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10 commits

Author SHA1 Message Date
John Ericson
c11836126b Harden tests' bash
Use `set -u` and `set -o pipefail` to catch accidental mistakes and
failures more strongly.

 - `set -u` catches the use of undefined variables
 - `set -o pipefail` catches failures (like `set -e`) earlier in the
   pipeline.

This makes the tests a bit more robust. It is nice to read code not
worrying about these spurious success paths (via uncaught) errors
undermining the tests. Indeed, I caught some bugs doing this.

There are a few tests where we run a command that should fail, and then
search its output to make sure the failure message is one that we
expect. Before, since the `grep` was the last command in the pipeline
the exit code of those failing programs was silently ignored. Now with
`set -o pipefail` it won't be, and we have to do something so the
expected failure doesn't accidentally fail the test.

To do that we use `expect` and a new `expectStderr` to check for the
exact failing exit code. See the comments on each for why.

`grep -q` is replaced with `grepQuiet`, see the comments on that
function for why.

`grep -v` when we just want the exit code is replaced with `grepInverse,
see the comments on that function for why.

`grep -q -v` together is, surprise surprise, replaced with
`grepQuietInverse`, which is both combined.

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
2023-03-08 10:26:30 -05:00
Théophane Hufschmitt
983efdbde4 Forbid the tilde expansion in pure eval mode
Fix #6684
2022-06-21 14:08:18 +02:00
regnat
dc89dfa7b3 Properly return false on builtins.pathExists /someNonAllowedPath
Follow-up from https://github.com/NixOS/nix/pull/5807 to fix https://github.com/NixOS/nix/pull/5807#issuecomment-1000135394
2021-12-23 10:49:33 +01:00
regnat
c47027f3a1 Fix the error when accessing a forbidden path in pure eval
If we’re in pure eval mode, then tell that in the error message rather
than (wrongly) speaking about restricted mode.

Fix https://github.com/NixOS/nix/issues/5611
2021-11-25 14:48:01 +01:00
Eelco Dolstra
b2d6c6161e Move 'nix hash-*' and 'nix to-*' to 'nix hash'
From the 'nix' UX review.
2020-12-03 17:55:55 +01:00
Eelco Dolstra
df552a2645 nix eval: Add option to write a directory
This is useful for generating the nix manpages, but it may have other
applications (like generating configuration files without a Nix store).
2020-12-02 23:23:23 +01:00
Eelco Dolstra
ca8caaec5e nix: Add --expr flag
This replaces the '(...)' installable syntax, which is not very
discoverable. The downside is that you can't have multiple expressions
or mix expressions and other installables.
2019-11-27 00:05:30 +01:00
Eelco Dolstra
ee1254d4f5 nix: Add --impure as a shorter alias of --no-pure-eval 2019-04-08 23:19:19 +02:00
Eelco Dolstra
d2875f6782 Fix tests 2019-04-08 16:11:36 +02:00
Eelco Dolstra
d4dcffd643
Add pure evaluation mode
In this mode, the following restrictions apply:

* The builtins currentTime, currentSystem and storePath throw an
  error.

* $NIX_PATH and -I are ignored.

* fetchGit and fetchMercurial require a revision hash.

* fetchurl and fetchTarball require a sha256 attribute.

* No file system access is allowed outside of the paths returned by
  fetch{Git,Mercurial,url,Tarball}. Thus 'nix build -f ./foo.nix' is
  not allowed.

Thus, the evaluation result is completely reproducible from the
command line arguments. E.g.

  nix build --pure-eval '(
    let
      nix = fetchGit { url = https://github.com/NixOS/nixpkgs.git; rev = "9c927de4b179a6dd210dd88d34bda8af4b575680"; };
      nixpkgs = fetchGit { url = https://github.com/NixOS/nixpkgs.git; ref = "release-17.09"; rev = "66b4de79e3841530e6d9c6baf98702aa1f7124e4"; };
    in (import (nix + "/release.nix") { inherit nix nixpkgs; }).build.x86_64-linux
  )'

The goal is to enable completely reproducible and traceable
evaluation. For example, a NixOS configuration could be fully
described by a single Git commit hash. 'nixos-rebuild' would do
something like

  nix build --pure-eval '(
    (import (fetchGit { url = file:///my-nixos-config; rev = "..."; })).system
  ')

where the Git repository /my-nixos-config would use further fetchGit
calls or Git externals to fetch Nixpkgs and whatever other
dependencies it has. Either way, the commit hash would uniquely
identify the NixOS configuration and allow it to reproduced.
2018-01-16 19:23:18 +01:00