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make back /etc/static absolute symlink

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danbst 2019-01-23 22:19:50 +02:00
parent fc8e1745c0
commit f47bfce584
2 changed files with 27 additions and 14 deletions
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14
nixos/doc/manual/release-notes/rl-1903.xml
View file

@ -459,10 +459,16 @@
</listitem>
<listitem>
<para>
Symlinks in <filename>/etc</filename> are now relative instead of absolute,
so that the links can be followed if the NixOS installation is not mounted as filesystem root.
In particular, this makes <filename>/etc/os-release</filename> adhere to
<link xlink:href="https://www.freedesktop.org/software/systemd/man/os-release.html">the standard</link>.
Symlinks in <filename>/etc</filename> (except <filename>/etc/static</filename>)
are now relative instead of absolute. This makes possible to examine
NixOS container's <filename>/etc</filename> directory from host system
(previously it pointed to host <filename>/etc</filename> when viewed from host,
and to container <filename>/etc</filename> when viewed from container chroot).
</para>
<para>
This also makes <filename>/etc/os-release</filename> adhere to
<link xlink:href="https://www.freedesktop.org/software/systemd/man/os-release.html">the standard</link>
for NixOS containers.
</para>
</listitem>
<listitem>

27
nixos/modules/system/etc/setup-etc.pl
View file

@ -13,18 +13,26 @@ sub atomicSymlink {
my ($source, $target) = @_;
my $tmp = "$target.tmp";
unlink $tmp;
# Create relative symlinks, so that the links can be followed if
# the NixOS installation is not mounted as filesystem root.
# Absolute symlinks violate the os-release format
# at https://www.freedesktop.org/software/systemd/man/os-release.html
# and break e.g. systemd-nspawn and os-prober.
symlink $source, $tmp or return 0;
rename $tmp, $target or return 0;
return 1;
}
# Create relative symlinks, so that the links can be followed if
# the NixOS installation is not mounted as filesystem root.
# Absolute symlinks violate the os-release format
# at https://www.freedesktop.org/software/systemd/man/os-release.html
# and break e.g. systemd-nspawn and os-prober.
sub atomicRelativeSymlink {
my ($source, $target) = @_;
my $tmp = "$target.tmp";
unlink $tmp;
my $rel = File::Spec->abs2rel($source, dirname $target);
symlink $rel, $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;
@ -37,8 +45,7 @@ sub isStatic {
if (-l $path) {
my $target = readlink $path;
my $rel = File::Spec->abs2rel("/etc/static", dirname $path);
return substr($target, 0, length $rel) eq $rel;
return substr($target, 0, length "/etc/static/") eq "/etc/static/";
}
if (-d $path) {
@ -111,7 +118,7 @@ sub link {
if (-e "$_.mode") {
my $mode = read_file("$_.mode"); chomp $mode;
if ($mode eq "direct-symlink") {
atomicSymlink readlink("$static/$fn"), $target or warn;
atomicRelativeSymlink readlink("$static/$fn"), $target or warn;
} else {
my $uid = read_file("$_.uid"); chomp $uid;
my $gid = read_file("$_.gid"); chomp $gid;
@ -125,7 +132,7 @@ sub link {
push @copied, $fn;
print CLEAN "$fn\n";
} elsif (-l "$_") {
atomicSymlink "$static/$fn", $target or warn;
atomicRelativeSymlink "$static/$fn", $target or warn;
}
}