[PATCH 2/2] perf evlist: Support pipe mode display

[Namhyung Kim]

Likewise, perf evlist command should print event attributes by reading
PERF_RECORD_HEADER_ATTR records.

Before:
  $ perf record -o- true | ./perf evlist -i-
  (prints nothing)

After:
  $ perf record -o- true | ./perf evlist -i-
  cycles:pppH

Signed-off-by: Namhyung Kim <namhy...@kernel.org>
---
 tools/perf/builtin-evlist.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-evlist.c b/tools/perf/builtin-evlist.c
index 98e992801251..4617b32c9c97 100644
--- a/tools/perf/builtin-evlist.c
+++ b/tools/perf/builtin-evlist.c
@@ -17,6 +17,14 @@
 #include "util/data.h"
 #include "util/debug.h"
 #include <linux/err.h>
+#include "util/tool.h"
+
+static int process_header_feature(struct perf_session *session __maybe_unused,
+                                 union perf_event *event __maybe_unused)
+{
+       session_done = 1;
+       return 0;
+}
 
 static int __cmd_evlist(const char *file_name, struct perf_attr_details 
*details)
 {
@@ -27,12 +35,20 @@ static int __cmd_evlist(const char *file_name, struct 
perf_attr_details *details
                .mode      = PERF_DATA_MODE_READ,
                .force     = details->force,
        };
+       struct perf_tool tool = {
+               /* only needed for pipe mode */
+               .attr = perf_event__process_attr,
+               .feature = process_header_feature,
+       };
        bool has_tracepoint = false;
 
-       session = perf_session__new(&data, 0, NULL);
+       session = perf_session__new(&data, 0, &tool);
        if (IS_ERR(session))
                return PTR_ERR(session);
 
+       if (data.is_pipe)
+               perf_session__process_events(session);
+
        evlist__for_each_entry(session->evlist, pos) {
                evsel__fprintf(pos, details, stdout);
 
-- 
2.29.2.576.ga3fc446d84-goog