From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Mon, 11 Jul 2022 19:48:49 +0000 (-0400)
Subject: Fix: sessiond: tsdl: don't prepend underscore for stream_id
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=2f35b2f5e29f337ad7c780e41d1eaeae378c1bc2

Fix: sessiond: tsdl: don't prepend underscore for stream_id

Although the CTF v1.8 specification recommends ignoring any leading
underscore, Some readers, such as Babeltrace 1.x, expect special
identifiers without a prepended underscore.

This causes problems in a follow-up patch since packet header, context,
and event headers become dynamically generated.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I0aeb24ab2e1c0ee1ea70d2fb9bb0eabbb2e9e035
---

diff --git a/src/bin/lttng-sessiond/tsdl-trace-class-visitor.cpp b/src/bin/lttng-sessiond/tsdl-trace-class-visitor.cpp
index c6c9c93db..b7777d203 100644
--- a/src/bin/lttng-sessiond/tsdl-trace-class-visitor.cpp
+++ b/src/bin/lttng-sessiond/tsdl-trace-class-visitor.cpp
@@ -14,8 +14,9 @@
 #include <common/uuid.hpp>
 
 #include <array>
-#include <queue>
 #include <locale>
+#include <queue>
+#include <set>
 
 namespace lst = lttng::sessiond::trace;
 namespace tsdl = lttng::sessiond::tsdl;
@@ -24,6 +25,12 @@ namespace {
 const auto ctf_spec_major = 1;
 const auto ctf_spec_minor = 8;
 
+/*
+ * Although the CTF v1.8 specification recommends ignoring any leading underscore, Some readers,
+ * such as Babeltrace 1.x, expect special identifiers without a prepended underscore.
+ */
+const std::set<std::string> safe_tsdl_identifiers = {"stream_id"};
+
 /*
  * A previous implementation always prepended '_' to the identifiers in order to
  * side-step the problem of escaping TSDL keywords and ensuring identifiers
@@ -38,6 +45,10 @@ std::string escape_tsdl_identifier(const std::string& original_identifier)
 		LTTNG_THROW_ERROR("Invalid 0-length identifier used in trace description");
 	}
 
+	if (safe_tsdl_identifiers.find(original_identifier) != safe_tsdl_identifiers.end()) {
+		return original_identifier;
+	}
+
 	std::string new_identifier;
 	/* Optimisticly assume most identifiers are valid and allocate the same length. */
 	new_identifier.reserve(original_identifier.size());