db-parser, pdbtool, graphite-output: fix glib assertion error

[furiel]

void
g_error_free (GError *error)
{
  g_return_if_fail (error != NULL);

  g_free (error->message);

  g_slice_free (GError, error);
}

g_error_free does not expect it's parameter to be null. If syslog-ng
is started with G_DEBUG=fatal-warnings, this causes a
crash. Otherwise there is a warning:

[2020-07-01T13:17:46.293581] g_error_free: assertion 'error != NULL' failed

Example configuration:

@version: 3.27

log {
  parser { db-parser(file("/tmp/patterndb.xml")); };
};

/tmp/patterndb.xml:

<patterndb version='4' pub_date='2020-03-03'>
  <ruleset name='test' id='x'>
  </ruleset>
</patterndb>

---

$ ../bin/pdbtool merge -D tmp --pdb output/merge.xml

(pdbtool:11058): GLib-CRITICAL **: g_error_free: assertion 'error != NULL' failed

(pdbtool:11058): GLib-CRITICAL **: g_error_free: assertion 'error != NULL' failed
$ echo $?
0
$  

---

@version: 3.27

log {
  source { example-msg-generator(num(1) values(test.key1 => value1 test.key2 => value2)); };
  destination { file(/dev/stdout template("$(graphite-output --timestamp 'custom_timestamp' --key test.*)")); };
};

$ ./syslog-ng -Fe -f ../etc/graphite.conf 
syslog-ng: Error setting capabilities, capability management disabled; error='Operation not permitted'
[2020-07-06T08:43:31.659210] g_error_free: assertion 'error != NULL' failed
[2020-07-06T08:43:31.659854] syslog-ng starting up; version='3.28.1.37.g3256a78'
test.key1 value1 custom_timestamp
test.key2 value2 custom_timestamp
^C[2020-07-06T08:43:33.184553] syslog-ng shutting down; version='3.28.1.37.g3256a78'
$ 

[kira-syslogng]

Build SUCCESS

[Kokan]

In the tf_graphite_parse_command_line_arguments function also there is an instance of possible error. (while documentation is not clear on, I think in case of success -> true, probably it won't set error.)

[szemere]

Unfortunately I introduced this error. :( Checked my earlier PR #3265, there are other places where we are mixing goto error with the normal code flow, and reach g_error_free without an actual error:

• https://github.com/syslog-ng/syslog-ng/pull/3265/files#diff-d9f8b4f62fd3294230ca43a28a2c0cb1R1194
• https://github.com/syslog-ng/syslog-ng/pull/3265/files#diff-0778d036dff782fd230d281dfbbf9ce2R219
• https://github.com/syslog-ng/syslog-ng/pull/3265/files#diff-6eb1e8df235465642eb85a26e4b84029R78

[kira-syslogng]

Build SUCCESS

[furiel]

Thanks for pointing these out. I fixed those too.

[kira-syslogng]

Build SUCCESS

[furiel]

I forgot about a signed off. Fixed.

[kira-syslogng]

Build SUCCESS