Introduce some basic test cases for virFileIsSharedFS(). More
will be added later. In order to achieve desired result, mocks
for setmntent() and statfs() need to be invented because the
first thing that virFileIsSharedFS() does is calling the latter.
If it finds a FUSE mount it'll call the former.
The mock might look a bit complicated, but in fact it's quite
simple. The test sets LIBVIRT_MTAB env variable to hold the
absolute path to a file containing mount table. Then, statfs()
returns matching FS it finds, and setmntent() is there just to
replace /proc/mounts with the file the test wants to load.
Adding this test also exposed a bug we have - because we assume
the given path points to a file we cut off what we assume is a
file name to obtain directory path and only then we call
statfs(). This is buggy because the passed path could be already
a mount point.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
