vppinfra: make _vec_len() read-only

Use of _vec_len() to set vector length breaks address sanitizer.
Users should use vec_set_len(), vec_inc_len(), vec_dec_len () instead.

Type: improvement
Change-Id: I441ae948771eb21c23a61f3ff9163bdad74a2cb8
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vppinfra/linux/sysfs.c b/src/vppinfra/linux/sysfs.c
index 758eaa1..a3e122c 100644
--- a/src/vppinfra/linux/sysfs.c
+++ b/src/vppinfra/linux/sysfs.c
@@ -70,7 +70,7 @@
       return clib_error_return_unix (0, "read `%s'", file_name);
     }
 
-  _vec_len (s) = sz;
+  vec_set_len (s, sz);
   unformat_init_vector (&input, s);
 
   va_list va;
@@ -154,7 +154,7 @@
       goto done;
     }
 
-  _vec_len (p) -= 1;
+  vec_dec_len (p, 1);
   p = format (p, "/hugepages/hugepages-%ukB/nr_hugepages%c", page_size, 0);
   clib_sysfs_write ((char *) p, "%d", nr);
 
@@ -207,7 +207,7 @@
       goto done;
     }
 
-  _vec_len (p) -= 1;
+  vec_dec_len (p, 1);
   p = format (p, "/hugepages/hugepages-%ukB/%s_hugepages%c", page_size,
 	      type, 0);
   error = clib_sysfs_read ((char *) p, "%d", val);