From 3287f48be61ef3491aff0a80b7185ac57b3d8a5d Mon Sep 17 00:00:00 2001
From: Kienan Stewart <kstewart@efficios.com>
Date: Mon, 27 Nov 2023 12:02:40 -0500
Subject: [PATCH] Add initial support for the multiple LTTNG_UST_APP_PATHs

The `$LTTNG_UST_APP_PATH` is split using ':' as a separator. There is
no provision for escaping the ':' separator.

Paths after the first path will be ignored for the moment and a
warning emitted.

Change-Id: I619a3578e00fd3c758d616b99b443fc15a1477df
Signed-off-by: Kienan Stewart <kstewart@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
 .../agent/client/LttngTcpSessiondClient.java  | 12 +++++-
 src/lib/lttng-ust/lttng-ust-comm.c            | 41 +++++++++++++++++--
 src/python-lttngust/lttngust/agent.py         | 10 ++++-
 3 files changed, 56 insertions(+), 7 deletions(-)

diff --git a/src/lib/lttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/client/LttngTcpSessiondClient.java b/src/lib/lttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/client/LttngTcpSessiondClient.java
index 82f2c2f0..ccffb9d3 100644
--- a/src/lib/lttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/client/LttngTcpSessiondClient.java
+++ b/src/lib/lttng-ust-java-agent/java/lttng-ust-agent-common/org/lttng/ust/agent/client/LttngTcpSessiondClient.java
@@ -208,8 +208,16 @@ public class LttngTcpSessiondClient implements Runnable {
 		this.outToSessiond = new DataOutputStream(sessiondSock.getOutputStream());
 	}
 
-	private static String getUstAppPath() {
-		return System.getenv("LTTNG_UST_APP_PATH");
+	private String getUstAppPath() {
+		String ustAppPath = System.getenv("LTTNG_UST_APP_PATH");
+		if (ustAppPath != null) {
+			String[] paths = ustAppPath.split(":");
+			if (paths.length > 1) {
+				log("':' separator in LTTNG_UST_APP_PATH, only the first path will be used");
+			}
+			return paths[0];
+		}
+		return ustAppPath;
 	}
 
 	private static String getHomePath() {
diff --git a/src/lib/lttng-ust/lttng-ust-comm.c b/src/lib/lttng-ust/lttng-ust-comm.c
index 229e457a..9745c182 100644
--- a/src/lib/lttng-ust/lttng-ust-comm.c
+++ b/src/lib/lttng-ust/lttng-ust-comm.c
@@ -411,10 +411,43 @@ const char *get_lttng_home_dir(void)
        return (const char *) lttng_ust_getenv("HOME");
 }
 
+/*
+ * Returns the LTTNG_UST_APP_PATH path. If environment variable exists
+ * and contains a ':', the first path before the ':' separator is returned.
+ * The return value should be freed by the caller if it is not NULL.
+ */
 static
-const char *get_lttng_ust_app_path(void)
+char *get_lttng_ust_app_path(void)
 {
-       return (const char *) lttng_ust_getenv("LTTNG_UST_APP_PATH");
+	const char *env_val = lttng_ust_getenv("LTTNG_UST_APP_PATH");
+	char *val = NULL;
+	char *sep = NULL;
+	if (env_val == NULL)
+		goto error;
+	sep = strchr((char*)env_val, ':');
+	if (sep) {
+		/*
+		 * Split into multiple paths using ':' as a separator.
+		 * There is no escaping of the ':' separator.
+		 */
+		WARN("':' separator in LTTNG_UST_APP_PATH, only the first path will be used.");
+		val = zmalloc(sep - env_val + 1);
+		if (!val) {
+			PERROR("zmalloc get_lttng_ust_app_path");
+			goto error;
+		}
+		memcpy(val, env_val, sep - env_val);
+		val[sep - env_val] = '\0';
+	} else {
+		val = strdup(env_val);
+		if (!val) {
+			PERROR("strdup");
+			goto error;
+		}
+	}
+
+error:
+	return val;
 }
 
 /*
@@ -517,7 +550,7 @@ void print_cmd(int cmd, int handle)
 static
 int setup_ust_apps(void)
 {
-	const char *ust_app_path;
+	char *ust_app_path = NULL;
 	int ret = 0;
 	uid_t uid;
 
@@ -562,6 +595,8 @@ int setup_ust_apps(void)
 
 	lttng_pthread_getname_np(ust_app.procname, LTTNG_UST_CONTEXT_PROCNAME_LEN);
 end:
+	if (ust_app_path)
+		free(ust_app_path);
 	return ret;
 }
 
diff --git a/src/python-lttngust/lttngust/agent.py b/src/python-lttngust/lttngust/agent.py
index 69caad69..58845b56 100644
--- a/src/python-lttngust/lttngust/agent.py
+++ b/src/python-lttngust/lttngust/agent.py
@@ -267,7 +267,13 @@ def _get_port_from_file(path):
     return port
 
 def _get_ust_app_path():
-    return os.getenv('LTTNG_UST_APP_PATH')
+    paths = os.getenv('LTTNG_UST_APP_PATH')
+    if paths is None:
+        return paths
+    paths = paths.split(':')
+    if len(paths) > 1:
+        dbg._pwarning("':' separator in LTTNG_UST_APP_PATH, only the first path will be used")
+    return paths[0]
 
 def _get_user_home_path():
     # $LTTNG_HOME overrides $HOME if it exists
@@ -326,7 +332,7 @@ def _init_threads():
         sys_port = None
 
     try:
-     if ust_app_port is not None:
+        if ust_app_port is not None:
             dbg._pdebug('creating ust_app client thread')
             t = threading.Thread(target=_client_thread_target,
                                  args=('ust_app', ust_app_port, reg_queue))
-- 
2.34.1