clan-infra/pkgs/writers.nix

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Nix
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2023-08-03 15:22:30 +00:00
{ lib
, bash
, coreutils
, gawk
, path
, # nixpkgs path
writeScript
, writeScriptBin
, ...
}:
let
# Create a script that runs in a `pure` environment, in the sense that:
# - the behavior is similar to `nix-shell --pure`
# - `PATH` only contains exactly the packages passed via the `PATH` arg
# - `NIX_PATH` is set to the path of the current `pkgs`
# - `TMPDIR` is set up and cleaned up even if the script fails
# - out, if set, is kept as-is
# - all environment variables are unset, except:
# - the ones listed in `keepVars` defined in ./default.nix
# - the ones listed via the `KEEP_VARS` variable
writePureShellScript = PATH: script:
writeScript "script.sh" (mkScript PATH script);
# Creates a script in a `bin/` directory in the output; suitable for use with `lib.makeBinPath`, etc.
# See {option}`writers.writePureShellScript`
writePureShellScriptBin = binName: PATH: script:
writeScriptBin binName (mkScript PATH script);
mkScript = PATH: scriptText: ''
#!${bash}/bin/bash
set -Eeuo pipefail
export PATH="${lib.makeBinPath PATH}"
export NIX_PATH=nixpkgs=${path}
export TMPDIR=$(${coreutils}/bin/mktemp -d)
trap "${coreutils}/bin/chmod -R +w '$TMPDIR'; ${coreutils}/bin/rm -rf '$TMPDIR'" EXIT
if [ -z "''${IMPURE:-}" ]; then
${cleanEnv}
fi
${scriptText}
'';
# list taken from nix source: src/nix-build/nix-build.cc
keepVars = lib.concatStringsSep " " [
"HOME"
"XDG_RUNTIME_DIR"
"USER"
"LOGNAME"
"DISPLAY"
"WAYLAND_DISPLAY"
"WAYLAND_SOCKET"
"PATH"
"TERM"
"IN_NIX_SHELL"
"NIX_SHELL_PRESERVE_PROMPT"
"TZ"
"PAGER"
"NIX_BUILD_SHELL"
"SHLVL"
"http_proxy"
"https_proxy"
"ftp_proxy"
"all_proxy"
"no_proxy"
# We want to keep our own variables as well
"out"
"IMPURE"
"KEEP_VARS"
"NIX_PATH"
"TMPDIR"
];
cleanEnv = ''
KEEP_VARS="''${KEEP_VARS:-}"
unsetVars=$(
${coreutils}/bin/comm \
<(${gawk}/bin/awk 'BEGIN{for(v in ENVIRON) print v}' | ${coreutils}/bin/cut -d = -f 1 | ${coreutils}/bin/sort) \
<(echo "${keepVars} $KEEP_VARS" | ${coreutils}/bin/tr " " "\n" | ${coreutils}/bin/sort) \
-2 \
-3
)
unset $unsetVars
'';
in
{
inherit
writePureShellScript
writePureShellScriptBin
;
}