bits, then encode them in a radix-32 representation (using digits
and letters except e, o, u, and t). This produces store paths like
/nix/store/4i0zb0z7f88mwghjirkz702a71dcfivn-aterm-2.3.1. The nice
thing about this is that the hash part of the file name is still 32
characters, as before with MD5.
(Of course, shortening SHA-256 to 160 bits makes it no better than
SHA-160 in theory, but hopefully it's a bit more resistant to
attacks; it's certainly a lot slower.)
* Start cleaning up unique store path generation (they weren't always
unique; in particular the suffix ("-aterm-2.2", "-builder.sh") was
not part of the hash, therefore changes to the suffix would cause
multiple store objects with the same hash).
files and hard-links them to each other to save disk space.
Currently it doesn't actually do the hard-linking, it just reports
the amount of space saved if it did.
http://www.daemonology.net/bsdiff/bsdiff-4.2.tar.gz) into the source
tree. The license is a bit peculiar, but it does allow verbatim
copying, which is what we do here (i.e., so don't make any changes
to the sources).
- Drop the store expression. So now a substitute is just a
command-line invocation (a program name + arguments). If you
register a substitute you are responsible for registering the
expression that built it (if any) as a root of the garbage
collector.
- Drop the substitutes-rev DB table.
substitute mechanism) creates a store path by downloading full NAR
archives and/or patches specified in the available manifests.
Any combination of present paths, full downloads, and patches can be
used to construct the target path. In particular, patches can be
chained in sequence; and full NAR archives of the target path can be
omitted (i.e., patch-only deployment is possible). A shortest path
algorithm is used to find the smallest set of files to be downloaded
(the edge weights are currently file sizes, but one can imagine
taking the network speed to the various source into account).
Patches are binary deltas between two store paths. To be precise,
they are the output of the `bsdiff' program applied to the NAR
archives obtained by dumping (`nix-store --dump') the two store
paths. The advantage of diff'ing NAR archives (and not, say, doing
file-by-file diffs) is that file renames/moves are handled
automatically. The disadvantage is that we cannot optimise creation
of unchanged files (by hard-linking).
