>From 6429ddf6047b50fb5d917d451fd6612ad57a5ed6 Thu, 2 Feb 2012 15:37:36 -0500
From: Daniel U. Thibault <[email protected]>
Date: Thu, 2 Feb 2012 15:37:24 -0500
Subject: [PATCH] disable_channels.c : Document and enforce return values, 
enforce exactly one domain flag, adjust usage() output accordingly, handle 
channel list errors

Signed-off-by: Daniel U. Thibault <[email protected]>

diff --git a/src/bin/lttng/commands/disable_channels.c 
b/src/bin/lttng/commands/disable_channels.c
index ccd5446..7dc3b39 100644
--- a/src/bin/lttng/commands/disable_channels.c
+++ b/src/bin/lttng/commands/disable_channels.c
@@ -67,6 +67,7 @@
 static void usage(FILE *ofp)
 {
        fprintf(ofp, "usage: lttng disable-channel 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");
@@ -75,7 +76,7 @@
 #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");
@@ -85,6 +86,7 @@
 
 /*
  * Disabling channel using the lttng API.
+ * Returns a CMD_* result value.
  */
 static int disable_channels(char *session_name)
 {
@@ -93,24 +95,24 @@
        struct lttng_domain dom;
 
        /* Create lttng domain */
+       /* cmd_disable_channels() 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 */
        }
 
        handle = lttng_create_handle(session_name, &dom);
        if (handle == NULL) {
-               ret = -1;
+               ret = CMD_FATAL;
                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);
 
@@ -123,12 +125,15 @@
                        MSG("%s channel %s disabled for session %s",
                                        opt_kernel ? "Kernel" : "UST", 
channel_name, session_name);
                }
+               ret = CMD_SUCCESS;
 
                /* Next channel */
                channel_name = strtok(NULL, ",");
        }
-
-       ret = CMD_SUCCESS;
+       if (ret == CMD_WARNING) {
+               ERR("No channels specified for %s session %s",
+                               (opt_kernel ? "kernel" : "UST"), session_name);
+       }
 
 error:
        if (warn) {
@@ -141,9 +146,8 @@
 }
 
 /*
- *  cmd_disable_channels
- *
- *  Disable channel to trace session
+ *  Disable channels of trace session
+ *  Returns a CMD_* result value.
  */
 int cmd_disable_channels(int argc, const char **argv)
 {
@@ -172,6 +176,18 @@
                }
        }
 
+       /* 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_channels = (char*) poptGetArg(pc);
        if (opt_channels == NULL) {
                ERR("Missing channel name(s).\n");
@@ -180,14 +196,10 @@
                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_channels(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/>

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