test_short_dio_read.c: add error handling

Add error handling for open() calls.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
ceph_authtool.cc: use empty() instead of size()

Use empty() since it should be prefered as it has, following the
standard, a constant time complexity regardless of the containter
type. The same is not guaranteed for size().

warning from cppchecker was:
[src/ceph_authtool.cc:124]: (performance) Possible inefficient
  checking for 'caps' emptiness.
[src/ceph_authtool.cc:237]: (performance) Possible inefficient
  checking for 'caps' emptiness.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
mds/CDentry.h: use projected.empty() instead of projected.size()

Use empty() since it should be prefered as it has, following the
standard, a constant time complexity regardless of the containter
type. The same is not guaranteed for size().

warning from cppchecker was:
[src/mds/CDentry.h:234]: (performance) Possible inefficient
  checking for 'projected' emptiness.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
mds/MDSMap.h: use up.empty() instead of up.size()

Use empty() since it should be prefered as it has, following the
standard, a constant time complexity regardless of the containter
type. The same is not guaranteed for size().

warning from cppchecker was:
[src/mds/MDSMap.h:448]: (performance) Possible inefficient
  checking for 'up' emptiness.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>