though). In particular it's now much easier to register a GC root.
Just place a symlink to whatever store path it is that you want to
keep in /nix/var/nix/gcroots.
This simplifies garbage collection and `nix-store --query
--requisites' since we no longer need to treat derivations
specially.
* Better maintaining of the invariants, e.g., setReferences() can only
be called on a valid/substitutable path.
`derivations.cc', etc.
* Store the SHA-256 content hash of store paths in the database after
they have been built/added. This is so that we can check whether
the store has been messed with (a la `rpm --verify').
* When registering path validity, verify that the closure property
holds.
representation of closures as ATerms in the Nix store. Instead, the
file system pointer graph is now stored in the Nix database. This
has many advantages:
- It greatly simplifies the implementation (we can drop the notion
of `successors', and so on).
- It makes registering roots for the garbage collector much easier.
Instead of specifying the closure expression as a root, you can
simply specify the store path that must be retained as a root.
This could not be done previously, since there was no way to find
the closure store expression containing a given store path.
- Better traceability: it is now possible to query what paths are
referenced by a path, and what paths refer to a path.
* Formalise the notion of fixed-output derivations, i.e., derivations
for which a cryptographic hash of the output is known in advance.
Changes to such derivations should not propagate upwards through the
dependency graph. Previously this was done by specifying the hash
component of the output path through the `id' attribute, but this is
insecure since you can lie about it (i.e., you can specify any hash
and then produce a completely different output). Now the
responsibility for checking the output is moved from the builder to
Nix itself.
A fixed-output derivation can be created by specifying the
`outputHash' and `outputHashAlgo' attributes, the latter taking
values `md5', `sha1', and `sha256', and the former specifying the
actual hash in hexadecimal or in base-32 (auto-detected by looking
at the length of the attribute value). MD5 is included for
compatibility but should be considered deprecated.
* Removed the `drvPath' pseudo-attribute in derivation results. It's
no longer necessary.
* Cleaned up the support for multiple output paths in derivation store
expressions. Each output now has a unique identifier (e.g., `out',
`devel', `docs'). Previously there was no way to tell output paths
apart at the store expression level.
* `nix-hash' now has a flag `--base32' to specify that the hash should
be printed in base-32 notation.
* `fetchurl' accepts parameters `sha256' and `sha1' in addition to
`md5'.
* `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a
flag to specify the hash.)
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).
Instead we generate data bindings (build and match functions) for
the constructors specified in `constructors.def'. In particular
this removes the conversions between AFuns and strings, and Nix
expression evaluation now seems 3 to 4 times faster.
profile. Arguments are either generation number, or `old' to delete
all non-current generations. Typical use:
$ nix-env --delete-generations old
$ nix-collect-garbage
* istringstream -> string2Int.
Previously there was the problem that all files read by nix-env
etc. should be reachable and readable by the Nix user. So for
instance building a Nix expression in your home directory meant that
the home directory should have at least g+x or o+x permission so
that the Nix user could reach the Nix expression. Now we just
switch back to the original user just prior to reading sources and
the like. The places where this happens are somewhat arbitrary,
however. Any scope that has a live SwitchToOriginalUser object in
it is executed as the original user.
* Back out r1385. setreuid() sets the saved uid to the new
real/effective uid, which prevents us from switching back to the
original uid. setresuid() doesn't have this problem (although the
manpage has a bug: specifying -1 for the saved uid doesn't leave it
unchanged; an explicit value must be specified).
* Builder output is written to standard error by default.
* The option `-B' is gone.
* The option `-Q' suppresses builder output.
The result of this is that most Nix invocations shouldn't need any
flags w.r.t. logging.
system types other than the current system. I.e., `nix-env -i'
won't install derivations for other system types, and `nix-env -q'
won't show them. The flag `--system-filter SYSTEM' can be used to
override the system type used for filtering (but not for
building!). The value `*' can be used not to filter anything.
Whenever Nix attempts to realise a derivation for which a closure is
already known, but this closure cannot be realised, fall back on
normalising the derivation.
The most common scenario in which this is useful is when we have
registered substitutes in order to perform binary distribution from,
say, a network repository. If the repository is down, the
realisation of the derivation will fail. When this option is
specified, Nix will build the derivation instead. Thus, binary
installation falls back on a source installation. This option is
not the default since it is generally not desirable for a transient
failure in obtaining the substitutes to lead to a full build from
source (with the related consumption of resources).
* A better substitute mechanism.
Instead of generating a store expression for each store path for
which we have a substitute, we can have a single store expression
that builds a generic program that is invoked to build the desired
store path, which is passed as an argument.
This means that operations like `nix-pull' only produce O(1) files
instead of O(N) files in the store when registering N substitutes.
(It consumes O(N) database storage, of course, but that's not a
performance problem).
* Added a test for the substitute mechanism.
* `nix-store --substitute' reads the substitutes from standard input,
instead of from the command line. This prevents us from running
into the kernel's limit on command line length.
print a nice backtrace of the stack, rather than vomiting a gigantic
(and useless) aterm on the screen. Example:
error: while evaluating file `.../pkgs/system/test.nix':
while evaluating attribute `subversion' at `.../pkgs/system/all-packages-generic.nix', line 533:
while evaluating function at `.../pkgs/applications/version-management/subversion/default.nix', line 1:
assertion failed at `.../pkgs/applications/version-management/subversion/default.nix', line 13
Since the Nix expression language is lazy, the trace may be
misleading. The purpose is to provide a hint as to the location of
the problem.
derivation (i.e., the closure store expression) a root of the
garbage collector. This ensures that running `nix-collect-garbage
--no-successors' is safe.
whether we want to upgrade if the current version is less than the
available version (default), when it is less or equal, or always.
* Added a flag `--dry-run' to show what would happen in `--install',
`--uninstall', and `--upgrade', without actually performing the
operation.
of the current profile, e.g.,
$ nix-env --list-generations
...
39 2004-02-02 17:53:53
40 2004-02-02 17:55:18
41 2004-02-02 17:55:41
42 2004-02-02 17:55:50 (current)
$ nix-env --switch-generation 39
$ ls -l /nix/var/nix/profiles/default
... default -> default-39-link
* Also a command `--rollback' which is just a convenience operation to
rollback to the oldest generation younger than the current one.
Note that generations properly form a tree. E.g., if after
switching to generation 39, we perform an installation action,
a generation 43 is created which is a descendant of 39, not 42. So
a rollback from 43 ought to go back to 39. This is not currently
implemented; generations form a linear sequence.
default -> default-94-link
default-82-link -> /nix/store/cc4480...
default-83-link -> /nix/store/caeec8...
...
default-94-link -> /nix/store/2896ca...
experimental -> experimental-2-link
experimental-1-link -> /nix/store/cc4480...
experimental-2-link -> /nix/store/a3148f...
* `--profile' / `-p' -> `--switch-profile' / `-S'
* `--link' / `-l' -> `--profile' / `-p'
* The default profile is stored in $prefix/var/nix/profiles.
$prefix/var/nix/links is gone. Profiles can be stored anywhere.
* The current profile is now referenced from ~/.nix-profile, not
~/.nix-userenv.
* The roots to the garbage collector now have extension `.gcroot', not
`.id'.
the output path of a derivation, not the path of its store
expression. This ensures that changes that affect the path of the
store expression but not the output path, do not affect the
`installed' state of a derivation.
path of the Nix expression to be used with the import, upgrade, and
query commands. For instance,
$ nix-env -I ~/nixpkgs/pkgs/system/i686-linux.nix
$ nix-env --query --available [aka -qa]
sylpheed-0.9.7
bison-1.875
pango-1.2.5
subversion-0.35.1
...
$ nix-env -i sylpheed
$ nix-env -u subversion
There can be only one default at a time.
* If the path to a Nix expression is a symlink, follow the symlink
prior to resolving relative path references in the expression.
the symlink ~/.nix-userenv to the given argument (which defaults to
.../links/current). /etc/profile.d/nix-profile creates this symlink
if it doesn't exist yet. Example use:
$ nix-env -l my_profile -i foo.nix subversion quake
$ nix-env -p my_profile
I don't like the term "profile". Let's deprecate it :-)
