From 52a0e9318791b1f188742059e904d42ee0d7e231 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Wed, 12 Dec 2018 15:39:53 -0500
Subject: [PATCH] Generate a UUID on lttng-sessiond launch
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

This commit adds a global sessiond_uuid which can be used to
uniquely identify a session daemon from a relay daemon's
perspective even when it communicates with multiple consumers.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 src/bin/lttng-sessiond/globals.c        | 11 +++++++++++
 src/bin/lttng-sessiond/lttng-sessiond.h |  4 ++++
 src/bin/lttng-sessiond/main.c           |  9 +++++++++
 src/common/compat/uuid.c                |  2 +-
 src/common/compat/uuid.h                |  8 +++++---
 5 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/bin/lttng-sessiond/globals.c b/src/bin/lttng-sessiond/globals.c
index efe80baaf..a8536afa3 100644
--- a/src/bin/lttng-sessiond/globals.c
+++ b/src/bin/lttng-sessiond/globals.c
@@ -18,6 +18,9 @@
  */
 
 #include "lttng-sessiond.h"
+#include <common/compat/uuid.h>
+
+lttng_uuid sessiond_uuid;
 
 int ust_consumerd64_fd = -1;
 int ust_consumerd32_fd = -1;
@@ -70,3 +73,11 @@ struct consumer_data ustconsumer32_data = {
 
 enum consumerd_state ust_consumerd_state;
 enum consumerd_state kernel_consumerd_state;
+
+static void __attribute__((constructor)) init_sessiond_uuid(void)
+{
+	if (lttng_uuid_generate(sessiond_uuid)) {
+		ERR("Failed to generate a session daemon UUID");
+		abort();
+	}
+}
diff --git a/src/bin/lttng-sessiond/lttng-sessiond.h b/src/bin/lttng-sessiond/lttng-sessiond.h
index d321fceda..5b6761f55 100644
--- a/src/bin/lttng-sessiond/lttng-sessiond.h
+++ b/src/bin/lttng-sessiond/lttng-sessiond.h
@@ -25,6 +25,7 @@
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/compat/poll.h>
 #include <common/compat/socket.h>
+#include <common/compat/uuid.h>
 
 #include "session.h"
 #include "ust-app.h"
@@ -41,6 +42,9 @@ enum consumerd_state {
 	CONSUMER_ERROR   = 3,
 };
 
+/* Unique identifier of a session daemon instance. */
+extern lttng_uuid sessiond_uuid;
+
 /*
  * This consumer daemon state is used to validate if a client command will be
  * able to reach the consumer. If not, the client is informed. For instance,
diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 57324820b..dd5cee4bd 100644
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -1369,6 +1369,14 @@ static int launch_run_as_worker(const char *procname)
 			&config);
 }
 
+static void sessiond_uuid_log(void)
+{
+	char uuid_str[UUID_STR_LEN];
+
+	lttng_uuid_to_str(sessiond_uuid, uuid_str);
+	DBG("Starting lttng-sessiond {%s}", uuid_str);
+}
+
 /*
  * main
  */
@@ -1465,6 +1473,7 @@ int main(int argc, char **argv)
 	set_clock_plugin_env();
 
 	sessiond_config_log(&config);
+	sessiond_uuid_log();
 
 	if (create_lttng_rundir()) {
 		retval = -1;
diff --git a/src/common/compat/uuid.c b/src/common/compat/uuid.c
index 8759de6f5..4f7e3a72b 100644
--- a/src/common/compat/uuid.c
+++ b/src/common/compat/uuid.c
@@ -18,7 +18,7 @@
 #include <stdio.h>
 #include <common/compat/uuid.h>
 
-void lttng_uuid_to_str(const unsigned char *uuid, char *uuid_str)
+void lttng_uuid_to_str(const lttng_uuid uuid, char *uuid_str)
 {
 	sprintf(uuid_str,
 			"%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
diff --git a/src/common/compat/uuid.h b/src/common/compat/uuid.h
index dcc4ed560..0da0b80db 100644
--- a/src/common/compat/uuid.h
+++ b/src/common/compat/uuid.h
@@ -31,6 +31,8 @@
 #define UUID_STR_LEN		37
 #define UUID_LEN		16
 
+typedef unsigned char lttng_uuid[UUID_LEN];
+
 #ifdef LTTNG_HAVE_LIBUUID
 #include <uuid/uuid.h>
 
@@ -38,7 +40,7 @@
  * uuid_out is of len UUID_LEN.
  */
 static inline
-int lttng_uuid_generate(unsigned char *uuid_out)
+int lttng_uuid_generate(lttng_uuid uuid_out)
 {
 	uuid_generate(uuid_out);
 	return 0;
@@ -52,7 +54,7 @@ int lttng_uuid_generate(unsigned char *uuid_out)
  * uuid_out is of len UUID_LEN.
  */
 static inline
-int lttng_uuid_generate(unsigned char *uuid_out)
+int lttng_uuid_generate(lttng_uuid uuid_out)
 {
 	uint32_t status;
 
@@ -74,6 +76,6 @@ int lttng_uuid_generate(unsigned char *uuid_out)
  * Assumes uuid_str is at least UUID_STR_LEN byte long.
  */
 LTTNG_HIDDEN
-void lttng_uuid_to_str(const unsigned char *uuid, char *uuid_str);
+void lttng_uuid_to_str(const lttng_uuid uuid, char *uuid_str);
 
 #endif /* LTTNG_UUID_H */
-- 
2.34.1