The data in the file tells ntfs to call an installable filter. That filter can then return data from somewhere else. The feature is used for lots of things like the Encrypting File System, the Removable Storage Management (that allows files to be archived while still appearing in the file system). It's what allows you to mount devices (both partitions and network shares) in folders of other drives rather than assigning a drive letter for each, a la unix. Most interestingly it is used by Exchange Server 2000 onwards to expose the contents of its database as a directory tree with items appearing as files.
If you want a parallel, think about the Linux loopback device. Although NTFS installable filters run in kernel space AFAIK, they can communicate with user space programs like Exchange Server to provide data. Technical details are in the DDK, but there's a high level description of what's possible in the following page: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnfiles /html/ntfs2.asp >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] On Behalf Of Jochen Wezel >Sent: 10 February 2004 15:16 >To: egonia; [EMAIL PROTECTED] >Subject: AW: AW: [Mono-list] Directory Symbolic link? > > >Hi Eric, > >You've trapped into a dark, seldom seen world. There is no >great documentation or anything else. My knowledge is from the >study of the NTFS file system and some tools which are >creating such symbolic links. A reparse point is a small >script or some data inside a file system entry which says: >"no, I'm not your file you're asking for, but I know where to >get it from" > >Regards >Jochen > > >-----Urspr�ngliche Nachricht----- >Von: egonia [mailto:[EMAIL PROTECTED] >Gesendet: Dienstag, 10. Februar 2004 15:12 >An: Jochen Wezel >Cc: Gonia Eric - egonia; Alejandro Mery; [EMAIL PROTECTED] >Betreff: Re: AW: [Mono-list] Directory Symbolic link? > >What exactly is a ReparsePoint? > >This is what the .Net SDK has to say about it: >"The file contains a reparse point, which is a block of >user-defined data associated with a file or a directory." > >I guess this is probably my own ignorance, but would someone >kindly explain reparse points to me? > >I could not find anything with google on the matter. > >Thanks, >Eric > > Jochen Wezel <[EMAIL PROTECTED]>: > >> Maybe, your question could be answered with the search for reparse >> points: >> >> System.IO.DirectoryInfo a; >> bool IsSymbolicLink = a.Attributes.ReparsePoint; >> >> Jochen >> > > >_______________________________________________ >Mono-list maillist - [EMAIL PROTECTED] >http://lists.ximian.com/mailman/listinfo/mono->list > _______________________________________________ Mono-list maillist - [EMAIL PROTECTED] http://lists.ximian.com/mailman/listinfo/mono-list
