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Allocating uninitialized file blocks

Allocating uninitialized file blocks

Posted Apr 19, 2012 20:51 UTC (Thu) by intgr (subscriber, #39733)
In reply to: Allocating uninitialized file blocks by joey
Parent article: Allocating uninitialized file blocks

> that used the equivilant option in Windows

Are you saying that there's an equivalent to the new proposed FALLOC_FL_NO_HIDE_STALE flag too? I'd be surprised. Can you link to the discussion?

(Maybe you're just confused. I'm sure there is a fallocate() equivalent feature in Windows -- but fallocate() doesn't leak any foreign file data, without this new proposed flag)


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Allocating uninitialized file blocks

Posted Apr 19, 2012 21:22 UTC (Thu) by Fowl (subscriber, #65667) [Link]

That would be the SetFileValidData function, which "is useful in very limited scenarios. "

To use it requires the SE_MANAGE_VOLUME_NAME privilege (ie. raw disk access).

"Applications should call SetFileValidData only on files that restrict access to those entities that have SE_MANAGE_VOLUME_NAME access. The application must ensure that the unwritten ranges of the file are never exposed, or security issues can result as follows."

[Something about giving just enough rope to hang yourself / trusting programmers to know what they're doing.]


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