CloudMirror / CFAPI / Can't get access to cloud data via system service.

[Modin-ua]

Turned out app started in service session (0) despite system privileges can't trigger data hydration from the cloud.
Although if data already pulled to sync root service app can read data without issues.

Exception discovered: if executable placed in %systemroot% it can trigger hydration.

Error client (service session) app receives: Access to the cloud file is denied. - 0x0000018B (395)
in ProcessMonitor(sysinternals) it would be error 0xC000CF18 indicated in CreateFile.

Issue can be reproduced by pointing any service app to not yet hydrated file in sync root for reading.

Or this way:

• Copy executable file C:\Windows\System32\more.com to C:\more.com

• Run in elevated console: psexec -h -s cmd

• Try open any file in local sync root like: C:\more.com C:\sync_root_folder\cloud_file
  get Cannot access file error.

• Run: C:\WINDOWS\system32\more.com C:\sync_root_folder\cloud_file
  see it opens fine.

Already discussed in Docs Q&A, directed to this issue tracker from there.
https://docs.microsoft.com/en-us/answers/questions/892349/cfapi-allow-data-fetch-for-services.html

Thanks,

[AliveDevil]

Same issue here.
Trying to create unit tests for CloudFiles with a Jenkins CI service account.

It's impossible to test now, as no callback is generated for file access from the sync provider process, and spawning a separate helper-process to perform file access to trigger callbacks fails with above issue.