From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 2 Mar 2012 23:17:33 +0000 (-0500)
Subject: Fix: meaningful error message
X-Git-Tag: v2.0.0-rc2~1
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=531d29f9e514ad5a4880600d5c7e373f2f254ead;p=lttng-tools.git

Fix: meaningful error message

Show a meaningful error message to users attempting to do kernel tracing
without root sessiond/tracing group creds.

Reported-by: "Brosseau, Yannick" <yannick.brosseau@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index ff29eb035..9e2b21b2d 100644
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -1845,7 +1845,11 @@ error_open:
 error:
 	WARN("No kernel tracer available");
 	kernel_tracer_fd = -1;
-	return LTTCOMM_KERN_NA;
+	if (!is_root) {
+		return LTTCOMM_NEED_ROOT_SESSIOND;
+	} else {
+		return LTTCOMM_KERN_NA;
+	}
 }
 
 /*
@@ -3254,7 +3258,11 @@ static int process_client_msg(struct command_ctx *cmd_ctx)
 
 	if (opt_no_kernel && need_domain
 			&& cmd_ctx->lsm->domain.type == LTTNG_DOMAIN_KERNEL) {
-		ret = LTTCOMM_KERN_NA;
+		if (!is_root) {
+			ret = LTTCOMM_NEED_ROOT_SESSIOND;
+		} else {
+			ret = LTTCOMM_KERN_NA;
+		}
 		goto error;
 	}
 
@@ -3316,7 +3324,7 @@ static int process_client_msg(struct command_ctx *cmd_ctx)
 	switch (cmd_ctx->lsm->domain.type) {
 	case LTTNG_DOMAIN_KERNEL:
 		if (!is_root) {
-			ret = LTTCOMM_KERN_NA;
+			ret = LTTCOMM_NEED_ROOT_SESSIOND;
 			goto error;
 		}
 
diff --git a/src/common/sessiond-comm/sessiond-comm.c b/src/common/sessiond-comm/sessiond-comm.c
index 477bd1c64..fdd5856c0 100644
--- a/src/common/sessiond-comm/sessiond-comm.c
+++ b/src/common/sessiond-comm/sessiond-comm.c
@@ -117,6 +117,7 @@ static const char *lttcomm_readable_code[] = {
 	[ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_ENOMEM) ] = "consumerd splice ENOMEM",
 	[ LTTCOMM_ERR_INDEX(CONSUMERD_SPLICE_ESPIPE) ] = "consumerd splice ESPIPE",
 	[ LTTCOMM_ERR_INDEX(LTTCOMM_NO_EVENT) ] = "Event not found",
+	[ LTTCOMM_ERR_INDEX(LTTCOMM_NEED_ROOT_SESSIOND) ] = "A root lttng-sessiond needs to be running, and client user part of the \"tracing\" group, to interact with kernel tracing",
 };
 
 /*
diff --git a/src/common/sessiond-comm/sessiond-comm.h b/src/common/sessiond-comm/sessiond-comm.h
index 31b7fe466..472ca35d4 100644
--- a/src/common/sessiond-comm/sessiond-comm.h
+++ b/src/common/sessiond-comm/sessiond-comm.h
@@ -151,6 +151,7 @@ enum lttcomm_return_code {
 	CONSUMERD_SPLICE_EINVAL,		/* EINVAL from splice(2) */
 	CONSUMERD_SPLICE_ENOMEM,		/* ENOMEM from splice(2) */
 	CONSUMERD_SPLICE_ESPIPE,		/* ESPIPE from splice(2) */
+	LTTCOMM_NEED_ROOT_SESSIOND,		/* root sessiond is needed */
 	/* MUST be last element */
 	LTTCOMM_NR,						/* Last element */
 };