Use wget download images.

Exec run special cmd, block until cmd exits.

FindMountPoint gets all wwcdocker mount point like /var/run/wwcdocker/mnt/balabalabala.

GetAllFdsOfProcess return all file descriptor of process.

TODO.

Must panics if err is not nil.

Must2 panics if the second parameter is not nil, Otherwise returns the first parameter.

WwcdockerRoot is container root.

Mount is shortcut of syscall.Mount.

Unmount is shortcut of syscall.Unmount.