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etc: remove obsolete directories

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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.
This commit is contained in:
Alexey Shmalko 2016-07-17 17:46:23 +03:00
parent 76e4164007
commit fe9cabedf0
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1 changed files with 37 additions and 0 deletions
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37
nixos/modules/system/etc/setup-etc.pl
View file

@ -22,6 +22,33 @@ sub atomicSymlink {
# 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
@ -63,6 +90,16 @@ sub link {
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") {