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nixpkgs/pkgs/build-support/build-fhs-userenv/default.nix
Nikolay Amiantov 74107a7867 buildFHSEnv: refactor and simplify, drop buildFHSChrootEnv
This takes another approach at binding FHS directory structure. We
now bind-mount all the root filesystem to directory "/host" in the target tree.
From that we symlink all the directories into the tree if they do not already
exist in FHS structure.

This probably makes `CHROOTENV_EXTRA_BINDS` unnecessary -- its main usecase was
to add bound directories from the host to the sandbox, and we not just symlink
all of them. I plan to get some feedback on its usage and maybe deprecate it.

This also drops old `buildFHSChrootEnv` infrastructure. The main problem with it
is it's very difficult to unmount a recursive-bound directory when mount is not
sandboxed. This problem is a bug even without these changes -- if
you have for example `/home/alice` mounted to somewhere, you wouldn't see
it in `buildFHSChrootEnv` now. With the new directory structure, it's
impossible to use regular bind at all. After some tackling with this I realized
that the fix would be brittle and dangerous (if you don't unmount everything
clearly and proceed to removing the temporary directory, bye-bye fs!). It also
probably doesn't worth it because I haven't heard that someone actually uses it
for a long time, and `buildFHSUserEnv` should cover most cases while being much
more maintainable and safe for the end-user.
2016-06-07 04:06:35 +03:00

55 lines
1.5 KiB
Nix

{ callPackage, runCommand, lib, writeScript, stdenv, coreutils, ruby }:
let buildFHSEnv = callPackage ./env.nix { }; in
args@{ name, runScript ? "bash", extraBindMounts ? [], extraInstallCommands ? "", meta ? {}, passthru ? {}, ... }:
let
env = buildFHSEnv (removeAttrs args [ "runScript" "extraBindMounts" "extraInstallCommands" "meta" "passthru" ]);
# Sandboxing script
chroot-user = writeScript "chroot-user" ''
#! ${ruby}/bin/ruby
${builtins.readFile ./chroot-user.rb}
'';
init = run: writeScript "${name}-init" ''
#! ${stdenv.shell}
for i in ${env}/* /host/*; do
path="/''${i##*/}"
[ -e "$path" ] || ${coreutils}/bin/ln -s "$i" "$path"
done
[ -d "$1" ] && [ -r "$1" ] && cd "$1"
shift
source /etc/profile
exec ${run} "$@"
'';
in runCommand name {
inherit meta;
passthru = passthru // {
env = runCommand "${name}-shell-env" {
shellHook = ''
export CHROOTENV_EXTRA_BINDS="${lib.concatStringsSep ":" extraBindMounts}:$CHROOTENV_EXTRA_BINDS"
exec ${chroot-user} ${init "bash"} "$(pwd)"
'';
} ''
echo >&2 ""
echo >&2 "*** User chroot 'env' attributes are intended for interactive nix-shell sessions, not for building! ***"
echo >&2 ""
exit 1
'';
};
} ''
mkdir -p $out/bin
cat <<EOF >$out/bin/${name}
#! ${stdenv.shell}
export CHROOTENV_EXTRA_BINDS="${lib.concatStringsSep ":" extraBindMounts}:\$CHROOTENV_EXTRA_BINDS"
exec ${chroot-user} ${init runScript} "\$(pwd)" "\$@"
EOF
chmod +x $out/bin/${name}
${extraInstallCommands}
''