This also bans various sneaking of negative numbers from the language
into unsuspecting builtins as was exposed while auditing the
consequences of changing the Nix language integer type to a newtype.
It's unlikely that this change comprehensively ensures correctness when
passing integers out of the Nix language and we should probably add a
checked-narrowing function or something similar, but that's out of scope
for the immediate change.
During the development of this I found a few fun facts about the
language:
- You could overflow integers by converting from unsigned JSON values.
- You could overflow unsigned integers by converting negative numbers
into them when going into Nix config, into fetchTree, and into flake
inputs.
The flake inputs and Nix config cannot actually be tested properly
since they both ban thunks, however, we put in checks anyway because
it's possible these could somehow be used to do such shenanigans some
other way.
Note that Lix has banned Nix language integer overflows since the very
first public beta, but threw a SIGILL about them because we run with
-fsanitize=signed-overflow -fsanitize-undefined-trap-on-error in
production builds. Since the Nix language uses signed integers, overflow
was simply undefined behaviour, and since we defined that to trap, it
did.
Trapping on it was a bad UX, but we didn't even entirely notice
that we had done this at all until it was reported as a bug a couple of
months later (which is, to be fair, that flag working as intended), and
it's got enough production time that, aside from code that is IMHO buggy
(and which is, in any case, not in nixpkgs) such as
https://git.lix.systems/lix-project/lix/issues/445, we don't think
anyone doing anything reasonable actually depends on wrapping overflow.
Even for weird use cases such as doing funny bit crimes, it doesn't make
sense IMO to have wrapping behaviour, since two's complement arithmetic
overflow behaviour is so *aggressively* not what you want for *any* kind
of mathematics/algorithms. The Nix language exists for package
management, a domain where bit crimes are already only dubiously in
scope to begin with, and it makes a lot more sense for that domain for
the integers to never lose precision, either by throwing errors if they
would, or by being arbitrary-precision.
Fixes: https://github.com/NixOS/nix/issues/10968
Original-CL: https://gerrit.lix.systems/c/lix/+/1596
Change-Id: I51f253840c4af2ea5422b8a420aa5fafbf8fae75
Few filesystem-related tests rely on PATH_MAX for buffers, and PATH_MAX
is optional in POSIX (and not available on the Hurd). To make them build
and pass, provide a fallback definition of PATH_MAX in case not
available.
Ideally speaking, the tests ought to not unconditionally rely on
PATH_MAX, do alternative strategies (e.g. dynamically allocate buffers,
expand them as needed, etc); OTOH this is test code, so it would be more
work that what it would be worth, so IMHO the define fallback is good
enough.
This should make the test more robust, considering the strange hang
in https://hydra.nixos.org/build/267517233/nixlog/8
`builder` seems to have reached `multi-user.target` before the
SSH connection was established, but this seems to be coincidental.
This does tell us that enforcing this has a minimal cost in terms
of runtime.
Waiting for `multi-user.target` on the client is honestly paranoid,
but flaky tests are very bad for productivity.
Trying to learn more about enigmatic spurious hang at
https://hydra.nixos.org/build/267517233/nixlog/8
- builder1 seems to have started properly
- ssh connection and session are established
- ssh client doesn't exit or client.succeed does not return
for some reason.
Seeing the stdout on the console might give a tiny bit more info.
Meson uses a venerable GNU convention described in
https://www.gnu.org/software/automake/manual/html_node/Scripts_002dbased-Testsuites.html
in which:
> When no test protocol is in use, an exit status of 0 from a test
> script will denote a success, an exit status of 77 a skipped test, an
> exit status of 99 a hard error, and any other exit status will denote
> a failure.
77 is thus what we want, not 99.
* fix NIX_PATH overriding
- test restricted evaluation
- test precedence for setting the search path
Co-authored-by: Robert Hensing <robert@roberthensing.nl>
Co-authored-by: John Ericson <git@JohnEricson.me>
... as well as match buildReadlineNoMarkdown.
Unfortunately it doesn't support long inputs or multiline inputs
for now.
This needs to make better use of the interacter interface.
Following what is outlined in #10766 refactor the uds-remote-store such
that the member variables (state) don't live in the store itself but in
the config object.
Additionally, the config object includes a new necessary constructor
that takes a scheme & authority.
Tests are commented out because of linking errors with the current config system.
When there is a new config system we can reenable them.
Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>
