Cellular Network Infrastructure » Core Network (CN) » OsmoMSC

was able to reproduce that error message using a docker image based on debian-sid (see http://git.osmocom.org/docker-playground/commit/?id=0642e33a371782771bf4effbbb90d689f99f3b1c "add debian-sid-build, osmo-dev-on-debian-sid")

with https://gerrit.osmocom.org/5205 I get:

20171206012939521 DDB <000d> ../../../../src/osmo-msc/src/libmsc/db.c:188 Running query: SELECT * FROM SMS WHERE sent IS NULL AND dest_addr > '' AND deliver_attempts <= 9 ORDER BY dest_addr, id LIMIT 1
20171206012939523 DDB <000d> ../../../../src/osmo-msc/src/libmsc/db.c:218 DBI: -6: An invalid or out-of-range index was passed to libdbi

With further investigation, it becomes clear that the error log comes from

if (!dbi_result_next_row(result)) {

i.e. from precisely the line that should determine whether any results have been returned. It is thus puzzling why the error cb is invoked here.

Even when I change it to a nonempty string, I get the error:

20171206014418800 DDB <000d> ../../../../src/osmo-msc/src/libmsc/db.c:188 Running query: SELECT * FROM SMS WHERE sent IS NULL AND dest_addr > '0' AND deliver_attempts <= 9 ORDER BY dest_addr, id LIMIT 1
20171206014418802 DDB <000d> ../../../../src/osmo-msc/src/libmsc/db.c:910 1
20171206014418802 DDB <000d> ../../../../src/osmo-msc/src/libmsc/db.c:913 2
20171206014418802 DDB <000d> ../../../../src/osmo-msc/src/libmsc/db.c:218 DBI: -6: An invalid or out-of-range index was passed to libdbi
20171206014418802 DDB <000d> ../../../src/libosmocore/src/backtrace.c:47 backtrace() returned 11 addresses

My initial conclusion is that this error is not caused by osmo-msc, but rather from an unstable libdbi.

However, I notice that the API offers dbi_result_*has*_next_row(), and if I call that before dbi_result_next_row(), the error output does not occur.
But we actually never do this elsewhere: we always just see whether the result is NULL, and if not go on to dbi_result_next_row() right away, relying on that return value.

I could write up a patch that adds this step everywhere, simple enough:

        if (!dbi_result_has_next_row(result)
            || !dbi_result_next_row(result)) {
                dbi_result_free(result);
                return NULL;
        }

OTOH I guess it this not important enough, after all it's just dbi, and it's just debian-unstable. What do you think?

neels wrote:

My initial conclusion is that this error is not caused by osmo-msc, but rather from an unstable libdbi.

recently there was a "fix" in libdbi. In case of an invalid index, the error handler was not called (the original call was commented out by error) and 0 was returned as a result of calling dbi_result_next_row() instead.
I think the error is due to result being 0 if the last row was already fetched and thus the preceding call to dbi_result_has_next_row() seems good.

OTOH I guess it this not important enough, after all it's just dbi, and it's just debian-unstable. What do you think?

debian unstable will become stable sooner or later ...

actually now my laptop has moved to debian testing and I don't want to see these useless warnings all the time, hence submitted https://gerrit.osmocom.org/5265