Ceph » RADOS

When firstly do_cmake.sh, it will create a ceph.conf .in build dir.
plugin dir = lib
erasure code dir = lib
When do ../src/vstart.sh -n, it print the following message:

ceph-mgr dashboard not built - disabling.
global_init: error reading config file.
global_init: error reading config file.
global_init: error reading config file.
global_init: error reading config file.
global_init: error reading config file.
dirname: missing operand
Try 'dirname --help' for more information.

From debug, code "asok_dir=`dirname $($CEPH_BIN/ceph-conf -c $conf_fn --show-config-value admin_socket)`" cause erro and make vstart.sh return.
So i simple code: "/bin/ceph-conf -c ceph.conf --show-config-value admin_socket"
global_init: error reading config file.

By git bisect, i found commit b1289290247fcd724c9f794716176089342f1110 cause this bug.

BTY: if remove ceph.conf, no problem occur. I think in ceph.conf no infos about admin_socket which cause dirname with null. If ceph.conf contain admin_socket, this bug not occur.