The flag ‘--check’ to ‘nix-store -r’ or ‘nix-build’ will cause Nix to
redo the build of a derivation whose output paths are already valid.
If the new output differs from the original output, an error is
printed. This makes it easier to test if a build is deterministic.
(Obviously this cannot catch all sources of non-determinism, but it
catches the most common one, namely the current time.)
For example:
$ nix-build '<nixpkgs>' -A patchelf
...
$ nix-build '<nixpkgs>' -A patchelf --check
error: derivation `/nix/store/1ipvxsdnbhl1rw6siz6x92s7sc8nwkkb-patchelf-0.6' may not be deterministic: hash mismatch in output `/nix/store/4pc1dmw5xkwmc6q3gdc9i5nbjl4dkjpp-patchelf-0.6.drv'
The --check build fails if not all outputs are valid. Thus the first
call to nix-build is necessary to ensure that all outputs are valid.
The current outputs are left untouched: the new outputs are either put
in a chroot or diverted to a different location in the store using
hash rewriting.
This is equivalent to running ‘nix-env -e '*'’ first, except that it
happens in a single transaction. Thus, ‘nix-env -i pkgs...’ replaces
the profile with the specified set of packages.
The main motivation is to support declarative package management
(similar to environment.systemPackages in NixOS). That is, if you
have a specification ‘profile.nix’ like this:
with import <nixpkgs> {};
[ thunderbird
geeqie
...
]
then after any change to ‘profile.nix’, you can run:
$ nix-env -f profile.nix -ir
to update the profile to match the specification. (Without the ‘-r’
flag, if you remove a package from ‘profile.nix’, it won't be removed
from the actual profile.)
Suggested by @zefhemel.
This prevents some duplicate evaluation in nix-env and
nix-instantiate.
Also, when traversing ~/.nix-defexpr, only read regular files with the
extension .nix. Previously it was reading files like
.../channels/binary-caches/<name>. The only reason this didn't cause
problems is pure luck (namely, <name> shadows an actual Nix
expression, the binary-caches files happen to be syntactically valid
Nix expressions, and we iterate over the directory contents in just
the right order).
Since we already cache files in normal form (fileEvalCache), caching
parse trees is redundant.
Note that getting rid of this cache doesn't actually save much memory
at the moment, because parse trees are currently not freed / GC'ed.
We now print all output paths of a package, e.g.
openssl-1.0.0i bin=/nix/store/gq2mvh0wb9l90djvsagln3aqywqmr6vl-openssl-1.0.0i-bin;man=/nix/store/7zwf5r5hsdarl3n86dasvb4chm2xzw9n-openssl-1.0.0i-man;/nix/store/cj7xvk7fjp9q887359j75pw3pzjfmqf1-openssl-1.0.0i
or (in XML mode)
<item attrPath="openssl" name="openssl-1.0.0i" system="x86_64-linux">
<output name="bin" path="/nix/store/gq2mvh0wb9l90djvsagln3aqywqmr6vl-openssl-1.0.0i-bin" />
<output name="man" path="/nix/store/7zwf5r5hsdarl3n86dasvb4chm2xzw9n-openssl-1.0.0i-man" />
<output name="out" path="/nix/store/cj7xvk7fjp9q887359j75pw3pzjfmqf1-openssl-1.0.0i" />
</item>
I.e. do what git does. I'm too lazy to keep the builtin help text up
to date :-)
Also add ‘--help’ to various commands that lacked it
(e.g. nix-collect-garbage).
Channels are implemented using a profile now, and profiles contain a
manifest.nix file. This should be ignored to prevent bogus packages
from showing up in nix-env.
queryValidPaths() combines multiple calls to isValidPath() in one.
This matters when using the Nix daemon because it reduces latency.
For instance, on "nix-env -qas \*" it reduces execution time from 5.7s
to 4.7s (which is indistinguishable from the non-daemon case).
This should also fix:
nix-instantiate: ./../boost/shared_ptr.hpp:254: T* boost::shared_ptr<T>::operator->() const [with T = nix::StoreAPI]: Assertion `px != 0' failed.
which was caused by hashDerivationModulo() calling the ‘store’
object (during store upgrades) before openStore() assigned it.
brackets, e.g.
import <nixpkgs/pkgs/lib>
are resolved by looking them up relative to the elements listed in
the search path. This allows us to get rid of hacks like
import "${builtins.getEnv "NIXPKGS_ALL"}/pkgs/lib"
The search path can be specified through the ‘-I’ command-line flag
and through the colon-separated ‘NIX_PATH’ environment variable,
e.g.,
$ nix-build -I /etc/nixos ...
If a file is not found in the search path, an error message is
lazily thrown.
checked too soon whether substitutes are available. That is, it did
so for every available package, rather than those matching installed
packages. This was very slow and subject to assertion failures. So
do the check much later. Idem for `nix-env -qab' and `nix-env -ib'.
a pointer to a Value, rather than the Value directly. This improves
the effectiveness of garbage collection a lot: if the Value is
stored inside the set directly, then any live pointer to the Value
causes all other attributes in the set to be live as well.
instance) "nix-env -i wine" works on x86_64-linux, even though Wine
is built on i686-linux. In the event that there are multiple
matching derivations, prefer those built for the current system.
errors with position info.
* For all positions, use the position of the first character of the
first token, rather than the last character of the first token plus
one.
