Commit 9f5764dac39b ("saveconfig: set right perms on /etc/target/ dir")
fixed CVE-2020-13867 by ensuring that the mode of the target
meta-data directory (/etc/target) was always mode 0600. But users
can specify a different directory, such as "/tmp", and we don't
want targetcli changing the mode of such directories to 0600. So
only change the mode of the directory, when saving a config file,
if the directory is /etc/target.

Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>

fallocate() can't be used to create sparse files because it
actually preallocates all the disk space that will be used by the file
backstore, sparse files do not have preallocated disk space
by definition.
We must therefore use ftruncate().

We can, on the other hand, use fallocate() to create non-sparse
files and fall back to the slower "while() fwrite()" if we
are running on Python version < 3.3 where fallocate() is not available

Fixes 3bd4d8ef7c9b154c53e8b8dd863a570bce7f5c2c

Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>

Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

set interactive mode as default to make it appear similar to cli approach,

$ targetcli
targetcli shell version 2.1.51
Entering targetcli interactive mode for daemonized approach.
Type 'exit' to quit.

/> pwd
/
/> cd /iscsi
/> pwd
/iscsi
/> exit

Here we introduce a new global option daemon_use_batch_mode for switching between
batch and interactive modes.

$ targetcli set global daemon_use_batch_mode=true
Parameter daemon_use_batch_mode is now 'true'.

$ targetcli
targetcli shell version 2.1.51
Entering targetcli batch mode for daemonized approach.
Enter multiple commands separated by newline and type 'exit' to run them
all in one go.

/> pwd
/> cd /iscsi
/> pwd
/
/iscsi

Fixes: #160
Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>