This, in default mode, caused buffered writing to be used, what
means that it looked like no output were written or partial
lines. Thanks to Michael Biebl for pointing out this bug.
Further testing turned out that the rsyslog core works correctly and
this fix is not needed. The concurrency we saw was actually caused by
other actions (even processes) during directory creation. See commit
9e5b31fc44136dbcc1e443cfe7714e9daf97d844 for further details.
Some types of malformed messages could trigger an off-by-one error
(for example, \0 or \n as the last character, and generally control
character escaption is questionable). This is due to not strictly
following a the \0 or string counted string paradigm (during the last
optimization on the cstring class). As a temporary fix, we have
introduced a proper recalculation of the size. However, a final
patch is expected in the future. See bug tracker for further details
and when the final patch will be available:
http://bugzilla.adiscon.com/show_bug.cgi?id=184
Note that the current patch is considered sufficient to solve the
situation, but it requires a bit more runtime than desirable.
This bug was triggered by an open failure. The the cache was full and
a new entry needed to be placed inside it, a victim for eviction was
selected. That victim was freed, then the open of the new file tried. If
the open failed, the victim entry was still freed, and the function
exited. However, on next invocation and cache search, the victim entry
was used as if it were populated, most probably resulting in a segfault.
If multiple files try to create a directory at (almost) the same time,
some of them may fail. This is a data race and also exists with other
processes that may create the same directory. We do now check for this
condition and gracefully handle it.
when dynaCache is enabled, the cache is full, a new entry needs to
be allocated, thus the LRU discarded, then a new entry is opend and that
fails. In that case, it looks like the discarded stream may be reused
improperly (based on code analysis, test case and confirmation pending)
In theory, the rsyslog core should never call in parallel into an output
module for the same instance. However, it looks like this seems to happen
under (strange?) circumstances. I have now enhanced omfile so that it guards
itself against being called in parallel on the same instance data. This is
done to help troubleshooting and may stay as an interim solution if it
proves to solve an anomaly we see in at least one installation (to trigger
this problem, an extremely large traffic volume is needed).
The previous fix fixed an issue with on/off bying used in the exact wrong
semantic. It corrected the situation, but failed to fix one spot where the
wrong semantics were used. This is done with this commit.
Note that this is NOT a bug seen in any released version.
currently being accessed buffer could be overwritten with new data.
While this probably did not cause access violations, it could case loss
and/or duplication of some data (definitely a race with no deterministic
outcome)
Note that this introduces a test case that breaks the current code. This
commit does NOT yet provide the necessary code patch. Thus "make check"
does currently hang.
Note that this introduces a test case that breaks the current code. This
commit does NOT yet provide the necessary code patch. Thus make check
does currently hang.
Previously, it could lead to garbagge output and, in extreme cases, also
to segfaults. Note: this was a problem only when debug output was
actually enabled, so it caused no problem in production use.
