trace-cmd: Add way to retrieve a list of event systems or events

Add tracecmd_event_systems() and tracecmd_system_events() to
retrieve the list of event systems or events under a system
that is in the /debug/tracing/events/* directory.

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

2 files changed, 188 insertions, 0 deletions

diff --git a/trace-cmd.h b/trace-cmd.h
index 22b45cc..ea6c356 100644
--- a/trace-cmd.h
+++ b/trace-cmd.h
@@ -35,6 +35,9 @@ struct plugin_list;
 struct plugin_list *tracecmd_load_plugins(struct pevent *pevent);
 void tracecmd_unload_plugins(struct plugin_list *list);
 
+char **tracecmd_event_systems(const char *tracing_dir);
+char **tracecmd_system_events(const char *tracing_dir, const char *system);
+
 enum {
         RINGBUF_TYPE_PADDING            = 29,
         RINGBUF_TYPE_TIME_EXTEND        = 30,
diff --git a/trace-util.c b/trace-util.c
index b8b6faf..456687c 100644
--- a/trace-util.c
+++ b/trace-util.c
@@ -227,6 +227,191 @@ char *tracecmd_find_tracing_dir(void)
         return tracing_dir;
 }
 
+static char *append_file(const char *dir, const char *name)
+{
+        char *file;
+
+        file = malloc_or_die(strlen(dir) + strlen(name) + 2);
+        if (!file)
+                return NULL;
+
+        sprintf(file, "%s/%s", dir, name);
+        return file;
+}
+
+static char **add_list(char **list, const char *name, int len)
+{
+        if (!list)
+                list = malloc_or_die(sizeof(*list) * 2);
+        else {
+                list = realloc(list, sizeof(*list) * (len + 2));
+                if (!list)
+                        die("Can not allocate list");
+        }
+
+        list[len] = strdup(name);
+        if (!list[len])
+                die("Can not allocate list");
+
+        list[len + 1] = NULL;
+
+        return list;
+}
+
+/**
+ * tracecmd_event_systems - return list of systems for tracing
+ * @tracing_dir: directory holding the "events" directory
+ *
+ * Returns an allocated list of system names. Both the names and
+ * the list must be freed with free().
+ * The list returned ends with a "NULL" pointer.
+ */
+char **tracecmd_event_systems(const char *tracing_dir)
+{
+        struct dirent *dent;
+        char **systems = NULL;
+        char *events_dir;
+        struct stat st;
+        DIR *dir;
+        int len = 0;
+        int ret;
+
+        if (!tracing_dir)
+                return NULL;
+
+        events_dir = append_file(tracing_dir, "events");
+        if (!events_dir)
+                return NULL;
+
+        /*
+         * Search all the directories in the events directory,
+         * and collect the ones that have the "enable" file.
+         */
+        ret = stat(events_dir, &st);
+        if (ret < 0 || !S_ISDIR(st.st_mode))
+                goto out_free;
+
+        dir = opendir(events_dir);
+        if (!dir)
+                goto out_free;
+
+        while ((dent = readdir(dir))) {
+                const char *name = dent->d_name;
+                char *enable;
+                char *sys;
+
+                if (strcmp(name, ".") == 0 ||
+                    strcmp(name, "..") == 0)
+                        continue;
+
+                sys = append_file(events_dir, name);
+                ret = stat(sys, &st);
+                if (ret < 0 || !S_ISDIR(st.st_mode)) {
+                        free(sys);
+                        continue;
+                }
+
+                enable = append_file(sys, "enable");
+
+                ret = stat(enable, &st);
+                if (ret >= 0)
+                        systems = add_list(systems, name, len++);
+
+                free(enable);
+                free(sys);
+        }
+
+        closedir(dir);
+
+ out_free:
+        free(events_dir);
+        return systems;
+}
+
+/**
+ * tracecmd_system_events - return list of events for system
+ * @tracing_dir: directory holding the "events" directory
+ * @system: the system to return the events for
+ *
+ * Returns an allocated list of event names. Both the names and
+ * the list must be freed with free().
+ * The list returned ends with a "NULL" pointer.
+ */
+char **tracecmd_system_events(const char *tracing_dir, const char *system)
+{
+        struct dirent *dent;
+        char **events = NULL;
+        char *events_dir;
+        char *system_dir;
+        struct stat st;
+        DIR *dir;
+        int len = 0;
+        int ret;
+
+        if (!tracing_dir || !system)
+                return NULL;
+
+        events_dir = append_file(tracing_dir, "events");
+        if (!events_dir)
+                return NULL;
+
+        /*
+         * Search all the directories in the systems directory,
+         * and collect the ones that have the "enable" file.
+         */
+        ret = stat(events_dir, &st);
+        if (ret < 0 || !S_ISDIR(st.st_mode))
+                goto out_free;
+
+        system_dir = append_file(events_dir, system);
+        if (!system_dir)
+                goto out_free;
+
+        ret = stat(system_dir, &st);
+        if (ret < 0 || !S_ISDIR(st.st_mode))
+                goto out_free_sys;
+
+        dir = opendir(system_dir);
+        if (!dir)
+                goto out_free_sys;
+
+        while ((dent = readdir(dir))) {
+                const char *name = dent->d_name;
+                char *enable;
+                char *event;
+
+                if (strcmp(name, ".") == 0 ||
+                    strcmp(name, "..") == 0)
+                        continue;
+
+                event = append_file(system_dir, name);
+                ret = stat(event, &st);
+                if (ret < 0 || !S_ISDIR(st.st_mode)) {
+                        free(event);
+                        continue;
+                }
+
+                enable = append_file(event, "enable");
+
+                ret = stat(enable, &st);
+                if (ret >= 0)
+                        events = add_list(events, name, len++);
+
+                free(enable);
+                free(event);
+        }
+
+        closedir(dir);
+
+ out_free_sys:
+        free(system_dir);
+
+ out_free:
+        free(events_dir);
+
+        return events;
+}
+
 static void
 trace_util_load_plugins_dir(struct pevent *pevent, const char *suffix,
                             const char *path,