Some tools which consume the "nix print-dev-env" rc script (such as
"nix-direnv") are sensitive to the use of unbound variables. They use
"set -u".
The "nix print-dev-env" rc script initially unsets "shellHook", then
loads variables from the derivation, and then evaluates "shellHook".
However, most derivations don't have a "shellHook" attribute.
So users get the error "shellHook: unbound variable". This can be
demonstrated with the command:
nix print-dev-env nixpkgs#hello | bash -u
This commit changes the rc script to provide an empty fallback value
for the "shellHook" variable.
Closes: #7951#8253
It is entirely possible for the path to be an empty string and many
unit tests actually pass it as an empty string (e.g. both_roundrip or
turnsEmptyPathIntoCWD). In this case, without this patch, absPath will
perform a one-byte out-of-bounds access.
This was discovered while enabling the nix test suite on Alpine where
we compile all software with `-D_GLIBCXX_ASSERTIONS=1`, thus resulting
in a test failure on Alpine.
As discussed in the maintainer meeting on 2024-01-29.
Mainly this is to avoid a situation where the name is parsed and
treated as a file name, mostly to protect users.
.-* and ..-* are also considered invalid because they might strip
on that separator to remove versions. Doesn't really work, but that's
what we decided, and I won't argue with it, because .-* probably
doesn't seem to have a real world application anyway.
We do still permit a 1-character name that's just "-", which still
poses a similar risk in such a situation. We can't start disallowing
trailing -, because a non-zero number of users will need it and we've
seen how annoying and painful such a change is.
What matters most is preventing a situation where . or .. can be
injected, and to just get this done.
To quote the method doc:
Non-impure derivations can still behave impurely, to the degree permitted
by the sandbox. Hence why this method isn't `isPure`: impure derivations
are not the negation of pure derivations. Purity can not be ascertained
except by rather heavy tools.
The code works fine on macOS, but the default stack size we attempt to
set is larger than what my system will allow (Nix attempts to set the
stack size to 67108864, but the maximum allowed is 67092480), so I've
instead used the requested stack size or the maximum allowed, whichever
is smaller.
I've also added an error message if setting the stack size fails. It
looks like this:
> Failed to increase stack size from 8372224 to 67108864 (maximum
> allowed stack size: 67092480): Invalid argument
This extends the `error: cannot coerce a TYPE to a string` message
to print the value that could not be coerced. This helps with debugging
by making it easier to track down where the value is being produced
from, especially in errors with deep or unhelpful stack traces.
This is more conceptually correct (the order does not matter), and also
matches what Hydra already does.
(Nix and Hydra matching is needed for dedup
https://github.com/NixOS/hydra/issues/1164)
More invariants are enforced in the type, and less state needs to be
stored in the main sink itself. The method here is roughly that known as
"session types".
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This avoids split-on-whitespace errors:
- No more `bash -c` needed
- No more `shellEscape` needed
- `remote-program` ssh store setting also cleanly supports args (e.g.
`nix daemon`)
- `ssh` uses `--` to separate args for SSH from args for the command to
run.
and will help with Hydra dedup.
Some code taken from #6628.
Co-Authored-By: Alexander Bantyev <balsoft@balsoft.ru>
Low-hanging fruit in the spirit of #9753 and #9754 (means 9999years did
all the hard work already).
This basically prints out what was attempted to be called as function,
i.e.
map (import <nixpkgs> {}) [ 1 2 3 ]
now gives the following error message:
error:
… while calling the 'map' builtin
at «string»:1:1:
1| map (import <nixpkgs> {}) [ 1 2 3 ]
| ^
… while evaluating the first argument passed to builtins.map
error: expected a function but found a set: { _type = "pkgs"; AAAAAASomeThingsFailToEvaluate = «thunk»; AMB-plugins = «thunk»; ArchiSteamFarm = «thunk»; BeatSaberModManager = «thunk»; CHOWTapeModel = «thunk»; ChowCentaur = «thunk»; ChowKick = «thunk»; ChowPhaser = «thunk»; CoinMP = «thunk»; «18783 attributes elided»}
Robert Hensing