pyrox.dev / nixpkgs
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etc: remove obsolete directories

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.

Alexey Shmalko fe9cabed 76e41640

options
unified split
Changed files
+37
nixos
modules
system
etc
setup-etc.pl
+37
nixos/modules/system/etc/setup-etc.pl 
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# current configuration.


     

       
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atomicSymlink $etc, $static or die;


     

       
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# Remove dangling symlinks that point to /etc/static.  These are


     

       
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# configuration files that existed in a previous configuration but not


     
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    my $target = "/etc/$fn";


     

       
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    File::Path::make_path(dirname $target);


     

       
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    $created{$fn} = 1;


     

       

       

       
     

       

       

       
     

       

       

       
     

       

       

       
     

       

       

       
     

       

       

       
     

       

       

       
     

       

       

       
     

       

       

       
     

       

       

       
     

       
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    if (-e "$_.mode") {


     

       
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        my $mode = read_file("$_.mode"); chomp $mode;


     

       
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        if ($mode eq "direct-symlink") {


     
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# current configuration.


     

       
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atomicSymlink $etc, $static or die;


     

       
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# Returns 1 if the argument points to the files in /etc/static.  That


     

       
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# means either argument is a symlink to a file in /etc/static or a


     

       
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# directory with all children being static.


     

       
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sub isStatic {


     

       
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    my $path = shift;


     

       
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    if (-l $path) {


     

       
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        my $target = readlink $path;


     

       
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        return substr($target, 0, length "/etc/static/") eq "/etc/static/";


     

       
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    }


     

       
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    if (-d $path) {


     

       
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        opendir DIR, "$path" or return 0;


     

       
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        my @names = readdir DIR or die;


     

       
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        closedir DIR;


     

       
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        foreach my $name (@names) {


     

       
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            next if $name eq "." || $name eq "..";


     

       
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            unless (isStatic("$path/$name")) {


     

       
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                return 0;


     

       
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            }


     

       
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        }


     

       
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        return 1;


     

       
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    }


     

       
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    return 0;


     

       
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}


     

       
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# Remove dangling symlinks that point to /etc/static.  These are


     

       
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# configuration files that existed in a previous configuration but not


     
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    my $target = "/etc/$fn";


     

       
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    File::Path::make_path(dirname $target);


     

       
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    $created{$fn} = 1;


     

       
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    # Rename doesn't work if target is directory.


     

       
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    if (-l $_ && -d $target) {


     

       
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        if (isStatic $target) {


     

       
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            rmtree $target or warn;


     

       
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        } else {


     

       
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            warn "$target directory contains user files. Symlinking may fail.";


     

       
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        }


     

       
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    }


     

       
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    if (-e "$_.mode") {


     

       
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        my $mode = read_file("$_.mode"); chomp $mode;


     

       
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        if ($mode eq "direct-symlink") {