trace-cmd: Add tracecmd_local_plugins()

Add tracecmd_local_plugins() that returns a list of available
tracer plugins.

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

2 files changed, 65 insertions, 3 deletions

diff --git a/trace-cmd.h b/trace-cmd.h
index b732484..c85bb9b 100644
--- a/trace-cmd.h
+++ b/trace-cmd.h
@@ -38,6 +38,7 @@ 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);
 struct pevent *tracecmd_local_events(const char *tracing_dir);
+char **tracecmd_local_plugins(const char *tracing_dir);
 
 enum {
         RINGBUF_TYPE_PADDING            = 29,
diff --git a/trace-util.c b/trace-util.c
index 6d813c5..82c3d1e 100644
--- a/trace-util.c
+++ b/trace-util.c
@@ -425,11 +425,11 @@ static int read_file(const char *file, char **buffer)
         if (fd < 0)
                 return -1;
 
-        buf = malloc_or_die(BUFSIZ);
+        buf = malloc_or_die(BUFSIZ + 1);
 
         while ((r = read(fd, buf + len, BUFSIZ)) > 0) {
                 len += r;
-                buf = realloc(buf, len + BUFSIZ);
+                buf = realloc(buf, len + BUFSIZ + 1);
                 if (!buf) {
                         len = -1;
                         goto out;
@@ -437,7 +437,7 @@ static int read_file(const char *file, char **buffer)
         }
 
         *buffer = buf;
-
+        buf[len] = 0;
  out:
         close(fd);
 
@@ -594,6 +594,67 @@ struct pevent *tracecmd_local_events(const char *tracing_dir)
         return pevent;
 }
 
+/**
+ * tracecmd_local_plugins - returns an array of available tracer plugins
+ * @tracing_dir: The directory that contains the tracing directory
+ *
+ * Returns an allocate list of plugins. The array ends with NULL.
+ * Both the plugin names and array must be freed with free().
+ */
+char **tracecmd_local_plugins(const char *tracing_dir)
+{
+        char *available_tracers;
+        struct stat st;
+        char **plugins = NULL;
+        char *buf;
+        char *str, *saveptr;
+        char *plugin;
+        int slen;
+        int len;
+        int ret;
+
+        if (!tracing_dir)
+                return NULL;
+
+        available_tracers = append_file(tracing_dir, "available_tracers");
+        if (!available_tracers)
+                return NULL;
+
+        ret = stat(available_tracers, &st);
+        if (ret < 0)
+                goto out_free;
+
+        len = read_file(available_tracers, &buf);
+        if (len < 0)
+                goto out_free;
+
+        len = 0;
+        for (str = buf; ; str = NULL) {
+                plugin = strtok_r(str, " ", &saveptr);
+                if (!plugin)
+                        break;
+                if (!(slen = strlen(plugin)))
+                        continue;
+
+                /* chop off any newlines */
+                if (plugin[slen - 1] == '\n')
+                        plugin[slen - 1] = '\0';
+
+                /* Skip the non tracers */
+                if (strcmp(plugin, "nop") == 0 ||
+                    strcmp(plugin, "none") == 0)
+                        continue;
+
+                plugins = add_list(plugins, plugin, len++);
+        }
+        free(buf);
+
+ out_free:
+        free(available_tracers);
+
+        return plugins;
+}
+
 static void
 trace_util_load_plugins_dir(struct pevent *pevent, const char *suffix,
                             const char *path,