Add basic parse_events function that takes a string and returns an
evlist. As the python evlist is embedded in a pyrf_evlist, and the
evsels are embedded in pyrf_evsels, copy the parsed data into those
structs and update evsel__clone to enable this.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/cgroup.c |  2 +-
 tools/perf/util/evsel.c  | 19 ++++++++-----
 tools/perf/util/evsel.h  |  2 +-
 tools/perf/util/python.c | 61 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 75 insertions(+), 9 deletions(-)

diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
index 0f759dd96db7..fbcc0626f9ce 100644
--- a/tools/perf/util/cgroup.c
+++ b/tools/perf/util/cgroup.c
@@ -473,7 +473,7 @@ int evlist__expand_cgroup(struct evlist *evlist, const char *str,
 
 		leader = NULL;
 		evlist__for_each_entry(orig_list, pos) {
-			evsel = evsel__clone(pos);
+			evsel = evsel__clone(/*dest=*/NULL, pos);
 			if (evsel == NULL)
 				goto out_err;
 
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index f745723d486b..5fd32b6729b4 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -454,7 +454,7 @@ static int evsel__copy_config_terms(struct evsel *dst, struct evsel *src)
  * The assumption is that @orig is not configured nor opened yet.
  * So we only care about the attributes that can be set while it's parsed.
  */
-struct evsel *evsel__clone(struct evsel *orig)
+struct evsel *evsel__clone(struct evsel *dest, struct evsel *orig)
 {
 	struct evsel *evsel;
 
@@ -467,7 +467,11 @@ struct evsel *evsel__clone(struct evsel *orig)
 	if (orig->bpf_obj)
 		return NULL;
 
-	evsel = evsel__new(&orig->core.attr);
+	if (dest)
+		evsel = dest;
+	else
+		evsel = evsel__new(&orig->core.attr);
+
 	if (evsel == NULL)
 		return NULL;
 
@@ -512,11 +516,12 @@ struct evsel *evsel__clone(struct evsel *orig)
 	evsel->core.leader = orig->core.leader;
 
 	evsel->max_events = orig->max_events;
-	free((char *)evsel->unit);
-	evsel->unit = strdup(orig->unit);
-	if (evsel->unit == NULL)
-		goto out_err;
-
+	zfree(&evsel->unit);
+	if (orig->unit) {
+		evsel->unit = strdup(orig->unit);
+		if (evsel->unit == NULL)
+			goto out_err;
+	}
 	evsel->scale = orig->scale;
 	evsel->snapshot = orig->snapshot;
 	evsel->per_pkg = orig->per_pkg;
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 04934a7af174..7f41d6f8cf6f 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -241,7 +241,7 @@ static inline struct evsel *evsel__new(struct perf_event_attr *attr)
 	return evsel__new_idx(attr, 0);
 }
 
-struct evsel *evsel__clone(struct evsel *orig);
+struct evsel *evsel__clone(struct evsel *dest, struct evsel *orig);
 
 int copy_config_terms(struct list_head *dst, struct list_head *src);
 void free_config_terms(struct list_head *config_terms);
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index 3e32a502a41c..c84c912874b7 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -13,6 +13,7 @@
 #include "evsel.h"
 #include "event.h"
 #include "print_binary.h"
+#include "strbuf.h"
 #include "thread_map.h"
 #include "trace-event.h"
 #include "mmap.h"
@@ -1201,6 +1202,60 @@ static PyObject *pyrf__tracepoint(struct pyrf_evsel *pevsel,
 #endif // HAVE_LIBTRACEEVENT
 }
 
+static PyObject *pyrf_evsel__from_evsel(struct evsel *evsel)
+{
+	struct pyrf_evsel *pevsel = PyObject_New(struct pyrf_evsel, &pyrf_evsel__type);
+
+	if (!pevsel)
+		return NULL;
+
+	memset(&pevsel->evsel, 0, sizeof(pevsel->evsel));
+	evsel__init(&pevsel->evsel, &evsel->core.attr, evsel->core.idx);
+
+	evsel__clone(&pevsel->evsel, evsel);
+	return (PyObject *)pevsel;
+}
+
+static PyObject *pyrf_evlist__from_evlist(struct evlist *evlist)
+{
+	struct pyrf_evlist *pevlist = PyObject_New(struct pyrf_evlist, &pyrf_evlist__type);
+	struct evsel *pos;
+
+	if (!pevlist)
+		return NULL;
+
+	memset(&pevlist->evlist, 0, sizeof(pevlist->evlist));
+	evlist__init(&pevlist->evlist, evlist->core.all_cpus, evlist->core.threads);
+	evlist__for_each_entry(evlist, pos) {
+		struct pyrf_evsel *pevsel = (void *)pyrf_evsel__from_evsel(pos);
+
+		evlist__add(&pevlist->evlist, &pevsel->evsel);
+	}
+	return (PyObject *)pevlist;
+}
+
+static PyObject *pyrf__parse_events(PyObject *self, PyObject *args)
+{
+	const char *input;
+	struct evlist evlist = {};
+	struct parse_events_error err;
+	PyObject *result;
+
+	if (!PyArg_ParseTuple(args, "s", &input))
+		return NULL;
+
+	parse_events_error__init(&err);
+	evlist__init(&evlist, NULL, NULL);
+	if (parse_events(&evlist, input, &err)) {
+		parse_events_error__print(&err, input);
+		PyErr_SetFromErrno(PyExc_OSError);
+		return NULL;
+	}
+	result = pyrf_evlist__from_evlist(&evlist);
+	evlist__exit(&evlist);
+	return result;
+}
+
 static PyMethodDef perf__methods[] = {
 	{
 		.ml_name  = "tracepoint",
@@ -1208,6 +1263,12 @@ static PyMethodDef perf__methods[] = {
 		.ml_flags = METH_VARARGS | METH_KEYWORDS,
 		.ml_doc	  = PyDoc_STR("Get tracepoint config.")
 	},
+	{
+		.ml_name  = "parse_events",
+		.ml_meth  = (PyCFunction) pyrf__parse_events,
+		.ml_flags = METH_VARARGS,
+		.ml_doc	  = PyDoc_STR("Parse a string of events and return an evlist.")
+	},
 	{ .ml_name = NULL, }
 };
 
-- 
2.47.0.338.g60cca15819-goog