This also moves the file handle into its own Sync object so we're not
holding the _state while acquiring the file lock. There was no real
deadlock risk here since locking a newly created file cannot block,
but it's still a bit nicer.
This has the same goal as b13fd4c58e81b2b2b0d72caa5ce80de861622610,but
achieves it in a different way in order to not break
`nix why-depends --derivation`.
In principle, this should avoid deadlocks where two instances of Nix are
holding a shared lock on big-lock and are both waiting to get an
exclusive lock.
However, it seems like `flock(2)` is supposed to do this automatically,
so it's not clear whether this is actually where the problem comes from.
This makes 'nix develop' set the Linux personality in the same way
that the actual build does, allowing a command like 'nix develop
nix#devShells.i686-linux.default' on x86_64-linux to work correctly.
Without this, the error is lost, and it makes for a hard to debug
situation. Also remove some of the busyness inside the sqlite_open_v2
args.
The errcode returned is not the extended one. The only way to make open
return an extended code, would be to add SQLITE_OPEN_EXRESCODE to the
flags. In the future it might be worth making this change,
which would also simplify the existing SQLiteError code.
This makes 'nix build' work on paths (which will be copied to the
store) and store paths (returned as is). E.g. the following flake
output attributes can be built using 'nix build .#foo':
foo = ./src;
foo = self.outPath;
foo = builtins.fetchTarball { ... };
foo = (builtins.fetchTree { .. }).outPath;
foo = builtins.fetchTree { .. } + "/README.md";
foo = builtins.storePath /nix/store/...;
Note that this is potentially risky, e.g.
foo = /.;
will cause Nix to try to copy the entire file system to the store.
What doesn't work yet:
foo = self;
foo = builtins.fetchTree { .. };
because we don't handle attrsets with an outPath attribute in it yet,
and
foo = builtins.storePath /nix/store/.../README.md;
since result symlinks have to point to a store path currently (rather
than a file inside a store path).
Fixes#7417.
They did not include the detailed error message, losing essential
information for troubleshooting.
Example message:
warning: creating statement 'insert or rplace into NARs(cache, hashPart, namePart, url, compression, fileHash, fileSize, narHash, narSize, refs, deriver, sigs, ca, timestamp, present) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 1)': at offset 10: SQL logic error, near "rplace": syntax error (in '/tmp/nix-shell.grQ6f7/nix-test/tests/binary-cache/test-home/.cache/nix/binary-cache-v6.sqlite')
It's not the best example; more important information will be in
the message for e.g. a constraint violation.
I don't see why this specific error is printed as a warning, but
that's for another commit.
Unsetting `build-users-group` (without `auto-allocate-uids` enabled)
gives the following error:
```
src/libstore/lock.cc:25: static std::unique_ptr<nix::UserLock> nix::SimpleUserLock::acquire(): Assertion `settings.buildUsersGroup != ""' failed.
```
Fix the logic in `useBuildUsers` and document the default value
for `build-users-group`.
This makes the position object used in exceptions abstract, with a
method getSource() to get the source code of the file in which the
error originated. This is needed for lazy trees because source files
don't necessarily exist in the filesystem, and we don't want to make
libutil depend on the InputAccessor type in libfetcher.
Make everything be in the form "while ..." (most things were already),
and in particular *don't* use other propositions that must go after or
before specific "while ..." clauses to make sense.
When debugging nix expressions the outermost trace tends to be more useful
than the innermost. It is therefore printed last to save developers from
scrolling.
We used to set enforceDeterminism to true in the settings (by default)
and thus did send a non-zero value over the wire. The value should
probably be ignored as it should only matter if nrRounds is non-zero
as well.
Having the old code here where the value is expected to be zero only
works with the same version of Nix where we are sending zero. We
should always test this against older Nix versions being client or
server as otherwise upgrade in larger networks might be a pain.
Fixes 8e0946e8df
Fix#6209
When trying to run `nix log <installable>`, try first to resolve the derivation pointed to
by `<installable>` as it is the resolved one that holds the build log.
This has a couple of shortcomings:
1. It’s expensive as it requires re-reading the derivation
2. It’s brittle because if the derivation doesn’t exist anymore or can’t
be resolved (which is the case if any one of its build inputs is missing),
then we can’t access the log anymore
However, I don’t think we can do better (at least not right now).
The alternatives I see are:
1. Copy the build log for the un-resolved derivation. But that means a
lot of duplication
2. Store the results of the resolving in the db. Which might be the best
long-term solution, but leads to a whole new class of potential
issues.
These only functioned if a very narrow combination of conditions held:
- The result path does not yet exist (--check did not result in
repeated builds), AND
- The result path is not available from any configured substituters, AND
- No remote builders that can build the path are available.
If any of these do not hold, a derivation would be built 0 or 1 times
regardless of the repeat option. Thus, remove it to avoid confusion.
The old way was not correct.
Here is an example:
```
$ nix-instantiate --eval --expr 'let x = a: throw "asdf"; in x 1' --show-trace
error: asdf
… while evaluating 'x'
at «string»:1:9:
1| let x = a: throw "asdf"; in x 1
| ^
… from call site
at «string»:1:29:
1| let x = a: throw "asdf"; in x 1
| ^
```
and yet also:
```
$ nix-instantiate --eval --expr 'let x = a: throw "asdf"; in x' --show-trace
<LAMBDA>
```
Here is the thing: in both cases we are evaluating `x`!
Nix is a higher-order languages, and functions are a sort of value. When
we write `x = a: ...`, `a: ...` is the expression that `x` is being
defined to be, and that is already a value. Therefore, we should *never*
get an trace that says "while evaluating `x`", because evaluating `a:
...` is *trival* and nothing happens during it!
What is actually happening here is we are applying `x` and evaluating
its *body* with arguments substituted for parameters. I think the
simplest way to say is just "while *calling* `x`", and so that is what I
changed it to.
Robert Hensing
Linus Heckemann
Jörg Thalheim