From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 5 Dec 2019 06:58:09 +0000 (-0500)
Subject: Fix: lttng-live format: do not error out on empty streams hang up
X-Git-Tag: v1.5.8~1
X-Git-Url: http://git.efficios.com/?p=babeltrace.git;a=commitdiff_plain;h=c8fd9d119dc98ef4785b4d7204939a8a259f67e2

Fix: lttng-live format: do not error out on empty streams hang up

Attaching to a stream hung up before providing any trace packet
causes ctf_open_mmap_stream_read() to return an error.

This kind of scenario can happen with the upcoming "lttng clear"
feature.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/formats/ctf/ctf.c b/formats/ctf/ctf.c
index 980ebc9a..1ba9017f 100644
--- a/formats/ctf/ctf.c
+++ b/formats/ctf/ctf.c
@@ -2571,8 +2571,13 @@ int ctf_open_mmap_stream_read(struct ctf_trace *td,
 	}
 
 	ret = prepare_mmap_stream_definition(td, file_stream, packet_seek);
-	if (ret)
+	if (ret) {
+		/* We need to check for EOF here for empty files. */
+		if (unlikely(file_stream->pos.offset == EOF)) {
+			ret = 0;
+		}
 		goto error_index;
+	}
 
 	/*
 	 * For now, only a single clock per trace is supported.