Commit graph

3449 commits

Author SHA1 Message Date
Théophane Hufschmitt 0f977bf91e
Remove a useless debug message in filetransfer.cc
Remove the `verify TLS: Nix CA file = 'blah'` message that Nix used to print when fetching anything as it's both useless (`libcurl` prints the same info in its logs) and misleading (gives the impression that a new TLS connection is being established which might not be the case because of multiplexing. See #7011 )
2022-09-19 08:42:43 +02:00
Théophane Hufschmitt 0f64bf445a
Merge pull request #6994 from agbrooks/master
Prevent tempdir from being GC-ed before addToStoreFromDump completes
2022-09-13 09:23:16 +02:00
Andrew Brooks 565d888e0f Address PR feedback on #6694 2022-09-12 11:33:23 -05:00
Andrew Brooks 84fe75a12a Keep created temp dirs inside store, but protect from GC
Implements the approach suggested by feedback on PR #6994, where
tempdir paths are created in the store (now with an exclusive lock).

As part of this work, the currently-broken and unused
`createTempDirInStore` function is updated to create an exclusive lock
on the temp directory in the store.

The GC now makes a non-blocking attempt to lock any store directories
that "look like" the temp directories created by this function, and if
it can't acquire one, ignores the directory.
2022-09-06 17:48:00 -05:00
Andrew Brooks 1f041ac54f Prevent tempdir from being GC-ed before addToStoreFromDump has renamed it
This fixes issue 6823 by placing the tempdir used in LocalStore::addToStoreFromDump
outside the Nix store, where automatic GC is no longer a concern.
2022-09-02 18:32:35 -05:00
Matthew Bauer 4894e567fb Don’t readDerivation if impure derivations feature is disabled
readDerivation is pretty slow, and while it may not be significant for
some use cases, on things like ghc-nix where we have thousands of
derivations is really slows things down.

So, this just doesn’t do the impure derivation check if the impure
derivation experimental feature is disabled. Perhaps we could cache
the result of isPure() and keep the check, but this is a quick fix to
for the slowdown introduced with impure derivations features in 2.8.0.
2022-09-02 11:46:34 -05:00
Adam Joseph 1ab913467e linkify mention of other options 2022-09-01 18:03:35 -07:00
Adam Joseph 59dc8346ca move substituter signature-checking conditions to configuration file documentation 2022-09-01 17:51:56 -07:00
Eelco Dolstra 7918adbb62
Merge pull request #6954 from winterqt/darwin-sandbox-trustd
fix(libstore): allow access to trustd on macOS
2022-08-26 11:45:00 +02:00
Winter Cute 8e5659423e fix(libstore): allow access to trustd on macOS 2022-08-24 13:09:44 -04:00
Eelco Dolstra 56d97d4b4d Remove redundant Finally 2022-08-24 14:49:58 +02:00
Eelco Dolstra 8d906b1f3b Fix macOS build 2022-08-24 14:11:03 +02:00
Eelco Dolstra f0358ed465 Fix a hang in nix-copy-ssh.sh
This hang for some reason didn't trigger in the Nix build, but did
running 'make installcheck' interactively. What happened:

* Store::addMultipleToStore() calls a SinkToSource object to copy a
  path, which in turn calls LegacySSHStore::narFromPath(), which
  acquires a connection.

* The SinkToSource object is not destroyed after the last bytes has
  been read, so the coroutine's stack is still alive and its
  destructors are not run. So the connection is not released.

* Then when the next path is copied, because max-connections = 1,
  LegacySSHStore::narFromPath() hangs forever waiting for a connection
  to be released.

The fix is to make sure that the source object is destroyed when we're
done with it.
2022-08-23 14:19:53 +02:00
Eelco Dolstra f865048332 Indentation 2022-08-22 15:32:53 +02:00
Eelco Dolstra 4c96761c2b Merge remote-tracking branch 'origin/master' into parallel-nix-copy 2022-08-22 15:29:10 +02:00
Eelco Dolstra 8d84634e26
Merge pull request #6926 from rapenne-s/download_limit
add a nix.conf option to set a download speed limit
2022-08-22 14:57:19 +02:00
Eelco Dolstra c21b1a7e67
Spelling 2022-08-22 14:14:14 +02:00
Solène Rapenne caad87e6db
Better documentation wording
Co-authored-by: Anderson Torres <torres.anderson.85@protonmail.com>
2022-08-20 18:21:36 +02:00
Solene Rapenne 0d2bf7acf9 add a nix.conf option to set a download speed limit 2022-08-19 12:40:22 +02:00
pennae 7d934f7880 don't read outputs into memory for output rewriting
RewritingSink can handle being fed input where a reference crosses a
chunk boundary. we don't need to load the whole source into memory, and
in fact *not* loading the whole source lets nix build FODs that do not
fit into memory (eg fetchurl'ing data files larger than system memory).
2022-08-19 11:26:26 +02:00
Eelco Dolstra 53e7b7e8ac Remove warnLargeDump()
This message was unhelpful (#1184) and probably misleading since
memory is O(1) in most cases now.
2022-08-17 11:32:01 +02:00
Théophane Hufschmitt 8f3fdef1e0
Merge pull request #6850 from NinjaTrappeur/nin/build-check
Fix Nix build --check flag
2022-08-10 17:44:06 +02:00
Théophane Hufschmitt 90f9680733 Only use renameFile where needed
In most places the fallback to copying isn’t needed and can actually be
bad, so we’d rather not transparently fallback
2022-08-03 10:27:25 +02:00
Théophane Hufschmitt d71d9e9fbf moveFile -> renameFile
`move` tends to have this `mv` connotation of “I will copy it for you if
needs be”
2022-08-03 10:27:25 +02:00
Théophane Hufschmitt c2de0a232c Create a wrapper around stdlib’s rename
Directly takes some c++ strings, and gently throws an exception on error
(rather than having to inline this logic everywhere)
2022-08-03 10:27:25 +02:00
Félix Baylac-Jacqué 1467a98d4c
derivation-goal.cc: remove bmCheck custom return branch on buildDone
Once a derivation goal has been completed, we check whether or not
this goal was meant to be repeated to check its output.

An early return branch was preventing the worker to reach that repeat
code branch, hence breaking the --check command (#2619).

It seems like this early return branch is an artifact of a passed
refactoring. As far as I can tell, buildDone's main branch also
cleanup the tmp directory before returning.
2022-08-01 11:39:19 +02:00
Théophane Hufschmitt 2805439335
Merge pull request #6814 from amjoseph-nixpkgs/pr/sandbox-error-messages
local-derivation-goal.cc: improve error messages when sandboxing fails
2022-07-22 13:27:52 +02:00
Théophane Hufschmitt 7ed91d6c6a
Merge branch 'master' into parallel-nix-copy 2022-07-20 10:05:34 +02:00
Alex Wied 722de8ddcc libstore/globals.cc: Move cgroup detection to libutil 2022-07-19 16:25:53 -04:00
Alex Wied 1af5d798a4 libstore/globals.cc: Automatically set cores based on cgroup CPU limit
By default, Nix sets the "cores" setting to the number of CPUs which are
physically present on the machine. If cgroups are used to limit the CPU
and memory consumption of a large Nix build, the OOM killer may be
invoked.

For example, consider a GitLab CI pipeline which builds a large software
package. The GitLab runner spawns a container whose CPU is limited to 4
cores and whose memory is limited to 16 GiB. If the underlying machine
has 64 cores, Nix will invoke the build with -j64. In many cases, that
level of parallelism will invoke the OOM killer and the build will
completely fail.

This change sets the default value of "cores" to be
ceil(cpu_quota / cpu_period), with a fallback to
std:🧵:hardware_concurrency() if cgroups v2 is not detected.
2022-07-19 16:03:58 -04:00
Théophane Hufschmitt 56f6f3725f Don't ultimately trust the signed paths
Like the old implem did (and like you'd want it to be anyways)
2022-07-19 19:46:00 +02:00
Adam Joseph 36e1383b6b local-derivation-goal.cc: save global errno to the stack before performing tests which might clobber it 2022-07-19 03:53:20 -07:00
Adam Joseph 99fcc91f67 as requested by @thufschmitt https://github.com/NixOS/nix/pull/6814#discussion_r924275777 2022-07-19 03:33:12 -07:00
Adam Joseph 5f51539f88 change warn() to notice() 2022-07-19 03:30:52 -07:00
Adam Joseph c8c6203c2c local-derivation-goal.cc: detect unprivileged_userns_clone failure mode
The workaround for "Some distros patch Linux" mentioned in
local-derivation-goal.cc will not help in the `--option
sandbox-fallback false` case.  To provide the user more helpful
guidance on how to get the sandbox working, let's check to see if the
`/proc` node created by the aforementioned patch is present and
configured in a way that will cause us problems.  If so, give the user
a suggestion for how to troubleshoot the problem.
2022-07-17 01:27:22 -07:00
Adam Joseph 6fc56318bf local-derivation-goal.cc: add comment re: CLONE_NEWUSER
local-derivation-goal.cc contains a comment stating that "Some distros
patch Linux to not allow unprivileged user namespaces."  Let's give a
pointer to a common version of this patch for those who want more
details about this failure mode.
2022-07-17 01:23:32 -07:00
Adam Joseph 8d35f387dc local-derivation-goal.cc: warn if failing and /proc/self/ns/user missing
This commit causes nix to `warn()` if sandbox setup has failed and
`/proc/self/ns/user` does not exist.  This is usually a sign that the
kernel was compiled without `CONFIG_USER_NS=y`, which is required for
sandboxing.
2022-07-16 19:37:27 -07:00
Adam Joseph 90830b1074 local-derivation-goal.cc: warn if failing due to max_user_namespaces==0
This commit uses `warn()` to notify the user if sandbox setup fails
with errno==EPERM and /proc/sys/user/max_user_namespaces is missing or
zero, since that is at least part of the reason why sandbox setup
failed.

Note that `echo -n 0 > /proc/sys/user/max_user_namespaces` or
equivalent at boot time has been the recommended mitigation for
several Linux LPE vulnerabilities over the past few years.  Many users
have applied this mitigation and then forgotten that they have done
so.
2022-07-16 19:30:53 -07:00
Adam Joseph 8ea3a911aa local-derivation-goal.cc: improve error messages when sandboxing fails
The failure modes for nix's sandboxing setup are pretty complicated.
When nix is unable to set up the sandbox, let's provide more detail
about what went wrong.  Specifically:

* Make sure the error message includes the word "sandbox" so the user
  knows that the failure was related to sandboxing.

* If `--option sandbox-fallback false` was provided, and removing it
  would have allowed further attempts to make progress, let the user
  know.
2022-07-16 14:56:24 -07:00
Alex Wied b88fb50e21 fix(libstore): allow Nix to access all Rosetta 2 paths on MacOS
Fixes: #5884
2022-07-15 12:10:56 -07:00
Eelco Dolstra 3bcd7a5474 Disable auto-chroot if $NIX_STATE_DIR is set
Issue #6732.
2022-07-15 12:32:29 +02:00
Eelco Dolstra ff49c75502 Disable auto-chroot if $NIX_STORE_DIR is set
Fixes #6732.
2022-07-14 17:47:09 +02:00
Eelco Dolstra 6cab528461 Don't fail if we can't create ~/.local/share/nix/root
https://hydra.nixos.org/build/182135943
2022-06-29 12:16:51 +02:00
Théophane Hufschmitt 56cf96a1b9
Merge pull request #6706 from lheckemann/cache-info-cache-invalidation
nar-info-disk-cache: refresh nix-cache-info weekly
2022-06-29 07:56:27 +02:00
Eelco Dolstra 586fa707fc
Merge pull request #6714 from edolstra/auto-chroot-store
Automatically use a chroot store if /nix doesn't exist
2022-06-25 00:03:35 +02:00
Eelco Dolstra 30d4aa5dd6 Only do the auto chroot store on Linux 2022-06-24 23:35:21 +02:00
Linus Heckemann 8cf26385cd [fixup] handle cache expiration in sqlite query 2022-06-23 14:54:25 -04:00
Cole Helbling 561a258f1d libstore/nar-info: drop unused system field
This was unused everywhere (and even the official NixOS binary cache
did not produce .narinfo files containing a "System:" field).
2022-06-23 14:25:10 -04:00
Eelco Dolstra 1cb376d60e
Fix typo
Co-authored-by: Cole Helbling <cole.e.helbling@outlook.com>
2022-06-23 17:18:22 +02:00
Eelco Dolstra 2a9fddc0b1 Automatically use a chroot store if /nix doesn't exist
Specifically, if we're not root and the daemon socket does not exist,
then we use ~/.local/share/nix/root as a chroot store. This enables
non-root users to download nix-static and have it work out of the box,
e.g.

  ubuntu@ip-10-13-1-146:~$ ~/nix run nixpkgs#hello
  warning: '/nix' does not exists, so Nix will use '/home/ubuntu/.local/share/nix/root' as a chroot store
  Hello, world!
2022-06-23 16:29:50 +02:00
Eelco Dolstra 3c57db1a0f
Merge pull request #6710 from edolstra/embedded-sandbox-shell
Embed the sandbox shell into the statically linked 'nix' binary
2022-06-23 15:34:16 +02:00
Eelco Dolstra 0b2ea0023c Fix typo 2022-06-23 14:22:11 +02:00
Théophane Hufschmitt 027f6a735f
Merge pull request #6673 from asymmetric/warn
libstore: improve warning message on missing sig
2022-06-23 06:42:48 +02:00
Eelco Dolstra 925b975224 Embed the sandbox shell into the statically linked 'nix' binary
With this, Nix will write a copy of the sandbox shell to /bin/sh in
the sandbox rather than bind-mounting it from the host filesystem.
This makes /bin/sh work out of the box with nix-static, i.e. you no
longer get

  /nix/store/qa36xhc5gpf42l3z1a8m1lysi40l9p7s-bootstrap-stage4-stdenv-linux/setup: ./configure: /bin/sh: bad interpreter: No such file or directory
2022-06-23 04:08:28 +02:00
Eelco Dolstra 184f4e40de Remove NIX_LIBEXEC_DIR 2022-06-23 01:32:46 +02:00
Eelco Dolstra d3176ce076 Fix build-remote in nix-static
'build-remote' is now executed via /proc/self/exe so it always works.
2022-06-23 01:32:46 +02:00
Linus Heckemann d533a88546 nar-info-disk-cache: refresh nix-cache-info weekly
This allows changes to nix-cache-info to be picked up by existing
clients. Previously, the only way for this to happen would be for
clients to delete binary-cache-v6.sqlite, which is quite awkward for
users.

On the other hand, updates to nix-cache-info should be pretty rare,
hence the choice of a fairly long TTL. Configurability is probably not
useful enough to warrant implementing it.
2022-06-22 10:49:18 -04:00
Lorenzo Manacorda 475249db8a libstore: improve warning message on missing sig
Clarifies that the substitute will be ignored/skipped.
2022-06-15 17:34:28 +02:00
Eelco Dolstra 9f58df4c91
Merge pull request #6619 from Jonpez2/patch-1
Add security.csm to ignored-acls
2022-06-13 16:23:13 +02:00
Eelco Dolstra 2fef24f528
Merge pull request #6634 from lovesegfault/fix-getgrouplist
fix(libstore/lock): support users that belong to more than 10 groups
2022-06-13 15:45:09 +02:00
Anders Kaseorg 754cd53faf Add missing rethrows in conditional exception handlers
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
2022-06-10 10:52:41 -07:00
Bernardo Meurer 931930feb1 fix(libstore/lock): support users that belong to more than 10 groups
The manpage for `getgrouplist` says:

> If the number of groups of which user is a member is less than or
> equal to *ngroups, then the value *ngroups is returned.
>
> If the user is a member of more than *ngroups groups, then
> getgrouplist() returns -1.  In this case, the value returned in
> *ngroups can be used to resize the buffer passed to a further
> call getgrouplist().

In our original code, however, we allocated a list of size `10` and, if
`getgrouplist` returned `-1` threw an exception. In practice, this
caused the code to fail for any user belonging to more than 10 groups.

While unusual for single-user systems, large companies commonly have a
huge number of POSIX groups users belong to, causing this issue to crop
up and make multi-user Nix unusable in such settings.

The fix is relatively simple, when `getgrouplist` fails, it stores the
real number of GIDs in `ngroups`, so we must resize our list and retry.
Only then, if it errors once more, we can raise an exception.

This should be backported to, at least, 2.9.x.
2022-06-08 13:45:41 -04:00
Théophane Hufschmitt 480c2b6699 Rewrite the CA paths when moving them between store
Bring back the possibility to copy CA paths with no reference (like the
outputs of FO derivations or stuff imported at eval time) between stores
that have a different prefix.
2022-06-08 15:13:11 +02:00
Théophane Hufschmitt cb0553ecd0 Restore the "low-latency" ssh copying 2022-06-08 14:03:46 +02:00
Jonpez2 a7d25d339d
Add security.csm to the default ignore list 2022-06-08 09:32:14 +01:00
Théophane Hufschmitt 95f47c28fb Make nix copy parallel again
FILLME
2022-06-03 17:01:16 +02:00
Eelco Dolstra 2097c30b08
Merge pull request #6600 from asymmetric/hash-comment
schema.sql: add comment about hash being in base16
2022-06-03 08:51:07 +02:00
Théophane Hufschmitt a5f7b934bd
Merge branch 'master' into lto 2022-06-01 17:55:03 +02:00
Lorenzo Manacorda a9358a6097 schema.sql: add comment about hash being in base16 2022-06-01 14:59:57 +02:00
Eelco Dolstra 6378f0bb32
RemoteStore::queryRealisationUncached(): Fix potential noexcept violation 2022-05-30 13:27:13 +02:00
Eelco Dolstra b8faa83742
HttpBinaryCacheStore::getFile(): Don't throw an exception
This violates the noexcept specification.

Fixes #6445.
2022-05-30 13:24:04 +02:00
pennae b092afe77d
Merge branch 'master' into lto 2022-05-25 11:55:13 +00:00
Eli Kogan-Wang e53349dd6e change priority conflict message 2022-05-16 16:16:06 +02:00
Eli Kogan-Wang be2b19041e Integrate review changes 2022-05-13 22:02:28 +02:00
Eli Kogan-Wang aefc6c4f41 Add priority for nix profile install 2022-05-11 12:16:35 +02:00
Eelco Dolstra 107613ad2b Fix compiler warning 2022-05-04 11:31:39 +02:00
Eelco Dolstra 3e87c8e62b Move json stuff out of util.cc 2022-05-04 11:22:06 +02:00
Alain Zscheile 1385b20078
Get rid of most .at calls (#6393)
Use one of `get` or `getOr` instead which will either return a null-pointer (with a nicer error message) or a default value when the key is missing.
2022-05-04 07:44:32 +02:00
Eelco Dolstra a3c6c5b1c7 nix profile: Support overriding outputs 2022-05-03 15:00:34 +02:00
Eelco Dolstra 4a79cba511 Allow selecting derivation outputs using 'installable!outputs'
E.g. 'nixpkgs#glibc^dev,static' or 'nixpkgs#glibc^*'.
2022-05-03 13:43:52 +02:00
Eelco Dolstra 70a30dbc00 Fix libcxx build
Fixes #6458.
2022-04-28 14:37:05 +02:00
Eelco Dolstra 4a9623b129 Fix passing $OUT_PATHS to the post-build hook
Fixes #6446.
2022-04-28 13:36:01 +02:00
Adam Joseph 49119072e7 local-derivation-goal.cc: seccomp filters for MIPS secondary arch/abi
A mips64el Linux MIPS kernel can execute userspace code using any of
three ABIs:

  mips64el-linux-*abin64
  mips64el-linux-*abin32
    mipsel-linux-*

The first of these is the native 64-bit ABI, and the only ABI with
64-bit pointers; this is sometimes called "n64".  The last of these is
the old legacy 32-bit ABI, whose binaries can execute natively on
32-bit MIPS hardware; this is sometimes called "o32".

The second ABI, "n32" is essentially the 64-bit ABI with 32-bit
pointers and address space.  Hardware 64-bit integer/floating
arithmetic is still allowed, as well as the much larger mips64
register set and more-efficient calling convention.

Let's enable seccomp filters for all of these.  Likewise for big
endian (mips64-linux-*).
2022-04-27 21:39:26 -07:00
pennae d6d6bbd9ef
Merge branch 'master' into lto 2022-04-25 14:02:37 +00:00
Eelco Dolstra ebad9213f7
Merge pull request #6431 from NixOS/unbreak-my-build
Make the default SQLiteError constructor public
2022-04-21 10:41:07 +02:00
Sergei Trofimovich 975b0b52e7 ca: add sqlite index on RealisationsRefs(realisationReference)
Without the change any CA deletion triggers linear scan on large
RealisationsRefs table:

    sqlite>.eqp full
    sqlite> delete from RealisationsRefs where realisationReference IN ( select id from Realisations where outputPath = 1234567890 );
    QUERY PLAN
    |--SCAN RealisationsRefs
    `--LIST SUBQUERY 1
       `--SEARCH Realisations USING COVERING INDEX IndexRealisationsRefsOnOutputPath (outputPath=?)

With the change it gets turned into a lookup:

    sqlite> CREATE INDEX IndexRealisationsRefsRealisationReference on RealisationsRefs(realisationReference);
    sqlite> delete from RealisationsRefs where realisationReference IN ( select id from Realisations where outputPath = 1234567890 );
    QUERY PLAN
    |--SEARCH RealisationsRefs USING INDEX IndexRealisationsRefsRealisationReference (realisationReference=?)
    `--LIST SUBQUERY 1
       `--SEARCH Realisations USING COVERING INDEX IndexRealisationsRefsOnOutputPath (outputPath=?)
2022-04-21 10:06:39 +02:00
regnat 86d7a11c6b Make sure to delete all the realisation refs
Deleting just one will only work in the test cases where I didn’t bother
creating too many of them :p
2022-04-21 10:06:39 +02:00
regnat 92656da0b9 Fix the gc with indirect self-references via the realisations
If the derivation `foo` depends on `bar`, and they both have the same
output path (because they are CA derivations), then this output path
will depend both on the realisation of `foo` and of `bar`, which
themselves depend on each other.
This confuses SQLite which isn’t able to automatically solve this
diamond dependency scheme.

Help it by adding a trigger to delete all the references between the
relevant realisations.

Fix #5320
2022-04-21 10:06:39 +02:00
Théophane Hufschmitt e7d79c7861 Make the default SQLiteError constructor public
Otherwise the clang builds fail because the constructor of `SQLiteBusy`
inherits it, `SQLiteError::_throw` tries to call it, which fails.

Strangely, gcc works fine with it. Not sure what the correct behavior is
and who is buggy here, but either way, making it public is at the worst
a reasonable workaround
2022-04-21 09:40:55 +02:00
John Ericson f63b0f4540 Actually, solve this in a lighter-weight way
The templating is very superficial
2022-04-20 17:37:59 +00:00
John Ericson 05ec0beb40 Move templated functions to sqlite-impl.hh
This ensures that use-sites properly trigger new monomorphisations on
one hand, and on the other hand keeps the main `sqlite.hh` clean and
interface-only. I think that is good practice in general, but in this
situation in particular we do indeed have `sqlite.hh` users that don't
need the `throw_` function.
2022-04-20 16:57:06 +00:00
John Ericson 3c220442ff Merge remote-tracking branch 'upstream/master' into fix-url-format 2022-04-20 16:53:16 +00:00
John Ericson 75b62e5260 Avoid fmt when constructor already does it
There is a correctnes issue here, but #3724 will fix that. This is just
a cleanup for brevity's sake.
2022-04-19 01:44:11 +00:00
Alex Ameen e5c934cd48
doc: rephrase connect-timeout help message
Co-authored-by: Cole Helbling <cole.e.helbling@outlook.com>
2022-04-17 18:17:37 -05:00
Alex Ameen 25c85f5a0e
doc: document nix.conf connect-timeout default 2022-04-17 17:14:38 -05:00
Sebastian Blunt 63d9a81819 Log builder args and environment variables
Previously it only logged the builder's path, this changes it to log the
arguments at the same log level, and the environment variables at the
vomit level.

This helped me debug https://github.com/svanderburg/node2nix/issues/75
2022-04-10 21:10:37 -07:00
Eelco Dolstra c68963eaea Remove duplicate "error:" 2022-04-08 11:48:30 +02:00
Eelco Dolstra 8bd9ebf52c Error: Remove unused sname() method 2022-04-08 11:31:51 +02:00
Eelco Dolstra 168ef9f3ab Remove unused Error.name field 2022-04-08 11:31:51 +02:00
Eelco Dolstra 318936366d Fix empty 'nix copy' error message
This was caused by SubstitutionGoal not setting the errorMsg field in
its BuildResult. We now get a more descriptive message than in 2.7.0, e.g.

  error: path '/nix/store/13mh...' is required, but there is no substituter that can build it

instead of the misleading (since there was no build)

  error: build of '/nix/store/13mh...' failed

Fixes #6295.
2022-04-06 12:43:53 +02:00