[PATCH v3 4/7] libtracefs: Implement tracefs_get_kprobes()

[Steven Rostedt <rostedt@goodmis.org>]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

Add the function tracefs_get_kprobes() that returns a list of kprobes that
are registered. The list contains strings that are of the format
"group/event" (i.e. "kprobes/open"). The last element in the list is a
NULL pointer. In the case that there are no kprobes, the list will return
a single entry of a NULL pointer.

NULL is returned in the case of error (mainly a memory issue, or bad
parsing).

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/tracefs.h     |  1 +
 src/tracefs-kprobes.c | 66 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/include/tracefs.h b/include/tracefs.h
index 64164c8c2b20..5f59c480d572 100644
--- a/include/tracefs.h
+++ b/include/tracefs.h
@@ -219,4 +219,5 @@ int tracefs_kprobe_raw(const char *system, const char *event,
 		       const char *addr, const char *format);
 int tracefs_kretprobe_raw(const char *system, const char *event,
 			  const char *addr, const char *format);
+char **tracefs_get_kprobes(void);
 #endif /* _TRACE_FS_H */
diff --git a/src/tracefs-kprobes.c b/src/tracefs-kprobes.c
index 9bd9b2df9287..8df3227d687f 100644
--- a/src/tracefs-kprobes.c
+++ b/src/tracefs-kprobes.c
@@ -105,3 +105,69 @@ int tracefs_kretprobe_raw(const char *system, const char *event,
 {
 	return insert_kprobe("r", system, event, addr, format);
 }
+
+/**
+ * tracefs_get_kprobes - return a list kprobes (by group/event name)
+ *
+ * Returns a list of strings that contain the kprobes that exist
+ * in the kprobe_events files. The strings returned are in the
+ * "group/event" format.
+ * The list must be freed with tracefs_list_free().
+ * If there are no kprobes, a list is still returned, but it contains
+ * only a NULL pointer.
+ * On error, NULL is returned.
+ */
+char **tracefs_get_kprobes(void)
+{
+	char **list = NULL;
+	char *content;
+	char *saveptr;
+	char *event;
+	char *p;
+	int cnt = 0;
+
+	content = tracefs_instance_file_read(NULL, KPROBE_EVENTS, NULL);
+	if (!content)
+		return NULL;
+
+	p = strtok_r(content, ":", &saveptr);
+
+	while (p) {
+		char **tmp;
+
+		/* Failed parsing always return a failure */
+		p = strtok_r(NULL, " ", &saveptr);
+		if (!p)
+			break;
+
+		event = strdup(p);
+		if (!event)
+			goto fail;
+
+		tmp = realloc(list, sizeof(*list) * (cnt + 2));
+		if (!tmp)
+			goto fail;
+
+		list = tmp;
+		list[cnt++] = event;
+		list[cnt] = NULL;
+
+		p = strtok_r(NULL, "\n", &saveptr);
+		/* Could be end of content */
+		if (!p)
+			break;
+
+		/* p is NULL on end of content */
+		p = strtok_r(NULL, ":", &saveptr);
+	}
+
+	if (!list)
+		list = calloc(1, sizeof(*list));
+ out:
+	free(content);
+	return list;
+ fail:
+	free(list);
+	list = NULL;
+	goto out;
+}
-- 
2.30.2