vfork confers a large performance advantage over fork, measured locally
at 16µs per vfork agains 90µs per fork. however nix *almost always*
follows a vfork up with an execve-family call, melting the performance
advantage from 6x to only 15%. in most of those cases it's doing things
that are undefined behavior (like manipulating the heap, or even
throwing exceptions and trashing the parent process stack).
most notably the one place that could benefit from the vfork performance
improvement is linux derivation sandbox setup—which doesn't use vfork.
Change-Id: I2037b7384d5a4ca24da219a569e1b1f39531410e
These now have equivalents in the standard lib in C++20. This change was
performed with a custom clang-tidy check which I will submit later.
Executed like so:
ninja -C build && run-clang-tidy -checks='-*,nix-*' -load=build/libnix-clang-tidy.so -p .. -fix ../tests | tee -a clang-tidy-result
Change-Id: I62679e315ff9e7ce72a40b91b79c3e9fc01b27e9
absPath: Explicitly check if path is empty before accessing it
(cherry picked from commit 6ec08b85f607852eb6f976c1392c4917d0a53787)
Change-Id: Ieeb53fb65d0e334e6017ceb3a48b3b6ae1047843
Increase stack size on macOS as well as Linux
(cherry picked from commit efb91d5979a625d5c50558aeabfd24e802ed9173,
4a2444b3f32a2f5d42c4d65302793b987d1ac667)
Change-Id: Ieb72283c61bb9e360683f531d6635697b293c313
When reviewing old PRs, I found that #9997 adds some code to ensure one
particular assert is always present. But, removing asserts isn't
something we do in our own release builds either in the flake here or in
nixpkgs, and is plainly a bad idea that increases support burden,
especially if other distros make bad choices of build flags in their Nix
packaging.
For context, the assert macro in the C standard is defined to do nothing
if NDEBUG is set.
There is no way in our build system to set -DNDEBUG without manually
adding it to CFLAGS, so this is simply a configuration we do not use.
Let's ban it at compile time.
I put this preprocessor directive in src/libutil.cc because it is not
obvious where else to put it, and it seems like the most logical file
since you are not getting a usable nix without it.
Upstream-PR: https://github.com/NixOS/nix/pull/10126
Original-Change-Id: I513cceaac1371decb3d96231e6ef9181c910c218
Change-Id: I531a51f6348a746e8e41d88203b08f614898356c
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.
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.
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.
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.
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 $XDG_STATE_HOME is not set, it is assumed to be ~/.local/state.
Co-authored-by: Théophane Hufschmitt <7226587+thufschmitt@users.noreply.github.com>
Co-authored-by: Tim Fenney <kodekata@gmail.com>
Co-authored-by: pasqui23 <pasqui23@users.noreply.github.com>
Co-authored-by: Artturin <Artturin@artturin.com>
Co-authored-by: John Ericson <Ericson2314@Yahoo.com>
Rather than using `/nix/var/nix/{profiles,gcroots}/per-user/`, put the user
profiles and gcroots under `$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.
- call close explicitly in writeFile to prevent the close exception
from being ignored
- fsync after writing schema file to flush data to disk
- fsync schema file parent to flush metadata to disk
https://github.com/NixOS/nix/issues/7064
Rather than directly copying the source to its dest, copy it first to a
temporary location, and eventually move that temporary.
That way, the move is at least atomic from the point-of-view of the destination
Useful because a default `sudo` on darwin doesn't clear `$HOME`, so things like `sudo nix-channel --list`
will surprisingly return the USER'S channels, rather than `root`'s.
Other counterintuitive outcomes can be seen in this PR description:
https://github.com/NixOS/nix/pull/6622
