Added by Mathieu Desnoyers about 10 years ago. Updated over 1 year ago.
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Description
lttng-tools src/lib/lttng-ctl/lttng-ctl.c:
lttng_enable_event_with_exclusions()
memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));
copy "ev" (non-packed) into a packed structure.
We should copy each field one by one (create a copy_event_to_event_packed() helper to do so).
How do you copy the union in the lttng_event field by field... ? That union contains non packed structure.
We need helper functions to copy field by field depending on the union type also.
The "lttng_event" struct is not defined with the packed attribute, this attribute is only added when "lttng_event" is declared as a member of the "lttcomm_session_msg" struct. Adding the packed attribute to an already defined struct is ignored by the compiler, when it's done outside of a parent struct it generates a warning.
What this all means is that we are not copying a non-packed struct into a packed struct because there is no packed version of lttng_event. This also means we are using unpacked structures in the communication protocol between the client and the sessiond.
This is a technical debt low-hanging fruit that we should do. It's not a complex task and would be a nice cleanup.