progress bar!

docker: move the docker file to https://github.com/NixOS/docker

We have automated builds at https://hub.docker.com/r/nixos/nix/ now. The master
branch of the "docker" repository is available as "latest". Branches that match
the regular expression "^[0-9.]+$" are pushed to the tag that corresponds to
their branch name. Other branches are ignored.

progress-bar: refresh occasionally even if no updates are received

release-common: prefer utillinuxMinimal to reduce compile-time deps

Slightly nicer behavior when updates are somewhat far apart
(during a long linking step, perhaps) ensuring things
don't appear unresponsive.

If we wait the maximum amount for the update,
don't bother waiting another 50ms (for rate-limiting purposes)
and just check if we should quit.

This also ensures we'll notice the request to quit within 1s
if quit is signalled but there is not an udpate.
(I'm not sure if this happens or not)

Honestly could probably use busybox here instead, but at least
with utillinuxMinimal there's no build-time dependency on systemd.

Fixes #2225.

libstore/gc.cc: ignore ESRCH when reading symlinks in /proc

readlink is also affected by the problem fixed for regular files in
c567afe355df

Fix optimise-store.cc to skip more paths on macOS

I hate to make this such a large check but the lack of documentation means we really have no idea what's allowed. All of them reported so far have been within ".app/Contents" directories. That appears to be a safe starting point. However, I would not be surprised to also find more paths that are disallowed for instance in .framework or .bundle directories.

Fixes #2031
Fixes #2229

This makes 'nix copy' and 'nix path-info' work on .drv store
paths. Removing special treatment of .drv files seems the most
future-proof approach given the possible removal of .drv files in the
future.

Note that 'nix build' will still build (rather than substitute) .drv
paths due to the unfortunate overloading in Store::buildPaths().

This makes 'nix copy --to /mnt /nix/store/bla.drv' work.

The former is removed in C++17.

EvalState contains a few counters (e.g. nrValues) that increase
quickly enough that they end up being interpreted as pointers by the
garbage collector. Moving it to the heap makes them invisible to the
garbage collector.

This reduces the max RSS doing 100 evaluations of
nixos.tests.firefox.x86_64-linux.drvPath from 455 MiB to 292 MiB.

Note: ideally, allocations would be much further up in the 64-bit
address space to reduce the odds of an integer being misinterpreted as
a pointer. Maybe we can use some linker magic to move the .bss segment
to a higher address.

This makes it possible to build with -DGC_DEBUG.

This reduces the risk of object liveness misdetection. For example,
Glibc has an internal variable "mp_" that often points to a Boehm
object, keeping it alive unnecessarily. Since we don't store any
actual roots in global variables, we can just disable data segment
scanning.

With this, the max RSS doing 100 evaluations of
nixos.tests.firefox.x86_64-linux.drvPath went from 718 MiB to 455 MiB.

This prevents EvalState::resetFileCache() from parsing everything all
over again.

Fix #2162: use getaddrinfo instead of curl to preload NSS

libstore/gc.cc: ignore ESRCH when reading /proc

If a process disappears between the time /proc/[pid]/maps is opened and
the time it is read, the read() syscall will return ESRCH. This should be ignored.

tests: more robust check for user namespaces availability (canUseSand…

manual: builtins.fromJSON: remove the claim that floats are not allowed

floating-point numbers are supported now, including the fromJSON
builtin. Reported on IRC by inquisitiv3

use debug instead of printTalkative to avoid spamming hydra queue-runner

runner logs.

Dockerfile: 2.0.4

Issue https://github.com/NixOS/nix/issues/2165