[lttng-dev] [PATCH] disable_channels.c improvements and fixes

[Thibault, Daniel]

>From 21f0eb1a7db1704645554d2f273bf80235be8240 Tue, 31 Jan 2012 15:13:29 -0500
From: Daniel U. Thibault <daniel.thibault at drdc-rddc.gc.ca>
Date: Tue, 31 Jan 2012 15:13:19 -0500
Subject: [PATCH] disable_channels.c improvements and fixes * Improve usage() printout * Document and enforce return values * Send --help to stdout * Issue CMD_WARNING for bad channel name(s) or an empty list of channel names * Fix a memory leak

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

diff --git a/src/bin/lttng/commands/disable_channels.c b/src/bin/lttng/commands/disable_channels.c
index bdbb657..4202963 100644
--- a/src/bin/lttng/commands/disable_channels.c
+++ b/src/bin/lttng/commands/disable_channels.c
@@ -70,25 +70,29 @@
 	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 on session name\n");
-	fprintf(ofp, "  -k, --kernel             Apply for the kernel tracer\n");
+	fprintf(ofp, "  -s, --session            Apply to session name\n");
+	fprintf(ofp, "  -k, --kernel             Apply to the kernel tracer\n");
 #if 0
-	fprintf(ofp, "  -u, --userspace [CMD]    Apply for the user-space tracer\n");
+	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, "                           (--kernel preempts --userspace)\n");
 	fprintf(ofp, "  -p, --pid PID            If -u, apply to specific PID (domain: UST PID)\n");
 #else
-	fprintf(ofp, "  -u, --userspace          Apply for the user-space tracer\n");
+	fprintf(ofp, "  -u, --userspace          Apply to the user-space tracer\n");
+	fprintf(ofp, "                           (--kernel preempts --userspace)\n");
 #endif
 	fprintf(ofp, "\n");
 }
 
 /*
- * Disabling channel using the lttng API.
+ * Disabling channel(s) using the lttng API.
+ * session_name must not be NULL.
+ * Returns one of the CMD_* result values.
  */
 static int disable_channels(char *session_name)
 {
-	int ret = CMD_SUCCESS;
+	int warn = 0, ret;
 	char *channel_name;
 	struct lttng_domain dom;
 
@@ -105,19 +109,25 @@
 
 	handle = lttng_create_handle(session_name, &dom);
 	if (handle == NULL) {
-		ret = -1;
+		ret = CMD_ERROR;
 		goto error;
 	}
 
 	/* Strip channel list */
 	channel_name = strtok(opt_channels, ",");
+	/* Default to a warning in case opt_channels is empty */
+	ret = CMD_WARNING;
 	while (channel_name != NULL) {
 		DBG("Disabling channel %s", channel_name);
 
 		ret = lttng_disable_channel(handle, channel_name);
 		if (ret < 0) {
-			goto error;
+			warn = 1;
+			ERR("%s channel %s unrecognised for session %s",
+					opt_kernel ? "Kernel" : "UST", channel_name,
+					session_name);
 		} else {
+			ret = CMD_SUCCESS;
 			MSG("%s channel %s disabled for session %s",
 					opt_kernel ? "Kernel" : "UST", channel_name,
 					session_name);
@@ -125,6 +135,13 @@
 
 		/* Next channel */
 		channel_name = strtok(NULL, ",");
+	}
+	if (ret == CMD_WARNING) {
+		ERR("No %s channel specified for session %s",
+				opt_kernel ? "kernel" : "UST", session_name);
+	}
+	if (warn) {
+		ret = CMD_WARNING;
 	}
 
 error:
@@ -134,13 +151,13 @@
 }
 
 /*
- *  cmd_disable_channels
- *
- *  Disable channel to trace session
+ *  Disable channel(s) of a trace session.
+ *  Bad channel names or an empty list of channels will yield a warning.
+ *  Returns a CMD_* result value.
  */
 int cmd_disable_channels(int argc, const char **argv)
 {
-	int opt, ret;
+	int opt, ret = CMD_SUCCESS;
 	static poptContext pc;
 	char *session_name = NULL;
 
@@ -150,15 +167,13 @@
 	while ((opt = poptGetNextOpt(pc)) != -1) {
 		switch (opt) {
 		case OPT_HELP:
-			usage(stderr);
-			ret = CMD_SUCCESS;
+			usage(stdout);
 			goto end;
 		case OPT_USERSPACE:
 			opt_userspace = 1;
 			break;
 		case OPT_LIST_OPTIONS:
 			list_cmd_options(stdout, long_options);
-			ret = CMD_SUCCESS;
 			goto end;
 		default:
 			usage(stderr);
@@ -171,22 +186,23 @@
 	if (opt_channels == NULL) {
 		ERR("Missing channel name(s).\n");
 		usage(stderr);
-		ret = CMD_SUCCESS;
+		ret = CMD_ERROR;
 		goto end;
 	}
 
-	if (!opt_session_name) {
-		session_name = get_session_name();
-		if (session_name == NULL) {
-			ret = -1;
-			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 cleanup;
 	}
 
 	ret = disable_channels(session_name);
 
+cleanup:
+	if (opt_session_name == NULL) {
+		free(session_name);
+	}
+
 end:
 	return ret;
 }
------------------------------

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/>