[TUHS] Unix filesystem semantics history - files with holes
richard at inf.ed.ac.uk
Fri Apr 12 01:57:48 AEST 2019
> When did the Unix filesystem add the semantics for "files with holes" (large,
> sparse files)?
It was there in the first edition:
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
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