[PATCH] trace-cmd: Have trace-cmd stat show instances

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

The "trace-cmd stat" command does not show what instances exist,
the only way to see it is to browse the instances directory manually.
It is useful to have such information in "stat" subcommand.

Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=206773
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 tracecmd/trace-stat.c | 47 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/tracecmd/trace-stat.c b/tracecmd/trace-stat.c
index 3a086a69..3f7b3493 100644
--- a/tracecmd/trace-stat.c
+++ b/tracecmd/trace-stat.c
@@ -122,6 +122,50 @@ static char *get_instance_file_content(struct buffer_instance *instance,
 	return str;
 }
 
+static void report_instances(void)
+{
+	struct dirent *dent;
+	bool first = true;
+	char *path = NULL;
+	DIR *dir = NULL;
+	struct stat st;
+	int ret;
+
+	path = tracefs_get_tracing_file("instances");
+	if (!path)
+		return;
+	ret = stat(path, &st);
+	if (ret < 0 || !S_ISDIR(st.st_mode))
+		goto out;
+
+	dir = opendir(path);
+	if (!dir)
+		goto out;
+
+	while ((dent = readdir(dir))) {
+		char *instance;
+
+		if (strcmp(dent->d_name, ".") == 0 ||
+		    strcmp(dent->d_name, "..") == 0)
+			continue;
+		instance = append_file(path, dent->d_name);
+		ret = stat(instance, &st);
+		free(instance);
+		if (ret < 0 || !S_ISDIR(st.st_mode))
+			continue;
+		if (first) {
+			first = false;
+			printf("\nInstances:\n");
+		}
+		printf(" %s\n", dent->d_name);
+	}
+
+out:
+	if (dir)
+		closedir(dir);
+	tracefs_put_tracing_file(path);
+}
+
 static void report_plugin(struct buffer_instance *instance)
 {
 	char *str;
@@ -860,7 +904,8 @@ static void stat_instance(struct buffer_instance *instance)
 			printf("---------------\n");
 		printf("Instance: %s\n",
 			tracefs_instance_get_name(instance->tracefs));
-	}
+	} else
+		report_instances();
 
 	report_plugin(instance);
 	report_events(instance);
-- 
2.24.1