tree: do not try to strdup NULL pointer

[igaw]

blktests nvme/003 using the loop transport fails because nvme_ctrl_alloc tries to strdup NULL pointers (address or sysfs_dir).

Introduce a 'safe' strdup version and start this version.

Reported-by: Tomáš Bžatek [email protected]
Reported-by: Yi Zhang [email protected]
Fixes: e642498 ("tree: free ctrl attributes when (re)configure ctrl")

Fixes: #1045 #linux-nvme/nvme-cli#2885

[igaw]

I am running blktests tr=loop with this version. Looks good so far. @MaisenbacherD do you think it would be simple to get a nightly build with blktests setup? I think you are finished with the heavy lifting for the in tree tests. Now it would be awesome to have blktests also run with the latest nvme-cli.

[tbzatek]

Thanks!

[MaisenbacherD]

I am running blktests tr=loop with this version. Looks good so far. @MaisenbacherD do you think it would be simple to get a nightly build with blktests setup? I think you are finished with the heavy lifting for the in tree tests. Now it would be awesome to have blktests also run with the latest nvme-cli.

Yes, this should be fairly easy to set up now.
I will post a PR for this soon. :)

[MaisenbacherD]

We have blktests running in nvme-cli: linux-nvme/nvme-cli#2915
For now, we are running the blktests with the libnvme version from subprojects/libnvme.wrap of nvme-cli.