[lttng-dev] [PATCH lttng-tools 1/5] Add --mi option to the list command

[dgoulet@efficios.com (David Goulet)]

Like we spoke the other day on IRC, the --mi patch needs more work for the
output format so we come up with something standard and documented.

So I've merged the 3 other patches that do not uses --mi option.

Cheers!
David

simon.marchi at polymtl.ca:
> From: Simon Marchi <simon.marchi@polymtl.ca>
> 
> The --mi option is used to ask lttng to print information in a format
> easily understandable by another program. Currently, only session
> printing is affected: it prints session names one per line.
> 
> The term mi stands for machine interface, and is stolen without any
> remorse from GDB's lexicon.
> 
> Signed-off-by: Simon Marchi <simon.marchi at polymtl.ca>
> ---
>  src/bin/lttng/commands/list.c |   35 ++++++++++++++++++++++++++---------
>  1 files changed, 26 insertions(+), 9 deletions(-)
> 
> diff --git a/src/bin/lttng/commands/list.c b/src/bin/lttng/commands/list.c
> index 1c7085d..9e13e6b 100644
> --- a/src/bin/lttng/commands/list.c
> +++ b/src/bin/lttng/commands/list.c
> @@ -30,6 +30,7 @@ static int opt_kernel;
>  static char *opt_channel;
>  static int opt_domain;
>  static int opt_fields;
> +static int opt_mi;
>  #if 0
>  /* Not implemented yet */
>  static char *opt_cmd_name;
> @@ -44,6 +45,7 @@ enum {
>  	OPT_HELP = 1,
>  	OPT_USERSPACE,
>  	OPT_LIST_OPTIONS,
> +	OPT_MI,
>  };
>  
>  static struct lttng_handle *handle;
> @@ -63,6 +65,7 @@ static struct poptOption long_options[] = {
>  	{"domain",    'd', POPT_ARG_VAL, &opt_domain, 1, 0, 0},
>  	{"fields",    'f', POPT_ARG_VAL, &opt_fields, 1, 0, 0},
>  	{"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
> +	{"mi", 0, POPT_ARG_NONE, &opt_mi, 0, NULL, NULL},
>  	{0, 0, 0, 0, 0, 0, 0}
>  };
>  
> @@ -80,6 +83,7 @@ static void usage(FILE *ofp)
>  	fprintf(ofp, "\n");
>  	fprintf(ofp, "  -h, --help              Show this help\n");
>  	fprintf(ofp, "      --list-options      Simple listing of options\n");
> +	fprintf(ofp, "      --mi                Prints data in a format suitable for parsing\n");
>  	fprintf(ofp, "  -k, --kernel            Select kernel domain\n");
>  	fprintf(ofp, "  -u, --userspace         Select user-space domain.\n");
>  	fprintf(ofp, "  -f, --fields            List event fields.\n");
> @@ -618,40 +622,53 @@ static int list_sessions(const char *session_name)
>  		ERR("%s", lttng_strerror(ret));
>  		goto error;
>  	} else if (count == 0) {
> -		MSG("Currently no available tracing session");
> +		if (!opt_mi) {
> +			MSG("Currently no available tracing session");
> +		}
>  		goto end;
>  	}
>  
> -	if (session_name == NULL) {
> +	if (session_name == NULL && !opt_mi) {
>  		MSG("Available tracing sessions:");
>  	}
>  
>  	for (i = 0; i < count; i++) {
> +
>  		if (session_name != NULL) {
>  			if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
>  				session_found = 1;
> -				MSG("Tracing session %s: [%s%s]", session_name,
> +
> +				if (opt_mi) {
> +					MSG("%s", session_name);
> +				} else {
> +					MSG("Tracing session %s: [%s%s]", session_name,
>  						active_string(sessions[i].enabled),
>  						snapshot_string(sessions[i].snapshot_mode));
> -				MSG("%sTrace path: %s\n", indent4, sessions[i].path);
> +					MSG("%sTrace path: %s\n", indent4, sessions[i].path);
> +				}
> +
>  				break;
>  			}
>  		} else {
> -			MSG("  %d) %s (%s) [%s%s]", i + 1, sessions[i].name, sessions[i].path,
> -					active_string(sessions[i].enabled),
> -					snapshot_string(sessions[i].snapshot_mode));
> +			if (opt_mi) {
> +				MSG("%s", sessions[i].name);
> +			} else {
> +				MSG("  %d) %s (%s) [%s%s]", i + 1, sessions[i].name, sessions[i].path,
> +						active_string(sessions[i].enabled),
> +						snapshot_string(sessions[i].snapshot_mode));
> +			}
>  		}
>  	}
>  
>  	free(sessions);
>  
> -	if (!session_found && session_name != NULL) {
> +	if (!session_found && session_name != NULL && !opt_mi) {
>  		ERR("Session '%s' not found", session_name);
>  		ret = CMD_ERROR;
>  		goto error;
>  	}
>  
> -	if (session_name == NULL) {
> +	if (session_name == NULL && !opt_mi) {
>  		MSG("\nUse lttng list <session_name> for more details");
>  	}
>