trace-cmd list: Have -o read the options directory instead of file

The trace_options file only shows the options that are available when a
tracer is set. This is annoying as one needs to enable the tracer in order
to see all the options that are available.

Starting with Linux v4.4, all tracers options are displayed in the options
directory. Walk through the options directory instead of simply reading
the trace_options file.

Link: https://lore.kernel.org/linux-trace-devel/20210416172331.3870833-2-rostedt@goodmis.org

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 46 insertions, 2 deletions

diff --git a/tracecmd/trace-list.c b/tracecmd/trace-list.c
index 900da73b..0574e563 100644
--- a/tracecmd/trace-list.c
+++ b/tracecmd/trace-list.c
@@ -399,13 +399,57 @@ static void show_tracers(void)
 	show_file("available_tracers");
 }
 
-
 static void show_options(void)
 {
+	struct dirent *dent;
+	struct stat st;
+	char *path;
+	DIR *dir;
+
+	path = tracefs_get_tracing_file("options");
+	if (!path)
+		goto show_file;
+	if (stat(path, &st) < 0)
+		goto show_file;
+
+	if ((st.st_mode & S_IFMT) != S_IFDIR)
+		goto show_file;
+
+	dir = opendir(path);
+	if (!dir)
+		die("Can not read instance directory");
+
+	while ((dent = readdir(dir))) {
+		const char *name = dent->d_name;
+		long long val;
+		char *file;
+		int ret;
+
+		if (strcmp(name, ".") == 0 ||
+		    strcmp(name, "..") == 0)
+			continue;
+
+		ret = asprintf(&file, "options/%s", name);
+		if (ret < 0)
+			die("Failed to allocate file name");
+		ret = tracefs_instance_file_read_number(NULL, file, &val);
+		if (!ret) {
+			if (val)
+				printf("%s\n", name);
+			else
+				printf("no%s\n", name);
+		}
+		free(file);
+	}
+	closedir(dir);
+	tracefs_put_tracing_file(path);
+	return;
+
+ show_file:
+	tracefs_put_tracing_file(path);
 	show_file("trace_options");
 }
 
-
 static void show_clocks(void)
 {
 	char *clocks;