fe9cabedf0
This patch adds handling of a directory becoming a symlink in /etc. Before this patch, the directory wasn't removed and then symlinking failed, which caused directory not being updated at all. The idea for the patch goes to @abbradar at https://github.com/NixOS/nixpkgs/issues/16978#issuecomment-232921903: > A heuristic idea for this -- a function `isStatic :: Path -> Bool`: > > * if path `/etc/foo` is a file, return True iff it's a symlink to `/etc/static/foo`. > * if path is a directory, return True iff for all items in it `isStatic` is True. > > On any conflicts, if old path is static, it's safe to replace and/or > delete stale. Otherwise make a backup and notify the user via a > journal entry and console output. The only difference here -- it will not replace user configs. This also fixes https://github.com/NixOS/nixpkgs/issues/16978.
139 lines
3.7 KiB
Perl
139 lines
3.7 KiB
Perl
use strict;
|
||
use File::Find;
|
||
use File::Copy;
|
||
use File::Path;
|
||
use File::Basename;
|
||
use File::Slurp;
|
||
|
||
my $etc = $ARGV[0] or die;
|
||
my $static = "/etc/static";
|
||
|
||
sub atomicSymlink {
|
||
my ($source, $target) = @_;
|
||
my $tmp = "$target.tmp";
|
||
unlink $tmp;
|
||
symlink $source, $tmp or return 0;
|
||
rename $tmp, $target or return 0;
|
||
return 1;
|
||
}
|
||
|
||
|
||
# Atomically update /etc/static to point at the etc files of the
|
||
# current configuration.
|
||
atomicSymlink $etc, $static or die;
|
||
|
||
# Returns 1 if the argument points to the files in /etc/static. That
|
||
# means either argument is a symlink to a file in /etc/static or a
|
||
# directory with all children being static.
|
||
sub isStatic {
|
||
my $path = shift;
|
||
|
||
if (-l $path) {
|
||
my $target = readlink $path;
|
||
return substr($target, 0, length "/etc/static/") eq "/etc/static/";
|
||
}
|
||
|
||
if (-d $path) {
|
||
opendir DIR, "$path" or return 0;
|
||
my @names = readdir DIR or die;
|
||
closedir DIR;
|
||
|
||
foreach my $name (@names) {
|
||
next if $name eq "." || $name eq "..";
|
||
unless (isStatic("$path/$name")) {
|
||
return 0;
|
||
}
|
||
}
|
||
return 1;
|
||
}
|
||
|
||
return 0;
|
||
}
|
||
|
||
# Remove dangling symlinks that point to /etc/static. These are
|
||
# configuration files that existed in a previous configuration but not
|
||
# in the current one. For efficiency, don't look under /etc/nixos
|
||
# (where all the NixOS sources live).
|
||
sub cleanup {
|
||
if ($File::Find::name eq "/etc/nixos") {
|
||
$File::Find::prune = 1;
|
||
return;
|
||
}
|
||
if (-l $_) {
|
||
my $target = readlink $_;
|
||
if (substr($target, 0, length $static) eq $static) {
|
||
my $x = "/etc/static/" . substr($File::Find::name, length "/etc/");
|
||
unless (-l $x) {
|
||
print STDERR "removing obsolete symlink ‘$File::Find::name’...\n";
|
||
unlink "$_";
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
find(\&cleanup, "/etc");
|
||
|
||
|
||
# Use /etc/.clean to keep track of copied files.
|
||
my @oldCopied = read_file("/etc/.clean", chomp => 1, err_mode => 'quiet');
|
||
open CLEAN, ">>/etc/.clean";
|
||
|
||
|
||
# For every file in the etc tree, create a corresponding symlink in
|
||
# /etc to /etc/static. The indirection through /etc/static is to make
|
||
# switching to a new configuration somewhat more atomic.
|
||
my %created;
|
||
my @copied;
|
||
|
||
sub link {
|
||
my $fn = substr $File::Find::name, length($etc) + 1 or next;
|
||
my $target = "/etc/$fn";
|
||
File::Path::make_path(dirname $target);
|
||
$created{$fn} = 1;
|
||
|
||
# Rename doesn't work if target is directory.
|
||
if (-l $_ && -d $target) {
|
||
if (isStatic $target) {
|
||
rmtree $target or warn;
|
||
} else {
|
||
warn "$target directory contains user files. Symlinking may fail.";
|
||
}
|
||
}
|
||
|
||
if (-e "$_.mode") {
|
||
my $mode = read_file("$_.mode"); chomp $mode;
|
||
if ($mode eq "direct-symlink") {
|
||
atomicSymlink readlink("$static/$fn"), $target or warn;
|
||
} else {
|
||
my $uid = read_file("$_.uid"); chomp $uid;
|
||
my $gid = read_file("$_.gid"); chomp $gid;
|
||
copy "$static/$fn", "$target.tmp" or warn;
|
||
chown int($uid), int($gid), "$target.tmp" or warn;
|
||
chmod oct($mode), "$target.tmp" or warn;
|
||
rename "$target.tmp", $target or warn;
|
||
}
|
||
push @copied, $fn;
|
||
print CLEAN "$fn\n";
|
||
} elsif (-l "$_") {
|
||
atomicSymlink "$static/$fn", $target or warn;
|
||
}
|
||
}
|
||
|
||
find(\&link, $etc);
|
||
|
||
|
||
# Delete files that were copied in a previous version but not in the
|
||
# current.
|
||
foreach my $fn (@oldCopied) {
|
||
if (!defined $created{$fn}) {
|
||
$fn = "/etc/$fn";
|
||
print STDERR "removing obsolete file ‘$fn’...\n";
|
||
unlink "$fn";
|
||
}
|
||
}
|
||
|
||
|
||
# Rewrite /etc/.clean.
|
||
close CLEAN;
|
||
write_file("/etc/.clean", map { "$_\n" } @copied);
|