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home-manager/modules/files.nix
Robert Helgesson f69816489d
home-manager: handle missing per-user profiles directory
Specifically, if the global per-user profiles path do not exist and we
cannot create it during the activation, then place our profile in the
Home Manager data directory. We prefer to use the global location,
though, since it makes it visible to `nix-collect-garbage`.

This is intended to improve compatibility with Nix version 2.14 and
later, which no longer creates the per-user directories.

Also, use the Home Manager data directory to manage the gcroot for the
current generation. It does not have to sit in the global per-user
gcroots directory since it should never be eligible for GC.
2023-03-07 23:53:06 +01:00

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{ pkgs, config, lib, ... }:
with lib;
let
cfg = filterAttrs (n: f: f.enable) config.home.file;
homeDirectory = config.home.homeDirectory;
fileType = (import lib/file-type.nix {
inherit homeDirectory lib pkgs;
}).fileType;
sourceStorePath = file:
let
sourcePath = toString file.source;
sourceName = config.lib.strings.storeFileName (baseNameOf sourcePath);
in
if builtins.hasContext sourcePath
then file.source
else builtins.path { path = file.source; name = sourceName; };
in
{
options = {
home.file = mkOption {
description = "Attribute set of files to link into the user home.";
default = {};
type = fileType "<envar>HOME</envar>" homeDirectory;
};
home-files = mkOption {
type = types.package;
internal = true;
description = "Package to contain all home files";
};
};
config = {
assertions = [(
let
dups =
attrNames
(filterAttrs (n: v: v > 1)
(foldAttrs (acc: v: acc + v) 0
(mapAttrsToList (n: v: { ${v.target} = 1; }) cfg)));
dupsStr = concatStringsSep ", " dups;
in {
assertion = dups == [];
message = ''
Conflicting managed target files: ${dupsStr}
This may happen, for example, if you have a configuration similar to
home.file = {
conflict1 = { source = ./foo.nix; target = "baz"; };
conflict2 = { source = ./bar.nix; target = "baz"; };
}'';
})
];
lib.file.mkOutOfStoreSymlink = path:
let
pathStr = toString path;
name = hm.strings.storeFileName (baseNameOf pathStr);
in
pkgs.runCommandLocal name {} ''ln -s ${escapeShellArg pathStr} $out'';
# This verifies that the links we are about to create will not
# overwrite an existing file.
home.activation.checkLinkTargets = hm.dag.entryBefore ["writeBoundary"] (
let
# Paths that should be forcibly overwritten by Home Manager.
# Caveat emptor!
forcedPaths =
concatMapStringsSep " " (p: ''"$HOME"/${escapeShellArg p}'')
(mapAttrsToList (n: v: v.target)
(filterAttrs (n: v: v.force) cfg));
check = pkgs.writeText "check" ''
${config.lib.bash.initHomeManagerLib}
# A symbolic link whose target path matches this pattern will be
# considered part of a Home Manager generation.
homeFilePattern="$(readlink -e ${escapeShellArg builtins.storeDir})/*-home-manager-files/*"
forcedPaths=(${forcedPaths})
newGenFiles="$1"
shift
for sourcePath in "$@" ; do
relativePath="''${sourcePath#$newGenFiles/}"
targetPath="$HOME/$relativePath"
forced=""
for forcedPath in "''${forcedPaths[@]}"; do
if [[ $targetPath == $forcedPath* ]]; then
forced="yeah"
break
fi
done
if [[ -n $forced ]]; then
$VERBOSE_ECHO "Skipping collision check for $targetPath"
elif [[ -e "$targetPath" \
&& ! "$(readlink "$targetPath")" == $homeFilePattern ]] ; then
# The target file already exists and it isn't a symlink owned by Home Manager.
if cmp -s "$sourcePath" "$targetPath"; then
# First compare the files' content. If they're equal, we're fine.
warnEcho "Existing file '$targetPath' is in the way of '$sourcePath', will be skipped since they are the same"
elif [[ ! -L "$targetPath" && -n "$HOME_MANAGER_BACKUP_EXT" ]] ; then
# Next, try to move the file to a backup location if configured and possible
backup="$targetPath.$HOME_MANAGER_BACKUP_EXT"
if [[ -e "$backup" ]]; then
errorEcho "Existing file '$backup' would be clobbered by backing up '$targetPath'"
collision=1
else
warnEcho "Existing file '$targetPath' is in the way of '$sourcePath', will be moved to '$backup'"
fi
else
# Fail if nothing else works
errorEcho "Existing file '$targetPath' is in the way of '$sourcePath'"
collision=1
fi
fi
done
if [[ -v collision ]] ; then
errorEcho "Please move the above files and try again or use 'home-manager switch -b backup' to back up existing files automatically."
exit 1
fi
'';
in
''
function checkNewGenCollision() {
local newGenFiles
newGenFiles="$(readlink -e "$newGenPath/home-files")"
find "$newGenFiles" \( -type f -or -type l \) \
-exec bash ${check} "$newGenFiles" {} +
}
checkNewGenCollision || exit 1
''
);
# This activation script will
#
# 1. Remove files from the old generation that are not in the new
# generation.
#
# 2. Switch over the Home Manager gcroot and current profile
# links.
#
# 3. Symlink files from the new generation into $HOME.
#
# This order is needed to ensure that we always know which links
# belong to which generation. Specifically, if we're moving from
# generation A to generation B having sets of home file links FA
# and FB, respectively then cleaning before linking produces state
# transitions similar to
#
# FA → FA ∩ FB → (FA ∩ FB) FB = FB
#
# and a failure during the intermediate state FA ∩ FB will not
# result in lost links because this set of links are in both the
# source and target generation.
home.activation.linkGeneration = hm.dag.entryAfter ["writeBoundary"] (
let
link = pkgs.writeShellScript "link" ''
newGenFiles="$1"
shift
for sourcePath in "$@" ; do
relativePath="''${sourcePath#$newGenFiles/}"
targetPath="$HOME/$relativePath"
if [[ -e "$targetPath" && ! -L "$targetPath" && -n "$HOME_MANAGER_BACKUP_EXT" ]] ; then
# The target exists, back it up
backup="$targetPath.$HOME_MANAGER_BACKUP_EXT"
$DRY_RUN_CMD mv $VERBOSE_ARG "$targetPath" "$backup" || errorEcho "Moving '$targetPath' failed!"
fi
if [[ -e "$targetPath" && ! -L "$targetPath" ]] && cmp -s "$sourcePath" "$targetPath" ; then
# The target exists but is identical don't do anything.
$VERBOSE_ECHO "Skipping '$targetPath' as it is identical to '$sourcePath'"
else
# Place that symlink, --force
# This can still fail if the target is a directory, in which case we bail out.
$DRY_RUN_CMD mkdir -p $VERBOSE_ARG "$(dirname "$targetPath")"
$DRY_RUN_CMD ln -Tsf $VERBOSE_ARG "$sourcePath" "$targetPath" || exit 1
fi
done
'';
cleanup = pkgs.writeShellScript "cleanup" ''
${config.lib.bash.initHomeManagerLib}
# A symbolic link whose target path matches this pattern will be
# considered part of a Home Manager generation.
homeFilePattern="$(readlink -e ${escapeShellArg builtins.storeDir})/*-home-manager-files/*"
newGenFiles="$1"
shift 1
for relativePath in "$@" ; do
targetPath="$HOME/$relativePath"
if [[ -e "$newGenFiles/$relativePath" ]] ; then
$VERBOSE_ECHO "Checking $targetPath: exists"
elif [[ ! "$(readlink "$targetPath")" == $homeFilePattern ]] ; then
warnEcho "Path '$targetPath' does not link into a Home Manager generation. Skipping delete."
else
$VERBOSE_ECHO "Checking $targetPath: gone (deleting)"
$DRY_RUN_CMD rm $VERBOSE_ARG "$targetPath"
# Recursively delete empty parent directories.
targetDir="$(dirname "$relativePath")"
if [[ "$targetDir" != "." ]] ; then
pushd "$HOME" > /dev/null
# Call rmdir with a relative path excluding $HOME.
# Otherwise, it might try to delete $HOME and exit
# with a permission error.
$DRY_RUN_CMD rmdir $VERBOSE_ARG \
-p --ignore-fail-on-non-empty \
"$targetDir"
popd > /dev/null
fi
fi
done
'';
in
''
function linkNewGen() {
_i "Creating home file links in %s" "$HOME"
local newGenFiles
newGenFiles="$(readlink -e "$newGenPath/home-files")"
find "$newGenFiles" \( -type f -or -type l \) \
-exec bash ${link} "$newGenFiles" {} +
}
function cleanOldGen() {
if [[ ! -v oldGenPath || ! -e "$oldGenPath/home-files" ]] ; then
return
fi
_i "Cleaning up orphan links from %s" "$HOME"
local newGenFiles oldGenFiles
newGenFiles="$(readlink -e "$newGenPath/home-files")"
oldGenFiles="$(readlink -e "$oldGenPath/home-files")"
# Apply the cleanup script on each leaf in the old
# generation. The find command below will print the
# relative path of the entry.
find "$oldGenFiles" '(' -type f -or -type l ')' -printf '%P\0' \
| xargs -0 bash ${cleanup} "$newGenFiles"
}
cleanOldGen
if [[ ! -v oldGenPath || "$oldGenPath" != "$newGenPath" ]] ; then
_i "Creating profile generation %s" $newGenNum
if [[ -e "$genProfilePath"/manifest.json ]] ; then
# Remove all packages from "$genProfilePath"
# `nix profile remove '.*' --profile "$genProfilePath"` was not working, so here is a workaround:
nix profile list --profile "$genProfilePath" \
| cut -d ' ' -f 4 \
| xargs -t $DRY_RUN_CMD nix profile remove $VERBOSE_ARG --profile "$genProfilePath"
$DRY_RUN_CMD nix profile install $VERBOSE_ARG --profile "$genProfilePath" "$newGenPath"
else
$DRY_RUN_CMD nix-env $VERBOSE_ARG --profile "$genProfilePath" --set "$newGenPath"
fi
$DRY_RUN_CMD nix-store --realise "$newGenPath" --add-root "$newGenGcPath" > "$DRY_RUN_NULL"
if [[ -e "$legacyGenGcPath" ]]; then
$DRY_RUN_CMD rm $VERBOSE_ARG "$legacyGenGcPath"
fi
else
_i "No change so reusing latest profile generation %s" "$oldGenNum"
fi
linkNewGen
''
);
home.activation.checkFilesChanged = hm.dag.entryBefore ["linkGeneration"] (
let
homeDirArg = escapeShellArg homeDirectory;
in ''
function _cmp() {
if [[ -d $1 && -d $2 ]]; then
diff -rq "$1" "$2" &> /dev/null
else
cmp --quiet "$1" "$2"
fi
}
declare -A changedFiles
'' + concatMapStrings (v:
let
sourceArg = escapeShellArg (sourceStorePath v);
targetArg = escapeShellArg v.target;
in ''
_cmp ${sourceArg} ${homeDirArg}/${targetArg} \
&& changedFiles[${targetArg}]=0 \
|| changedFiles[${targetArg}]=1
'') (filter (v: v.onChange != "") (attrValues cfg))
+ ''
unset -f _cmp
''
);
home.activation.onFilesChange = hm.dag.entryAfter ["linkGeneration"] (
concatMapStrings (v: ''
if (( ''${changedFiles[${escapeShellArg v.target}]} == 1 )); then
if [[ -v DRY_RUN || -v VERBOSE ]]; then
echo "Running onChange hook for" ${escapeShellArg v.target}
fi
if [[ ! -v DRY_RUN ]]; then
${v.onChange}
fi
fi
'') (filter (v: v.onChange != "") (attrValues cfg))
);
# Symlink directories and files that have the right execute bit.
# Copy files that need their execute bit changed.
home-files = pkgs.runCommandLocal
"home-manager-files"
{
nativeBuildInputs = [ pkgs.xorg.lndir ];
}
(''
mkdir -p $out
# Needed in case /nix is a symbolic link.
realOut="$(realpath -m "$out")"
function insertFile() {
local source="$1"
local relTarget="$2"
local executable="$3"
local recursive="$4"
# If the target already exists then we have a collision. Note, this
# should not happen due to the assertion found in the 'files' module.
# We therefore simply log the conflict and otherwise ignore it, mainly
# to make the `files-target-config` test work as expected.
if [[ -e "$realOut/$relTarget" ]]; then
echo "File conflict for file '$relTarget'" >&2
return
fi
# Figure out the real absolute path to the target.
local target
target="$(realpath -m "$realOut/$relTarget")"
# Target path must be within $HOME.
if [[ ! $target == $realOut* ]] ; then
echo "Error installing file '$relTarget' outside \$HOME" >&2
exit 1
fi
mkdir -p "$(dirname "$target")"
if [[ -d $source ]]; then
if [[ $recursive ]]; then
mkdir -p "$target"
lndir -silent "$source" "$target"
else
ln -s "$source" "$target"
fi
else
[[ -x $source ]] && isExecutable=1 || isExecutable=""
# Link the file into the home file directory if possible,
# i.e., if the executable bit of the source is the same we
# expect for the target. Otherwise, we copy the file and
# set the executable bit to the expected value.
if [[ $executable == inherit || $isExecutable == $executable ]]; then
ln -s "$source" "$target"
else
cp "$source" "$target"
if [[ $executable == inherit ]]; then
# Don't change file mode if it should match the source.
:
elif [[ $executable ]]; then
chmod +x "$target"
else
chmod -x "$target"
fi
fi
fi
}
'' + concatStrings (
mapAttrsToList (n: v: ''
insertFile ${
escapeShellArgs [
(sourceStorePath v)
v.target
(if v.executable == null
then "inherit"
else toString v.executable)
(toString v.recursive)
]}
'') cfg
));
};
}