Setting the UNAME26 personality causes "uname" to return "2.6.x",
regardless of the kernel version. This improves determinism in
a few misbehaved packages.
Sometimes when doing "nix-build --run-env" you don't want all
dependencies to be built. For instance, if we want to do "--run-env"
on the "build" attribute in Hydra's release.nix (to get Hydra's build
environment), we don't want its "tarball" dependency to be built. So
we can do:
$ nix-build --run-env release.nix -A build --exclude 'hydra-tarball'
This will skip the dependency whose name matches the "hydra-tarball"
regular expression. The "--exclude" option can be repeated any number
of times.
Make the garbage collector more concurrent by deleting valid paths
outside the region where we're holding the global GC lock. This
should greatly reduce the time during which new builds are blocked,
since the deletion accounts for the vast majority of the time spent in
the GC.
To ensure that this is safe, the valid paths are invalidated and
renamed to some arbitrary path while we're holding the lock. This
ensures that we when we finally delete the path, it's not a (newly)
valid or locked path.
This command builds or fetches all dependencies of the given
derivation, then starts a shell with the environment variables from
the derivation. This shell also sources $stdenv/setup to initialise
the environment further.
The current directory is not changed. Thus this is a convenient way
to reproduce a build environment in an existing working tree.
Existing environment variables are left untouched (unless the
derivation overrides them). As a special hack, the original value of
$PATH is appended to the $PATH produced by $stdenv/setup.
Example session:
$ nix-build --run-env '<nixpkgs>' -A xterm
(the dependencies of xterm are built/fetched...)
$ tar xf $src
$ ./configure
$ make
$ emacs
(... hack source ...)
$ make
$ ./xterm
Ensuring that the tests work from the build tree requires a growing
number of nasty hacks. The tests also don't verify that the installed
Nix actually works. Thus, the tests now require "make install" to
have been run.
Nix now requires SQLite and bzip2 to be pre-installed. SQLite is
detected using pkg-config. We required DBD::SQLite anyway, so
depending on SQLite is not a big problem.
The --with-bzip2, --with-openssl and --with-sqlite flags are gone.
By moving the destructor object to libstore.so, it's also run when
download-using-manifests and nix-prefetch-url exit. This prevents
them from cluttering /nix/var/nix/temproots with stale files.
Not all SQLite builds have the function sqlite3_table_column_metadata.
We were only using it in a schema upgrade check for compatibility with
databases that were probably never seen in the wild. So remove it.
The variable ‘useChroot’ was not initialised properly. This caused
random failures if using the build hook. Seen on Mac OS X 10.7 with Clang.
Thanks to KolibriFX for finding this :-)
Chroots are initialised by hard-linking inputs from the Nix store to
the chroot. This doesn't work if the input has its immutable bit set,
because it's forbidden to create hard links to immutable files. So
temporarily clear the immutable bit when creating and destroying the
chroot.
Note that making regular files in the Nix store immutable isn't very
reliable, since the bit can easily become cleared: for instance, if we
run the garbage collector after running ‘nix-store --optimise’. So
maybe we should only make directories immutable.
I was bitten one time too many by Python modifying the Nix store by
creating *.pyc files when run as root. On Linux, we can prevent this
by setting the immutable bit on files and directories (as in ‘chattr
+i’). This isn't supported by all filesystems, so it's not an error
if setting the bit fails. The immutable bit is cleared by the garbage
collector before deleting a path. The only tricky aspect is in
optimiseStore(), since it's forbidden to create hard links to an
immutable file. Thus optimiseStore() temporarily clears the immutable
bit before creating the link.
directory. Previously in this situation we did add the Nix
expressions from the channel to allow installation from source, but
this doesn't work for binary-only channels and leads to confusing
error messages.
