[config-package-dev] [PATCH] transform: let users pick local files as source

[Geoffrey Thomas]

On Sun, 11 Jun 2017, Luca Boccassi wrote:

> I have a use case where I would like to transform and displace a file
> shipped from the same upstream source, so that 2 binary packages (that
> conflict with each other) can be built from the same repository without
> having to keep local copies.
>
> The first check, dpkg-divert --truename, immediately fails if the path
> is not absolute. A simple patch is attached.

Hi Luca,

If I'm understanding you correctly, you have a single Debian source 
package that builds two binary packages that conflict with each other, and 
you want the second binary package to modify a file that's shipped in the 
first binary package. Is that correct?

If so, then you don't need config-package-dev at all. The idea of 
config-package-dev is to modify one file in some other package that's 
already installed on the system, to prevent updates to the original 
package from overwriting the modified version of the file, and to make 
sure the original version of the file goes back when the config package is 
uninstalled.

But if the two packages conflict, the second package will uninstall the 
first package, and the original file won't be present.

I think you can just do something like this:

## debian/control
Source: something
...

Package: package1
Conflicts: package2
...

Package: package2
Conflicts: package1
...

## debian/package1.install
usr/bin/something
etc/something.conf

## debian/package2.install
usr/bin/something

## debian/rules
%:
 	dh $@

override_dh_install:
 	dh_install
 	sed "s/foo/bar" < debian/tmp/etc/something.conf > debian/package2/etc/something.conf

which would put /usr/bin/something in both packages, the unmodified 
/etc/something.conf in the first package, and a modified one in the second 
package. And then config-package-dev isn't involved at all.

If you want to use config-package-dev's transform feature, you'd have 
package2 depend on package1, instead of conflicting with it, so that 
there's something for dpkg-divert to divert when the package is installed. 
But the above approach seems like it makes more sense to me for your use 
case. config-package-dev was designed for the use case of, e.g., shipping 
a config package for Firefox that doesn't require rebuilding the entire 
Firefox source. But if you _are_ the same source package as the package 
you're configuring, this concern doesn't apply and it seems simpler to 
build things the normal Debian way.

Let me know if I'm misunderstanding the use case, though! I think the 
patch looks fine, I just want to make sure this is the right thing to do.

-- 
Geoffrey Thomas
https://ldpreload.com
geofft at ldpreload.com

>
> Kind regards,
> Luca Boccassi
>
>
> From 15864748b3170217ed0665e3cc2716c1fdf6754c Mon Sep 17 00:00:00 2001
> From: Luca Boccassi <luca.boccassi at gmail.com>
> Date: Sun, 11 Jun 2017 16:29:49 +0100
> Subject: [PATCH] transform: let users pick local files as source
>
> In some case it's desirable to use a local file as the source of the
> transform operation. For example, an upstream file from the same
> repository that could be sourced at built time.
> Skip dpkg checks on the source file if it does not start with /
> ---
>  dh_configpackage | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/dh_configpackage b/dh_configpackage
> index 942766f..e76048c 100755
> --- a/dh_configpackage
> +++ b/dh_configpackage
> @@ -369,9 +369,13 @@ foreach my $package (@{$dh{DOPACKAGES}}) {
>          my $file = shift @$line;
>          $file =~ s|^/?|/|;
>          my $source;
> +        my $source_is_local = 0;
>          if (@$line[0] =~ /^</) {
>              $source = shift @$line;
>              $source =~ s/^<//;
> +            if ($source !~ m!^/!) {
> +                $source_is_local = 1;
> +            }
>          } else {
>              $source = displace_files_replace_name($package, $file, "");
>              if ($source eq $file) {
> @@ -386,7 +390,10 @@ foreach my $package (@{$dh{DOPACKAGES}}) {
>          #    chmod 0755, $rest;
>          #}
>  
> -        $source = check_file($source);
> +        # Let users use local files as input
> +        if (! $source_is_local) {
> +            $source = check_file($source);
> +        }
>          my $destdir = dirname("$tmp/$file");
>          if (! -d $destdir) {
>              doit("install", "-d", $destdir);
> -- 
> 2.11.0