trace-cmd: Add helper function tracecmd_add_id()

Several places are creating list of event ids as an array
with the ids ending in -1.

To use this, simply:

	int *events = NULL;
	intt len = 0;

	/* Fictious for statement */
	for (event = get_event(); event; event = next_event(event))
		events = tracecmd_add_id(events, event->id, len++);

	/* ... */

	free(events);

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

2 files changed, 51 insertions, 0 deletions

diff --git a/trace-cmd.h b/trace-cmd.h
index cbd563e..901a843 100644
--- a/trace-cmd.h
+++ b/trace-cmd.h
@@ -42,6 +42,7 @@ char **tracecmd_local_plugins(const char *tracing_dir);
 
 char **tracecmd_add_list(char **list, const char *name, int len);
 void tracecmd_free_list(char **list);
+int *tracecmd_add_id(int *list, int id, int len);
 
 enum {
         RINGBUF_TYPE_PADDING            = 29,
diff --git a/trace-util.c b/trace-util.c
index 058c9d2..33dbdf0 100644
--- a/trace-util.c
+++ b/trace-util.c
@@ -241,6 +241,19 @@ static char *append_file(const char *dir, const char *name)
         return file;
 }
 
+/**
+ * tracecmd_add_list - add an new string to a string list.
+ * @list: list to add the string to (may be NULL)
+ * @name: the string to add
+ * @len: current length of list of strings.
+ *
+ * The typical usage is:
+ *
+ *    systems = tracecmd_add_list(systems, name, len++);
+ *
+ * Returns the new allocated list with an allocated name added.
+ * The list will end with NULL.
+ */
 char **tracecmd_add_list(char **list, const char *name, int len)
 {
         if (!list)
@@ -260,6 +273,12 @@ char **tracecmd_add_list(char **list, const char *name, int len)
         return list;
 }
 
+/**
+ * tracecmd_free_list - free a list created with tracecmd_add_list.
+ * @list: The list to free.
+ *
+ * Frees the list as well as the names within the list.
+ */
 void tracecmd_free_list(char **list)
 {
         int i;
@@ -274,6 +293,37 @@ void tracecmd_free_list(char **list)
 }
 
 /**
+ * tracecmd_add_id - add an int to the event id list
+ * @list: list to add the id to
+ * @id: id to add
+ * @len: current length of list of ids.
+ *
+ * The typical usage is:
+ *
+ *    events = tracecmd_add_id(events, id, len++);
+ *
+ * Returns the new allocated list with the id included.
+ * the list will contain a '-1' at the end.
+ *
+ * The returned list should be freed with free().
+ */
+int *tracecmd_add_id(int *list, int id, int len)
+{
+        if (!list)
+                list = malloc_or_die(sizeof(*list) * 2);
+        else {
+                list = realloc(list, sizeof(*list) * (len + 2));
+                if (!list)
+                        die("Can ont allocate list");
+        }
+
+        list[len++] = id;
+        list[len] = -1;
+
+        return list;
+}
+
+/**
  * tracecmd_event_systems - return list of systems for tracing
  * @tracing_dir: directory holding the "events" directory
  *