scripts: Add GnuPG 2.x support

Add gnupg2 and gpgv2 as alternative Recommends to gnupg and gpgv (to
not pull them by default, as that would change the current default
build environment pulled in by dpkg-dev), but prefer gpgv2 over gpgv,
and gpg2 over gpg at run-time if they are available, so that users
installing the alternatives can benefit from the new implementations.

debian/changelog

@@ -97,6 +97,9 @@ dpkg (1.17.2) UNRELEASED; urgency=low
       @tar_ignore_default_pattern package variables.
     - Dpkg::Changelog::Entry::Debian: Deprecate $regex_header and
       $regex_trailer package variables.
+  * Add GnuPG 2.x support. Add gnupg2 and gpgv2 as alternative Recommends to
+    gnupg and gpgv (to not pull them by default), but prefer gpgv2 over gpgv,
+    and gpg2 over gpg at run-time if they are available.
 
   [ Updated programs translations ]
   * German (Sven Joachim).

debian/control

@@ -51,7 +51,8 @@ Architecture: all
 Multi-Arch: foreign
 Depends: libdpkg-perl (= ${source:Version}), bzip2, xz-utils,
  patch, make, binutils, base-files (>= 5.0.0), ${misc:Depends}
-Recommends: gcc | c-compiler, build-essential, fakeroot, gnupg, gpgv, libalgorithm-merge-perl
+Recommends: gcc | c-compiler, build-essential, fakeroot,
+ gnupg | gnupg2, gpgv | gpgv2, libalgorithm-merge-perl
 Suggests: debian-keyring
 Breaks: dpkg-cross (<< 2.0.0), devscripts (<< 2.10.26)
 Replaces: manpages-it (<< 2.80-4)
@@ -69,7 +70,8 @@ Architecture: all
 Multi-Arch: foreign
 Depends: dpkg (>= 1.15.8), perl, libtimedate-perl, ${misc:Depends}
 Recommends: libfile-fcntllock-perl, bzip2, xz-utils
-Suggests: debian-keyring, gnupg, gpgv, gcc | c-compiler, binutils, patch
+Suggests: debian-keyring, gnupg | gnupg2, gpgv | gpgv2,
+ gcc | c-compiler, binutils, patch
 Breaks: dpkg-dev (<< 1.15.6)
 Replaces: dpkg (<< 1.15.8), dpkg-dev (<< 1.15.6)
 Description: Dpkg perl modules

scripts/Dpkg/Source/Package.pm

@@ -370,8 +370,13 @@ sub check_signature {
     my ($self) = @_;
     my $dsc = $self->get_filename();
     my @exec;
-    if (find_command('gpgv')) {
+
+    if (find_command('gpgv2')) {
+        push @exec, 'gpgv2';
+    } elsif (find_command('gpgv')) {
         push @exec, 'gpgv';
+    } elsif (find_command('gpg2')) {
+        push @exec, 'gpg2', '--no-default-keyring', '-q', '--verify';
     } elsif (find_command('gpg')) {
         push @exec, 'gpg', '--no-default-keyring', '-q', '--verify';
     }

scripts/dpkg-buildpackage.pl

@@ -324,9 +324,12 @@ if (build_sourceonly) {
 
 if (!defined $signcommand &&
     (($ENV{GNUPGHOME} && -e $ENV{GNUPGHOME}) ||
-     ($ENV{HOME} && -e "$ENV{HOME}/.gnupg")) &&
-    find_command('gpg')) {
-    $signcommand = 'gpg';
+     ($ENV{HOME} && -e "$ENV{HOME}/.gnupg"))) {
+    if (find_command('gpg2')) {
+        $signcommand = 'gpg2';
+    } elsif (find_command('gpg')) {
+        $signcommand = 'gpg';
+    }
 }
 
 if (not $signcommand) {