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autopaho publisher example: panic due to nil pointer

bronger opened this issue · comments

commented

I get a nil pointer dereference in the autopaho publisher example because pr can be nil even if err is also nil.

commented

Yep - if you publish with Qos=0 then there will be no response, so pr will be nil. That should be the only time that this happens (any other occurrence would be a bug). I'm going to assume that you are using 0 QOS.

I can think of two possible fixes:

  • Check cfg.qos >0 in the example.
  • Change Publish such that a pointer to a default (empty) PublishResponse is returned.

I'm tempted by option 2 because I think it would be easy to write some code using QOS1/2 and then change to QOS0 without considering that there is no longer a response to check.

Thoughts?

commented

If a zero value for PublishResponse is semantically senseful for QoS==0 (sorry but I’m not really competent to say that), go for option 2.