From: Simon Marchi <simon.marchi@efficios.com>
Date: Thu, 6 Jan 2022 18:27:55 +0000 (-0500)
Subject: lttng-sessiond: remove goto in ust_metadata_channel_statedump
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=e4589ae2396a53ed0b17251616694afeefba2986

lttng-sessiond: remove goto in ust_metadata_channel_statedump

A follow-up patch uses an std::vector declared in the middle of
ust_metadata_channel_statedump. This isn't compatible with the
goto-based error handling, since gotos should not jump over object
initialization (otherwise, the object gets destroyed without having been
constructed).

Moving the std::vector declaration to the beginning of the function
would work, but it would be a pessimization: we would construct an
object that we may not need, depending on the code path taken. We
therefore want to declare (and construct) the std::vector just before
we need it.

Fix this by replacing gotos with return statements.

Also, add a `ret` check after the last lttng_metadata_printf call. If
this call failed, for some reason, we would return an error, but still
set chan->metadata_dumped. That makes this case different than the other
error paths in the function, where chan->metadata_dumped doesn't get
set. Adding the check makes this case like the other ones.

Change-Id: Iba81422a7c3bac96a8d209bba6b4d53ad26b3e4e
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/ust-metadata.cpp b/src/bin/lttng-sessiond/ust-metadata.cpp
index b507f7870..d08cb40ae 100644
--- a/src/bin/lttng-sessiond/ust-metadata.cpp
+++ b/src/bin/lttng-sessiond/ust-metadata.cpp
@@ -899,7 +899,7 @@ end:
 int ust_metadata_channel_statedump(struct ust_registry_session *session,
 		struct ust_registry_channel *chan)
 {
-	int ret = 0;
+	int ret;
 
 	/* Don't dump metadata events */
 	if (chan->chan_id == -1U)
@@ -918,37 +918,40 @@ int ust_metadata_channel_statedump(struct ust_registry_session *session,
 			"struct event_header_compact" :
 			"struct event_header_large");
 	if (ret) {
-		goto end;
+		return ret;
 	}
 
 	if (chan->ctx_fields) {
 		ret = lttng_metadata_printf(session,
 			"	event.context := struct {\n");
 		if (ret) {
-			goto end;
+			return ret;
 		}
 	}
 	ret = _lttng_context_metadata_statedump(session,
 		chan->nr_ctx_fields,
 		chan->ctx_fields);
 	if (ret) {
-		goto end;
+		return ret;
 	}
 	if (chan->ctx_fields) {
 		ret = lttng_metadata_printf(session,
 			"	};\n");
 		if (ret) {
-			goto end;
+			return ret;
 		}
 	}
 
 	ret = lttng_metadata_printf(session,
 		"};\n\n");
+	if (ret) {
+		return ret;
+	}
+
 	/* Flag success of metadata dump. */
 	chan->metadata_dumped = 1;
 
-end:
-	return ret;
+	return 0;
 }
 
 static