utilfdt_read: pass back up the length of data read

For a follow up commit, we want to be able to scan the buffer that was
returned to us.  In order to do that safely, we need to know how big
the buffer actually is, so create a new set of funcs to pass that back.

Acked-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

util.h

@@ -84,6 +84,13 @@ char get_escape_char(const char *s, int *i);
  */
 char *utilfdt_read(const char *filename);
 
+/**
+ * Like utilfdt_read(), but also passes back the size of the file read.
+ *
+ * @param len		If non-NULL, the amount of data we managed to read
+ */
+char *utilfdt_read_len(const char *filename, off_t *len);
+
 /**
  * Read a device tree file into a buffer. Does not report errors, but only
  * returns them. The value returned can be passed to strerror() to obtain
@@ -95,6 +102,12 @@ char *utilfdt_read(const char *filename);
  */
 int utilfdt_read_err(const char *filename, char **buffp);
 
+/**
+ * Like utilfdt_read_err(), but also passes back the size of the file read.
+ *
+ * @param len		If non-NULL, the amount of data we managed to read
+ */
+int utilfdt_read_err_len(const char *filename, char **buffp, off_t *len);
 
 /**
  * Write a device tree buffer to a file. This will report any errors on