Previously, the .chroot directory had permission 750 or 755 (depending
on the uid-range system feature) and was owned by root/nixbld. This
makes it possible for any nixbld user (if uid-range is disabled) or
any user (if uid-range is enabled) to inspect the contents of the
chroot of an active build and maybe interfere with it (e.g. via /tmp
in the chroot, which has 1777 permission).
To prevent this, the root is now a subdirectory of .chroot, which has
permission 700 and is owned by root/root.
Instead of running the builds under
`$TMPDIR/{unique-build-directory-owned-by-the-build-user}`, run them
under `$TMPDIR/{unique-build-directory-owned-by-the-daemon}/{subdir-owned-by-the-build-user}`
where the build directory is only readable and traversable by the daemon user.
This achieves two things:
1. It prevents builders from making their build directory world-readable
(or even writeable), which would allow the outside world to interact
with them.
2. It prevents external processes running as the build user (either
because that somehow leaked, maybe as a consequence of 1., or because
`build-users` isn't in use) from gaining access to the build
directory.
the `std::filesystem::create_directories` can fail due to insufficient
permissions. We convert this error into a `SysError` and catch it
wherever required.
#2230 broadened the scope of macOS hardlink exclusion but did not change the comments. This was a little confusing for me, so I figured the comments should be updated.
The documentation is clear about the supported formats (with at least
`builtins.fetchTarball`). The way the code was written previously it
supported all the formats that libarchive supported. That is a
surprisingly large amount of formats that are likely not on the radar
of the Nix developers and users. Before people end up relying on
this (or if they do) it is better to break it now before it becomes a
widespread "feature".
Zip file support has been retained as (at least to my knowledge)
historically that has been used to fetch nixpkgs in some shell
expressions *many* years back.
Fixes https://github.com/NixOS/nix/issues/10917
Special thanks to everyone that has worked on a Meson port so far,
@p01arst0rm and @Qyriad in particular.
Co-Authored-By: p01arst0rm <polar@ever3st.com>
Co-Authored-By: Artemis Tosini <lix@artem.ist>
Co-Authored-By: Artemis Tosini <me@artem.ist>
Co-Authored-By: Felix Uhl <felix.uhl@outlook.com>
Co-Authored-By: Jade Lovelace <lix@jade.fyi>
Co-Authored-By: Lunaphied <lunaphied@lunaphied.me>
Co-Authored-By: Maximilian Bosch <maximilian@mbosch.me>
Co-Authored-By: Pierre Bourdon <delroth@gmail.com>
Co-Authored-By: Qyriad <qyriad@qyriad.me>
Co-Authored-By: Rebecca Turner <rbt@sent.as>
Co-Authored-By: Winter <winter@winter.cafe>
Co-Authored-By: eldritch horrors <pennae@lix.systems>
Co-Authored-By: jade <lix@jade.fyi>
Co-Authored-By: julia <midnight@trainwit.ch>
Co-Authored-By: rebecca “wiggles” turner <rbt@sent.as>
Co-Authored-By: wiggles dog <rbt@sent.as>
Co-Authored-By: fricklerhandwerk <valentin@fricklerhandwerk.de>
Co-authored-by: Eli Schwartz <eschwartz93@gmail.com>
I hope this will make it easier to maintain, and also make it easier for
others to assist with porting the rest of the build system to Meson.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Previously (in cfc18a7739), we forgot to
compare the algo at all. This means we keep the same ordering as before
by making the stuff we always have compared take priority.
The idea is two-fold:
- Replace autotools with Meson
- Build each library in its own derivation
The interaction of these two features is that Meson's "subprojects"
feature (https://mesonbuild.com/Subprojects) allows us to have single
dev shell for building all libraries still, while also building things
separately. This allows us to break up the build without a huge
productivity lost.
I tested the Linux native build, and NetBSD and Windows cross builds.
Also do some clean ups of the Flake in the process of supporting new
jobs.
Special thanks to everyone that has worked on a Meson port so far,
@p01arst0rm and @Qyriad in particular.
Co-Authored-By: p01arst0rm <polar@ever3st.com>
Co-Authored-By: Artemis Tosini <lix@artem.ist>
Co-Authored-By: Artemis Tosini <me@artem.ist>
Co-Authored-By: Felix Uhl <felix.uhl@outlook.com>
Co-Authored-By: Jade Lovelace <lix@jade.fyi>
Co-Authored-By: Lunaphied <lunaphied@lunaphied.me>
Co-Authored-By: Maximilian Bosch <maximilian@mbosch.me>
Co-Authored-By: Pierre Bourdon <delroth@gmail.com>
Co-Authored-By: Qyriad <qyriad@qyriad.me>
Co-Authored-By: Rebecca Turner <rbt@sent.as>
Co-Authored-By: Winter <winter@winter.cafe>
Co-Authored-By: eldritch horrors <pennae@lix.systems>
Co-Authored-By: jade <lix@jade.fyi>
Co-Authored-By: julia <midnight@trainwit.ch>
Co-Authored-By: rebecca “wiggles” turner <rbt@sent.as>
Co-Authored-By: wiggles dog <rbt@sent.as>
Co-Authored-By: fricklerhandwerk <valentin@fricklerhandwerk.de>
Co-authored-By: Eli Schwartz <eschwartz93@gmail.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This is not really part of the evaluator: it is just an integration
between Boehm GC and Boost coroutines usable for any purpose. The
evaluator (merely) optionally uses it.
The implementation of `nix::createDirs` allows it to be a simple wrapper
around `std::filesystem::create_directories` as its return value is not
used anywhere.
throwing exceptions is fine, but throwing exceptions during exception
handling is hard enough to do correctly that we should just forbid it
entirely out of an overabundance of caution. in cases where terminate
is the correct answer the users of Finally must call it manually now.
Source: 6c777476c9
Before, `-lnixutil` was just stuck in `nix-store.pc`, but that doesn't
seem so nice.
This prepares us to distribute `libnixutil` in a separate package if we
want, but it should be a good change either way. I suspect it wasn't
done before because libutil was an extra unstable interface, but I don't
think we need worry about that. *All* the C++ is less stable than the C
(or that's the goal at least).
For what it's worth, Lix also created this pkg-config file *en passant*
during their rename:
c97e17144e (diff-3c4f60cc44a0e35444c7f45331cfa50f76637118)
This re-enables support for older bwdgc versions without complicating
the code too much.
Coroutines generally only interfere with GC during source filtering,
so it's not too bad of a regression on older bdwgc.
This seems preferable over conditional compilation to enable the patch
etc; we've already spent a lot of complexity budget on this GC-coroutine
interaction...
Manually tested by printing to stderr in both branches (sp in os
stack, or not), and triggering a GC in a filterSource function,
e.g.:
let
generateTree = n: if n == 0 then "ha" else { left = generateTree (n - 1); right = generateTree (n - 1); };
in
builtins.deepSeq (generateTree 18) ...
Note that the darwin still uses the strategy of disabling GC, despite
having an implementation that compiles. The proper solution will be
enabled and tested later.
... so that we may perhaps later extend the interface.
Note that Nixpkgs' lib.warn already requires a string coercible
argument, so this is reasonable. Also note that string coercible
values aren't all strings, but in practice, for warn, they are.
Progress on #10832
This doesn't switch to auto-deriving the fields, but by defining `<=>`
we allow deriving `<=>` in downstream types where `Hash` is used.
Fixes assertion failure if outputsToInstall is empty by defaulting to the "out"
output. That is, behavior between the following commands should be consistent:
$ nix build --no-link --json .#nothing-to-install-no-out
error: derivation '/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-nothing-to-install-no-out.drv' does not have wanted outputs 'out'
$ nix build --no-link --file default.nix --json nothing-to-install-no-out
error: derivation '/nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-nothing-to-install-no-out.drv' does not have wanted outputs 'out'
Real-world example of this issue:
$ nix build --json .#.legacyPackages.aarch64-linux.texlive.pkgs.iwona
error: derivation '/nix/store/dj0h6b0pnlnan5nidnhqa0bmzq4rv6sx-iwona-0.995b.drv' does not have wanted outputs 'out'
$ git rev-parse HEAD
eee33247cf6941daea8398c976bd2dda7962b125
$ nix build --json --file . texlive.pkgs.iwona
nix: src/libstore/outputs-spec.hh:46: nix::OutputsSpec::Names::Names(std::set<std::__cxx11::basic_string<char> >&&): Assertion `!empty()' failed.
Aborted (core dumped)
1. Fix build by making the legacy SSH Storey's secret `logFD` setting
not a setting on Windows. (It doesn't make sense to specify `void *`
handles by integer cross-proccess, I don't think.)
2. Move some files that don't need to be Unix-only anymore back to their
original locations.
Before:
$ nix flake lock --override-input nixpkgs gitlab:simple-nixos-mailserver/nixos-mailserver/nonexistent
fetching git input 'git+file:///home/linus/projects/lix'
fetching gitlab input 'gitlab:simple-nixos-mailserver/nixos-mailserver/nonexistent'
error: [json.exception.type_error.302] type must be string, but is null
After:
/tmp/inst/bin/nix flake lock --override-input nixpkgs gitlab:simple-nixos-mailserver/nixos-mailserver/nonexistent
warning: unknown experimental feature 'repl-flake'
error:
… while updating the lock file of flake 'git+file:///home/joerg/git/nix?ref=refs/heads/master&rev=62693c2c37c8edd92f95114eb1387b461fc671df'
… while updating the flake input 'nixpkgs'
… while fetching the input 'gitlab:simple-nixos-mailserver/nixos-mailserver/nonexistent'
error: No commits returned by GitLab API -- does the git ref really exist?
Adapted from: 3df013597d
This turns errors like:
error: flake output attribute 'hydraJobs' is not a derivation or path
into errors like:
error: expected flake output attribute 'hydraJobs' to be a derivation or
path but found a set: { binaryTarball = «thunk»; build = «thunk»; etc> }
This change affects all InstallableFlake commands.
Source: 20981461d4
Signed-off-by: Jörg Thalheim <joerg@thalheim.io>
* docs: mention importNative/exec in allow-unsafe-native-code-during-evaluation
Both of these still needs their own actual documentation, but they are
at least now mentioned that they exist and what they're enabled by.
Co-authored-by: Qyriad <qyriad@qyriad.me>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
- Get a rump derivation goal: hook instance will come later, local
derivation goal will come after that.
- Start cleaning up the channel / waiting code with an abstraction.
By moving `host` to the config, we can do a lot further cleanups and
dedups. This anticipates a world where we always go `StoreReference` ->
`*StoreConfig` -> `Store*` rather than skipping the middle step too.
Progress on #10766
Progress on https://github.com/NixOS/hydra/issues/1164
This increases test coverage, and gets the worker protocol ready to be
used by Hydra.
Why don't we just try to use the store interface in Hydra? Well, the
problem is that the store interface works on connection pools, with each
opreation getting potentially a different connection, but the way temp
roots work requires that we keep one logical "transaction" (temp root
session) using the same connection.
The longer-term solution probably is making connections themselves
implement the store interface, but that is something that builds on
this, so I feel OK that this is not churn in the wrong direction.
Fixes#9584
We don't want to rely on how C assigns numbers for enums in the wire
format. Sure, this is totally determined by the ABI, but it obscures the
code and makes it harder to safely change the enum definition (should we
need to) without accidentally breaking the wire format.
Do this instead of an unchecked cast
I redid this to use the serialisation framework (including a unit test),
but I am keeping the reference to credit Jade for spotting the issue.
Change-Id: Icf6af7935e8f139bef36b40ad475e973aa48855c
(adapted from commit 2a7a824d83dc5fb33326b8b89625685f283a743b)
Co-Authored-By: Jade Lovelace <lix@jade.fyi>
File not found while importing is not currently caught by the tab-completion handler.
Original bug report: https://git.lix.systems/lix-project/lix/issues/340
Fix has been adapted from https://gerrit.lix.systems/c/lix/+/1189
Example crash:
$ cat /tmp/foo.nix
{
someImport = import ./this_file_does_not_exist;
}
$ ./src/nix/nix repl --file /tmp/foo.nix
warning: unknown experimental feature 'repl-flake'
Nix 2.23.0pre20240517_dirty
Type :? for help.
Loading installable ''...
Added 1 variables.
nix-repl> someImport.<TAB>
This way we can commit the same amount of stack size (64 MB) without a conditional.
Includes nix, libnixexpr-tests, libnixfetchers-tests, libnixstore-tests, libnixutil-tests.
https://github.com/NixOS/nix/pull/10555 added a check requiring
that output parameters always have an uninitialized Value as argument.
Unfortunately the output parameter of the primop callback received
a thunk instead.
See the comment for implementation considerations.
This was accidentally removed in
e989c83b44. I restored it and also did a
few other cleanups:
- Make a static method for namespacing purposes
- Put the test files in the data dir with the other test data
- Avoid mutating globals in the machine config tests
This will be used by Hydra.
Need to decouple parsing from actually opening a store for Machine
configs.
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
In particular `local://<path>` and `unix://` (without any path) now
work, and mean the same things as `local` and `daemon`, respectively. We
thus now have the opportunity to desguar `local` and `daemon` early.
This will allow me to make a change to
https://github.com/NixOS/nix/pull/9839 requested during review to
desugar those earlier.
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
1. Hydra currently queries for multiple path infos at once, so let us
make a connection item for that.
2. The minimum of the two versions should always be used, see #9584.
(The issue remains open because the daemon protocol needs to be
likewise updated.)
The JSON format no longer uses the legacy ATerm `r:` prefixing nonsese,
but separate fields.
Progress on #9866
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Basically I'd expect the same behavior as with `nix-build`, i.e.
with `--keep-going` the hash-mismatch error of each failing
fixed-output derivation is shown.
The approach is derived from `Store::buildPaths` (`entry-point.cc`):
instead of throwing the first build-result, check if there are any build
errors and if so, display all of them and throw after that.
Unfortunately, the BuildResult struct doesn't have an `ErrorInfo`
(there's a FIXME for that at least), so I have to construct my own here.
This is a rather cheap bugfix and I decided against touching too many
parts of libstore for that (also I don't know if that's in line with the
ongoing refactoring work).
Closes https://git.lix.systems/lix-project/lix/issues/302
Change-Id: I378ab984fa271e6808c6897c45e0f070eb4c6fac
Signed-off-by: Jörg Thalheim <joerg@thalheim.io>
On several occasions I've found myself confused when trying to delete
a store path, because I am told it's still alive, but
nix-store --query --roots doesn't show anything. Let's save future
users this confusion by mentioning that a path might be alive due to
having referrers, not just roots.
In addition:
- Take the opportunity to add a bunch more missing hyperlinks, too.
- Remove some glossary entries that are now subsumed by dedicated pages.
We used to not be able to do this without breaking link fragments, but
now we can, so pick up where we left off.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This is useful for diagnosing whether an evaluation is copying large
paths to the store. Example:
$ nix build .#packages.x86_64-linux.default --large-path-warning-threshold 1000000
warning: copied large path '/home/eelco/Dev/nix-master/' to the store (6271792 bytes)
warning: copied large path '«github:NixOS/nixpkgs/b550fe4b4776908ac2a861124307045f8e717c8e?narHash=sha256-7kkJQd4rZ%2BvFrzWu8sTRtta5D1kBG0LSRYAfhtmMlSo%3D»/' to the store (155263768 bytes)
warning: copied large path '«github:libgit2/libgit2/45fd9ed7ae1a9b74b957ef4f337bc3c8b3df01b5?narHash=sha256-oX4Z3S9WtJlwvj0uH9HlYcWv%2Bx1hqp8mhXl7HsLu2f0%3D»/' to the store (22175416 bytes)
warning: copied large path '/nix/store/z985088mcd6w23qwdlirsinnyzayagki-source' to the store (5885872 bytes)
This fixes https://github.com/NixOS/nixpkgs/pull/290775 by not expanding aliases
when sourcing the stdenv setup script. The way bash handles aliases is to expand
them when a function is defined, not when it is used. I.e.:
$ alias echo="echo bar "
$ echo foo
bar foo
$ xyzzy() { echo foo; }
$ shopt -u expand_aliases
$ xyzzy
bar foo
$ xyzzy2() { echo foo; }
$ xyzzy2
foo
The problem is that ~/.bashrc is sourced before the stdenv setup, and bashrc
commonly sets aliases for ‘cp’, ‘mv’ and ‘rm’ which you don’t want to take
effect in the stdenv derivation builders. The original commit introducing this
feature (5fd8cf7667) even mentioned this very
alias.
The only way to avoid this is to disable aliases entirely while sourcing the
stdenv setup, and reenable them afterwards.
Passing the commit message as an argument causes update failures on repositories with lots of flake inputs. In some cases, the commit message is over 250,000 bytes.
the old `copyFile` was just a wrapper that was calling the `copy`
function. This wrapper function is removed and the `copy` function is
renamed to `copyFile`.
Building derivations is a lot harder, but the downloading goals is
portable enough.
The "common channel" code is due to Volth. I wonder if there is a way we
can factor it out into separate functions / files to avoid some
within-function CPP.
Co-authored-by: volth <volth@volth.com>
In streaming mode, libarchive doesn't handle symlinks in zip files
correctly. So write the entire file to disk so libarchive can access
it in random-access mode.
Fixes#10649. This was broken in cabee98152.
* Document string context
Now what we have enough primops, we can document how string contexts
work.
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
Co-authored-by: Valentin Gagarin <valentin.gagarin@tweag.io>
Co-authored-by: Felix Uhl <iFreilicht@users.noreply.github.com>
builtins.strictDerivation returns an attribute set with drvPath and
output paths. For some reason, current implementation forbids drv
instead of drvPath.
Sometimes we read a directory with children we cannot stat. It's a pitty
we even try to stat at all (wasteful) in the `DT_UNKNOWN` case, but at
least this should get rid of the failure.
This was changed in #10611, which caused the derivation paths of
anything using builtin:fetchurl to change (i.e. all of
Nixpkgs). However, impureEnvVars doesn't actually do anything for
builtin:fetchurl, so we can just set it to its historical value.
This makes for shorter and more portable code.
The only tricky part is catching exceptions: I just searched for near by
`catch (Error &)` or `catch (SysError &)` and adjusted them to `catch
(std::filesystem::filesystem_error &)` according to my human judgement.
Good for windows portability; will help @siddhantk232 with his GSOC
project.
Different parts of the project honor different sets of proxy environment
variables. With this commit all parts of the project will honor the same
set of proxy environment variables.
---------
Co-authored-by: Your Name <you@example.com>
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
Now that SourcePath uses a SourceAccessor instead of an InputAccessor,
we can use it in function signatures instead of passing a
SourceAccessor and CanonPath separately.
Make sure that `extraSandboxProfile` is set before we check whether it's
empty or not (in the `sandbox=true` case).
Also adds a test case for this.
Co-Authored-By: Artemis Tosini <lix@artem.ist>
Co-Authored-By: Eelco Dolstra <edolstra@gmail.com>
After the removal of the InputAccessor::fetchToStore() method, the
only remaining functionality in InputAccessor was `fingerprint` and
`getLastModified()`, and there is no reason to keep those in a
separate class.
Fix formatting violations, update blacklist to reflect moved files.
PR #10556 passed CI before the new formating rules were added, and our
CI has the race condition of allowing old results, resulting in master
getting broken.
This missing GC root wasn't much of a problem before, because the
heap would end up with a reference to the `baseEnv` pretty soon,
but when unit testing, the construction of `EvalState` doesn't
necessarily happen well before GC runs for the first time.
Found while unit testing the Rust bindings that currently reside
at https://github.com/nixops4/nixops4/tree/main/rust
Add a method to check if a value has been initialized. This helps avoid
segfaults when calling `type()`.
Useful in the context of the new C API.
Closes#10524
Windows now has some basic Unix Domain Socket support, see
https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/
Building `nix daemon` on Windows I've left for later, because the daemon
currently forks per connection but this is not an option on Windows. But
we can get the client part working right away.
With Linux kernel >=6.6 & glibc 2.39 a `fchmodat2(2)` is available that
isn't filtered away by the libseccomp sandbox.
Being able to use this to bypass that restriction has surprising results
for some builds such as lxc[1]:
> With kernel ≥6.6 and glibc 2.39, lxc's install phase uses fchmodat2,
> which slips through 9b88e52846/src/libstore/build/local-derivation-goal.cc (L1650-L1663).
> The fixupPhase then uses fchmodat, which fails.
> With older kernel or glibc, setting the suid bit fails in the
> install phase, which is not treated as fatal, and then the
> fixup phase does not try to set it again.
Please note that there are still ways to bypass this sandbox[2] and this is
mostly a fix for the breaking builds.
This change works by creating a syscall filter for the `fchmodat2`
syscall (number 452 on most systems). The problem is that glibc 2.39
and seccomp 2.5.5 are needed to have the correct syscall number available
via `__NR_fchmodat2` / `__SNR_fchmodat2`, but this flake is still on
nixpkgs 23.11. To have this change everywhere and not dependent on the
glibc this package is built against, I added a header
"fchmodat2-compat.hh" that sets the syscall number based on the
architecture. On most platforms its 452 according to glibc with a few
exceptions:
$ rg --pcre2 'define __NR_fchmodat2 (?!452)'
sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h
58:#define __NR_fchmodat2 1073742276
sysdeps/unix/sysv/linux/mips/mips64/n32/arch-syscall.h
67:#define __NR_fchmodat2 6452
sysdeps/unix/sysv/linux/mips/mips64/n64/arch-syscall.h
62:#define __NR_fchmodat2 5452
sysdeps/unix/sysv/linux/mips/mips32/arch-syscall.h
70:#define __NR_fchmodat2 4452
sysdeps/unix/sysv/linux/alpha/arch-syscall.h
59:#define __NR_fchmodat2 562
I tested the change by adding the diff below as patch to
`pkgs/tools/package-management/nix/common.nix` & then built a VM from
the following config using my dirty nixpkgs master:
{
vm = { pkgs, ... }: {
virtualisation.writableStore = true;
virtualisation.memorySize = 8192;
virtualisation.diskSize = 12 * 1024;
nix.package = pkgs.nixVersions.nix_2_21;
};
}
The original issue can be triggered via
nix build -L github:nixos/nixpkgs/d6dc19adbda4fd92fe9a332327a8113eaa843894#lxc \
--extra-experimental-features 'nix-command flakes'
however the problem disappears with this patch applied.
Closes#10424
[1] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2031073804
[2] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2030844251
With Nix 2.3, it was possible to pass a subpath of a store path to
exportReferencesGraph:
with import <nixpkgs> {};
let
hello = writeShellScriptBin "hello" ''
echo ${toString builtins.currentTime}
'';
in
writeClosure [ "${hello}/bin/hello" ]
This regressed with Nix 2.4, with a very confusing error message, that
presumably indicates it was unintentional:
error: path '/nix/store/3gl7kgjr4pwf03f0x70dgx9ln3bhl7zc-hello/bin/hello' is not in the Nix store
At this point many features are stripped out, but this works:
- Can run libnix{util,store,expr} unit tests
- Can run some Nix commands
Co-Authored-By volth <volth@volth.com>
Co-Authored-By Brian McKenna <brian@brianmckenna.org>
This also reworks the Mercurial fetcher (which was still using the
old cache interface) to have two distinct cache mappings:
* A ref-to-rev mapping, which is store-independent.
* A rev-to-store-path mapping.
Code operating on store objects (including creating them) should, in
general, use `ContentAddressMethod` rather than `FileIngestionMethod`.
See also dfc876531f which included some
similar refactors.
See https://github.com/NixOS/nix/pull/8699#discussion_r1554312181
Casting a function pointer to `void*` is undefined behavior in the C
spec, since there are platforms with different sizes for these two kinds
of pointers. A safe alternative might be `void (*callback)()`
* add intermediate variables and clarifying comments
Co-authored-by: Alexander Groleau <alex@proof.construction>
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
https://github.com/NixOS/nix/pull/10456 fixed the addition of symlink
store paths to the sandbox, but also made it so that the hardcoded
sandbox paths (like `/etc/hosts`) were now bind-mounted without
following the possible symlinks. This made these files unreadable if
there were symlinks (because the sandbox would now contain a symlink to
an unreachable file rather than the underlying file).
In particular, this broke FOD derivations on NixOS as `/etc/hosts` is a
symlink there.
Fix that by canonicalizing all these hardcoded sandbox paths before
adding them to the sandbox.
