core: ptrbox: Add ptrbox_malloc() function

Signed-off-by: Ian Moffett <ian@mirocom.org>

include/common/ptrbox.h

@@ -60,6 +60,17 @@ int ptrbox_init(struct ptrbox *ptrbox);
  */
 char *ptrbox_strdup(struct ptrbox *ptrbox, const char *s);
 
+/*
+ * Allocate a number of bytes on the heap and store the reference
+ *
+ * @ptrbox: Pointer box
+ * @length: Number of bytes to allocate
+ *
+ * Returns the base of the allocated memory on success, otherwise
+ * NULL on failure.
+ */
+void *ptrbox_malloc(struct ptrbox *ptrbox, size_t length);
+
 /*
  * Destroy all elements within a pointer box
  *