Dpkg::Control::Fields: Detangle Dpkg::Vendor

Move the bulk of the code into two new vendor-neutral Core sub-modules
Dpkg::Control::FieldsCore and Dpkg::Control::HashCore, that get
imported by Dpkg::Control::Fields and Dpkg::Control::Hash respectively;
so that modules like Dpkg::Control::HashCore can make use of
Dpkg::Control::FieldsCore w/o getting into a circular import due
to Dpkg::Vendor previously using Dpkg::Control::Hash.

The old dependency graph would have been:

  Control::Hash → Control::Fields
              ↑    ↓
              Vendor

The new one would be:

  Control::Hash → Control::Fields
  ↓               ↓   ↓
  ↓          Vendor   ↓
  ↓          ↓        ↓
  Control::HashCore → Control::FieldsCore

4 files changed, 1119 insertions, 1025 deletions

diff --git a/scripts/Dpkg/Control/Fields.pm b/scripts/Dpkg/Control/Fields.pm
index e7bd103b9..a3d9b74fe 100644
--- a/scripts/Dpkg/Control/Fields.pm
+++ b/scripts/Dpkg/Control/Fields.pm
@@ -21,319 +21,10 @@ use warnings;
 our $VERSION = '1.00';
 
 use Exporter qw(import);
-use Dpkg::Gettext;
-use Dpkg::ErrorHandling;
-use Dpkg::Control::Types;
-use Dpkg::Checksums;
+use Dpkg::Control::FieldsCore;
 use Dpkg::Vendor qw(run_vendor_hook);
 
-our @EXPORT = qw(field_capitalize field_is_official field_is_allowed_in
-                 field_transfer_single field_transfer_all
-                 field_list_src_dep field_list_pkg_dep field_get_dep_type
-                 field_ordered_list field_register
-                 field_insert_after field_insert_before);
-
-use constant {
-    ALL_PKG => CTRL_INFO_PKG | CTRL_INDEX_PKG | CTRL_PKG_DEB | CTRL_FILE_STATUS,
-    ALL_SRC => CTRL_INFO_SRC | CTRL_INDEX_SRC | CTRL_PKG_SRC,
-    ALL_CHANGES => CTRL_FILE_CHANGES | CTRL_CHANGELOG,
-};
-
-# The canonical list of fields
-
-# Note that fields used only in dpkg's available file are not listed
-# Deprecated fields of dpkg's status file are also not listed
-our %FIELDS = (
-    'Architecture' => {
-        allowed => (ALL_PKG | ALL_SRC | CTRL_FILE_CHANGES) & (~CTRL_INFO_SRC),
-    },
-    'Binary' => {
-        allowed => CTRL_PKG_SRC | CTRL_FILE_CHANGES,
-    },
-    'Binary-Only' => {
-        allowed => ALL_CHANGES,
-    },
-    'Breaks' => {
-        allowed => ALL_PKG,
-        dependency => 'union',
-        dep_order => 7,
-    },
-    'Bugs' => {
-        allowed => (ALL_PKG | CTRL_INFO_SRC | CTRL_FILE_VENDOR) & (~CTRL_INFO_PKG),
-    },
-    'Build-Conflicts' => {
-        allowed => ALL_SRC,
-        dependency => 'union',
-        dep_order => 4,
-    },
-    'Build-Conflicts-Arch' => {
-        allowed => ALL_SRC,
-        dependency => 'union',
-        dep_order => 5,
-    },
-    'Build-Conflicts-Indep' => {
-        allowed => ALL_SRC,
-        dependency => 'union',
-        dep_order => 6,
-    },
-    'Build-Depends' => {
-        allowed => ALL_SRC,
-        dependency => 'normal',
-        dep_order => 1,
-    },
-    'Build-Depends-Arch' => {
-        allowed => ALL_SRC,
-        dependency => 'normal',
-        dep_order => 2,
-    },
-    'Build-Depends-Indep' => {
-        allowed => ALL_SRC,
-        dependency => 'normal',
-        dep_order => 3,
-    },
-    'Built-Using' => {
-        allowed => ALL_PKG,
-        dependency => 'union',
-        dep_order => 10,
-    },
-    'Changed-By' => {
-        allowed => CTRL_FILE_CHANGES,
-    },
-    'Changes' => {
-        allowed => ALL_CHANGES,
-    },
-    'Closes' => {
-        allowed => ALL_CHANGES,
-    },
-    'Conffiles' => {
-        allowed => CTRL_FILE_STATUS,
-    },
-    'Config-Version' => {
-        allowed => CTRL_FILE_STATUS,
-    },
-    'Conflicts' => {
-        allowed => ALL_PKG,
-        dependency => 'union',
-        dep_order => 6,
-    },
-    'Date' => {
-        allowed => ALL_CHANGES,
-    },
-    'Depends' => {
-        allowed => ALL_PKG,
-        dependency => 'normal',
-        dep_order => 2,
-    },
-    'Description' => {
-        allowed => ALL_PKG | CTRL_FILE_CHANGES,
-    },
-    'Directory' => {
-        allowed => CTRL_INDEX_SRC,
-    },
-    'Distribution' => {
-        allowed => ALL_CHANGES,
-    },
-    'Enhances' => {
-        allowed => ALL_PKG,
-        dependency => 'union',
-        dep_order => 5,
-    },
-    'Essential' => {
-        allowed => ALL_PKG,
-    },
-    'Filename' => {
-        allowed => CTRL_INDEX_PKG,
-    },
-    'Files' => {
-        allowed => CTRL_PKG_SRC | CTRL_FILE_CHANGES,
-    },
-    'Format' => {
-        allowed => CTRL_PKG_SRC | CTRL_FILE_CHANGES,
-    },
-    'Homepage' => {
-        allowed => ALL_SRC | ALL_PKG,
-    },
-    'Installed-Size' => {
-        allowed => ALL_PKG & ~CTRL_INFO_PKG,
-    },
-    'Installer-Menu-Item' => {
-        allowed => ALL_PKG,
-    },
-    'Kernel-Version' => {
-        allowed => ALL_PKG,
-    },
-    'Origin' => {
-        allowed => (ALL_PKG | ALL_SRC) & (~CTRL_INFO_PKG),
-    },
-    'Maintainer' => {
-        allowed => CTRL_PKG_DEB | ALL_SRC | ALL_CHANGES,
-    },
-    'Multi-Arch' => {
-        allowed => ALL_PKG,
-    },
-    'Package' => {
-        allowed => ALL_PKG,
-    },
-    'Package-List' => {
-        allowed => ALL_SRC & ~CTRL_INFO_SRC,
-    },
-    'Package-Type' => {
-        allowed => ALL_PKG,
-    },
-    'Parent' => {
-        allowed => CTRL_FILE_VENDOR,
-    },
-    'Pre-Depends' => {
-        allowed => ALL_PKG,
-        dependency => 'normal',
-        dep_order => 1,
-    },
-    'Priority' => {
-        allowed => CTRL_INFO_SRC | CTRL_INDEX_SRC | ALL_PKG,
-    },
-    'Provides' => {
-        allowed => ALL_PKG,
-        dependency => 'union',
-        dep_order => 9,
-    },
-    'Recommends' => {
-        allowed => ALL_PKG,
-        dependency => 'normal',
-        dep_order => 3,
-    },
-    'Replaces' => {
-        allowed => ALL_PKG,
-        dependency => 'union',
-        dep_order => 8,
-    },
-    'Section' => {
-        allowed => CTRL_INFO_SRC | CTRL_INDEX_SRC | ALL_PKG,
-    },
-    'Size' => {
-        allowed => CTRL_INDEX_PKG,
-    },
-    'Source' => {
-        allowed => (ALL_PKG | ALL_SRC | ALL_CHANGES) &
-                   (~(CTRL_INDEX_SRC | CTRL_INFO_PKG)),
-    },
-    'Standards-Version' => {
-        allowed => ALL_SRC,
-    },
-    'Status' => {
-        allowed => CTRL_FILE_STATUS,
-    },
-    'Subarchitecture' => {
-        allowed => ALL_PKG,
-    },
-    'Suggests' => {
-        allowed => ALL_PKG,
-        dependency => 'normal',
-        dep_order => 4,
-    },
-    'Tag' => {
-        allowed => ALL_PKG,
-    },
-    'Task' => {
-        allowed => ALL_PKG,
-    },
-    'Triggers-Awaited' => {
-        allowed => CTRL_FILE_STATUS,
-    },
-    'Triggers-Pending' => {
-        allowed => CTRL_FILE_STATUS,
-    },
-    'Uploaders' => {
-        allowed => ALL_SRC,
-    },
-    'Urgency' => {
-        allowed => ALL_CHANGES,
-    },
-    'Vcs-Browser' => {
-        allowed => ALL_SRC,
-    },
-    'Vcs-Arch' => {
-        allowed => ALL_SRC,
-    },
-    'Vcs-Bzr' => {
-        allowed => ALL_SRC,
-    },
-    'Vcs-Cvs' => {
-        allowed => ALL_SRC,
-    },
-    'Vcs-Darcs' => {
-        allowed => ALL_SRC,
-    },
-    'Vcs-Git' => {
-        allowed => ALL_SRC,
-    },
-    'Vcs-Hg' => {
-        allowed => ALL_SRC,
-    },
-    'Vcs-Mtn' => {
-        allowed => ALL_SRC,
-    },
-    'Vcs-Svn' => {
-        allowed => ALL_SRC,
-    },
-    'Vendor' => {
-        allowed => CTRL_FILE_VENDOR,
-    },
-    'Vendor-Url' => {
-        allowed => CTRL_FILE_VENDOR,
-    },
-    'Version' => {
-        allowed => (ALL_PKG | ALL_SRC | ALL_CHANGES) &
-                    (~(CTRL_INFO_SRC | CTRL_INFO_PKG)),
-    },
-);
-
-my @checksum_fields = map { &field_capitalize("Checksums-$_") } checksums_get_list();
-my @sum_fields = map { $_ eq 'md5' ? 'MD5sum' : &field_capitalize($_) }
-                 checksums_get_list();
-&field_register($_, CTRL_PKG_SRC | CTRL_FILE_CHANGES) foreach @checksum_fields;
-&field_register($_, CTRL_INDEX_PKG) foreach @sum_fields;
-
-our %FIELD_ORDER = (
-    CTRL_PKG_DEB() => [
-        qw(Package Package-Type Source Version Built-Using Kernel-Version
-        Architecture Subarchitecture Installer-Menu-Item Essential Origin Bugs
-        Maintainer Installed-Size), &field_list_pkg_dep(),
-        qw(Section Priority Multi-Arch Homepage Description Tag Task)
-    ],
-    CTRL_PKG_SRC() => [
-        qw(Format Source Binary Architecture Version Origin Maintainer
-        Uploaders Homepage Standards-Version Vcs-Browser
-        Vcs-Arch Vcs-Bzr Vcs-Cvs Vcs-Darcs Vcs-Git Vcs-Hg Vcs-Mtn
-        Vcs-Svn), &field_list_src_dep(), qw(Package-List),
-        @checksum_fields, qw(Files)
-    ],
-    CTRL_FILE_CHANGES() => [
-        qw(Format Date Source Binary Binary-Only Architecture Version
-        Distribution Urgency Maintainer Changed-By Description
-        Closes Changes),
-        @checksum_fields, qw(Files)
-    ],
-    CTRL_CHANGELOG() => [
-        qw(Source Binary-Only Version Distribution Urgency Maintainer
-        Date Closes Changes)
-    ],
-    CTRL_FILE_STATUS() => [ # Same as fieldinfos in lib/dpkg/parse.c
-        qw(Package Essential Status Priority Section Installed-Size Origin
-        Maintainer Bugs Architecture Multi-Arch Source Version Config-Version
-        Replaces Provides Depends Pre-Depends Recommends Suggests Breaks
-        Conflicts Enhances Conffiles Description Triggers-Pending
-        Triggers-Awaited)
-    ],
-);
-# Order for CTRL_INDEX_PKG is derived from CTRL_PKG_DEB
-$FIELD_ORDER{CTRL_INDEX_PKG()} = [ @{$FIELD_ORDER{CTRL_PKG_DEB()}} ];
-&field_insert_before(CTRL_INDEX_PKG, 'Section', 'Filename', 'Size', @sum_fields);
-# Order for CTRL_INDEX_SRC is derived from CTRL_PKG_SRC
-$FIELD_ORDER{CTRL_INDEX_SRC()} = [ @{$FIELD_ORDER{CTRL_PKG_SRC()}} ];
-@{$FIELD_ORDER{CTRL_INDEX_SRC()}} = map { $_ eq 'Source' ? 'Package' : $_ }
-                                  @{$FIELD_ORDER{CTRL_PKG_SRC()}};
-&field_insert_after(CTRL_INDEX_SRC, 'Version', 'Priority', 'Section');
-&field_insert_before(CTRL_INDEX_SRC, 'Checksums-Md5', 'Directory');
+our @EXPORT = @Dpkg::Control::FieldsCore::EXPORT;
 
 # Register vendor specifics fields
 foreach my $op (run_vendor_hook('register-custom-fields')) {
@@ -358,253 +49,10 @@ Dpkg::Control::Fields - manage (list of official) control fields
 
 =head1 DESCRIPTION
 
-The modules contains a list of fieldnames with associated meta-data explaining
-in which type of control information they are allowed. The types are the
-CTRL_* constants exported by Dpkg::Control.
-
-=head1 FUNCTIONS
-
-=over 4
-
-=item my $f = field_capitalize($field_name)
-
-Returns the field name properly capitalized. All characters are lowercase,
-except the first of each word (words are separated by a dash in field names).
-
-=cut
-
-sub field_capitalize($) {
-    my $field = lc(shift);
-    # Some special cases due to history
-    return 'MD5sum' if $field eq 'md5sum';
-    return uc($field) if checksums_is_supported($field);
-    # Generic case
-    return join '-', map { ucfirst } split /-/, $field;
-}
-
-=item field_is_official($fname)
-
-Returns true if the field is official and known.
-
-=cut
-
-sub field_is_official($) {
-    return exists $FIELDS{field_capitalize($_[0])};
-}
-
-=item field_is_allowed_in($fname, @types)
-
-Returns true (1) if the field $fname is allowed in all the types listed in
-the list. Note that you can use type sets instead of individual types (ex:
-CTRL_FILE_CHANGES | CTRL_CHANGELOG).
-
-field_allowed_in(A|B, C) returns true only if the field is allowed in C
-and either A or B.
-
-Undef is returned for non-official fields.
-
-=cut
-
-sub field_is_allowed_in($@) {
-    my ($field, @types) = @_;
-    $field = field_capitalize($field);
-    return unless field_is_official($field);
-
-    return 0 if not scalar(@types);
-    foreach my $type (@types) {
-        next if $type == CTRL_UNKNOWN; # Always allowed
-        return 0 unless $FIELDS{$field}{allowed} & $type;
-    }
-    return 1;
-}
-
-=item field_transfer_single($from, $to, $field)
-
-If appropriate, copy the value of the field named $field taken from the
-$from Dpkg::Control object to the $to Dpkg::Control object.
-
-Official fields are copied only if the field is allowed in both types of
-objects. Custom fields are treated in a specific manner. When the target
-is not among CTRL_PKG_SRC, CTRL_PKG_DEB or CTRL_FILE_CHANGES, then they
-are alway copied as is (the X- prefix is kept). Otherwise they are not
-copied except if the target object matches the target destination encoded
-in the field name. The initial X denoting custom fields can be followed by
-one or more letters among "S" (Source: corresponds to CTRL_PKG_SRC), "B"
-(Binary: corresponds to CTRL_PKG_DEB) or "C" (Changes: corresponds to
-CTRL_FILE_CHANGES).
-
-Returns undef if nothing has been copied or the name of the new field
-added to $to otherwise.
-
-=cut
-
-sub field_transfer_single($$;$) {
-    my ($from, $to, $field) = @_;
-    $field //= $_;
-    my ($from_type, $to_type) = ($from->get_type(), $to->get_type());
-    $field = field_capitalize($field);
-
-    if (field_is_allowed_in($field, $from_type, $to_type)) {
-        $to->{$field} = $from->{$field};
-        return $field;
-    } elsif ($field =~ /^X([SBC]*)-/i) {
-        my $dest = $1;
-        if (($dest =~ /B/i and $to_type == CTRL_PKG_DEB) or
-            ($dest =~ /S/i and $to_type == CTRL_PKG_SRC) or
-            ($dest =~ /C/i and $to_type == CTRL_FILE_CHANGES))
-        {
-            my $new = $field;
-            $new =~ s/^X([SBC]*)-//i;
-            $to->{$new} = $from->{$field};
-            return $new;
-        } elsif ($to_type != CTRL_PKG_DEB and
-		 $to_type != CTRL_PKG_SRC and
-		 $to_type != CTRL_FILE_CHANGES)
-	{
-	    $to->{$field} = $from->{$field};
-	    return $field;
-	}
-    } elsif (not field_is_allowed_in($field, $from_type)) {
-        warning(_g("unknown information field '%s' in input data in %s"),
-                $field, $from->get_option('name') || _g('control information'));
-    }
-    return;
-}
-
-=item field_transfer_all($from, $to)
-
-Transfer all appropriate fields from $from to $to. Calls
-field_transfer_single() on all fields available in $from.
-
-Returns the list of fields that have been added to $to.
-
-=cut
-
-sub field_transfer_all($$) {
-    my ($from, $to) = @_;
-    my (@res, $res);
-    foreach my $k (keys %$from) {
-        $res = field_transfer_single($from, $to, $k);
-        push @res, $res if $res and defined wantarray;
-    }
-    return @res;
-}
-
-=item field_ordered_list($type)
-
-Returns an ordered list of fields for a given type of control information.
-This list can be used to output the fields in a predictable order.
-The list might be empty for types where the order does not matter much.
-
-=cut
-
-sub field_ordered_list($) {
-    my ($type) = @_;
-    return @{$FIELD_ORDER{$type}} if exists $FIELD_ORDER{$type};
-    return ();
-}
-
-=item field_list_src_dep()
-
-List of fields that contains dependencies-like information in a source
-Debian package.
-
-=cut
-
-sub field_list_src_dep() {
-    my @list = sort {
-        $FIELDS{$a}{dep_order} <=> $FIELDS{$b}{dep_order}
-    } grep {
-        field_is_allowed_in($_, CTRL_PKG_SRC) and
-        exists $FIELDS{$_}{dependency}
-    } keys %FIELDS;
-    return @list;
-}
-
-=item field_list_pkg_dep()
-
-List of fields that contains dependencies-like information in a binary
-Debian package. The fields that express real dependencies are sorted from
-the stronger to the weaker.
-
-=cut
-
-sub field_list_pkg_dep() {
-    my @keys = keys %FIELDS;
-    my @list = sort {
-        $FIELDS{$a}{dep_order} <=> $FIELDS{$b}{dep_order}
-    } grep {
-        field_is_allowed_in($_, CTRL_PKG_DEB) and
-        exists $FIELDS{$_}{dependency}
-    } @keys;
-    return @list;
-}
-
-=item field_get_dep_type($field)
-
-Return the type of the dependency expressed by the given field. Can
-either be "normal" for a real dependency field (Pre-Depends, Depends, ...)
-or "union" for other relation fields sharing the same syntax (Conflicts,
-Breaks, ...). Returns undef for fields which are not dependencies.
-
-=cut
-
-sub field_get_dep_type($) {
-    my $field = field_capitalize($_[0]);
-    return unless field_is_official($field);
-    return $FIELDS{$field}{dependency} if exists $FIELDS{$field}{dependency};
-    return;
-}
-
-=item field_register($field, $allowed_types, %opts)
-
-Register a new field as being allowed in control information of specified
-types. %opts is optional
-
-=cut
-
-sub field_register($$;@) {
-    my ($field, $types, %opts) = @_;
-    $field = field_capitalize($field);
-    $FIELDS{$field} = {
-        allowed => $types,
-        %opts
-    };
-}
-
-=item field_insert_after($type, $ref, @fields)
-
-Place field after another one ($ref) in output of control information of
-type $type.
-
-=cut
-sub field_insert_after($$@) {
-    my ($type, $field, @fields) = @_;
-    return 0 if not exists $FIELD_ORDER{$type};
-    ($field, @fields) = map { field_capitalize($_) } ($field, @fields);
-    @{$FIELD_ORDER{$type}} = map {
-        ($_ eq $field) ? ($_, @fields) : $_
-    } @{$FIELD_ORDER{$type}};
-    return 1;
-}
-
-=item field_insert_before($type, $ref, @fields)
-
-Place field before another one ($ref) in output of control information of
-type $type.
-
-=cut
-sub field_insert_before($$@) {
-    my ($type, $field, @fields) = @_;
-    return 0 if not exists $FIELD_ORDER{$type};
-    ($field, @fields) = map { field_capitalize($_) } ($field, @fields);
-    @{$FIELD_ORDER{$type}} = map {
-        ($_ eq $field) ? (@fields, $_) : $_
-    } @{$FIELD_ORDER{$type}};
-    return 1;
-}
-
-=back
+The module contains a list of vendor-neutral and vendor-specific fieldnames
+with associated meta-data explaining in which type of control information
+they are allowed. The vendor-neutral fieldnames and all functions are
+inherited from Dpkg::Control::FieldsCore.
 
 =head1 AUTHOR
 
diff --git a/scripts/Dpkg/Control/FieldsCore.pm b/scripts/Dpkg/Control/FieldsCore.pm
new file mode 100644
index 000000000..1f34eaeed
--- /dev/null
+++ b/scripts/Dpkg/Control/FieldsCore.pm
@@ -0,0 +1,599 @@
+# Copyright © 2007-2009 Raphaël Hertzog <hertzog@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Dpkg::Control::FieldsCore;
+
+use strict;
+use warnings;
+
+our $VERSION = '1.00';
+
+use Exporter qw(import);
+use Dpkg::Gettext;
+use Dpkg::ErrorHandling;
+use Dpkg::Control::Types;
+use Dpkg::Checksums;
+
+our @EXPORT = qw(field_capitalize field_is_official field_is_allowed_in
+                 field_transfer_single field_transfer_all
+                 field_list_src_dep field_list_pkg_dep field_get_dep_type
+                 field_ordered_list field_register
+                 field_insert_after field_insert_before);
+
+use constant {
+    ALL_PKG => CTRL_INFO_PKG | CTRL_INDEX_PKG | CTRL_PKG_DEB | CTRL_FILE_STATUS,
+    ALL_SRC => CTRL_INFO_SRC | CTRL_INDEX_SRC | CTRL_PKG_SRC,
+    ALL_CHANGES => CTRL_FILE_CHANGES | CTRL_CHANGELOG,
+};
+
+# The canonical list of fields
+
+# Note that fields used only in dpkg's available file are not listed
+# Deprecated fields of dpkg's status file are also not listed
+our %FIELDS = (
+    'Architecture' => {
+        allowed => (ALL_PKG | ALL_SRC | CTRL_FILE_CHANGES) & (~CTRL_INFO_SRC),
+    },
+    'Binary' => {
+        allowed => CTRL_PKG_SRC | CTRL_FILE_CHANGES,
+    },
+    'Binary-Only' => {
+        allowed => ALL_CHANGES,
+    },
+    'Breaks' => {
+        allowed => ALL_PKG,
+        dependency => 'union',
+        dep_order => 7,
+    },
+    'Bugs' => {
+        allowed => (ALL_PKG | CTRL_INFO_SRC | CTRL_FILE_VENDOR) & (~CTRL_INFO_PKG),
+    },
+    'Build-Conflicts' => {
+        allowed => ALL_SRC,
+        dependency => 'union',
+        dep_order => 4,
+    },
+    'Build-Conflicts-Arch' => {
+        allowed => ALL_SRC,
+        dependency => 'union',
+        dep_order => 5,
+    },
+    'Build-Conflicts-Indep' => {
+        allowed => ALL_SRC,
+        dependency => 'union',
+        dep_order => 6,
+    },
+    'Build-Depends' => {
+        allowed => ALL_SRC,
+        dependency => 'normal',
+        dep_order => 1,
+    },
+    'Build-Depends-Arch' => {
+        allowed => ALL_SRC,
+        dependency => 'normal',
+        dep_order => 2,
+    },
+    'Build-Depends-Indep' => {
+        allowed => ALL_SRC,
+        dependency => 'normal',
+        dep_order => 3,
+    },
+    'Built-Using' => {
+        allowed => ALL_PKG,
+        dependency => 'union',
+        dep_order => 10,
+    },
+    'Changed-By' => {
+        allowed => CTRL_FILE_CHANGES,
+    },
+    'Changes' => {
+        allowed => ALL_CHANGES,
+    },
+    'Closes' => {
+        allowed => ALL_CHANGES,
+    },
+    'Conffiles' => {
+        allowed => CTRL_FILE_STATUS,
+    },
+    'Config-Version' => {
+        allowed => CTRL_FILE_STATUS,
+    },
+    'Conflicts' => {
+        allowed => ALL_PKG,
+        dependency => 'union',
+        dep_order => 6,
+    },
+    'Date' => {
+        allowed => ALL_CHANGES,
+    },
+    'Depends' => {
+        allowed => ALL_PKG,
+        dependency => 'normal',
+        dep_order => 2,
+    },
+    'Description' => {
+        allowed => ALL_PKG | CTRL_FILE_CHANGES,
+    },
+    'Directory' => {
+        allowed => CTRL_INDEX_SRC,
+    },
+    'Distribution' => {
+        allowed => ALL_CHANGES,
+    },
+    'Enhances' => {
+        allowed => ALL_PKG,
+        dependency => 'union',
+        dep_order => 5,
+    },
+    'Essential' => {
+        allowed => ALL_PKG,
+    },
+    'Filename' => {
+        allowed => CTRL_INDEX_PKG,
+    },
+    'Files' => {
+        allowed => CTRL_PKG_SRC | CTRL_FILE_CHANGES,
+    },
+    'Format' => {
+        allowed => CTRL_PKG_SRC | CTRL_FILE_CHANGES,
+    },
+    'Homepage' => {
+        allowed => ALL_SRC | ALL_PKG,
+    },
+    'Installed-Size' => {
+        allowed => ALL_PKG & ~CTRL_INFO_PKG,
+    },
+    'Installer-Menu-Item' => {
+        allowed => ALL_PKG,
+    },
+    'Kernel-Version' => {
+        allowed => ALL_PKG,
+    },
+    'Origin' => {
+        allowed => (ALL_PKG | ALL_SRC) & (~CTRL_INFO_PKG),
+    },
+    'Maintainer' => {
+        allowed => CTRL_PKG_DEB | ALL_SRC | ALL_CHANGES,
+    },
+    'Multi-Arch' => {
+        allowed => ALL_PKG,
+    },
+    'Package' => {
+        allowed => ALL_PKG,
+    },
+    'Package-List' => {
+        allowed => ALL_SRC & ~CTRL_INFO_SRC,
+    },
+    'Package-Type' => {
+        allowed => ALL_PKG,
+    },
+    'Parent' => {
+        allowed => CTRL_FILE_VENDOR,
+    },
+    'Pre-Depends' => {
+        allowed => ALL_PKG,
+        dependency => 'normal',
+        dep_order => 1,
+    },
+    'Priority' => {
+        allowed => CTRL_INFO_SRC | CTRL_INDEX_SRC | ALL_PKG,
+    },
+    'Provides' => {
+        allowed => ALL_PKG,
+        dependency => 'union',
+        dep_order => 9,
+    },
+    'Recommends' => {
+        allowed => ALL_PKG,
+        dependency => 'normal',
+        dep_order => 3,
+    },
+    'Replaces' => {
+        allowed => ALL_PKG,
+        dependency => 'union',
+        dep_order => 8,
+    },
+    'Section' => {
+        allowed => CTRL_INFO_SRC | CTRL_INDEX_SRC | ALL_PKG,
+    },
+    'Size' => {
+        allowed => CTRL_INDEX_PKG,
+    },
+    'Source' => {
+        allowed => (ALL_PKG | ALL_SRC | ALL_CHANGES) &
+                   (~(CTRL_INDEX_SRC | CTRL_INFO_PKG)),
+    },
+    'Standards-Version' => {
+        allowed => ALL_SRC,
+    },
+    'Status' => {
+        allowed => CTRL_FILE_STATUS,
+    },
+    'Subarchitecture' => {
+        allowed => ALL_PKG,
+    },
+    'Suggests' => {
+        allowed => ALL_PKG,
+        dependency => 'normal',
+        dep_order => 4,
+    },
+    'Tag' => {
+        allowed => ALL_PKG,
+    },
+    'Task' => {
+        allowed => ALL_PKG,
+    },
+    'Triggers-Awaited' => {
+        allowed => CTRL_FILE_STATUS,
+    },
+    'Triggers-Pending' => {
+        allowed => CTRL_FILE_STATUS,
+    },
+    'Uploaders' => {
+        allowed => ALL_SRC,
+    },
+    'Urgency' => {
+        allowed => ALL_CHANGES,
+    },
+    'Vcs-Browser' => {
+        allowed => ALL_SRC,
+    },
+    'Vcs-Arch' => {
+        allowed => ALL_SRC,
+    },
+    'Vcs-Bzr' => {
+        allowed => ALL_SRC,
+    },
+    'Vcs-Cvs' => {
+        allowed => ALL_SRC,
+    },
+    'Vcs-Darcs' => {
+        allowed => ALL_SRC,
+    },
+    'Vcs-Git' => {
+        allowed => ALL_SRC,
+    },
+    'Vcs-Hg' => {
+        allowed => ALL_SRC,
+    },
+    'Vcs-Mtn' => {
+        allowed => ALL_SRC,
+    },
+    'Vcs-Svn' => {
+        allowed => ALL_SRC,
+    },
+    'Vendor' => {
+        allowed => CTRL_FILE_VENDOR,
+    },
+    'Vendor-Url' => {
+        allowed => CTRL_FILE_VENDOR,
+    },
+    'Version' => {
+        allowed => (ALL_PKG | ALL_SRC | ALL_CHANGES) &
+                    (~(CTRL_INFO_SRC | CTRL_INFO_PKG)),
+    },
+);
+
+my @checksum_fields = map { &field_capitalize("Checksums-$_") } checksums_get_list();
+my @sum_fields = map { $_ eq 'md5' ? 'MD5sum' : &field_capitalize($_) }
+                 checksums_get_list();
+&field_register($_, CTRL_PKG_SRC | CTRL_FILE_CHANGES) foreach @checksum_fields;
+&field_register($_, CTRL_INDEX_PKG) foreach @sum_fields;
+
+our %FIELD_ORDER = (
+    CTRL_PKG_DEB() => [
+        qw(Package Package-Type Source Version Built-Using Kernel-Version
+        Architecture Subarchitecture Installer-Menu-Item Essential Origin Bugs
+        Maintainer Installed-Size), &field_list_pkg_dep(),
+        qw(Section Priority Multi-Arch Homepage Description Tag Task)
+    ],
+    CTRL_PKG_SRC() => [
+        qw(Format Source Binary Architecture Version Origin Maintainer
+        Uploaders Homepage Standards-Version Vcs-Browser
+        Vcs-Arch Vcs-Bzr Vcs-Cvs Vcs-Darcs Vcs-Git Vcs-Hg Vcs-Mtn
+        Vcs-Svn), &field_list_src_dep(), qw(Package-List),
+        @checksum_fields, qw(Files)
+    ],
+    CTRL_FILE_CHANGES() => [
+        qw(Format Date Source Binary Binary-Only Architecture Version
+        Distribution Urgency Maintainer Changed-By Description
+        Closes Changes),
+        @checksum_fields, qw(Files)
+    ],
+    CTRL_CHANGELOG() => [
+        qw(Source Binary-Only Version Distribution Urgency Maintainer
+        Date Closes Changes)
+    ],
+    CTRL_FILE_STATUS() => [ # Same as fieldinfos in lib/dpkg/parse.c
+        qw(Package Essential Status Priority Section Installed-Size Origin
+        Maintainer Bugs Architecture Multi-Arch Source Version Config-Version
+        Replaces Provides Depends Pre-Depends Recommends Suggests Breaks
+        Conflicts Enhances Conffiles Description Triggers-Pending
+        Triggers-Awaited)
+    ],
+);
+# Order for CTRL_INDEX_PKG is derived from CTRL_PKG_DEB
+$FIELD_ORDER{CTRL_INDEX_PKG()} = [ @{$FIELD_ORDER{CTRL_PKG_DEB()}} ];
+&field_insert_before(CTRL_INDEX_PKG, 'Section', 'Filename', 'Size', @sum_fields);
+# Order for CTRL_INDEX_SRC is derived from CTRL_PKG_SRC
+$FIELD_ORDER{CTRL_INDEX_SRC()} = [ @{$FIELD_ORDER{CTRL_PKG_SRC()}} ];
+@{$FIELD_ORDER{CTRL_INDEX_SRC()}} = map { $_ eq 'Source' ? 'Package' : $_ }
+                                  @{$FIELD_ORDER{CTRL_PKG_SRC()}};
+&field_insert_after(CTRL_INDEX_SRC, 'Version', 'Priority', 'Section');
+&field_insert_before(CTRL_INDEX_SRC, 'Checksums-Md5', 'Directory');
+
+=encoding utf8
+
+=head1 NAME
+
+Dpkg::Control::FieldsCore - manage (list of official) control fields
+
+=head1 DESCRIPTION
+
+The modules contains a list of fieldnames with associated meta-data explaining
+in which type of control information they are allowed. The types are the
+CTRL_* constants exported by Dpkg::Control.
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item my $f = field_capitalize($field_name)
+
+Returns the field name properly capitalized. All characters are lowercase,
+except the first of each word (words are separated by a dash in field names).
+
+=cut
+
+sub field_capitalize($) {
+    my $field = lc(shift);
+    # Some special cases due to history
+    return 'MD5sum' if $field eq 'md5sum';
+    return uc($field) if checksums_is_supported($field);
+    # Generic case
+    return join '-', map { ucfirst } split /-/, $field;
+}
+
+=item field_is_official($fname)
+
+Returns true if the field is official and known.
+
+=cut
+
+sub field_is_official($) {
+    return exists $FIELDS{field_capitalize($_[0])};
+}
+
+=item field_is_allowed_in($fname, @types)
+
+Returns true (1) if the field $fname is allowed in all the types listed in
+the list. Note that you can use type sets instead of individual types (ex:
+CTRL_FILE_CHANGES | CTRL_CHANGELOG).
+
+field_allowed_in(A|B, C) returns true only if the field is allowed in C
+and either A or B.
+
+Undef is returned for non-official fields.
+
+=cut
+
+sub field_is_allowed_in($@) {
+    my ($field, @types) = @_;
+    $field = field_capitalize($field);
+    return unless field_is_official($field);
+
+    return 0 if not scalar(@types);
+    foreach my $type (@types) {
+        next if $type == CTRL_UNKNOWN; # Always allowed
+        return 0 unless $FIELDS{$field}{allowed} & $type;
+    }
+    return 1;
+}
+
+=item field_transfer_single($from, $to, $field)
+
+If appropriate, copy the value of the field named $field taken from the
+$from Dpkg::Control object to the $to Dpkg::Control object.
+
+Official fields are copied only if the field is allowed in both types of
+objects. Custom fields are treated in a specific manner. When the target
+is not among CTRL_PKG_SRC, CTRL_PKG_DEB or CTRL_FILE_CHANGES, then they
+are alway copied as is (the X- prefix is kept). Otherwise they are not
+copied except if the target object matches the target destination encoded
+in the field name. The initial X denoting custom fields can be followed by
+one or more letters among "S" (Source: corresponds to CTRL_PKG_SRC), "B"
+(Binary: corresponds to CTRL_PKG_DEB) or "C" (Changes: corresponds to
+CTRL_FILE_CHANGES).
+
+Returns undef if nothing has been copied or the name of the new field
+added to $to otherwise.
+
+=cut
+
+sub field_transfer_single($$;$) {
+    my ($from, $to, $field) = @_;
+    $field //= $_;
+    my ($from_type, $to_type) = ($from->get_type(), $to->get_type());
+    $field = field_capitalize($field);
+
+    if (field_is_allowed_in($field, $from_type, $to_type)) {
+        $to->{$field} = $from->{$field};
+        return $field;
+    } elsif ($field =~ /^X([SBC]*)-/i) {
+        my $dest = $1;
+        if (($dest =~ /B/i and $to_type == CTRL_PKG_DEB) or
+            ($dest =~ /S/i and $to_type == CTRL_PKG_SRC) or
+            ($dest =~ /C/i and $to_type == CTRL_FILE_CHANGES))
+        {
+            my $new = $field;
+            $new =~ s/^X([SBC]*)-//i;
+            $to->{$new} = $from->{$field};
+            return $new;
+        } elsif ($to_type != CTRL_PKG_DEB and
+		 $to_type != CTRL_PKG_SRC and
+		 $to_type != CTRL_FILE_CHANGES)
+	{
+	    $to->{$field} = $from->{$field};
+	    return $field;
+	}
+    } elsif (not field_is_allowed_in($field, $from_type)) {
+        warning(_g("unknown information field '%s' in input data in %s"),
+                $field, $from->get_option('name') || _g('control information'));
+    }
+    return;
+}
+
+=item field_transfer_all($from, $to)
+
+Transfer all appropriate fields from $from to $to. Calls
+field_transfer_single() on all fields available in $from.
+
+Returns the list of fields that have been added to $to.
+
+=cut
+
+sub field_transfer_all($$) {
+    my ($from, $to) = @_;
+    my (@res, $res);
+    foreach my $k (keys %$from) {
+        $res = field_transfer_single($from, $to, $k);
+        push @res, $res if $res and defined wantarray;
+    }
+    return @res;
+}
+
+=item field_ordered_list($type)
+
+Returns an ordered list of fields for a given type of control information.
+This list can be used to output the fields in a predictable order.
+The list might be empty for types where the order does not matter much.
+
+=cut
+
+sub field_ordered_list($) {
+    my ($type) = @_;
+    return @{$FIELD_ORDER{$type}} if exists $FIELD_ORDER{$type};
+    return ();
+}
+
+=item field_list_src_dep()
+
+List of fields that contains dependencies-like information in a source
+Debian package.
+
+=cut
+
+sub field_list_src_dep() {
+    my @list = sort {
+        $FIELDS{$a}{dep_order} <=> $FIELDS{$b}{dep_order}
+    } grep {
+        field_is_allowed_in($_, CTRL_PKG_SRC) and
+        exists $FIELDS{$_}{dependency}
+    } keys %FIELDS;
+    return @list;
+}
+
+=item field_list_pkg_dep()
+
+List of fields that contains dependencies-like information in a binary
+Debian package. The fields that express real dependencies are sorted from
+the stronger to the weaker.
+
+=cut
+
+sub field_list_pkg_dep() {
+    my @keys = keys %FIELDS;
+    my @list = sort {
+        $FIELDS{$a}{dep_order} <=> $FIELDS{$b}{dep_order}
+    } grep {
+        field_is_allowed_in($_, CTRL_PKG_DEB) and
+        exists $FIELDS{$_}{dependency}
+    } @keys;
+    return @list;
+}
+
+=item field_get_dep_type($field)
+
+Return the type of the dependency expressed by the given field. Can
+either be "normal" for a real dependency field (Pre-Depends, Depends, ...)
+or "union" for other relation fields sharing the same syntax (Conflicts,
+Breaks, ...). Returns undef for fields which are not dependencies.
+
+=cut
+
+sub field_get_dep_type($) {
+    my $field = field_capitalize($_[0]);
+    return unless field_is_official($field);
+    return $FIELDS{$field}{dependency} if exists $FIELDS{$field}{dependency};
+    return;
+}
+
+=item field_register($field, $allowed_types, %opts)
+
+Register a new field as being allowed in control information of specified
+types. %opts is optional
+
+=cut
+
+sub field_register($$;@) {
+    my ($field, $types, %opts) = @_;
+    $field = field_capitalize($field);
+    $FIELDS{$field} = {
+        allowed => $types,
+        %opts
+    };
+}
+
+=item field_insert_after($type, $ref, @fields)
+
+Place field after another one ($ref) in output of control information of
+type $type.
+
+=cut
+sub field_insert_after($$@) {
+    my ($type, $field, @fields) = @_;
+    return 0 if not exists $FIELD_ORDER{$type};
+    ($field, @fields) = map { field_capitalize($_) } ($field, @fields);
+    @{$FIELD_ORDER{$type}} = map {
+        ($_ eq $field) ? ($_, @fields) : $_
+    } @{$FIELD_ORDER{$type}};
+    return 1;
+}
+
+=item field_insert_before($type, $ref, @fields)
+
+Place field before another one ($ref) in output of control information of
+type $type.
+
+=cut
+sub field_insert_before($$@) {
+    my ($type, $field, @fields) = @_;
+    return 0 if not exists $FIELD_ORDER{$type};
+    ($field, @fields) = map { field_capitalize($_) } ($field, @fields);
+    @{$FIELD_ORDER{$type}} = map {
+        ($_ eq $field) ? (@fields, $_) : $_
+    } @{$FIELD_ORDER{$type}};
+    return 1;
+}
+
+=back
+
+=head1 AUTHOR
+
+Raphaël Hertzog <hertzog@debian.org>.
+
+=cut
+
+1;
diff --git a/scripts/Dpkg/Control/Hash.pm b/scripts/Dpkg/Control/Hash.pm
index 59217ec56..d1a4f1889 100644
--- a/scripts/Dpkg/Control/Hash.pm
+++ b/scripts/Dpkg/Control/Hash.pm
@@ -22,17 +22,9 @@ our $VERSION = '1.00';
 
 use Dpkg::Gettext;
 use Dpkg::ErrorHandling;
+use Dpkg::Control::Fields; # Force execution of vendor hook.
 
-# This module must absolutely not use Dpkg::Control::Fields
-# it's used by other modules that are required to compile
-# Dpkg::Control::Fields itself (Dpkg::Vendor)
-# That's why field_capitalize is duplicated
-
-use parent qw(Dpkg::Interface::Storable);
-
-use overload
-    '%{}' => sub { ${$_[0]}->{fields} },
-    'eq' => sub { "$_[0]" eq "$_[1]" };
+use parent qw(Dpkg::Control::HashCore);
 
 =encoding utf8
 
@@ -42,463 +34,8 @@ Dpkg::Control::Hash - parse and manipulate a block of RFC822-like fields
 
 =head1 DESCRIPTION
 
-The Dpkg::Control::Hash object is a hash-like representation of a set of
-RFC822-like fields. The fields names are case insensitive and are always
-capitalized the same when output (see field_capitalize function in
-Dpkg::Control::Fields).
-The order in which fields have been set is remembered and is used
-to be able to dump back the same content. The output order can also be
-overridden if needed.
-
-You can store arbitrary values in the hash, they will always be properly
-escaped in the output to conform to the syntax of control files. This is
-relevant mainly for multilines values: while the first line is always output
-unchanged directly after the field name, supplementary lines are
-modified. Empty lines and lines containing only dots are prefixed with
-" ." (space + dot) while other lines are prefixed with a single space.
-
-During parsing, trailing spaces are stripped on all lines while leading
-spaces are stripped only on the first line of each field.
-
-=head1 FUNCTIONS
-
-=over 4
-
-=item my $c = Dpkg::Control::Hash->new(%opts)
-
-Creates a new object with the indicated options. Supported options
-are:
-
-=over 8
-
-=item allow_pgp
-
-Configures the parser to accept PGP signatures around the control
-information. Value can be 0 (default) or 1.
-
-=item allow_duplicate
-
-Configures the parser to allow duplicate fields in the control
-information. Value can be 0 (default) or 1.
-
-=item drop_empty
-
-Defines if empty fields are dropped during the output. Value can be 0
-(default) or 1.
-
-=item name
-
-The user friendly name of the information stored in the object. It might
-be used in some error messages or warnings. A default name might be set
-depending on the type.
-
-=back
-
-=cut
-
-sub new {
-    my ($this, %opts) = @_;
-    my $class = ref($this) || $this;
-
-    # Object is a scalar reference and not a hash ref to avoid
-    # infinite recursion due to overloading hash-derefencing
-    my $self = \{
-        in_order => [],
-        out_order => [],
-        allow_pgp => 0,
-        allow_duplicate => 0,
-        drop_empty => 0,
-    };
-    bless $self, $class;
-
-    $$self->{fields} = Dpkg::Control::Hash::Tie->new($self);
-
-    # Options set by the user override default values
-    $$self->{$_} = $opts{$_} foreach keys %opts;
-
-    return $self;
-}
-
-# There is naturally a circular reference between the tied hash and its
-# containing object. Happily, the extra layer of scalar reference can
-# be used to detect the destruction of the object and break the loop so
-# that everything gets garbage-collected.
-
-sub DESTROY {
-    my ($self) = @_;
-    delete $$self->{fields};
-}
-
-=item $c->set_options($option, %opts)
-
-Changes the value of one or more options.
-
-=cut
-
-sub set_options {
-    my ($self, %opts) = @_;
-    $$self->{$_} = $opts{$_} foreach keys %opts;
-}
-
-=item my $value = $c->get_option($option)
-
-Returns the value of the corresponding option.
-
-=cut
-
-sub get_option {
-    my ($self, $k) = @_;
-    return $$self->{$k};
-}
-
-=item $c->load($file)
-
-Parse the content of $file. Exits in case of errors. Returns true if some
-fields have been parsed.
-
-=item $c->parse($fh, $description)
-
-Parse a control file from the given filehandle. Exits in case of errors.
-$description is used to describe the filehandle, ideally it's a filename
-or a description of where the data comes from. It's used in error
-messages. Returns true if some fields have been parsed.
-
-=cut
-
-sub parse {
-    my ($self, $fh, $desc) = @_;
-
-    my $paraborder = 1;
-    my $parabody = 0;
-    my $cf; # Current field
-    my $expect_pgp_sig = 0;
-    my $pgp_signed = 0;
-
-    while (<$fh>) {
-	s/\s*\n$//;
-	next if (m/^$/ and $paraborder);
-	next if (m/^#/);
-	$paraborder = 0;
-	if (m/^(\S+?)\s*:\s*(.*)$/) {
-	    $parabody = 1;
-	    if (exists $self->{$1}) {
-		unless ($$self->{allow_duplicate}) {
-		    syntaxerr($desc, sprintf(_g('duplicate field %s found'), $1));
-		}
-	    }
-	    $self->{$1} = $2;
-	    $cf = $1;
-	} elsif (m/^\s(\s*\S.*)$/) {
-	    my $line = $1;
-	    unless (defined($cf)) {
-                syntaxerr($desc, _g('continued value line not in field'));
-            }
-	    if ($line =~ /^\.+$/) {
-		$line = substr $line, 1;
-	    }
-	    $self->{$cf} .= "\n$line";
-	} elsif (m/^-----BEGIN PGP SIGNED MESSAGE-----$/) {
-	    $expect_pgp_sig = 1;
-	    if ($$self->{allow_pgp} and not $parabody) {
-		# Skip PGP headers
-		while (<$fh>) {
-		    last if m/^\s*$/;
-		}
-	    } else {
-		syntaxerr($desc, _g('PGP signature not allowed here'));
-	    }
-	} elsif (m/^$/ || ($expect_pgp_sig && m/^-----BEGIN PGP SIGNATURE-----$/)) {
-	    if ($expect_pgp_sig) {
-		# Skip empty lines
-		$_ = <$fh> while defined($_) && $_ =~ /^\s*$/;
-		length($_) ||
-                    syntaxerr($desc, _g('expected PGP signature, found EOF ' .
-                                        'after blank line'));
-		s/\s*\n$//;
-		unless (m/^-----BEGIN PGP SIGNATURE-----$/) {
-		    syntaxerr($desc, sprintf(_g('expected PGP signature, ' .
-                                                "found something else \`%s'"), $_));
-                }
-		# Skip PGP signature
-		while (<$fh>) {
-		    s/\s*\n$//;
-		    last if m/^-----END PGP SIGNATURE-----$/;
-		}
-		unless (defined($_)) {
-                    syntaxerr($desc, _g('unfinished PGP signature'));
-                }
-		# This does not mean the signature is correct, that needs to
-		# be verified by gnupg.
-		$pgp_signed = 1;
-	    }
-	    last; # Finished parsing one block
-	} else {
-	    syntaxerr($desc,
-                      _g('line with unknown format (not field-colon-value)'));
-	}
-    }
-
-    if ($expect_pgp_sig and not $pgp_signed) {
-        syntaxerr($desc, _g('unfinished PGP signature'));
-    }
-
-    return defined($cf);
-}
-
-=item $c->find_custom_field($name)
-
-Scan the fields and look for a user specific field whose name matches the
-following regex: /X[SBC]*-$name/i. Return the name of the field found or
-undef if nothing has been found.
-
-=cut
-
-sub find_custom_field {
-    my ($self, $name) = @_;
-    foreach my $key (keys %$self) {
-        return $key if $key =~ /^X[SBC]*-\Q$name\E$/i;
-    }
-    return;
-}
-
-=item $c->get_custom_field($name)
-
-Identify a user field and retrieve its value.
-
-=cut
-
-sub get_custom_field {
-    my ($self, $name) = @_;
-    my $key = $self->find_custom_field($name);
-    return $self->{$key} if defined $key;
-    return;
-}
-
-=item $c->save($filename)
-
-Write the string representation of the control information to a
-file.
-
-=item my $str = $c->output()
-
-=item "$c"
-
-Get a string representation of the control information. The fields
-are sorted in the order in which they have been read or set except
-if the order has been overridden with set_output_order().
-
-=item $c->output($fh)
-
-Print the string representation of the control information to a
-filehandle.
-
-=cut
-
-sub output {
-    my ($self, $fh) = @_;
-    my $str = '';
-    my @keys;
-    if (@{$$self->{out_order}}) {
-        my $i = 1;
-        my $imp = {};
-        $imp->{$_} = $i++ foreach @{$$self->{out_order}};
-        @keys = sort {
-            if (defined $imp->{$a} && defined $imp->{$b}) {
-                $imp->{$a} <=> $imp->{$b};
-            } elsif (defined($imp->{$a})) {
-                -1;
-            } elsif (defined($imp->{$b})) {
-                1;
-            } else {
-                $a cmp $b;
-            }
-        } keys %$self;
-    } else {
-        @keys = @{$$self->{in_order}};
-    }
-
-    foreach my $key (@keys) {
-	if (exists $self->{$key}) {
-	    my $value = $self->{$key};
-            # Skip whitespace-only fields
-            next if $$self->{drop_empty} and $value !~ m/\S/;
-	    # Escape data to follow control file syntax
-	    my @lines = split(/\n/, $value);
-	    $value = (scalar @lines) ? shift @lines : '';
-	    foreach (@lines) {
-		s/\s+$//;
-		if (/^$/ or /^\.+$/) {
-		    $value .= "\n .$_";
-		} else {
-		    $value .= "\n $_";
-		}
-	    }
-	    # Print it out
-            if ($fh) {
-	        print $fh "$key: $value\n" ||
-                    syserr(_g('write error on control data'));
-            }
-	    $str .= "$key: $value\n" if defined wantarray;
-	}
-    }
-    return $str;
-}
-
-=item $c->set_output_order(@fields)
-
-Define the order in which fields will be displayed in the output() method.
-
-=cut
-
-sub set_output_order {
-    my ($self, @fields) = @_;
-
-    $$self->{out_order} = [@fields];
-}
-
-=item $c->apply_substvars($substvars)
-
-Update all fields by replacing the variables references with
-the corresponding value stored in the Dpkg::Substvars object.
-
-=cut
-
-sub apply_substvars {
-    my ($self, $substvars, %opts) = @_;
-
-    # Add substvars to refer to other fields
-    foreach my $f (keys %$self) {
-        $substvars->set_as_used("F:$f", $self->{$f});
-    }
-
-    foreach my $f (keys %$self) {
-        my $v = $substvars->substvars($self->{$f}, %opts);
-	if ($v ne $self->{$f}) {
-	    # If we replaced stuff, ensure we're not breaking
-	    # a dependency field by introducing empty lines, or multiple
-	    # commas
-	    $v =~ s/\n[ \t]*(\n|$)/$1/; # Drop empty/whitespace-only lines
-	    # TODO: do this only for dependency fields
-	    $v =~ s/,[\s,]*,/,/g;
-	    $v =~ s/^\s*,\s*//;
-	    $v =~ s/\s*,\s*$//;
-	}
-        $v =~ s/\$\{\}/\$/g; # XXX: what for?
-
-        $self->{$f} = $v;
-    }
-}
-
-package Dpkg::Control::Hash::Tie;
-
-# This object is used to tie a hash. It implements hash-like functions by
-# normalizing the name of fields received in keys (using
-# Dpkg::Control::Fields::field_capitalize). It also stores the order in
-# which fields have been added in order to be able to dump them in the
-# same order. But the order information is stored in a parent object of
-# type Dpkg::Control.
-
-use Dpkg::Checksums;
-
-use Tie::Hash;
-use parent -norequire, qw(Tie::ExtraHash);
-
-sub field_capitalize($) {
-    my $field = lc(shift);
-    # Some special cases due to history
-    return 'MD5sum' if $field eq 'md5sum';
-    return uc($field) if checksums_is_supported($field);
-    # Generic case
-    return join '-', map { ucfirst } split /-/, $field;
-}
-
-# $self->[0] is the real hash
-# $self->[1] is a reference to the hash contained by the parent object.
-# This reference bypasses the top-level scalar reference of a
-# Dpkg::Control::Hash, hence ensuring that that reference gets DESTROYed
-# properly.
-
-# Dpkg::Control::Hash->new($parent)
-#
-# Return a reference to a tied hash implementing storage of simple
-# "field: value" mapping as used in many Debian-specific files.
-
-sub new {
-    my $class = shift;
-    my $hash = {};
-    tie %{$hash}, $class, @_;
-    return $hash;
-}
-
-sub TIEHASH  {
-    my ($class, $parent) = @_;
-    die 'Parent object must be Dpkg::Control::Hash'
-        if not $parent->isa('Dpkg::Control::Hash');
-    return bless [ {}, $$parent ], $class;
-}
-
-sub FETCH {
-    my ($self, $key) = @_;
-    $key = lc($key);
-    return $self->[0]->{$key} if exists $self->[0]->{$key};
-    return;
-}
-
-sub STORE {
-    my ($self, $key, $value) = @_;
-    my $parent = $self->[1];
-    $key = lc($key);
-    if (not exists $self->[0]->{$key}) {
-	push @{$parent->{in_order}}, field_capitalize($key);
-    }
-    $self->[0]->{$key} = $value;
-}
-
-sub EXISTS {
-    my ($self, $key) = @_;
-    $key = lc($key);
-    return exists $self->[0]->{$key};
-}
-
-sub DELETE {
-    my ($self, $key) = @_;
-    my $parent = $self->[1];
-    my $in_order = $parent->{in_order};
-    $key = lc($key);
-    if (exists $self->[0]->{$key}) {
-	delete $self->[0]->{$key};
-	@$in_order = grep { lc($_) ne $key } @$in_order;
-	return 1;
-    } else {
-	return 0;
-    }
-}
-
-sub FIRSTKEY {
-    my $self = shift;
-    my $parent = $self->[1];
-    foreach (@{$parent->{in_order}}) {
-	return $_ if exists $self->[0]->{lc($_)};
-    }
-}
-
-sub NEXTKEY {
-    my ($self, $last) = @_;
-    my $parent = $self->[1];
-    my $found = 0;
-    foreach (@{$parent->{in_order}}) {
-	if ($found) {
-	    return $_ if exists $self->[0]->{lc($_)};
-	} else {
-	    $found = 1 if $_ eq $last;
-	}
-    }
-    return;
-}
-
-1;
-
-=back
+This module is just like Dpkg::Control::HashCore, with vendor-specific
+field knowledge.
 
 =head1 AUTHOR
 
diff --git a/scripts/Dpkg/Control/HashCore.pm b/scripts/Dpkg/Control/HashCore.pm
new file mode 100644
index 000000000..53d826f29
--- /dev/null
+++ b/scripts/Dpkg/Control/HashCore.pm
@@ -0,0 +1,510 @@
+# Copyright © 2007-2009 Raphaël Hertzog <hertzog@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Dpkg::Control::HashCore;
+
+use strict;
+use warnings;
+
+our $VERSION = '1.00';
+
+use Dpkg::Gettext;
+use Dpkg::ErrorHandling;
+
+# This module must absolutely not use Dpkg::Control::Fields
+# it's used by other modules that are required to compile
+# Dpkg::Control::Fields itself (Dpkg::Vendor)
+# That's why field_capitalize is duplicated
+
+use parent qw(Dpkg::Interface::Storable);
+
+use overload
+    '%{}' => sub { ${$_[0]}->{fields} },
+    'eq' => sub { "$_[0]" eq "$_[1]" };
+
+=encoding utf8
+
+=head1 NAME
+
+Dpkg::Control::HashCore - parse and manipulate a block of RFC822-like fields
+
+=head1 DESCRIPTION
+
+The Dpkg::Control::Hash object is a hash-like representation of a set of
+RFC822-like fields. The fields names are case insensitive and are always
+capitalized the same when output (see field_capitalize function in
+Dpkg::Control::Fields).
+The order in which fields have been set is remembered and is used
+to be able to dump back the same content. The output order can also be
+overridden if needed.
+
+You can store arbitrary values in the hash, they will always be properly
+escaped in the output to conform to the syntax of control files. This is
+relevant mainly for multilines values: while the first line is always output
+unchanged directly after the field name, supplementary lines are
+modified. Empty lines and lines containing only dots are prefixed with
+" ." (space + dot) while other lines are prefixed with a single space.
+
+During parsing, trailing spaces are stripped on all lines while leading
+spaces are stripped only on the first line of each field.
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item my $c = Dpkg::Control::Hash->new(%opts)
+
+Creates a new object with the indicated options. Supported options
+are:
+
+=over 8
+
+=item allow_pgp
+
+Configures the parser to accept PGP signatures around the control
+information. Value can be 0 (default) or 1.
+
+=item allow_duplicate
+
+Configures the parser to allow duplicate fields in the control
+information. Value can be 0 (default) or 1.
+
+=item drop_empty
+
+Defines if empty fields are dropped during the output. Value can be 0
+(default) or 1.
+
+=item name
+
+The user friendly name of the information stored in the object. It might
+be used in some error messages or warnings. A default name might be set
+depending on the type.
+
+=back
+
+=cut
+
+sub new {
+    my ($this, %opts) = @_;
+    my $class = ref($this) || $this;
+
+    # Object is a scalar reference and not a hash ref to avoid
+    # infinite recursion due to overloading hash-derefencing
+    my $self = \{
+        in_order => [],
+        out_order => [],
+        allow_pgp => 0,
+        allow_duplicate => 0,
+        drop_empty => 0,
+    };
+    bless $self, $class;
+
+    $$self->{fields} = Dpkg::Control::HashCore::Tie->new($self);
+
+    # Options set by the user override default values
+    $$self->{$_} = $opts{$_} foreach keys %opts;
+
+    return $self;
+}
+
+# There is naturally a circular reference between the tied hash and its
+# containing object. Happily, the extra layer of scalar reference can
+# be used to detect the destruction of the object and break the loop so
+# that everything gets garbage-collected.
+
+sub DESTROY {
+    my ($self) = @_;
+    delete $$self->{fields};
+}
+
+=item $c->set_options($option, %opts)
+
+Changes the value of one or more options.
+
+=cut
+
+sub set_options {
+    my ($self, %opts) = @_;
+    $$self->{$_} = $opts{$_} foreach keys %opts;
+}
+
+=item my $value = $c->get_option($option)
+
+Returns the value of the corresponding option.
+
+=cut
+
+sub get_option {
+    my ($self, $k) = @_;
+    return $$self->{$k};
+}
+
+=item $c->load($file)
+
+Parse the content of $file. Exits in case of errors. Returns true if some
+fields have been parsed.
+
+=item $c->parse($fh, $description)
+
+Parse a control file from the given filehandle. Exits in case of errors.
+$description is used to describe the filehandle, ideally it's a filename
+or a description of where the data comes from. It's used in error
+messages. Returns true if some fields have been parsed.
+
+=cut
+
+sub parse {
+    my ($self, $fh, $desc) = @_;
+
+    my $paraborder = 1;
+    my $parabody = 0;
+    my $cf; # Current field
+    my $expect_pgp_sig = 0;
+    my $pgp_signed = 0;
+
+    while (<$fh>) {
+	s/\s*\n$//;
+	next if (m/^$/ and $paraborder);
+	next if (m/^#/);
+	$paraborder = 0;
+	if (m/^(\S+?)\s*:\s*(.*)$/) {
+	    $parabody = 1;
+	    if (exists $self->{$1}) {
+		unless ($$self->{allow_duplicate}) {
+		    syntaxerr($desc, sprintf(_g('duplicate field %s found'), $1));
+		}
+	    }
+	    $self->{$1} = $2;
+	    $cf = $1;
+	} elsif (m/^\s(\s*\S.*)$/) {
+	    my $line = $1;
+	    unless (defined($cf)) {
+                syntaxerr($desc, _g('continued value line not in field'));
+            }
+	    if ($line =~ /^\.+$/) {
+		$line = substr $line, 1;
+	    }
+	    $self->{$cf} .= "\n$line";
+	} elsif (m/^-----BEGIN PGP SIGNED MESSAGE-----$/) {
+	    $expect_pgp_sig = 1;
+	    if ($$self->{allow_pgp} and not $parabody) {
+		# Skip PGP headers
+		while (<$fh>) {
+		    last if m/^\s*$/;
+		}
+	    } else {
+		syntaxerr($desc, _g('PGP signature not allowed here'));
+	    }
+	} elsif (m/^$/ || ($expect_pgp_sig && m/^-----BEGIN PGP SIGNATURE-----$/)) {
+	    if ($expect_pgp_sig) {
+		# Skip empty lines
+		$_ = <$fh> while defined($_) && $_ =~ /^\s*$/;
+		length($_) ||
+                    syntaxerr($desc, _g('expected PGP signature, found EOF ' .
+                                        'after blank line'));
+		s/\s*\n$//;
+		unless (m/^-----BEGIN PGP SIGNATURE-----$/) {
+		    syntaxerr($desc, sprintf(_g('expected PGP signature, ' .
+                                                "found something else \`%s'"), $_));
+                }
+		# Skip PGP signature
+		while (<$fh>) {
+		    s/\s*\n$//;
+		    last if m/^-----END PGP SIGNATURE-----$/;
+		}
+		unless (defined($_)) {
+                    syntaxerr($desc, _g('unfinished PGP signature'));
+                }
+		# This does not mean the signature is correct, that needs to
+		# be verified by gnupg.
+		$pgp_signed = 1;
+	    }
+	    last; # Finished parsing one block
+	} else {
+	    syntaxerr($desc,
+                      _g('line with unknown format (not field-colon-value)'));
+	}
+    }
+
+    if ($expect_pgp_sig and not $pgp_signed) {
+        syntaxerr($desc, _g('unfinished PGP signature'));
+    }
+
+    return defined($cf);
+}
+
+=item $c->find_custom_field($name)
+
+Scan the fields and look for a user specific field whose name matches the
+following regex: /X[SBC]*-$name/i. Return the name of the field found or
+undef if nothing has been found.
+
+=cut
+
+sub find_custom_field {
+    my ($self, $name) = @_;
+    foreach my $key (keys %$self) {
+        return $key if $key =~ /^X[SBC]*-\Q$name\E$/i;
+    }
+    return;
+}
+
+=item $c->get_custom_field($name)
+
+Identify a user field and retrieve its value.
+
+=cut
+
+sub get_custom_field {
+    my ($self, $name) = @_;
+    my $key = $self->find_custom_field($name);
+    return $self->{$key} if defined $key;
+    return;
+}
+
+=item $c->save($filename)
+
+Write the string representation of the control information to a
+file.
+
+=item my $str = $c->output()
+
+=item "$c"
+
+Get a string representation of the control information. The fields
+are sorted in the order in which they have been read or set except
+if the order has been overridden with set_output_order().
+
+=item $c->output($fh)
+
+Print the string representation of the control information to a
+filehandle.
+
+=cut
+
+sub output {
+    my ($self, $fh) = @_;
+    my $str = '';
+    my @keys;
+    if (@{$$self->{out_order}}) {
+        my $i = 1;
+        my $imp = {};
+        $imp->{$_} = $i++ foreach @{$$self->{out_order}};
+        @keys = sort {
+            if (defined $imp->{$a} && defined $imp->{$b}) {
+                $imp->{$a} <=> $imp->{$b};
+            } elsif (defined($imp->{$a})) {
+                -1;
+            } elsif (defined($imp->{$b})) {
+                1;
+            } else {
+                $a cmp $b;
+            }
+        } keys %$self;
+    } else {
+        @keys = @{$$self->{in_order}};
+    }
+
+    foreach my $key (@keys) {
+	if (exists $self->{$key}) {
+	    my $value = $self->{$key};
+            # Skip whitespace-only fields
+            next if $$self->{drop_empty} and $value !~ m/\S/;
+	    # Escape data to follow control file syntax
+	    my @lines = split(/\n/, $value);
+	    $value = (scalar @lines) ? shift @lines : '';
+	    foreach (@lines) {
+		s/\s+$//;
+		if (/^$/ or /^\.+$/) {
+		    $value .= "\n .$_";
+		} else {
+		    $value .= "\n $_";
+		}
+	    }
+	    # Print it out
+            if ($fh) {
+	        print $fh "$key: $value\n" ||
+                    syserr(_g('write error on control data'));
+            }
+	    $str .= "$key: $value\n" if defined wantarray;
+	}
+    }
+    return $str;
+}
+
+=item $c->set_output_order(@fields)
+
+Define the order in which fields will be displayed in the output() method.
+
+=cut
+
+sub set_output_order {
+    my ($self, @fields) = @_;
+
+    $$self->{out_order} = [@fields];
+}
+
+=item $c->apply_substvars($substvars)
+
+Update all fields by replacing the variables references with
+the corresponding value stored in the Dpkg::Substvars object.
+
+=cut
+
+sub apply_substvars {
+    my ($self, $substvars, %opts) = @_;
+
+    # Add substvars to refer to other fields
+    foreach my $f (keys %$self) {
+        $substvars->set_as_used("F:$f", $self->{$f});
+    }
+
+    foreach my $f (keys %$self) {
+        my $v = $substvars->substvars($self->{$f}, %opts);
+	if ($v ne $self->{$f}) {
+	    # If we replaced stuff, ensure we're not breaking
+	    # a dependency field by introducing empty lines, or multiple
+	    # commas
+	    $v =~ s/\n[ \t]*(\n|$)/$1/; # Drop empty/whitespace-only lines
+	    # TODO: do this only for dependency fields
+	    $v =~ s/,[\s,]*,/,/g;
+	    $v =~ s/^\s*,\s*//;
+	    $v =~ s/\s*,\s*$//;
+	}
+        $v =~ s/\$\{\}/\$/g; # XXX: what for?
+
+        $self->{$f} = $v;
+    }
+}
+
+package Dpkg::Control::HashCore::Tie;
+
+# This object is used to tie a hash. It implements hash-like functions by
+# normalizing the name of fields received in keys (using
+# Dpkg::Control::Fields::field_capitalize). It also stores the order in
+# which fields have been added in order to be able to dump them in the
+# same order. But the order information is stored in a parent object of
+# type Dpkg::Control.
+
+use Dpkg::Checksums;
+
+use Tie::Hash;
+use parent -norequire, qw(Tie::ExtraHash);
+
+sub field_capitalize($) {
+    my $field = lc(shift);
+    # Some special cases due to history
+    return 'MD5sum' if $field eq 'md5sum';
+    return uc($field) if checksums_is_supported($field);
+    # Generic case
+    return join '-', map { ucfirst } split /-/, $field;
+}
+
+# $self->[0] is the real hash
+# $self->[1] is a reference to the hash contained by the parent object.
+# This reference bypasses the top-level scalar reference of a
+# Dpkg::Control::Hash, hence ensuring that that reference gets DESTROYed
+# properly.
+
+# Dpkg::Control::Hash->new($parent)
+#
+# Return a reference to a tied hash implementing storage of simple
+# "field: value" mapping as used in many Debian-specific files.
+
+sub new {
+    my $class = shift;
+    my $hash = {};
+    tie %{$hash}, $class, @_;
+    return $hash;
+}
+
+sub TIEHASH  {
+    my ($class, $parent) = @_;
+    die 'Parent object must be Dpkg::Control::Hash'
+        if not $parent->isa('Dpkg::Control::HashCore') and
+           not $parent->isa('Dpkg::Control::Hash');
+    return bless [ {}, $$parent ], $class;
+}
+
+sub FETCH {
+    my ($self, $key) = @_;
+    $key = lc($key);
+    return $self->[0]->{$key} if exists $self->[0]->{$key};
+    return;
+}
+
+sub STORE {
+    my ($self, $key, $value) = @_;
+    my $parent = $self->[1];
+    $key = lc($key);
+    if (not exists $self->[0]->{$key}) {
+	push @{$parent->{in_order}}, field_capitalize($key);
+    }
+    $self->[0]->{$key} = $value;
+}
+
+sub EXISTS {
+    my ($self, $key) = @_;
+    $key = lc($key);
+    return exists $self->[0]->{$key};
+}
+
+sub DELETE {
+    my ($self, $key) = @_;
+    my $parent = $self->[1];
+    my $in_order = $parent->{in_order};
+    $key = lc($key);
+    if (exists $self->[0]->{$key}) {
+	delete $self->[0]->{$key};
+	@$in_order = grep { lc($_) ne $key } @$in_order;
+	return 1;
+    } else {
+	return 0;
+    }
+}
+
+sub FIRSTKEY {
+    my $self = shift;
+    my $parent = $self->[1];
+    foreach (@{$parent->{in_order}}) {
+	return $_ if exists $self->[0]->{lc($_)};
+    }
+}
+
+sub NEXTKEY {
+    my ($self, $last) = @_;
+    my $parent = $self->[1];
+    my $found = 0;
+    foreach (@{$parent->{in_order}}) {
+	if ($found) {
+	    return $_ if exists $self->[0]->{lc($_)};
+	} else {
+	    $found = 1 if $_ eq $last;
+	}
+    }
+    return;
+}
+
+1;
+
+=back
+
+=head1 AUTHOR
+
+Raphaël Hertzog <hertzog@debian.org>.
+
+=cut
+
+1;