nixpkgs/modules/system/etc/setup-etc.pl
Eelco Dolstra ed1bc1e180 * Handle the case where a symlink in /etc needs to change into a
directory.  This happened with /etc/polkit-1, which used to be a
  symlink to /etc/static/polkit-1, which was itself a symlink but now
  is a directory.  Not handling this correctly led to /etc/static
  being clobbered with symlinks pointing to themselves.

svn path=/nixos/trunk/; revision=29061
2011-09-06 12:32:07 +00:00

69 lines
1.9 KiB
Perl
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

use strict;
use File::Find;
use File::Copy;
use File::Path;
use File::Basename;
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 1;
rename $tmp, $target or return 1;
return 1;
}
# Atomically update /etc/static to point at the etc files of the
# current configuration.
atomicSymlink $etc, $static or die;
# Remove dangling symlinks that point to /etc/static. These are
# configuration files that existed in a previous configuration but not
# in the current one. For efficiency, don't look under /etc/nixos
# (where all the NixOS sources live).
sub cleanup {
if ($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");
# 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.
sub link {
my $fn = substr $File::Find::name, length($etc) + 1 or next;
my $target = "/etc/$fn";
File::Path::make_path(dirname $target);
if (-e "$_.mode") {
open MODE, "<$_.mode";
my $mode = <MODE>; chomp $mode;
close MODE;
copy "$static/$fn", "$target.tmp" or warn;
chmod oct($mode), "$target.tmp" or warn;
rename "$target.tmp", $target or warn;
} elsif (-l "$_") {
atomicSymlink "$static/$fn", $target or warn;
}
}
find(\&link, $etc);