[lttng-dev] [PATCH babeltrace-1.5 6/6] Fix: lttng-live format: do not error out on empty streams hang up

[Mathieu Desnoyers]

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 at efficios.com>
---
 formats/ctf/ctf.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

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.
-- 
2.17.1