 Mavericks, we
now have to link using -framework. This should also work in all previous
versions of OS X.
Signed-off-by: Florian Forster <octo@collectd.org>
Florian Forster [Wed, 13 Nov 2013 18:59:27 +0000 (19:59 +0100)]
src/types.db: Remove maximum value on "cache_size".
Fixes #466. Thanks to @dlacko for pointing this out!
Marc Fournier [Mon, 14 Oct 2013 13:47:05 +0000 (06:47 -0700)]
Merge pull request #393 from mfournier/prevent-building-with-old-libpcap
Prevent building with old libpcap
Marc Fournier [Mon, 7 Oct 2013 21:11:44 +0000 (23:11 +0200)]
fix error message in target_{replace,set}
Remove erroneous hint that "Type" can be altered. Also correct a small
typo. Thanks to @mjulian for pointing that out !
Fixes GH#448
Fabien Wernli [Fri, 27 Sep 2013 07:42:46 +0000 (09:42 +0200)]
Update collectd.conf.pod
spotted by lukas227 in IRC:
23:43 < lukas227> Hi, I think I found a mistake in the threshold.conf(5) man page: the example
THRESHOLD CONFIGURATION is within <Threshold></Threshold> tags, but should
probably be within <Plugin "threshold"></Plugin> tags (doesn work with
<Threshold> for me)
Day changed to 27 Sep 2013
Signed-off-by: Florian Forster <octo@collectd.org>
Tim Laszlo [Tue, 24 Sep 2013 18:20:29 +0000 (13:20 -0500)]
Avoid using first person in the error message
Signed-off-by: Florian Forster <octo@collectd.org>
Tim Laszlo [Tue, 24 Sep 2013 15:35:22 +0000 (10:35 -0500)]
Replace you with your in error message
Signed-off-by: Florian Forster <octo@collectd.org>
Florian Forster [Mon, 19 Aug 2013 15:04:11 +0000 (17:04 +0200)]
zfs_arc plugin: Collect "allocated" and "stolen" on FreeBSD only.
The appropriate log messages have been demoted to WARNING.
Github: #305
Jim Radford [Sat, 10 Aug 2013 16:14:27 +0000 (09:14 -0700)]
curl_json plugin: avoid accessing off the end of the avl_tree_s
It's not written this way, but really we have a union { *key; *tree; }
which is differentiated by checking for the presence a magic field
which only exists in key. This leads to accesses off the end of the
tree. Putting the magic at start of the key avoids this.
Signed-off-by: Florian Forster <octo@collectd.org>
Jim Radford [Sat, 10 Aug 2013 16:10:56 +0000 (09:10 -0700)]
curl_json plugin: avoid unlikely overrun
Signed-off-by: Florian Forster <octo@collectd.org>