[lttng-dev] [PATCH] disable_events.c : Document and enforce return values, enforce exactly one domain flag, adjust usage() output accordingly, handle event list errors

[Thibault, Daniel]

>From a40c0bda2e4849befbfc51cbcd3f92729e0443ce Thu, 2 Feb 2012 15:29:38 -0500
From: Daniel U. Thibault <daniel.thibault at drdc-rddc.gc.ca>
Date: Thu, 2 Feb 2012 15:29:27 -0500
Subject: [PATCH] disable_events.c : Document and enforce return values, enforce exactly one domain flag, adjust usage() output accordingly, handle event list errors

Signed-off-by: Daniel U. Thibault <daniel.thibault at drdc-rddc.gc.ca>

diff --git a/src/bin/lttng/commands/disable_events.c b/src/bin/lttng/commands/disable_events.c
index b30ec1f..062a784 100644
--- a/src/bin/lttng/commands/disable_events.c
+++ b/src/bin/lttng/commands/disable_events.c
@@ -71,17 +71,18 @@
 static void usage(FILE *ofp)
 {
 	fprintf(ofp, "usage: lttng disable-event NAME[,NAME2,...] [options]\n");
+	fprintf(ofp, "Exactly one domain (-k/--kernel or -u/--userspace) must be specified.\n");
 	fprintf(ofp, "\n");
 	fprintf(ofp, "  -h, --help               Show this help\n");
 	fprintf(ofp, "      --list-options       Simple listing of options\n");
 	fprintf(ofp, "  -s, --session            Apply to session name\n");
 	fprintf(ofp, "  -c, --channel            Apply to this channel\n");
 	fprintf(ofp, "  -a, --all-events         Disable all tracepoints\n");
-	fprintf(ofp, "  -k, --kernel             Apply for the kernel tracer\n");
+	fprintf(ofp, "  -k, --kernel             Apply to the kernel tracer\n");
 #if 0
 	fprintf(ofp, "  -u, --userspace [CMD]    Apply to the user-space tracer\n");
 	fprintf(ofp, "                           If no CMD, the domain used is UST global\n");
-	fprintf(ofp, "                           or else the domain is UST EXEC_NAME\n");
+	fprintf(ofp, "                           otherwise the domain is UST EXEC_NAME\n");
 	fprintf(ofp, "  -p, --pid PID            If -u, apply to specific PID (domain: UST PID)\n");
 #else
 	fprintf(ofp, "  -u, --userspace          Apply to the user-space tracer\n");
@@ -90,9 +91,8 @@
 }
 
 /*
- *  disable_events
- *
  *  Disabling event using the lttng API.
+ *  Returns a CMD_* result value.
  */
 static int disable_events(char *session_name)
 {
@@ -101,14 +101,12 @@
 	struct lttng_domain dom;
 
 	/* Create lttng domain */
+	/* cmd_disable_events() enforces the existence of just one domain flag */
 	if (opt_kernel) {
 		dom.type = LTTNG_DOMAIN_KERNEL;
-	} else if (opt_userspace) {
+	} else { /* if (opt_userspace) { */
 		dom.type = LTTNG_DOMAIN_UST;
-	} else {
-		ERR("Please specify a tracer (-k/--kernel or -u/--userspace)");
-		ret = CMD_ERROR;
-		goto error;
+	/* TODO As LTTNG_DOMAIN_* values are added, capture them here */
 	}
 
 	/* Get channel name */
@@ -124,17 +122,19 @@
 
 	handle = lttng_create_handle(session_name, &dom);
 	if (handle == NULL) {
-		ret = -1;
+		ret = CMD_FATAL;
 		goto error;
 	}
 
 	if (opt_disable_all) {
 		ret = lttng_disable_event(handle, NULL, channel_name);
 		if (ret < 0) {
-			/* Don't set ret so lttng can interpret the sessiond error. */
+			ERR("Event %s: %s (channel %s, session %s)", "<all>",
+					lttng_strerror(ret), channel_name, session_name);
+			ret = CMD_ERROR;
 			goto error;
 		}
-
+		ret = CMD_SUCCESS;
 		MSG("All %s events are disabled in channel %s",
 				opt_kernel ? "kernel" : "UST", channel_name);
 		goto end;
@@ -142,6 +142,8 @@
 
 	/* Strip event list */
 	event_name = strtok(opt_event_list, ",");
+	/* Default to a warning in case opt_event_list is empty */
+	ret = CMD_WARNING;
 	while (event_name != NULL) {
 		DBG("Disabling event %s", event_name);
 
@@ -155,12 +157,15 @@
 					opt_kernel ? "kernel" : "UST", event_name, channel_name,
 					session_name);
 		}
+		ret = CMD_SUCCESS;
 
 		/* Next event */
 		event_name = strtok(NULL, ",");
 	}
-
-	ret = CMD_SUCCESS;
+	if (ret == CMD_WARNING) {
+		ERR("No event specified for %s channel %s, session %s",
+				(opt_kernel ? "kernel" : "UST"), channel_name, session_name);
+	}
 
 end:
 error:
@@ -176,9 +181,8 @@
 }
 
 /*
- *  cmd_disable_events
- *
- *  Disable event to trace session
+ *  Disable events of trace session
+ *  Returns a CMD_* result value.
  */
 int cmd_disable_events(int argc, const char **argv)
 {
@@ -207,6 +211,18 @@
 		}
 	}
 
+	/* Enforce requirement for exactly one domain */
+	/* Five LTTNG_DOMAIN_* values are currently planned */
+	if (!opt_userspace && !opt_kernel) {
+		ERR("No domain specified: Use one of -k/--kernel or -u/--userspace");
+		ret = CMD_ERROR;
+		goto end;
+	} else if (opt_userspace && opt_kernel) {
+		ERR("More than one domain specified");
+		ret = CMD_ERROR;
+		goto end;
+	}
+
 	opt_event_list = (char*) poptGetArg(pc);
 	if (opt_event_list == NULL && opt_disable_all == 0) {
 		ERR("Missing event name(s).\n");
@@ -215,14 +231,10 @@
 		goto end;
 	}
 
-	if (!opt_session_name) {
-		session_name = get_session_name();
-		if (session_name == NULL) {
-			ret = CMD_ERROR;
-			goto end;
-		}
-	} else {
-		session_name = opt_session_name;
+	session_name = opt_session_name ? opt_session_name : get_session_name();
+	if (session_name == NULL) {
+		ret = CMD_ERROR;
+		goto end;
 	}
 
 	ret = disable_events(session_name);
------------------------------

Daniel U. Thibault
R & D pour la défense Canada - Valcartier (RDDC Valcartier) / Defence R&D Canada - Valcartier (DRDC Valcartier)
Système de systèmes (SdS) / System of Systems (SoS)
Solutions informatiques et expérimentations (SIE) / Computing Solutions and Experimentations (CSE)
2459 Boul. Pie XI Nord
Québec, QC  G3J 1X5
CANADA
Vox : (418) 844-4000 x4245
Fax : (418) 844-4538
NAC: 918V QSDJ
Gouvernement du Canada / Government of Canada
<http://www.valcartier.drdc-rddc.gc.ca/>