[lttng-dev] [RFC PATCH lttng-tools 13/18] Add serialized versions of lttng_event structs

[mathieu.desnoyers@efficios.com (Mathieu Desnoyers)]

----- On Apr 18, 2019, at 12:18 PM, Yannick Lamarre ylamarre at efficios.com wrote:

> Serialized versions of lttng_event, lttng_event_function_attr and
> lttng_event_probe_attr are packed structures to be used in communication
> protocols for consistent sizes across platforms. The serialized versions are
> stripped of pointers and padding.
> 
> Pointers are removed since their size can vary on platforms supporting
> variable sized registers (x86-64).

Same question about explanation as prior commits.

> Padding is also removed since it defeats the purpose of a packed struct.

Same question about documenting how the protocol is expected to be extended
as prior commits.

Thanks,

Mathieu

> 
> Signed-off-by: Yannick Lamarre <ylamarre at efficios.com>
> ---
> include/lttng/event-internal.h | 38 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
> 
> diff --git a/include/lttng/event-internal.h b/include/lttng/event-internal.h
> index 09b4d232..a43007de 100644
> --- a/include/lttng/event-internal.h
> +++ b/include/lttng/event-internal.h
> @@ -27,6 +27,44 @@
> 
> struct lttng_userspace_probe_location;
> 
> +struct lttng_event_probe_attr_serialized {
> +	uint64_t addr;
> +
> +	uint64_t offset;
> +	char symbol_name[LTTNG_SYMBOL_NAME_LEN];
> +} LTTNG_PACKED;
> +
> +struct lttng_event_function_attr_serialized {
> +	char symbol_name[LTTNG_SYMBOL_NAME_LEN];
> +} LTTNG_PACKED;
> +
> +struct lttng_event_serialized {
> +	uint32_t type; /* enum lttng_event_type */
> +
> +	char name[LTTNG_SYMBOL_NAME_LEN];
> +
> +	uint32_t loglevel_type; /* enum lttng_loglevel_type */
> +
> +	int loglevel;
> +
> +	int32_t enabled;	/* Does not apply: -1 */
> +
> +	pid_t pid;
> +
> +	unsigned char filter;	/* filter enabled ? */
> +
> +	unsigned char exclusion; /* exclusions added ? */
> +
> +	/* Event flag, from 2.6 and above. */
> +	uint32_t flags; /* enum lttng_event_flag */
> +
> +	/* Per event type configuration */
> +	union {
> +		struct lttng_event_probe_attr_serialized probe;
> +		struct lttng_event_function_attr_serialized ftrace;
> +	} attr;
> +} LTTNG_PACKED;
> +
> struct lttng_event_perf_counter_ctx_serialized {
> 	uint32_t type;
> 	uint64_t config;
> --
> 2.11.0
> 
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-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com