perf tools: Use perf_data_file__fd() consistently

Do not reference file->fd directly since we want hide the
implementation details from outside for possible future changes.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1422518843-25818-8-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 84df2de..a13641e 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -343,6 +343,7 @@
 	int ret = -EINVAL;
 	struct perf_session *session = inject->session;
 	struct perf_data_file *file_out = &inject->output;
+	int fd = perf_data_file__fd(file_out);
 
 	signal(SIGINT, sig_handler);
 
@@ -376,7 +377,7 @@
 	}
 
 	if (!file_out->is_pipe)
-		lseek(file_out->fd, session->header.data_offset, SEEK_SET);
+		lseek(fd, session->header.data_offset, SEEK_SET);
 
 	ret = perf_session__process_events(session, &inject->tool);
 
@@ -385,7 +386,7 @@
 			perf_header__set_feat(&session->header,
 					      HEADER_BUILD_ID);
 		session->header.data_size = inject->bytes_written;
-		perf_session__write_header(session, session->evlist, file_out->fd, true);
+		perf_session__write_header(session, session->evlist, fd, true);
 	}
 
 	return ret;