- Don't assert: Derivation ATerms are not necessarily produced by Nix,
and parsers should always throw graceful errors
- Improve error message from `static void except(..)`, shows both what
we expected and what we actually got.
The intention is that we backport it, and then hopefully a few people
might get slightly better errors if they try out new experimental drv
files (for RFC 92) with an old version of Nix.
Continue with the characterization testing idioms begun in
c70484454f, but this time for unit tests.
Co-authored-by: Andreas Rammhold <andreas@rammhold.de>
Solves 1/3 of the infinite recursion at unknown location meme.
See #8879 for ensuring we always have a trace (for stack overflows)
We might want to re-add this for finding missing location info
*while hacking on that problem only*.
To avoid dealing with an optional `drvPath` (because we might not know
it yet) everywhere, make an `CreateDerivationAndRealiseGoal`. This goal
just builds/substitutes the derivation file, and then kicks of a build
for that obtained derivation; in other words it does the chaining of
goals when the drv file is missing (as can already be the case) or
computed (new case).
This also means the `getDerivation` state can be removed from
`DerivationGoal`, which makes the `BasicDerivation` / in memory case and
`Derivation` / drv file file case closer together.
The map type is factored out for clarity, and because we will soon hvae
a second use for it (`Derivation` itself).
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
We're about to split up `DerivationGoal` a bit. At that point
`makeDerivationGoal` will mean something more specific than it does
today. (Perhaps a future rename will make this clearer.)
On the other hand, the more public `Worker::makeGoal` function will
continue to work exactly as before. So by moving some call sites to use
that instead, we preemptively avoid issues in the next step.
An attrPath prefix of "." indicates no need to try default attrPath prefixes. For example 1nixpkgs#legacyPackages.x86_64-linux.ERROR` searches through
```
trying flake output attribute 'packages.x86_64-linux.legacyPackages.x86_64-linux.ERROR'
using cached attrset attribute ''
trying flake output attribute 'legacyPackages.x86_64-linux.legacyPackages.x86_64-linux.ERROR'
using cached attrset attribute 'legacyPackages.x86_64-linux'
trying flake output attribute 'legacyPackages.x86_64-linux.ERROR'
using cached attrset attribute 'legacyPackages.x86_64-linux'
```
And there is no way to specify that one does not want the automatic
search behavior. Now one can specify
`nixpkgs#.legacyPackages.x86_64-linux.ERROR` to only refer to the rooted
attribute path without any default injection of attribute search path or
system.
This function is now trivial enough that it doesn't need to exist.
`EvalState` can still be initialized with a custom search path, but we
don't have a need to mutate the search path after it has been
constructed, and I don't see why we would need to in the future.
Fixes#8229
Types converted:
- `NixStringContextElem`
- `OutputsSpec`
- `ExtendedOutputsSpec`
- `DerivationOutput`
- `DerivationType`
Existing ones mostly conforming the pattern cleaned up:
- `ContentAddressMethod`
- `ContentAddressWithReferences`
The `DerivationGoal::derivationType` field had a bogus initialization,
now caught, so I made it `std::optional`. I think #8829 can make it
non-optional again because it will ensure we always have the derivation
when we construct a `DerivationGoal`.
See that issue (#7479) for details on the general goal.
`git grep 'Raw::Raw'` indicates the two types I didn't yet convert
`DerivedPath` and `BuiltPath` (and their `Single` variants) . This is
because @roberth and I (can't find issue right now...) plan on reworking
them somewhat, so I didn't want to churn them more just yet.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
If you have a URL that needs to be percent-encoded, such as
`http://localhost:8181/test/+3d.tar.gz`, and try to lock that in a Nix
flake such as the following:
{
inputs.test = { url = "http://localhost:8181/test/+3d.tar.gz"; flake = false; };
outputs = { test, ... }: {
t = builtins.readFile test;
};
}
running `nix flake metadata` shows that the input URL has been
incorrectly double-encoded (despite the flake.lock being correctly
encoded only once):
[...snip...]
Inputs:
└───test: http://localhost:8181/test/%252B3d.tar.gz?narHash=sha256-EFUdrtf6Rn0LWIJufrmg8q99aT3jGfLvd1//zaJEufY%3D
(Notice the `%252B`? That's just `%2B` but percent-encoded again)
With this patch, the double-encoding is gone; running `nix flake
metadata` will show the proper URL:
[...snip...]
Inputs:
└───test: http://localhost:8181/test/%2B3d.tar.gz?narHash=sha256-EFUdrtf6Rn0LWIJufrmg8q99aT3jGfLvd1//zaJEufY%3D
---
As far as I can tell, this happens because Nix already percent-encodes
the URL and stores this as the value of `inputs.asdf.url`.
However, when Nix later tries to read this out of the eval state as a
string (via `getStrAttr`), it has to run it through `parseURL` again to
get the `ParsedURL` structure.
Now, this itself isn't a problem -- the true problem arises when using
`ParsedURL::to_string` later, which then _re-escapes the path_. It is
at this point that what would have been `%2B` (`+`) becomes `%252B`
(`%2B`).
Without the change build with `-D_GLIBCXX_ASSERTIONS` exposes testsuite
assertion:
$ gdb src/libexpr/tests/libnixexpr-tests
Reading symbols from src/libexpr/tests/libnixexpr-tests...
(gdb) break __glibcxx_assert_fail
(gdb) run
(gdb) bt
in std::__glibcxx_assert_fail(char const*, int, char const*, char const*)@plt () from /mnt/archive/big/git/nix/src/libexpr/libnixexpr.so
in std::basic_string_view<char, std::char_traits<char> >::operator[] (this=0x7fffffff56c0, __pos=4)
at /nix/store/r74fw2j8rx5idb0w8s1s6ynwwgs0qmh9-gcc-14.0.0/include/c++/14.0.0/string_view:258
in nix::SearchPath::Prefix::suffixIfPotentialMatch (this=0x7fffffff5780, path=...) at src/libexpr/search-path.cc:15
in nix::SearchPathElem_suffixIfPotentialMatch_partialPrefix_Test::TestBody (this=0x555555a17540) at src/libexpr/tests/search-path.cc:62
As string sizes are usigned types `(a - b) > 0` effectively means
`a != b`. While the intention should be `a > b`.
The change fixes test suite pass.
In the Nix language, given a drv path, we should be able to construct
another string referencing to one of its output. We can do this today
with `(import drvPath).output`, but this only works for derivations we
already have.
With dynamic derivations, however, that doesn't work well because the
`drvPath` isn't yet built: importing it like would need to trigger IFD,
when the whole point of this feature is to do "dynamic build graph"
without IFD!
Instead, what we want to do is create a placeholder value with the right
string context to refer to the output of the as-yet unbuilt derivation.
A new primop in the language, analogous to `builtins.placeholder` can be
used to create one. This will achieve all the right properties. The
placeholder machinery also will match out the `outPath` attribute for CA
derivations works.
In 60b7121d2c we added that type of
placeholder, and the derived path and string holder changes necessary to
support it. Then in the previous commit we cleaned up the code
(inspiration finally hit me!) to deduplicate the code and expose exactly
what we need. Now, we can wire up the primop trivally!
Part of RFC 92: dynamic derivations (tracking issue #6316)
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
`EvalState::mkSingleDerivedPathString` previously contained its own
inverse (printing, rather than parsing) in order to validate what was
parsed. Now that is pulled out into its own separate function:
`EvalState::coerceToSingleDerivedPath`.
In additional that pulled out logic is deduplicated with
`EvalState::mkOutputString` via `EvalState::mkOutputStringRaw`, which is
itself deduplicated (and generalized) with
`DownstreamPlaceholder::mkOutputStringRaw`.
All these changes make the unit tests simpler.
(We would ideally write more unit tests for `mkSingleDerivedPathString`
`coerceToSingleDerivedPath` directly, but we cannot yet do that because
the IO in reading the store path won't work when the dummy store cannot
hold anything. Someday we'll have a proper in-memory store which will
work for this.)
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
std::move(state->data) and data.empty() were called in a loop, and
could run with no other threads intervening. Accessing moved objects
is undefined behavior, and could cause a crash.
Virtual methods are no longer valid once the derived destructor has
run. This means the compiler is free to optimize them to be
non-virtual.
Found using clang-tidy
We want to be able to write down `foo.drv^bar.drv^baz`:
`foo.drv^bar.drv` is the dynamic derivation (since it is itself a
derivation output, `bar.drv` from `foo.drv`).
To that end, we create `Single{Derivation,BuiltPath}` types, that are
very similar except instead of having multiple outputs (in a set or
map), they have a single one. This is for everything to the left of the
rightmost `^`.
`NixStringContextElem` has an analogous change, and now can reuse
`SingleDerivedPath` at the top level. In fact, if we ever get rid of
`DrvDeep`, `NixStringContextElem` could be replaced with
`SingleDerivedPath` entirely!
Important note: some JSON formats have changed.
We already can *produce* dynamic derivations, but we can't refer to them
directly. Today, we can merely express building or example at the top
imperatively over time by building `foo.drv^bar.drv`, and then with a
second nix invocation doing `<result-from-first>^baz`, but this is not
declarative. The ethos of Nix of being able to write down the full plan
everything you want to do, and then execute than plan with a single
command, and for that we need the new inductive form of these types.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
This enables nix to correctly report what will be fetched in the case
that everything is a cache hit.
Note however that if an intermediate build of something which is not
cached could still cause products to end up being substituted if the
intermediate build results in a CA path which is in the cache.
Fixes#8615.
Signed-off-by: Peter Waller <p@pwaller.net>
When receiving a stream of NARs through the ssh-ng protocol, an already
existing path would cause the NAR archive to not be read in the stream,
resulting in trying to parse the NAR as a ValidPathInfo. This results in
the error message:
error: not an absolute path: 'nix-archive-1'
Fixes#6253
Usually this problem is avoided by running QueryValidPaths before
AddMultipleToStore, but can arise when two parallel nix processes gets
the same response from QueryValidPaths. This makes the problem more
prominent when running builds in parallel.
When loading a derivation from a JSON, malformed input would trigger
cryptic "assertion failed" errors. Simply replacing calls to `operator []`
with calls to `.at()` was not enough, as this would cause json.execptions
to be printed verbatim.
Display nice error messages instead and give some indication where the
error happened.
*Before:*
```
$ echo 4 | nix derivation add
error: [json.exception.type_error.305] cannot use operator[] with a string argument with number
$ nix derivation show nixpkgs#hello | nix derivation add
Assertion failed: (it != m_value.object->end()), function operator[], file /nix/store/8h9pxgq1776ns6qi5arx08ifgnhmgl22-nlohmann_json-3.11.2/include/nlohmann/json.hpp, line 2135.
$ nix derivation show nixpkgs#hello | jq '.[] | .name = 5' | nix derivation add
error: [json.exception.type_error.302] type must be string, but is object
$ nix derivation show nixpkgs#hello | jq '.[] | .outputs = { out: "/nix/store/8j3f8j-hello" }' | nix derivation add
error: [json.exception.type_error.302] type must be object, but is string
```
*After:*
```
$ echo 4 | nix derivation add
error: Expected JSON of derivation to be of type 'object', but it is of type 'number'
$ nix derivation show nixpkgs#hello | nix derivation add
error: Expected JSON object to contain key 'name' but it doesn't
$ nix derivation show nixpkgs#hello | jq '.[] | .name = 5' | nix derivation add
error: Expected JSON value to be of type 'string' but it is of type 'number'
$ nix derivation show nixpkgs#hello | jq '.[] | .outputs = { out: "/nix/store/8j3f8j-hello" }' | nix derivation add
error:
… while reading key 'outputs'
error: Expected JSON value to be of type 'object' but it is of type 'string'
```
I haven't checked when this was exactly introduced, but on Nix 2.16 I
realized that the additional lines inserted when using `--precise` are
completely separated from the tree:
nix why-depends /nix/store/ccgr4faaxys39s091qridxg1947lggh4-evcxr-0.14.2 /nix/store/b7hvml0m3qmqraz1022fwvyyg6fc1vdy-gcc-12.2.0 --precise --extra-experimental-features nix-command
/nix/store/ccgr4faaxys39s091qridxg1947lggh4-evcxr-0.14.2
→ /nix/store/lcf37pgp3rgww67v9x2990hbfwx96c1w-gcc-wrapper-12.2.0
→ /nix/store/b7hvml0m3qmqraz1022fwvyyg6fc1vdy-gcc-12.2.0
└───bin/evcxr: …':'}.PATH=${PATH/':''/nix/store/lcf37pgp3rgww67v9x2990hbfwx96c1w-gcc-wrapper-12.2.0/bin'':'/':'}…
└───bin/cpp: …k disable=SC2193.[[ "/nix/store/b7hvml0m3qmqraz1022fwvyyg6fc1vdy-gcc-12.2.0/bin/cpp" = *++ ]] &&…
This is apparently because `std::cout` is buffered and flushed in the
end whereas the rest of the output isn't. The fix is rather simple, just
use `logger->cout` as it's already the case for the rest of the code.
This way we also don't need to insert additional newlines in the `hits`
map since that's something the logger takes care of.
Also added a small test to make sure that the layout of this is somehow
tested to reduce the risk of further regressions here.
Avoid duplicated code, and also avoid "on the fly" path construction
(which makes it harder to keep track of which paths we use).
The factored out code doesn't create the Nix state dir anymore, but this
is fine because other in nix-env and nix-channel does:
- nix-channel: Line 158 in this commit
- nix-env: Line 1407 in this commit
Special-casing the file name is rather ugly, so we shouldn't do
that. So now any {file,http,https} URL is handled by
TarballInputScheme, except for non-flake inputs (i.e. inputs that have
the attribute `flake = false`).
It was initially unclear to me which of these are temporary state for
the verify paths computation, and which of these are the results of that
computation to be used in the rest of the function. Now, it is clear,
and enforced.
We don't care about non-store-paths in there (things like `.links`, are,
in fact, allowed). So let's just skip them up front and be more strongly
typed.
Over the last year or so I've run into several use cases where I need to
parse and/or serialize URLs for use by `builtins.fetchTree` or
`builtins.getFlake`, largely in order to produce _lockfile-like_ files
for lang2nix frameworks or tools which use `nix` internally to drive
builds.
I've gone through the painstaking process of emulating
`nix::FlakeRef::fromAttrs` and `nix::parseFlakeRef` several times with
mixed success; but these are difficult to create and even harder to
maintain if I hope to stay aligned with changes to the real
parser/serializer.
I understand why adding new `builtins` isn't something we want to do
flagrantly. I'm recommending this addition simply because I keep
encountering use cases where I need to parse/serialize these URIs in
`nix` expressions, and I want a reliable solution.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Co-authored-by: John Ericson <git@JohnEricson.me>
Will need to do subclass-specific implementations in the next commit.
This isn't because there will be multiple variations of the daemon
protocol (whew!) but because different clients pick and choose different
parts to use.
This makes it more useful. In general, the derivation will be in one
store, and the realisation info is in another.
This also helps us avoid duplication. See how `resolveDerivedPath` is
now simpler because it uses `queryPartialDerivationOutputMap`. In #8369
we get more flavors of derived path, and need more code to resolve them
all, and this problem only gets worse.
The fact that we need a new method to deal with the multiple dispatch is
unfortunate, but this generally relates to the fact that `Store` is a
sub-par interface, too bulky/unwieldy and conflating separate concerns.
Solving that is out of scope of this PR.
This is part of the RFC 92 work. See tracking issue #6316
the original change broke many pre-existing anchor links.
also change formatting of the constants listing slightly:
- the type should not be part of the anchor
- add highlight to the "impure only" note
We were bedeviled by sandboxing issues when working on the layered
store. The problem ended up being that when we have nested nix builds,
and the inner store is inside the build dir (e.g. store is
`/build/nix-test/$name/store`, build dir is `/build`) bind mounts
clobber each other and store paths cannot be found.
After thoroughly cleaning up `local-derivation-goal.cc`, we might be
able to make that work. But that is a lot of work. For now, we just fail
earlier with a proper error message.
Finally, test this: nested sandboxing without the problematic store dir
should work, and with should fail with the expected error message.
Co-authored-by: Dylan Green <67574902+cidkidnix@users.noreply.github.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
- Better types
- Own header / C++ file pair
- Test factored out methods
- Pass parsed thing around more than strings
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Whereas `ContentAddressWithReferences` is a sum type complex because different
varieties support different notions of reference, and
`ContentAddressMethod` is a nested enum to support that,
`ContentAddress` can be a simple pair of a method and hash.
`ContentAddress` does not need to be a sum type on the outside because
the choice of method doesn't effect what type of hashes we can use.
Co-Authored-By: Cale Gibbard <cgibbard@gmail.com>
'resolvedRef' was incorrect, since a resolved ref is one after
registry resolution, which may still be unlocked (e.g. 'nixpkgs' ->
'github:NixOS/nixpkgs').
If we call `adjustLoc`, the global variable `prev_yylloc` is shared
between threads and racy.
Currently, nix itself does not concurrently parsing files, but this is
helpful for libexpr users. (The parser is thread-safe except this.)
When explicitly requested by the caller, as suggested in the meeting
(https://github.com/NixOS/nix/pull/8090#issuecomment-1531139324)
> @edolstra: { toPath } vs { fromPath } is too implicit
I've opted for the `inputAddressed = true` requirement, because it
we did not agree on renaming the path attributes.
> @roberth: more explicit
> @edolstra: except for the direction; not immediately clear in which direction the rewriting happens
This is in fact the most explicit syntax and a bit redundant, which is
good, because that redundancy lets us deliver an error message that
reminds expression authors that CA provides a better experience to
their users.
This is done in roughly the same way builtin functions are documented.
Also auto-link experimental features for primops, subsuming PR #8371.
Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
* nix flake check: improve error message if overlay is not a lambda
Suppose you have an overlay like this
{
inputs = { /* ... */ };
outputs = { flake-utils, ... }: flake-utils.lib.eachDefaultSystem
(system: {
overlays.default = final: prev: {
};
});
}
then `nix flake check` (correctly) fails because `overlays` are supposed
to have the structure `overlays.<name> = final: prev: exp`. However, the
error-message is a little bit counter-intuitive:
error: overlay does not take an argument named 'final'
While one might guess where the error actually comes from because the
trace above says `… while checking the overlay 'overlays.x86_64-linux'`
this is still pretty confusing because it complains about an argument
not being named `final` even though that's evidently the case.
With this change, the error-message actually makes it clear what's
wrong:
[ma27@carsten:~/Projects/nix/tmp]$ nix flake check --extra-experimental-features 'nix-command flakes' path:$(pwd)
error:
… while checking flake output 'overlays'
at /nix/store/clgblnxx003hyrq8qkz5ab6kgqkck6qc-source/flake.nix:4:5:
3| outputs = { ... }: {
4| overlays.x86_64-linux.snens = final: prev: {
| ^
5| kek = throw "snens";
… while checking the overlay 'overlays.x86_64-linux'
at /nix/store/clgblnxx003hyrq8qkz5ab6kgqkck6qc-source/flake.nix:4:5:
3| outputs = { ... }: {
4| overlays.x86_64-linux.snens = final: prev: {
| ^
5| kek = throw "snens";
error: overlay is not a lambda, but a set instead
I got very confused trying to keep all the `first` and `second` straight
reading the code, *especially* as there is also another `(boolean,
string)` pair type also being used.
Named fields is much better.
There are other cleanups that we can do (for example, the existing
TODO), but we can do them later. Doing them now would just make this
harder to review.
- Improved API docs from comment
- Exit codes are for `nix-build`, not just `nix-store --release`
- Make note in tests so the magic numbers are not surprising
Picking up where #8387 left off.
Previously it was not possible to open a local store when its database is on a read-only filesystem. Obviously a store on a read-only filesystem cannot be modified, but it would still be useful to be able to query it.
This change adds a new read-only setting to LocalStore. When set to true, Nix will skip operations that fail when the database is on a read-only filesystem (acquiring big-lock, schema migration, etc), and the store database will be opened in immutable mode.
Co-authored-by: Ben Radford <benradf@users.noreply.github.com>
Co-authored-by: cidkidnix <cidkidnix@protonmail.com>
Co-authored-by: Dylan Green <67574902+cidkidnix@users.noreply.github.com>
Co-authored-by: John Ericson <git@JohnEricson.me>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
If the garbage collector has acquired the global GC lock, but hasn't
created the GC socket yet, then a client attempting to connect would
get ENOENT. Note that this only happens when the GC runs for the first
time on a machine. Subsequently clients will get ECONNREFUSED which
was already handled.
Fixes#7370.
Pass this around instead of `Source &` and `Sink &` directly. This will
give us something to put the protocol version on once the time comes.
To do this ergonomically, we need to expose `RemoteStore::Connection`,
so do that too. Give it some more API docs while we are at it.
The motivation is exactly the same as for the last commit. In addition,
this anticipates us formally defining separate serialisers for the serve
protocol.
See API docs on that struct for why. The pasing as as template argument
doesn't yet happen in that commit, but will instead happen in later
commit.
Also make `WorkerOp` (now `Op`) and enum struct. This led us to catch
that two operations were not handled!
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This is generally a fine practice: Putting implementations in headers
makes them harder to read and slows compilation. Unfortunately it is
necessary for templates, but we can ameliorate that by putting them in a
separate header. Only files which need to instantiate those templates
will need to include the header with the implementation; the rest can
just include the declaration.
This is now documenting in the contributing guide.
Also, it just happens that these polymorphic serializers are the
protocol agnostic ones. (Worker and serve protocol have the same logic
for these container types.) This means by doing this general template
cleanup, we are also getting a head start on better indicating which
code is protocol-specific and which code is shared between protocols.
- Greatly expand API docs
- Clean up code in misc ways
- Instead of a complicated single loop on generations, do different
operations in successive subsequent steps.
- Avoid `ref` in one place where `&` is fine
- Just return path instead of mutating an argument in `makeName`
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Rather than doing `allowEmpty` as boolean, have separate types and use
`std::optional`. This makes it harder to forget the possibility of an
empty path.
The `build-hook` setting was categorized as a `PathSetting`, but
actually it was split into arguments. No good! Now, it is
`Setting<Strings>` which actually reflects what it means and how it is
used.
Because of the subtyping, we now also have support for
`Setting<std::optional<String>>` in general. I imagine this can be used
to clean up many more settings also.
The code accidentally conflated `std::string::size_type` and `long unsigned int`.
This was fine on 64bits machines where they are apparently the same in
practice, but not on 32bits. Fix that by using `std::string::size_type`
everywhere.
A library shouldn't require changes to the caller's argument handling,
especially if it doesn't have to, and indeed we don't have to.
This changes the lookup order to prioritize the hardcoded path to nix
if it exists. The static executable still finds itself through /proc
and the like.
Introduce what substituters "are" in the configuration option entry.
Remove arbitrary line breaks for easier editing in the future.
Link glossary some more.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: John Ericson <git@JohnEricson.me>
The remaining constructor RegisterPrimOp::RegisterPrimOp(Info && info)
allows specifying the documentation in .args and .doc members of the
Info structure.
Commit 8ec1ba0210 removed all uses of the removed constructor in the
nix binary. Here, we remove the constructor completely as well as its
use in a plugin test. According to #8515, we didn't promis to maintain
compatibility with external plugins.
Fixes#8515
`filesystem.cc` is the only place where `createSymlink()` is used with three arguments:
in the definition of `replaceSymlink()` with three parameters that _is not used at all_.
Closes#8495
Previously, for tarball flakes, we recorded the original URL of the
tarball flake, rather than the URL to which it ultimately
redirects. Thus, a flake URL like
http://example.org/patchelf-latest.tar that redirects to
http://example.org/patchelf-<revision>.tar was not really usable. We
couldn't record the redirected URL, because sites like GitHub redirect
to CDN URLs that we can't rely on to be stable.
So now we use the redirected URL only if the server returns the
`x-nix-is-immutable` or `x-amz-meta-nix-is-immutable` headers in its
response.
This will allow documenting them (in later commits).
Note that we keep the old constructor even if it is no longer used by
Nix code, because it is used in tests/plugins/plugintest.cc, which
suggests that it might be used by some external plugin.
This is necessary when we're in a chroot environment, where the
process root is not the same as the root of the mount namespace
(e.g. in nixos-enter).
Fixes#7602.
Currently `fromTOML` throws an exception when encountering a timestamp
since the Nix language lacks a way to represent them.
This patch changes this beaviour and makes `fromTOML` parse timestamps as
attrsets of the format
{ _type = "timestamp"; value = "1979-05-27T07:32:00Z"; }
This is guarded by an experimental feature flag to leave room for iterating on the representation.
* Document manual migration for use-xdg-base-directories
As there's currently no automatic migration for use-xdg-base-directories
option, add instructions for manual migration to the option's
description.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Add support to --list-generations
as another way to say
nix-env --profile /nix/var/nix/profiles/per-user/$USER/channels --list-generations
the way we did for nix-channel --rollback [generation id]
And fix a test failure in the sandbox due to /home
existing on Darwin but not being accessible in the sandbox since it's a
symlink to /System/Volumes/Data/home, see
https://github.com/NixOS/nix/actions/runs/4205378453/jobs/7297384658#step:6:2127:
C++ exception with description "error: getting status of /home/schnitzel/darmstadt/pommes: Operation not permitted" thrown in the test body.
On Linux this wasn't a problem because there /home doesn't exist in the sandbox
The primop `builtins.replaceStrings` currently always strictly evaluates the
replacement strings, however time and space are wasted for their computation
if the corresponding pattern do not occur in the input string. This commit
makes the evaluation of the replacement strings lazy by deferring their
evaluation to when the corresponding pattern are matched and memoize the result
for efficient retrieval on subsequent matches.
The testcases for replaceStrings was updated to check for lazy evaluation
of the replacements. A note was also added in the release notes to
document the behavior change.
When encountering a build error, Nix moves the output paths out of the
chroot into their final location (for “easier debugging of build
failures”). However this was broken for chroot stores as it was moving
it to the _logical_ location, not the _physical_ one.
Fix it by moving to the physical (_real_) location.
Fix https://github.com/NixOS/nix/issues/8395
The `hashed-mirrors` option did use to have this default value,
but it was removed and re-added with an empty default value.
As the autogenerated docs show the (actual) default values from code,
remove this incorrect reference from the docs.
I was updating my nix.conf settings after a few years and noticed this.
This adds a new configuration option to Nix, `always-allow-substitutes`,
whose effect is simple: it causes the `allowSubstitutes` attribute in
derivations to be ignored, and for substituters to always be used.
This is extremely valuable for users of Nix in CI, where usually
`nix-build-uncached` is used. There, derivations which disallow
substitutes cause headaches as the inputs for building already-cached
derivations need to be fetched to spuriously rebuild some simple text
file.
This option should be a good middle-ground, since it doesn't imply
rebuilding the world, such as the approach I took in
https://github.com/NixOS/nixpkgs/pull/221048
Using abstract types like can help cut down on compilation time, both
from scratch, and especially incremental builds during development. The
idea is that `worker-protocol.hh` can declare all the (de)serializers, but
only again abstract types; when code needs to use some (de)serializers, it can
include headers just for the data types it needs to (de)serialize.
`store-api.hh` in particular is a bit of a sledgehammer, and the data
types we want to serialize have their own headers.
This is the more typically way to do [Argument-dependent
lookup](https://en.cppreference.com/w/cpp/language/adl)-leveraging
generic serializers in C++. It makes the relationship between the `read`
and `write` methods more clear and rigorous, and also looks more
familiar to users coming from other languages that do not have C++'s
libertine ad-hoc overloading.
I am returning to this because during the review in
https://github.com/NixOS/nix/pull/6223, it came up as something that
would make the code easier to read --- easier today hopefully already,
but definitely easier if we were have multiple codified protocols with
code sharing between them as that PR seeks to accomplish.
If I recall correctly, the main criticism of this the first time around
(in 2020) was that having to specify the type when writing, e.g.
`WorkerProto<MyType>::write`, was too verbose and cumbersome. This is
now addressed with the `workerProtoWrite` wrapper function.
This method is also the way `nlohmann::json`, which we have used for a
number of years now, does its serializers, for what its worth.
This reverts commit 45a0ed82f0. That
commit in turn reverted 9ab07e99f5.
This is good in general, but in particular ensures when we heavily
refactor it in the next commit there is less likelihood for an
unintentional change in behavior to sneak in.
These items are not templates, and they declared in
`worker-protocol.hh`; therefore they should live in a
`worker-protocol.cc`.
Anything else needlessly diverges from convention. After all, it is not
like this code is only used in `remote-store.cc`; it is also used in
`daemon.cc`. There is no good reason to place it with the client
implementation or the server implementation when it used equally by
both.
- If the element comes from a flake, print the full flakeref (with the
fragment part) and not just the reference to the flake itself
- If the element doesn't come from a flake, print its store path(s)
This is a bit too verbose, but has the advantages of being correct (and
not crashing), so it's strictly better than the previous situation
Fix https://github.com/NixOS/nix/issues/8284
They were improperly added in 8a93b5a551.
They were not `.gitignore`d because they were stale in that commit --
build artifacts no longer used that name by then and so `.gitignore` was
updated accordingly.
As discussed in #7417, it would be good to make more string values work
as installables. That is to say, if an installable refers to a value,
and the value is a string, it used to not work at all, since #7484, it
works somewhat, and this PR make it work some more.
The new cases that are added for `BuiltPath` contexts:
- Fixed input- or content-addressed derivation:
```
nix-repl> hello.out.outPath
"/nix/store/jppfl2bp1zhx8sgs2mgifmsx6dv16mv2-hello-2.12"
nix-repl> :p builtins.getContext hello.out.outPath
{ "/nix/store/c7jrxqjhdda93lhbkanqfs07x2bzazbm-hello-2.12.drv" = { outputs = [ "out" ]; }; }
The string matches the specified single output of that derivation, so
it should also be valid.
- Floating content-addressed derivation:
```
nix-repl> (hello.overrideAttrs (_: { __contentAddressed = true; })).out.outPath
"/1a08j26xqc0zm8agps8anxpjji410yvsx4pcgyn4bfan1ddkx2g0"
nix-repl> :p builtins.getContext (hello.overrideAttrs (_: { __contentAddressed = true; })).out.outPath
{ "/nix/store/qc645pyf9wl37c6qvqzaqkwsm1gp48al-hello-2.12.drv" = { outputs = [ "out" ]; }; }
```
The string is not a path but a placeholder, however it also matches
the context, and because it is a CA derivation we have no better
option. This should also be valid.
We may also want to think about richer attrset based values (also
discussed in that issue and #6507), but this change "completes" our
string-based building blocks, from which the others can be desugared
into or at least described/document/taught in terms of.
Progress towards #7417
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Fixes#8309
This regression was because both `CmdDevelop` and `CmdPrintDevEnv` were
switched to be `InstallableValueCommand` subclasses, but actually
neither should have been.
The `nixpkgsFlakeRef` method should indeed not be on the base
installable class, because "flake refs" and "nixpkgs" are not
installable-wide notions, but that doesn't mean these commands should
only accept installable values.
This fixes a bug in commands like `nix eval' which would emit invalid attribute
sets if they contained reserved keywords such as "assert", "let", etc.
These keywords will not be quoted when printed, making them valid expressions.
All keywords recognized by the lexer are quoted except "or", which does not
require quotation.
it's probably better not to show the manifest file documentation in the
command-specific pages, because these are implementation details that are not really practically useful.
this means no additional hassle for building the manual, but clutters
the table of contents a bit.
Previously, we relied on the `shutdown()` function to terminate `accept()`
calls on a listening socket. However, this approach did not work on macOS as
the waiting `accept()` call is not considered a connected socket, resulting in
an `ENOTCONN` error. Instead, we now close the listening socket to terminate
the `accept()` call.
Additionally, we fixed a resource management issue where we set the
`daemonSocket` variable to -1, triggering resource cleanup and causing the
`stopDaemon` function to be called twice. This resulted in errors as the socket
was already closed by the time the second `stopDaemon` call was made. Instead of
setting `daemonSocket` to -1, we now release the socket using the `release()`
method on a unique pointer. This properly transfers ownership and allows for
correct resource cleanup.
These changes ensure proper behavior and resource management for the
recursive-nix feature on macOS.
Motivation
`PathSet` is not correct because string contexts have other forms
(`Built` and `DrvDeep`) that are not rendered as plain store paths.
Instead of wrongly using `PathSet`, or "stringly typed" using
`StringSet`, use `std::std<StringContextElem>`.
-----
In support of this change, `NixStringContext` is now defined as
`std::std<StringContextElem>` not `std:vector<StringContextElem>`. The
old definition was just used by a `getContext` method which was only
used by the eval cache. It can be deleted altogether since the types are
now unified and the preexisting `copyContext` function already suffices.
Summarizing the previous paragraph:
Old:
- `value/context.hh`: `NixStringContext = std::vector<StringContextElem>`
- `value.hh`: `NixStringContext Value::getContext(...)`
- `value.hh`: `copyContext(...)`
New:
- `value/context.hh`: `NixStringContext = std::set<StringContextElem>`
- `value.hh`: `copyContext(...)`
----
The string representation of string context elements no longer contains
the store dir. The diff of `src/libexpr/tests/value/context.cc` should
make clear what the new representation is, so we recommend reviewing
that file first. This was done for two reasons:
Less API churn:
`Value::mkString` and friends did not take a `Store` before. But if
`NixStringContextElem::{parse, to_string}` *do* take a store (as they
did before), then we cannot have the `Value` functions use them (in
order to work with the fully-structured `NixStringContext`) without
adding that argument.
That would have been a lot of churn of threading the store, and this
diff is already large enough, so the easier and less invasive thing to
do was simply make the element `parse` and `to_string` functions not
take the `Store` reference, and the easiest way to do that was to simply
drop the store dir.
Space usage:
Dropping the `/nix/store/` (or similar) from the internal representation
will safe space in the heap of the Nix programming being interpreted. If
the heap contains many strings with non-trivial contexts, the saving
could add up to something significant.
----
The eval cache version is bumped.
The eval cache serialization uses `NixStringContextElem::{parse,
to_string}`, and since those functions are changed per the above, that
means the on-disk representation is also changed.
This is simply done by changing the name of the used for the eval cache
from `eval-cache-v4` to eval-cache-v5`.
----
To avoid some duplication `EvalCache::mkPathString` is added to abstract
over the simple case of turning a store path to a string with just that
string in the context.
Context
This PR picks up where #7543 left off. That one introduced the fully
structured `NixStringContextElem` data type, but kept `PathSet context`
as an awkward middle ground between internal `char[][]` interpreter heap
string contexts and `NixStringContext` fully parsed string contexts.
The infelicity of `PathSet context` was specifically called out during
Nix team group review, but it was agreeing that fixing it could be left
as future work. This is that future work.
A possible follow-up step would be to get rid of the `char[][]`
evaluator heap representation, too, but it is not yet clear how to do
that. To use `NixStringContextElem` there we would need to get the STL
containers to GC pointers in the GC build, and I am not sure how to do
that.
----
PR #7543 effectively is writing the inverse of a `mkPathString`,
`mkOutputString`, and one more such function for the `DrvDeep` case. I
would like that PR to have property tests ensuring it is actually the
inverse as expected.
This PR sets things up nicely so that reworking that PR to be in that
more elegant and better tested way is possible.
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
In other words, use a plain `ContentAddress` not
`ContentAddressWithReferences` for `DerivationOutput::CAFixed`.
Supporting fixed output derivations with (fixed) references would be a
cool feature, but it is out of scope at this moment.
Recently, I encountered the "NAR info file 'xxxx' is corrupt" error
with my binary cache. The message is not helpful in determining, which
kind of corruption happened. The file, fetched with curl, looked
reasonably.
This commit adds more information to the error message, which should
allow debugging and hopefully fixing the problem.
We finally test the status quo of remote build trust in a number of
ways. We create a new experimental feature on `nix-daemon` to do so.
PR #3921, which improves the situation with trustless remote building,
will build upon these changes. This code / tests was pull out of there
to make this, so everything is easier to review, and in particular we
test before and after so the new behavior in that PR is readily apparent
from the testsuite diff alone.
Issues:
1. Features gated on disabled experimental settings should warn and be
ignored, not silently succeed.
2. Experimental settings in the same config "batch" (file or env var)
as the enabling of the experimental feature should work.
3. For (2), the order should not matter.
These are analogous to the issues @roberth caught with my changes for
arg handling, but they are instead for config handling.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
In many cases we are dealing with a collection of realisations, they are
all outputs of the same derivation. In that case, we don't need
"derivation hashes modulos" to be part of our map key, because the
output names alone will be unique. Those hashes are still part of the
realisation proper, so we aren't loosing any information, we're just
"normalizing our schema" by narrowing the "primary key".
Besides making our data model a bit "tighter" this allows us to avoid a
double `for` loop in `DerivationGoal::waiteeDone`. The inner `for` loop
was previously just to select the output we cared about without knowing
its hash. Now we can just select the output by name directly.
Note that neither protocol is changed as part of this: we are still
transferring `DrvOutputs` over the wire for `BuildResult`s. I would only
consider revising this once #6223 is merged, and we can mention protocol
versions inside factored-out serialization logic. Until then it is
better not change anything because it would come a the cost of code
reuse.
If my memory is correct, @edolstra objected to modifying `wantedOutputs`
upon falling back to doing a build (as we did before), because we should
only modify it in response to new requests --- *actual* wants --- and
not because we are "incidentally" building all the outptus beyond what
may have been requested.
That's a fair point, and the alternative is to replace the boolean soup
with proper enums: Instead of modifying `wantedOuputs` som more, we'll
modify `needsRestart` to indicate we are passed the need.
In https://github.com/NixOS/nix/pull/6311#discussion_r834863823, I
realized since derivation goals' wanted outputs can "grow" due to
overlapping dependencies (See `DerivationGoal::addWantedOutputs`, called
by `Worker::makeDerivationGoalCommon`), the previous bug fix had an
unfortunate side effect of causing more pointless rebuilds.
In paticular, we have this situation:
1. Goal made from `DerivedPath::Built { foo, {a} }`.
2. Goal gives on on substituting, starts building.
3. Goal made from `DerivedPath::Built { foo, {b} }`, in fact is just
modified original goal.
4. Though the goal had gotten as far as building, so all outputs were
going to be produced, `addWantedOutputs` no longer knows that and so
the goal is flagged to be restarted.
This might sound far-fetched with input-addressed drvs, where we usually
basically have all our goals "planned out" before we start doing
anything, but with CA derivation goals and especially RFC 92, where *drv
resolution* means goals are created after some building is completed, it
is more likely to happen.
So the first thing to do was restore the clearing of `wantedOutputs` we
used to do, and then filter the outputs in `buildPathsWithResults` to
only get the ones we care about.
But fix also has its own side effect in that the `DerivedPath` in the
`BuildResult` in `DerivationGoal` cannot be trusted; it is merely the
*first* `DerivedPath` for which this goal was originally created.
To remedy this, I made `BuildResult` be like it was before, and instead
made `KeyedBuildResult` be a subclass wit the path. Only
`buildPathsWithResults` returns `KeyedBuildResult`s, everything else
just becomes like it was before, where the "key" is unambiguous from
context.
I think separating the "primary key" field(s) from the other fields is
good practical in general anyways. (I would like to do the same thing
for `ValidPathInfo`.) Among other things, it allows constructions like
`std::map<Key, ThingWithKey>` where doesn't contain duplicate keys and
just precludes the possibility of those duplicate keys being out of
sync.
We might leverage the above someday to overload `buildPathsWithResults`
to take a *set* of return a *map* per the above.
-----
Unfortunately, we need to avoid C++20 strictness on designated
initializers.
(BTW
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2287r1.html
this offers some new syntax for this use-case. Hopefully this will be
adopted and we can eventually use it.)
No having that yet, maybe it would be better to not make
`KeyedBuildResult` a subclass to just avoid this.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
As requested by @roberth, it is good to call out the specific instances
we care about, which is `!` for the RPC protocols, and `^` for humans.
This doesn't take advantage of parametricity as much, but since the
human and computer interfaces are good to decouple anyways (we don't
care if they drift further apart over time in the slightest) some
separation and slight duplication is fine.
Also, unit test both round trips.
More progress on issue #5729
The method trivially generalizes to be store-implementation-agnostic, in
fact.
However, we force it to continue to be unimplemented with `RemoteStore`
and `LegacySSHStore` because the implementation we'd get via the
generalization is probably not the one users expect. This keeps our
hands untied to do it right going forward.
For more about the tension between the scheduler logic being
store-type-agnostic and remote stores doing their own scheduling, see
issues #5025 and #5056.
- Create a glossary entry for experimental features.
- Have the man page experimental feature notice link `nix-commmand`.
(Eventually this should be programmed, based on whether the command is
experimental, and if so what experimental feature does it depend on.)
- Document which installables depend on which experimental features.
I tried to use the same style (bold warning and block quote) that the
top of the man page uses.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
The warning message should produce an installable name that can be
passed to `nix build`, `nix path-info`, etc. again. Since the CLI
expects that the .drv path and the output names are separated by
a caret, the warning message must also separate the .drv path and output
names with a caret.
However, `DerivedPath::Built.to_string()` uses an exclamation point as
the separator instead. This commit adds a `separator` argument to the
to_string method.
This changes the warning message from:
If this command is now failing try again with '/nix/store/foo.drv!*'
to:
If this command is now failing try again with '/nix/store/foo.drv^*'
More progress on issue #5729.
Instead of having it by the default method in `Store` itself, have it be
the implementation in `DummyStore` and `LegacySSHStore`. Then just the
implementations which fail to provide the method pay the "penalty" of
dealing with the icky `unimplemented` function for non-compliance.
Combined with my other recent PRs, this finally makes `Store` have no
`unsupported` calls!
This is somewhat hacky fix just for 2.15. I unintentionally hid them
from the manual, when no one wanted to hide them that (including
myself). I also required the experimental feature to be enabled in an
order-dependent way, which is not good.
The simplest fix for this immanent release is just to always show them,
and always allow them to be set.
Effectively undoes some changes from aa663b7e89
Getting the occasional SQLITE_BUSY is expected when the database is being
accessed concurrently. The retry will likely succeed so it is pointless to warn
immediately. Instead we track how long each retrySQLite block has been running,
and only begin warning after a second has elapsed (and then every 10 seconds
subsequently).
Some of the factoring out was taken from #7912 by @mupdt. Thanks!
No behavior should be changed in this commit.
Co-Authored-By: mupdt <25388474+mupdt@users.noreply.github.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
How signals should be handled depends on what kind of process Nix
is integrated into. The signal handler thread used by the stand-alone
Nix commands / processes may not work well in the context of other
runtime systems, such as those of Python, Perl, or Haskell.
libutil is a dependency of libstore, so it should always be
initialized as such.
libutil is also a dependency of libmain. Being explicit about this
dependency might be good, but not worth the slight code complexity
until the library structure gets more advanced.
Part of an effort to make it easier to initialize the right things,
by moving code into the appropriate libraries.
Quote
Why not initLibExpr()? initGC() is essentially that, but
detectStackOverflow is not an instance of the init function concept, as
it may have to be invoked more than once per process.
Furthermore, renaming initGC to initLibExpr is more trouble than it's
worth at this time.
This code is bad. We shouldn't unset variables in programs whose
children may need them. Fixing one issue at a time, so postponing.
See https://github.com/NixOS/nix/issues/7731
Part of an effort to make it easier to initialize the right things,
by moving code into the appropriate libraries.
It is required for the sandbox, which is a libstore responsibility;
not just libmain.
Part of an effort to make it easier to initialize the right things,
by moving code into the appropriate libraries.
Part of an effort to make it easier to initialize the right things,
by moving code into the appropriate libraries.
The goal of this reordering is to make initLibStore self-sufficient
in a following commit.
Part of an effort to make it easier to initialize the right things,
by moving code into the appropriate libraries.
Using libstore without loading the config file is risky, as sqlite
may then be misconfigured. See https://github.com/cachix/cachix/issues/475
* Finish converting existing comments for internal API docs
99% of this was just reformatting existing comments. Only two exceptions:
- Expanded upon `BuildResult::status` compat note
- Split up file-level `symbol-table.hh` doc comments to get
per-definition docs
Also fixed a few whitespace goofs, turning leading tabs to spaces and
removing trailing spaces.
Picking up from #8133
* Fix two things from comments
* Use triple-backtick not indent for `dumpPath`
* Convert GNU-style `\`..'` quotes to markdown style in API docs
This will render correctly.
This is non-breaking change in the to-JSON direction. This *is* a
breaking change in the from-JSON direction, but we don't care, as that
is brand new in this PR.
`nix show-derivation --help` currently has the sole public documentation
of this format, it is updated accordingly.
The `write` name is ambiguous and could lead to some funny bugs like
https://github.com/NixOS/nix/pull/8173#issuecomment-1500009480. So
rename it to the more explicit `writeUnbuffered`.
Besides, this method shouldn't be (and isn't) used outside of the class
implementation, so mark it `protected`.
This makes it more symetrical to `BufferedSource` which uses a
`protected readUnbuffered` method.
This function returns true or false depending on whether the Nix client
is trusted or not. Mostly relevant when speaking to a remote store with
a daemon.
We include this information in `nix ping store` and `nix doctor`
Co-Authored-By: John Ericson <John.Ericson@Obsidian.Systems>
They are put in the manual separate pages under the new overarching
description of experimental features.
The settings page just lists the valid experimental feature names (so
people know what a valid setting entry looks like), with links to those
pages. It doesn't attempt to describe each experimental feature as that
is too much information for the configuration settings section.
This introduces the SourcePath type from lazy-trees as an abstraction
for accessing files from inputs that may not be materialized in the
real filesystem (e.g. Git repositories). Currently, however, it's just
a wrapper around CanonPath, so it shouldn't change any behaviour. (On
lazy-trees, SourcePath is a <InputAccessor, CanonPath> tuple.)
Instead of constructing a markdown list in C++ (which involved all sorts
of nasty string literals), export some JSON and assemble it with the
manual build system.
Besides following the precedent set with other dumped data, this is a
better separate of content and presentation; if we decide for example we
want to display this information in a different way, or in a different
section of the manual, it will become much easier to do so.
switch statements must now match all enum values or disable the
warning.
Explicit is good. This has helped us find two bugs, after solving
another one by debugging.
From now on, adding to an enum will raise errors where they are
not explicitly handled, which is good for productivity, and helps
us decide the correct behavior in all usages.
Notably still excluded from this though are the cases where the
warning is disabled by local pragmas.
fromTOML.cc did not build despite a top-level pragma, so I've had
to resort to a makefile solution for that.
Prior to this, there was an ad-hoc whitelist in `main.cc`. Now, every
command states its stability.
In a future PR, we will adjust the manual to take advantage of this new
information in the JSON.
(It will be easier to do that once we have some experimental feature
docs to link too; see #5930 and #7798.)
The code is not local-store-specific, so we should share it with all
stores. More uniform behavior is better, and a less store-specific
functionality is more maintainable.
This fixes a FIXME added in f73d911628 by @edolstra himself.
Documentation on "classic" commands with many sub-commands are
notoriously hard to discover due to lack of overview and anchor links.
Additionally the information on common options and environment variables
is not accessible offline in man pages, and therefore often overlooked
by readers.
With this change, each sub-command of nix-store and nix-env gets its
own page in the manual (listed in the table of contents), and each own
man page.
Also, man pages for each subcommand now (again) list common options
and environment variables. While this makes each page quite long and
some common parameters don't apply, this should still make it easier
to navigate as that additional information was not accessible on the
command line at all.
It is now possible to run 'nix-store --<subcommand> --help` to display
help pages for the given subcommand.
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
This fixes the issue that `nix-build`, without experimental feature
'nix-command' enabled, recommends the experimental CLI `nix log` to view
build logs. Now it'll recommend the stable `nix-store -l` CLI instead.
Fixes https://github.com/NixOS/nix/issues/8118
See the note in the test.
We don't want these flags showing up for commands where they are
irrelevant.
Eventually, this needs a proper fix, but it need not be a blocker for
stabilize: for a quick-n-dirty punt, just put these flags behind the
`nix-command` unstable feature.
This is fine because they are only relevant for commands which we don't
need to stabilize for a while.
`legacyPackages` of nixpkgs trigger eval errors in `hasContent`, causing
the whole `legacyPackages` being skipped. We should treat it as
has-content in that case.
Instead of having a bunch of optional fields, have a few subclasses
which can have mandatory fields.
Additionally, the new `getExtraPathInfo`, and `nixpkgsFlakeRef`, are
moved to `InstallableValue`.
I did these things because https://github.com/NixOS/rfcs/pull/134 ; with
these things moved to `InstallableValue`, the base `Installable` no
longer depends on libexpr! This is a major step towards that.
Also, add a bunch of doc comments for sake of the internal API docs.
Otherwise, a trace consisting of
frame
frame
frame
non-frame
... would reach the non-frame and print the suggestion, even though
it would have ignored the non-frame anyway.
This resulted in a peculariar situation where --show-trace would have
no apparent effect, as the trace was actually already complete.
Pause logger before starting SSH connections, and resume it after the
connection is established, so that SSH password prompts are not erased
by the logger's updates.
Otherwise, when running as root and user namespaces are enabled,
opening the slave fails with EPERM.
Fixes "opening pseudoterminal slave: Permission denied" followed by a
hang (https://hydra.nixos.org/build/213104244), and "error: getting
sandbox mount namespace: No such file or directory" (#8072), which
happens when the child fails very quickly and consequently reading
/proc/<child>/ns fails.
If we conditionally "declare" the argument, as we did before, based upon
weather the feature is enabled, commands like
nix --experimental-features=foo ... --thing-gated-on-foo
won't work, because the experimental feature isn't enabled until *after*
we start parsing.
Instead, allow arguments to also be associated with experimental
features (just as we did for builtins and settings), and then the
command line parser will filter out the experimental ones.
Since the effects of arguments (handler functions) are performed right
away, we get the required behavior: earlier arguments can enable later
arguments enabled!
There is just one catch: we want to keep non-positional
flags...non-positional. So if
nix --experimental-features=foo ... --thing-gated-on-foo
works, then
nix --thing-gated-on-foo --experimental-features=foo ...
should also work.
This is not my favorite long-term solution, but for now this is
implemented by delaying the requirement of needed experimental features
until *after* all the arguments have been parsed.
We hide them in various ways if the experimental feature isn't enabled.
To do this, we had to move the experimental features list out of
libnixstore, because the setting machinary itself depends on it. To do
that, we made a new `ExperimentalFeatureSettings`.
This provides a platform-independent way to configure the SSL
certificates file in the Nix daemon. Previously we provided
instructions for overriding the environment variable in launchd, but
that obviously doesn't work with systemd. Now we can just tell users
to add
ssl-cert-file = /etc/ssl/my-certificate-bundle.crt
to their nix.conf.
These methods would previously fail on the other `Installable`s, so
moving them to this class is more correct as to where they actually
work.
Additionally, a `InstallableValueCommand` is created to make it easier
(or rather no worse than before) to write commands that just work on
`InstallableValue`s.
Besides being a cleanup to avoid failing default methods, this gets us
closer to https://github.com/NixOS/rfcs/pull/134.
Already, we had classes like `BuiltPathsCommand` and `StorePathsCommand`
which provided alternative `run` virtual functions providing the
implementation with more arguments. This was a very nice and easy way to
make writing command; just fill in the virtual functions and it is
fairly clear what to do.
However, exception to this pattern were `Installable{,s}Command`. These
two classes instead just had a field where the installables would be
stored, and various side-effecting `prepare` and `load` machinery too
fill them in. Command would wish out those fields.
This isn't so clear to use.
What this commit does is make those command classes like the others,
with richer `run` functions.
Not only does this restore the pattern making commands easier to write,
it has a number of other benefits:
- `prepare` and `load` are gone entirely! One command just hands just
hands off to the next.
- `useDefaultInstallables` because `defaultInstallables`. This takes
over `prepare` for the one case that needs it, and provides enough
flexiblity to handle `nix repl`'s idiosyncratic migration.
- We can use `ref` instead of `std::shared_ptr`. The former must be
initialized (so it is like Rust's `Box` rather than `Option<Box>`,
This expresses the invariant that the installable are in fact
initialized much better.
This is possible because since we just have local variables not
fields, we can stop worrying about the not-yet-initialized case.
- Fewer lines of code! (Finally I have a large refactor that makes the
number go down not up...)
- `nix repl` is now implemented in a clearer way.
The last item deserves further mention. `nix repl` is not like the other
installable commands because instead working from once-loaded
installables, it needs to be able to load them again and again.
To properly support this, we make a new superclass
`RawInstallablesCommand`. This class has the argument parsing and
completion logic, but does *not* hand off parsed installables but
instead just the raw string arguments.
This is exactly what `nix repl` needs, and allows us to instead of
having the logic awkwardly split between `prepare`,
`useDefaultInstallables,` and `load`, have everything right next to each
other. I think this will enable future simplifications of that argument
defaulting logic, but I am saving those for a future PR --- best to keep
code motion and more complicated boolean expression rewriting separate
steps.
The "diagnostic ignored `-Woverloaded-virtual`" pragma helps because C++
doesn't like our many `run` methods. In our case, we don't mind the
shadowing it all --- it is *intentional* that the derived class only
provides a `run` method, and doesn't call any of the overridden `run`
methods.
Helps with https://github.com/NixOS/rfcs/pull/134
Add the --base64 and --sri flags for the Base64 and SRI format output.
Add the --base16 flag to explicitly specify the hexadecimal format.
Add the --to-base64 and --to-sri flag to convert a hash to the above
mentioned format.
Hopefully this fixes "unexpected EOF" failures on macOS
(#3137, #3605, #7242, #7702).
The problem appears to be that under some circumstances, macOS
discards the output written to the slave side of the
pseudoterminal. Hence the parent never sees the "sandbox initialized"
message from the child, even though it succeeded. The conditions are:
* The child finishes very quickly. That's why this bug is likely to
trigger in nix-env tests, since that uses a builtin builder. Adding
a short sleep before the child exits makes the problem go away.
* The parent has closed its duplicate of the slave file
descriptor. This shouldn't matter, since the child has a duplicate
as well, but it does. E.g. moving the close to the bottom of
startBuilder() makes the problem go away. However, that's not a
solution because it would make Nix hang if the child dies before
sending the "sandbox initialized" message.
* The system is under high load. E.g. "make installcheck -j16" makes
the issue pretty reproducible, while it's very rare under "make
installcheck -j1".
As a fix/workaround, we now open the pseudoterminal slave in the
child, rather than the parent. This removes the second condition
(i.e. the parent no longer needs to close the slave fd) and I haven't
been able to reproduce the "unexpected EOF" with this.
This allows having multiple separate lockfiles for a single
project, which can be useful for testing against different versions of
nixpkgs; it also allows tracking custom input overrides for remote
flakes without requiring local clones of these flakes.
For example, if I want to build Nix against my locally pinned nixpkgs,
and have a lock file tracking this override independently of future
updates to said nixpkgs:
nix flake lock --output-lock-file /tmp/nix-flake.lock --override-input nixpkgs flake:nixpkgs
nix build --reference-lock-file /tmp/nix-flake.lock
Co-Authored-By: Will Fancher <elvishjerricco@gmail.com>
I saw this random failure in https://hydra.nixos.org/build/211811692:
error: opening /proc/15307/fd: No such process
while running nix-collect-garbage in a readfile-context.sh. This is
because we're not handling ESRCH errors reading /proc/<pid>/fd. So
just move the read inside the try/catch where we do handle it.
`nix copy` operations did not show progress. This is quite confusing.
Add a `progressSink` which displays the progress during `copyPaths`,
pretty much copied from `copyStorePath`.
Fixes https://github.com/NixOS/nix/issues/8000
This was causing random failures in tests/ca/substitute.ca: 'nix copy
--file ./content-addressed.nix' wouldn't get the default installable
'.' applied in InstallablesCommand::load(), so it would do nothing.
The curl download can outlive DrvOutputSubstitutionGoal (if some other
error occurs), so at shutdown setting the promise to an exception will
fail because 'this' is no longer valid in the callback. This can
manifest itself as a segfault, "corrupted double-linked list" or hang.
the term was hard to discover, as its definition and explanation were in
a very long document lacking an overview section.
search did not help because it occurs so often.
- clarify wording in the definition
- add an overview of installable types
- add "installable" to glossary
- link to definition from occurrences of the term
- be more precise about where store derivation outputs are processed
- installable Nix expressions must evaluate to a derivation
Co-authored-by: Adam Joseph <54836058+amjoseph-nixpkgs@users.noreply.github.com>
Presently when nix says something like:
```
these 486 paths will be fetched (511.54 MiB download, 6458.64 MiB unpacked):
...path1
...path2
...path3
...
...
...path486
```
It sorts path1, path2, path3, ..., path486 in lexicographic order of the
store path.
After this commit, nix will show path1, path2, path3, ..., path486 sorted by
StorePath name() (basically everything after the hash) rather than the store path.
This makes it easier to review what exactly is being downloaded at a glance,
especially when many paths need to be fetched.
We make sure the env var paths are actually set (ie. not "") before
sending them to the canonicalization function. If we forget to do so,
the user will end up facing a puzzled failed assertion internal error.
We issue a non-failing warning as a stop-gap measure. We could want to
revisit this to issue a detailed failing error message in the future.
Currently the valid key is only present when the path is invalid, which
makes checking path validity more complex than it should be. With this
change, the valid key can always be used to check if a path is valid
The release notes document the change in behavior, I don't include it
here so there is no risk to it getting out of sync.
> Motivation
>> Plumbing CLI should be simple
Store derivation installations are intended as "plumbing": very simple
utilities for advanced users and scripts, and not what regular users
interact with. (Similarly, regular Git users will use branch and tag
names not explicit hashes for most things.)
The plumbing CLI should prize simplicity over convenience; that is its
raison d'etre. If the user provides a path, we should treat it the same
way not caring what sort of path it is.
>> Scripting
This is especially important for the scripting use-case. when arbitrary
paths are sent to e.g. `nix copy` and the script author wants consistent
behavior regardless of what those store paths are. Otherwise the script
author needs to be careful to filter out `.drv` ones, and then run `nix
copy` again with those paths and `--derivation`. That is not good!
>> Surprisingly low impact
Only two lines in the tests need changing, showing that the impact of
this is pretty light.
Many command, like `nix log` will continue to work with just the
derivation passed as before. This because we used to:
- Special case the drv path and replace it with it's outputs (what this
gets rid of).
- Turn those output path *back* into the original drv path.
Now we just skip that entire round trip!
> Context
Issue #7261 lays out a broader vision for getting rid of `--derivation`,
and has this as one of its dependencies. But we can do this with or
without that.
`Installable::toDerivations` is changed to handle the case of a
`DerivedPath::Opaque` ending in `.drv`, which is new: it simply doesn't
need to do any extra work in that case. On this basis, commands like
`nix {show-derivation,log} /nix/store/...-foo.drv` still work as before,
as described above.
When testing older daemons, the post-build-hook will be run against the
old CLI, so we need the old version of the post-build-hook to support
that use-case.
Co-authored-by: Travis A. Everett <travis.a.everett@gmail.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Resolves#7437 for new `nix` commands only by adding a `--stdin` flag.
If paths are also passed on the cli they will be combined with the ones
from standard input.
Whenever a file conflict happens during "nix profile install" an error
is shown that was previously thrown inside builtins.buildEnv.
We catch BuildProfileConflictError here so that we can provide the user
with more useful instructions on what to do next.
Most notably, we give the user concrete commands to use with all
parameters already filled in. This avoids the need for the user to look
up these commands in manual pages.
At the moment an Error is thrown that only holds an error message
regarding `nix-env` and `nix profile`. These tools make use of
builtins.buildEnv, but buildEnv is also used in other places. These
places are unrelated to Nix profiles, so the error shouldn't mention
these tools.
This generic error is now BuildEnvFileConflictError, which holds more
contextual information about the files that were conflicting while
building the environment.
It would be incorrect to say that the `sourceInfo` has an `outPath`
that isn't the root. `sourceInfo` is about the root, whereas only
the flake may not be about the root. Thanks Eelco for pointing that
out.
It is independent of SourceExprCommand, which is about parsing
installables, except for the fact that parsing installables is one of
the many things influenced by read-only mode.
If this documentation is inaccurate in any way please do not hesitate to suggest corrections.
My understanding of this function is strictly from reading the source code and some limited experience implementing fetchers.
We are looking for *$ because it indicate that it was constructed with a new but
not release. De-referencing shallow copy so deleting as whole might create
dangling pointer that's why we move it so we delete a empty containers + the
nice perf boost.
Nixpkgs on aarch64-linux is currently stuck on GCC 9
(https://github.com/NixOS/nixpkgs/issues/208412) and using gcc11Stdenv
doesn't work either.
So use c++2a instead of c++20 for now. Unfortunately this means we
can't use some C++20 features for now (like std::span).
Descriptions for commandline flags may not include newlines and should
be rather short for display in a shell. Truncate the description string
of a flag on '\n' or '.' to and add an ellipsis if needed.
XDG Base Directory is a standard for locations for storing various
files. Nix has a few files which seem to fit in the standard, but
currently use a custom location directly in the user's ~, polluting
it:
- ~/.nix-profile
- ~/.nix-defexpr
- ~/.nix-channels
This commit adds a config option (use-xdg-base-directories) to follow
the XDG spec and instead use the following locations:
- $XDG_STATE_HOME/nix/profile
- $XDG_STATE_HOME/nix/defexpr
- $XDG_STATE_HOME/nix/channels
If $XDG_STATE_HOME is not set, it is assumed to be ~/.local/state.
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
Co-authored-by: Tim Fenney <kodekata@gmail.com>
Co-authored-by: pasqui23 <pasqui23@users.noreply.github.com>
Co-authored-by: Artturin <Artturin@artturin.com>
Co-authored-by: John Ericson <Ericson2314@Yahoo.com>
Fixes#3898
The entire `BinaryCaches` row used to get replaced after it became
stale according to the `timestamp` column. In a concurrent scenario,
this leads to foreign key conflicts as different instances of the
in-process `state.caches` cache now differ, with the consequence that
the older process still tries to use the `id` number of the old record.
Furthermore, this phenomenon appears to have caused the cache for
actual narinfos to be erased about every week, while the default
ttl for narinfos was supposed to be 30 days.
This is slightly more accurate considering that an outdated record
may exist in the persistent cache. Possibly-outdated records are
quite relevant as they may be foreign keys to more recent information
that we want to keep, but we will not return them here.
In unprivileged podman containers, /proc is not fully visible (there
are other filesystems mounted on subdirectories of /proc). Therefore
we can't mount a new /proc in the sandbox that matches the PID
namespace of the sandbox. So this commit automatically disables
sandboxing if /proc is not fully visible.
This didn't work because sandboxing doesn't work in Docker. However,
the sandboxing check is done lazily - after clone(CLONE_NEWNS) fails,
we retry with sandboxing disabled. But at that point, we've already
done UID allocation under the assumption that user namespaces are
enabled.
So let's get rid of the "goto fallback" logic and just detect early
whether user / mount namespaces are enabled.
This commit also gets rid of a compatibility hack for some ancient
Linux kernels (<2.13).
Previously we would completely refetch the submodules from the
network, even though the repo might already have them. Now we copy the
.git/modules directory from the repo as an optimisation. This speeds
up evaluating
builtins.fetchTree { type = "git"; url = "/path/to/blender"; submodules = true; }
(where /path/to/blender already has the needed submodules) from 121s
to 57s.
This is still pretty inefficient and a hack, but a better solution is
best done on the lazy-trees branch.
This change also help in the case where the repo already has the
submodules but the origin is unfetchable for whatever reason
(e.g. there have been cases where Nix in a GitHub action doesn't have
the right authentication set up).
We cannot use 'actualUrl', because for file:// repos that's not the
original URL that the repo was fetched from. This is a problem since
submodules may be relative to the original URL.
Fixes e.g.
nix eval --impure --json --expr 'builtins.fetchTree { type = "git"; url = "/path/to/blender"; submodules = true; }'
where /path/to/blender is a clone of
https://github.com/blender/blender.git (which has several relative
submodules like '../blender-addons.git').
Previously, build-remote would show a warning if all build slots were
taken, even if they would open up later. This caused a lot of spam in
the logs. Disable this warning when maxJobs > 0.
See #6263
Per the old FIXME, this flag was on too many commands, and mostly
ignored. Now it is just on the commands where it actually has an effect.
Per https://github.com/NixOS/nix/issues/7261, I would still like to get
rid of it entirely, but that is a separate project. This change should
be good with or without doing that.
`nix app` had something called `InstallableDerivedPath` which is
actually the same thing. We go with the later's name because it has
become more correct.
I originally did this change (more hurriedly) as part of #6225 --- a
mini store-only Nix and a full Nix need to share this code. In the first
RFC meeting for https://github.com/NixOS/rfcs/pull/134 we discussed how
some splitting of the massive `installables.cc` could begin prior, as
that is a good thing anyways. (@edolstra's words, not mine!) This would
be one such PR.
tl;dr: With this 1 line change I was able to get a speedup of 1.5x on 1Gbit/s
wan connections by enabling zstd compression in nginx.
Also nix already supported all common compression format for http
transfer, webservers usually only enable them if they are advertised
through the Accept-Encoding header.
This pull requests makes nix advertises content compression support for
zstd, br, gzip and deflate.
It's particular useful to add transparent compression for binary caches
that serve packages from the host nix store in particular nix-serve,
nix-serve-ng and harmonia.
I tried so far gzip, brotli and zstd, whereas only zstd was able to bring
me performance improvements for 1Gbit/s WAN connections.
The following nginx configuration was used in combination with the
[zstd module](https://github.com/tokers/zstd-nginx-module) and
[harmonia](https://github.com/nix-community/harmonia/)
```nix
{
services.nginx.virtualHosts."cache.yourhost.com" = {
locations."/".extraConfig = ''
proxy_pass http://127.0.0.1:5000;
proxy_set_header Host $host;
proxy_redirect http:// https://;
proxy_http_version 1.1;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;
zstd on;
zstd_types application/x-nix-archive;
'';
};
}
```
For testing I unpacked a linux kernel tarball to the nix store using
this command `nix-prefetch-url --unpack https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.1.8.tar.gz`.
Before:
```console
$ nix build && rm -rf /tmp/hello && time ./result/bin/nix copy --no-check-sigs --from https://cache.thalheim.io --to 'file:///tmp/hello?compression=none' '/nix/store/j42mahch5f0jvfmayhzwbb88sw36fvah-linux-6.1.8.tar.gz'
warning: Git tree '/scratch/joerg/nix' is dirty
real 0m18,375s
user 0m2,889s
sys 0m1,558s
```
After:
```console
$ nix build && rm -rf /tmp/hello && time ./result/bin/nix copy --no-check-sigs --from https://cache.thalheim.io --to 'file:///tmp/hello?compression=none' '/nix/store/j42mahch5f0jvfmayhzwb
b88sw36fvah-linux-6.1.8.tar.gz'
real 0m11,884s
user 0m4,130s
sys 0m1,439s
```
Signed-off-by: Jörg Thalheim <joerg@thalheim.io>
Update src/libstore/filetransfer.cc
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
These settings are not needed for libstore at all, they are just used by
the nix daemon *command* for authorization on unix domain sockets. My
moving them to a new configuration struct just in that file, we avoid
them leaking anywhere else.
Also, it is good to break up the mammoth `Settings` struct in general.
Issue #5638 tracks this.
The message is not changed because I do not want to regress in
convenience to the user. Just saying "this connection is not trusted"
doesn't tell them out to fix the issue. The ideal thing to do would be
to somehow parameterize `processCommand` on how the error should be
displayed, so different sorts of connections can display different
information to the user based on how authentication is performed for the
connection in question. This, however, is a good bit more work, so it is
left for the future.
This came up with me thinking about the tcp:// store (#5265). The larger
project is not TCP *per se*, but the idea that it should be possible for
something else to manage access control to services like the Nix Daemon,
and those services simply trust or trust the incoming connection as they
are told. This is a more capability-oriented way of thinking about trust
than "every server implements its own auth separately" as we are used to today.
Its very great that libstore itself already implements just this model,
and so via this refactor I basically want to "enshrine" that so it
continues to be the case.
With the switch to C++20, the rules became more strict, and we can no
longer initialize base classes. Make them comments instead.
(BTW
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2287r1.html
this offers some new syntax for this use-case. Hopefully this will be
adopted and we can eventually use it.)
I don't think the `narHash` is in need of documentation more than the
other undocumented fields, but regardless this change has nothing to do
with that field and so we should leave the comment as is.
`&` without space before is far more common on this codebase than I
thought, so it is not worth changing just this one file. Maybe we will
adopt a formatter someday but until then this is fine.
For frameworks it's important that structures are as lazy as possible
to prevent infinite recursions, performance issues and errors that
aren't related to the thing to evaluate. As a consequence, they have
to emit more attributes than strictly (sic) necessary.
However, these attributes with empty values are not useful to the user
so we omit them.
The references set seems to have been unused since `LegacySSHStore`
references were first created in
caa5793b4a.
The method decls never were upstream, and accidentally added by me in
062533f7cd (probably due to `git rerere`).
Sorry!
This reduces the diff from #3746.
No other getDefaultFlakeAttrPaths implementation has this trailing dot,
and the dot can show up in error messages like:
error: flake '...' does not provide attribute 'packages.x86_64-linux.', ...
- Clarify doc comments, Installables::getCursors returns non-empty
vector
- Use vector::at in Installable::getCursor instead of checking for empty
vector and throwing an exception with error message.
Handle the case where none of getActualAttrPaths() actually exists,
in which case instead of returning an empty vector.
This fixes the case where the user misspells the attribute name in nix
search. Instead of getting no search results, now it shows an error with
suggestions.
Also remove InstallableFlake::getCursor() override since it's now
equivalent to the base class version.
Avoid needless work and throwing away invariants.
These conversions date back to when `StorePath` was in Rust and there
were issues with it missing utility methods.
Previously, getDefaultNixPath was called too early: at initialisation
time, before CLI and config have been processed, when `restrictEval` and
`pureEval` both have their default value `false`. Call it when
initialising the EvalState instead, and use `setDefault`.
clangStdenv compiles with a single warning:
```
warning: destructor called on non-final 'nix::PosAdapter' that has virtual functions but non-virtual destructor [-Wdelete-non-abstract-non-virtual-dtor]
```
This fixes the warning by making the destructor of PosAdapter virtual,
deffering to the correct destructor from the concrete child classes.
This has no impact in the end, as none of these classes have specific
destructors.
Technicaly, it may be faster not to have this indirection, but as per
the warning, there is only one place where we have to delete abstract
PosAdapter values.
Not worth bikesheding I guess.
Allows checking directory entry type of a single file/directory.
This was added to optimize the use of `builtins.readDir` on some
filesystems and operating systems which cannot detect this information
using POSIX's `readdir`.
Previously `builtins.readDir` would eagerly use system calls to lookup
these filetypes using other interfaces; this change makes these
operations lazy in the attribute values for each file with application
of `builtins.readFileType`.
We had some local variables left over from the older (more
complicated) implementation of this function. They should all be unused,
but one wasn't by mistake.
Delete them all, and replace the one that was still in use as intended.
It's used as the “system” profile in a bunch of places, so better not
touch it. Besides, it doesn't hurt to keep it since it's owned by root
any way, so it doesn't have the `chown` problem that the user profiles
had and that led to wanting to move them on the client-side.
Rather than using `/nix/var/nix/{profiles,gcroots}/per-user/`, put the user
profiles and gcroots under `$XDG_DATA_DIR/nix/{profiles,gcroots}`.
This means that the daemon no longer needs to manage these paths itself
(they are fully handled client-side). In particular, it doesn’t have to
`chown` them anymore (removing one need for root).
This does change the layout of the gc-roots created by nix-env, and is
likely to break some stuff, so I’m not sure how to properly handle that.
