Messages in this thread | | | Subject | Re: Implementing Meta File information in Linux (and a note at the end on current reiserfs status) | Date | Wed, 02 Sep 1998 19:32:44 -0300 | From | "Brandon S. Allbery KF8NH" <> |
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In message <Pine.GSO.4.02A.9809021631240.15750-100000@red.seas.upenn.edu>, Vlad imir Dergachev writes: +----- | databases. In fact, /etc/passwd is nothing else but a database, though | one wasn't concerned very much with perfomance of it. GUI stuff is +--->8
*cough* *choke* *gasp* Andrew cluster *splutter*
I suspect Ted could make a similar remark with respect to MIT... then again, probably not. (HESIOD?) (I've yet to figure out why CMU thinks that local password files are a good thing....)
| One could also envision the file itself being associated with database | entries. In this context the copying of the file will copy the entries | as well. If one would attempt to copy the file outside of ext2 that should | produce those ".fork" database files. +--->8
One thought I had was that read() on a file with metadata returns a structured file containing all the data and metadata *unless* the program issues an fcntl() to switch to metadata mode. (Note that metadata/"forks" and databases are not disjoint --- Mac System 6 and later, IIRC, use a btree for the resource fork.) Having done that, read() returns only normal data and other fcntl() operations are used to access metadata.
If you hide the fcntl()s and metadata-aware read() inside other functions, you also get an API which could be implemented as a library on systems lacking metadata (the physical disk file actually is the above structured file) --- and to provide cross-platform metadata routines for Mac, NTFS, OS/2, etc. Of course, at this point the claim could be made that one doesn't need the fcntl() stuff, just the library (but! it will perform horribly unless the "structured file" is really a file and a backing (e.g.) reiserfs directory --- in which case you can lose by not realing that you need to copy the directory as well as the file.
-- brandon s. allbery [os/2][linux][solaris][japh] allbery@kf8nh.apk.net system administrator [WAY too many hats] allbery@ece.cmu.edu electrical and computer engineering KF8NH carnegie mellon university
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