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* Re: [TUHS] Unix filesystem semantics history - files with holes
@ 2019-04-11 15:57 Richard Tobin
  2019-04-11 19:09 ` William Corcoran
  2019-04-11 19:49 ` Bakul Shah
  0 siblings, 2 replies; 5+ messages in thread
From: Richard Tobin @ 2019-04-11 15:57 UTC (permalink / raw)
  To: Erik E. Fair, The Eunuchs Hysterical Society

> When did the Unix filesystem add the semantics for "files with holes" (large,
> sparse files)?

It was there in the first edition:

https://www.bell-labs.com/usr/dmr/www/pdfs/man51.pdf

The FILE SYSTEM (V) man page includes a last paragraph identical to
that of FILSYS (V) in seventh edition:

  If block b in a file exists, it is not necessary that all blocks
  less than b exist.  A zero block number either in the address words
  of the the i-node or in an indirect block indicates that the
  corresponding block has never been allocated.  Such a missing block
  reads as if it contained all zero words.

The first edition indirect blocks were a bit different though: if the
file was bigger than 8 blocks (4kB), all the blocks in the inode were
(singly) indirect.

-- Richard

-- 
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.


^ permalink raw reply	[flat|nested] 5+ messages in thread
* [TUHS] Unix filesystem semantics history - files with holes
@ 2019-04-11  2:37 Erik E. Fair
  2019-04-11  5:28 ` Ronald Natalie
  0 siblings, 1 reply; 5+ messages in thread
From: Erik E. Fair @ 2019-04-11  2:37 UTC (permalink / raw)
  To: The Eunuchs Hysterical Society

When did the Unix filesystem add the semantics for "files with holes" (large,
sparse files)?

Just an idle question that was sparked by a conversation I had today.

	Erik <fair@clock.org>

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2019-04-11 19:50 UTC | newest]

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2019-04-11 15:57 [TUHS] Unix filesystem semantics history - files with holes Richard Tobin
2019-04-11 19:09 ` William Corcoran
2019-04-11 19:49 ` Bakul Shah
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2019-04-11  2:37 Erik E. Fair
2019-04-11  5:28 ` Ronald Natalie

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