SharePoint support

[blizzz]

Contributes to #2672

Add a SharePoint Backend to files_external

configuration:

requirements

• NTLM Auth enabled on SP. We strictly require NTLM Auth. Basic did not work for me, I assume because of the SP/IIS configuration. Apparently NTLM is > then Basic anyhow.

environment

• tested and developed against SharePoint 2016, but
• SharePoint 2013 should work, however this is not proven
• removes queries on the go so they don't get stuck on exceptions vgrem/phpSPO#63 is applied to phpSPO lib

features

• dir listings, trying to identify and hide hidden system directories (e.g. "Forms").
• creating dirs
• down- and upload of files (via streams, exception: new files)
• renames
• removing files and folders (using recycle method i.e. putting it into the wastebin)
• determine CRUD permissions

[mention-bot]

@blizzz, thanks for your PR! By analyzing the history of the files in this pull request, we identified @icewind1991, @Xenopathic and @LukasReschke to be potential reviewers.

[icewind1991]

Any chance we can keep the dragons contained in their own app?

[blizzz]

@icewind1991 i caught one dragon for you: on mkdir('foo/bar') an opendir against 'foo' is performed. why?

So, the scanner kicks in (external storage), but it is necessary when triggered by httpMkcol()? The direct trigger is getNodeForPath() from our ObjectTree Connector. At this point however there is no information about the operation. Hm.

[codecov-io]

Codecov Report

Merging #4106 into master will decrease coverage by 0.44%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #4106      +/-   ##
============================================
- Coverage      54.2%   53.76%   -0.45%     
- Complexity    21597    21838     +241     
============================================
  Files          1327     1277      -50     
  Lines         82538    76276    -6262     
  Branches       1305        0    -1305     
============================================
- Hits          44739    41007    -3732     
+ Misses        37799    35269    -2530

Impacted Files	Coverage Δ	Complexity Δ
apps/dav/lib/DAV/Sharing/Backend.php	71.08% <0%> (-16.87%)	17% <0%> (ø)
apps/sharebymail/lib/Settings/SettingsManager.php	25% <0%> (-15%)	3% <0%> (+1%)
apps/user_ldap/appinfo/routes.php	66.66% <0%> (-10.61%)	0% <0%> (ø)
apps/sharebymail/lib/ShareByMailProvider.php	60.07% <0%> (-8.68%)	87% <0%> (+22%)
apps/comments/lib/EventHandler.php	79.16% <0%> (-8.34%)	7% <0%> (ø)
settings/Controller/CheckSetupController.php	70.52% <0%> (-8.1%)	56% <0%> (ø)
apps/dav/lib/CalDAV/Calendar.php	73.68% <0%> (-3.42%)	52% <0%> (+3%)
apps/user_ldap/lib/User/User.php	80.53% <0%> (-2.15%)	123% <0%> (+32%)
apps/dav/lib/CardDAV/AddressBook.php	64.63% <0%> (-2.04%)	27% <0%> (+3%)
apps/user_ldap/lib/User_LDAP.php	74.35% <0%> (-1.54%)	72% <0%> (+3%)
... and 186 more

[blizzz]

After some off-github discussions, this is deprecated in favor of a separate app → https://github.com/nextcloud/sharepoint