[pve-devel] [RFC PATCH storage] Plugins: en/decode notes as UTF-8

[Thomas Lamprecht]

On 08.03.22 15:41, Dominik Csapak wrote:
> When writing into the file, explicitly utf8 encode it, and then try to
> utf8 decode it on read.
> 
> If the notes are not valid utf8, we assume it was an iso-8859 comment
> and return is at is was.
> 
> Technically this is a breaking change, since there are iso-8859 comments
> that would sucessfully decode as utf8, for example:

s/sucessfully/successfully/

> the byte sequence "C2 A9" would be "£" in iso, but would decode to "£".
> 
> From what i can tell though, this is rather unlikely to happen for
> "real world" notes, because the first byte would be in the range of
> C0-F7 (which are mostly language dependent characters like "Â")
> and the following bytes would have to be in the range of
> 80-BF, which are only special characters like "£" (or undefined)

IMO a bit strange to trying to reason about free-form content that end user can
edit is hardly going to be right, but oh well you made it sound like really being
more of an edge case and I'd like to avoid versioning comment notes, so fine for me.

> 
> Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
> ---
> we may want to have this 'try_decode_utf8' in PVE::Tools i guess?
> i just put it here for the RFC, so its more easy to review

meh, it's hardly any complicated logic, just calling into Encode and falling
back, but yeah the version below makes it seem a bit bloated, you made a one
liner expand into 14 ^^

> 
>  PVE/Storage.pm           | 17 +++++++++++++++++
>  PVE/Storage/DirPlugin.pm |  9 +++++++--
>  PVE/Storage/Plugin.pm    |  2 +-
>  3 files changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/PVE/Storage.pm b/PVE/Storage.pm
> index b1d31bb..4335ee9 100755
> --- a/PVE/Storage.pm
> +++ b/PVE/Storage.pm
> @@ -14,6 +14,7 @@ use File::Path;
>  use Cwd 'abs_path';
>  use Socket;
>  use Time::Local qw(timelocal);
> +use Encode qw(decode);
>  
>  use PVE::Tools qw(run_command file_read_firstline dir_glob_foreach $IPV6RE);
>  use PVE::Cluster qw(cfs_read_file cfs_write_file cfs_lock_file);
> @@ -2077,4 +2078,20 @@ sub normalize_content_filename {
>      return $filename;
>  }
>  
> +sub try_decode_utf8 {
> +    my ($data) = @_;
> +
> +    my $decoded = eval {
> +	decode('UTF-8', $data, 1);
> +    };

assignment evals should to be in a single line if text width allows it

> +
> +    if (!defined($decoded)) {
> +	# we could not decode, it's probably iso-8859,
> +	# so return original value

please stop breaking up comments always that early

> +	return $data;
> +    }
> +
> +    return $decoded;
> +}
> +

In general, why not just inline it? The following would be just as good as the whole
14 line method here...

my $foo = eval { decode('UTF-8', $data, 1) } // $data;


And if we want it centrally, then we want a set/get_notes helper somewhere around
that does the note-exists check + encode stuff, but as all is very centrally for now
and churn is not /that/ likely I'd slightly favoring just in-lining it..

>  1;
> diff --git a/PVE/Storage/DirPlugin.pm b/PVE/Storage/DirPlugin.pm
> index c60818b..bc559e6 100644
> --- a/PVE/Storage/DirPlugin.pm
> +++ b/PVE/Storage/DirPlugin.pm
> @@ -7,6 +7,7 @@ use Cwd;
>  use File::Path;
>  use IO::File;
>  use POSIX;
> +use Encode qw(encode);
>  
>  use PVE::Storage::Plugin;
>  use PVE::JSONSchema qw(get_standard_option);
> @@ -103,7 +104,10 @@ sub get_volume_notes {
>      my $path = $class->filesystem_path($scfg, $volname);
>      $path .= $class->SUPER::NOTES_EXT;
>  
> -    return PVE::Tools::file_get_contents($path) if -f $path;
> +    if (-f $path) {
> +	my $data = PVE::Tools::file_get_contents($path);
> +	return PVE::Storage::try_decode_utf8($data);

return eval { decode('UTF-8', $data, 1) } // $data;

> +    }
>  
>      return '';
>  }
> @@ -120,7 +124,8 @@ sub update_volume_notes {
>      $path .= $class->SUPER::NOTES_EXT;
>  
>      if (defined($notes) && $notes ne '') {
> -	PVE::Tools::file_set_contents($path, $notes);
> +	my $encoded = encode('UTF-8', $notes);
> +	PVE::Tools::file_set_contents($path, $encoded);
>      } else {
>  	unlink $path or $! == ENOENT or die "could not delete notes - $!\n";
>      }
> diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
> index a6b0bdd..edec516 100644
> --- a/PVE/Storage/Plugin.pm
> +++ b/PVE/Storage/Plugin.pm
> @@ -1172,7 +1172,7 @@ my $get_subdir_files = sub {
>  	    my $notes_fn = $original.NOTES_EXT;
>  	    if (-f $notes_fn) {
>  		my $notes = PVE::Tools::file_read_firstline($notes_fn);
> -		$info->{notes} = $notes if defined($notes);
> +		$info->{notes} = PVE::Storage::try_decode_utf8($notes) if defined($notes);

$info->{notes} = eval { decode('UTF-8', $notes, 1) } // $notes if defined($notes)

>  	    }
>  
>  	    $info->{protected} = 1 if -e PVE::Storage::protection_file_path($original);