Linux build: Use sysroot when calculating dependencies

third_party/dpkg-dev/scripts/dpkg-shlibdeps.pl

+#!/usr/bin/perl
+#
+# dpkg-shlibdeps
+#
+# Copyright © 1996 Ian Jackson
+# Copyright © 2000 Wichert Akkerman
+# Copyright © 2006 Frank Lichtenheld
+# Copyright © 2006-2010,2012-2013 Guillem Jover <guillem@debian.org>
+# Copyright © 2007 Raphaël Hertzog
+#
+# 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 <https://www.gnu.org/licenses/>.
+
+use strict;
+use warnings;
+
+use POSIX qw(:errno_h);
+use Cwd qw(realpath);
+use File::Basename qw(dirname);
+
+use Dpkg ();
+use Dpkg::Gettext;
+use Dpkg::ErrorHandling;
+use Dpkg::Util qw(:list);
+use Dpkg::Path qw(relative_to_pkg_root guess_pkg_root_dir
+  check_files_are_the_same get_control_path);
+use Dpkg::Version;
+use Dpkg::Shlibs qw(find_library get_library_paths);
+use Dpkg::Shlibs::Objdump;
+use Dpkg::Shlibs::SymbolFile;
+use Dpkg::Arch qw(get_host_arch);
+use Dpkg::Deps;
+use Dpkg::Control::Info;
+use Dpkg::Control::Fields;
+
+
+use constant {
+  WARN_SYM_NOT_FOUND => 1,
+  WARN_DEP_AVOIDABLE => 2,
+  WARN_NOT_NEEDED => 4,
+};
+
+# By increasing importance
+my @depfields = qw(Suggests Recommends Depends Pre-Depends);
+my $i = 0; my %depstrength = map { $_ => $i++ } @depfields;
+
+textdomain('dpkg-dev');
+
+my $admindir = $Dpkg::ADMINDIR;
+my $shlibsoverride = "$Dpkg::CONFDIR/shlibs.override";
+my $shlibsdefault = "$Dpkg::CONFDIR/shlibs.default";
+my $shlibslocal = 'debian/shlibs.local';
+my $packagetype = 'deb';
+my $dependencyfield = 'Depends';
+my $varlistfile = 'debian/substvars';
+my $varnameprefix = 'shlibs';
+my $ignore_missing_info = 0;
+my $warnings = 3;
+my $debug = 0;
+my @exclude = ();
+my @pkg_dir_to_search = ();
+my $host_arch = get_host_arch();
+
+my (@pkg_shlibs, @pkg_symbols, @pkg_root_dirs);
+if (-d 'debian') {
+  push @pkg_symbols, glob 'debian/*/DEBIAN/symbols';
+  push @pkg_shlibs, glob 'debian/*/DEBIAN/shlibs';
+  my %uniq = map { guess_pkg_root_dir($_) => 1 } (@pkg_symbols, @pkg_shlibs);
+  push @pkg_root_dirs, keys %uniq;
+}
+
+my ($stdout, %exec);
+foreach (@ARGV) {
+  if (m/^-T(.*)$/) {
+        $varlistfile = $1;
+  } elsif (m/^-p(\w[-:0-9A-Za-z]*)$/) {
+        $varnameprefix = $1;
+  } elsif (m/^-L(.*)$/) {
+        $shlibslocal = $1;
+  } elsif (m/^-l(.*)$/) {
+        Dpkg::Shlibs::add_library_dir($1);
+  } elsif (m/^-S(.*)$/) {
+        push @pkg_dir_to_search, $1;
+  } elsif (m/^-O$/) {
+        $stdout = 1;
+  } elsif (m/^-O(.+)$/) {
+        $varlistfile = $1;
+  } elsif (m/^-(\?|-help)$/) {
+        usage(); exit(0);
+  } elsif (m/^--version$/) {
+        version(); exit(0);
+  } elsif (m/^--admindir=(.*)$/) {
+        $admindir = $1;
+        if (not -d $admindir) {
+      error(_g("administrative directory '%s' does not exist"), $admindir);
+        }
+        $ENV{DPKG_ADMINDIR} = $admindir;
+  } elsif (m/^-d(.*)$/) {
+        $dependencyfield = field_capitalize($1);
+        if (not defined $depstrength{$dependencyfield}) {
+      warning(_g("unrecognized dependency field '%s'"), $dependencyfield);
+        }
+  } elsif (m/^-e(.*)$/) {
+        if (exists $exec{$1}) {
+      # Affect the binary to the most important field
+      if ($depstrength{$dependencyfield} > $depstrength{$exec{$1}}) {
+                $exec{$1} = $dependencyfield;
+      }
+        } else {
+      $exec{$1} = $dependencyfield;
+        }
+  } elsif (m/^--ignore-missing-info$/) {
+        $ignore_missing_info = 1;
+  } elsif (m/^--warnings=(\d+)$/) {
+        $warnings = $1;
+  } elsif (m/^-t(.*)$/) {
+        $packagetype = $1;
+  } elsif (m/^-v$/) {
+        $debug++;
+  } elsif (m/^-x(.*)$/) {
+        push @exclude, $1;
+  } elsif (m/^-/) {
+        usageerr(_g("unknown option \`%s'"), $_);
+  } else {
+        if (exists $exec{$_}) {
+      # Affect the binary to the most important field
+      if ($depstrength{$dependencyfield} > $depstrength{$exec{$_}}) {
+                $exec{$_} = $dependencyfield;
+      }
+        } else {
+      $exec{$_} = $dependencyfield;
+        }
+  }
+}
+usageerr(_g('need at least one executable')) unless scalar keys %exec;
+
+my $control = Dpkg::Control::Info->new();
+my $fields = $control->get_source();
+my $bd_value = deps_concat($fields->{'Build-Depends'}, $fields->{'Build-Depends-Arch'});
+my $build_deps = deps_parse($bd_value, build_dep => 1, reduce_restrictions => 1);
+error(_g('error occurred while parsing %s'), 'Build-Depends/Build-Depends-Arch')
+  unless defined $build_deps;
+
+my %dependencies;
+
+# Statictics on soname seen in the whole run (with multiple analysis of
+# binaries)
+my %global_soname_notfound;
+my %global_soname_used;
+my %global_soname_needed;
+
+# Symfile and objdump caches
+my %symfile_cache;
+my %objdump_cache;
+my %symfile_has_soname_cache;
+
+# Used to count errors due to missing libraries
+my $error_count = 0;
+
+my $cur_field;
+foreach my $file (keys %exec) {
+  $cur_field = $exec{$file};
+  print ">> Scanning $file (for $cur_field field)\n" if $debug;
+
+  my $obj = Dpkg::Shlibs::Objdump::Object->new($file);
+  my @sonames = $obj->get_needed_libraries;
+
+  # Load symbols files for all needed libraries (identified by SONAME)
+  my %libfiles;
+  my %altlibfiles;
+  my %soname_notfound;
+  my %alt_soname;
+  foreach my $soname (@sonames) {
+        my $lib = my_find_library($soname, $obj->{RPATH}, $obj->{format}, $file);
+        unless (defined $lib) {
+      $soname_notfound{$soname} = 1;
+      $global_soname_notfound{$soname} = 1;
+      my $msg = _g("couldn't find library %s needed by %s (ELF " .
+                   "format: '%s'; RPATH: '%s')");
+      if (scalar(split_soname($soname))) {
+                errormsg($msg, $soname, $file, $obj->{format}, join(':', @{$obj->{RPATH}}));
+                $error_count++;
+      } else {
+                warning($msg, $soname, $file, $obj->{format}, join(':', @{$obj->{RPATH}}));
+      }
+      next;
+        }
+        $libfiles{$lib} = $soname;
+        my $reallib = realpath($lib);
+        if ($reallib ne $lib) {
+      $altlibfiles{$reallib} = $soname;
+        }
+        print "Library $soname found in $lib\n" if $debug;
+  }
+  my $file2pkg = find_packages(keys %libfiles, keys %altlibfiles);
+  my $symfile = Dpkg::Shlibs::SymbolFile->new();
+  my $dumplibs_wo_symfile = Dpkg::Shlibs::Objdump->new();
+  my @soname_wo_symfile;
+  foreach my $lib (keys %libfiles) {
+        my $soname = $libfiles{$lib};
+
+        if (none { $_ ne '' } @{$file2pkg->{$lib}}) {
+      # The path of the library as calculated is not the
+      # official path of a packaged file, try to fallback on
+      # on the realpath() first, maybe this one is part of a package
+      my $reallib = realpath($lib);
+      if (exists $file2pkg->{$reallib}) {
+                $file2pkg->{$lib} = $file2pkg->{$reallib};
+      }
+        }
+        if (none { $_ ne '' } @{$file2pkg->{$lib}}) {
+      # If the library is really not available in an installed package,
+      # it's because it's in the process of being built
+      # Empty package name will lead to consideration of symbols
+      # file from the package being built only
+      $file2pkg->{$lib} = [''];
+      print "No associated package found for $lib\n" if $debug;
+        }
+
+        # Load symbols/shlibs files from packages providing libraries
+        foreach my $pkg (@{$file2pkg->{$lib}}) {
+      my $symfile_path;
+      my $haslocaldep = 0;
+      if (-e $shlibslocal and
+          defined(extract_from_shlibs($soname, $shlibslocal)))
+      {
+        $haslocaldep = 1;
+      }
+      if ($packagetype eq 'deb' and not $haslocaldep) {
+                # Use fine-grained dependencies only on real deb
+        # and only if the dependency is not provided by shlibs.local
+                $symfile_path = find_symbols_file($pkg, $soname, $lib);
+      }
+      if (defined($symfile_path)) {
+        # Load symbol information
+        print "Using symbols file $symfile_path for $soname\n" if $debug;
+        unless (exists $symfile_cache{$symfile_path}) {
+          $symfile_cache{$symfile_path} =
+            Dpkg::Shlibs::SymbolFile->new(file => $symfile_path);
+        }
+        $symfile->merge_object_from_symfile($symfile_cache{$symfile_path}, $soname);
+      }
+      if (defined($symfile_path) && $symfile->has_object($soname)) {
+                # Initialize dependencies with the smallest minimal version
+        # of all symbols (unversioned dependency is not ok as the
+        # library might not have always been available in the
+        # package and we really need it)
+                my $dep = $symfile->get_dependency($soname);
+                my $minver = $symfile->get_smallest_version($soname) || '';
+                foreach my $subdep (split /\s*,\s*/, $dep) {
+          if (not exists $dependencies{$cur_field}{$subdep}) {
+                        $dependencies{$cur_field}{$subdep} = Dpkg::Version->new($minver);
+            print " Initialize dependency ($subdep) with minimal " .
+              "version ($minver)\n" if $debug > 1;
+          }
+                }
+      } else {
+                # No symbol file found, fall back to standard shlibs
+        print "Using shlibs+objdump for $soname (file $lib)\n" if $debug;
+        unless (exists $objdump_cache{$lib}) {
+          $objdump_cache{$lib} = Dpkg::Shlibs::Objdump::Object->new($lib);
+        }
+        my $libobj = $objdump_cache{$lib};
+        my $id = $dumplibs_wo_symfile->add_object($libobj);
+                if (($id ne $soname) and ($id ne $lib)) {
+          warning(_g('%s has an unexpected SONAME (%s)'), $lib, $id);
+          $alt_soname{$id} = $soname;
+                }
+                push @soname_wo_symfile, $soname;
+                # Only try to generate a dependency for libraries with a SONAME
+                if ($libobj->is_public_library() and not
+                    add_shlibs_dep($soname, $pkg, $lib)) {
+          # This failure is fairly new, try to be kind by
+          # ignoring as many cases that can be safely ignored
+          my $ignore = 0;
+          # 1/ when the lib and the binary are in the same
+          # package
+          my $root_file = guess_pkg_root_dir($file);
+          my $root_lib = guess_pkg_root_dir($lib);
+          $ignore++ if defined $root_file and defined $root_lib
+                        and check_files_are_the_same($root_file, $root_lib);
+          # 2/ when the lib is not versioned and can't be
+          # handled by shlibs
+          $ignore++ unless scalar(split_soname($soname));
+          # 3/ when we have been asked to do so
+          $ignore++ if $ignore_missing_info;
+          error(_g('no dependency information found for %s ' .
+                   '(used by %s)'), $lib, $file)
+            unless $ignore;
+                }
+      }
+        }
+  }
+
+  # Scan all undefined symbols of the binary and resolve to a
+  # dependency
+  my %soname_used;
+  foreach (@sonames) {
+    # Initialize statistics
+    $soname_used{$_} = 0;
+    $global_soname_used{$_} = 0 unless exists $global_soname_used{$_};
+    if (exists $global_soname_needed{$_}) {
+      push @{$global_soname_needed{$_}}, $file;
+    } else {
+      $global_soname_needed{$_} = [ $file ];
+    }
+  }
+  my $nb_warnings = 0;
+  my $nb_skipped_warnings = 0;
+  # Disable warnings about missing symbols when we have not been able to
+  # find all libs
+  my $disable_warnings = scalar(keys(%soname_notfound));
+  my $in_public_dir = 1;
+  if (my $relname = relative_to_pkg_root($file)) {
+    my $parent_dir = '/' . dirname($relname);
+    $in_public_dir = any { $parent_dir eq $_ } get_library_paths();
+  } else {
+    warning(_g('binaries to analyze should already be ' .
+               "installed in their package's directory"));
+  }
+  print "Analyzing all undefined symbols\n" if $debug > 1;
+  foreach my $sym ($obj->get_undefined_dynamic_symbols()) {
+        my $name = $sym->{name};
+        if ($sym->{version}) {
+      $name .= '@' . "$sym->{version}";
+        } else {
+      $name .= '@' . 'Base';
+        }
+    print " Looking up symbol $name\n" if $debug > 1;
+        my %symdep = $symfile->lookup_symbol($name, \@sonames);
+        if (keys %symdep) {
+      my $depends = $symfile->get_dependency($symdep{soname},
+                                             $symdep{symbol}{dep_id});
+      print " Found in symbols file of $symdep{soname} (minver: " .
+        "$symdep{symbol}{minver}, dep: $depends)\n" if $debug > 1;
+      $soname_used{$symdep{soname}}++;
+      $global_soname_used{$symdep{soname}}++;
+      if (exists $alt_soname{$symdep{soname}}) {
+        # Also count usage on alternate soname
+        $soname_used{$alt_soname{$symdep{soname}}}++;
+        $global_soname_used{$alt_soname{$symdep{soname}}}++;
+      }
+      update_dependency_version($depends, $symdep{symbol}{minver});
+        } else {
+      my $syminfo = $dumplibs_wo_symfile->locate_symbol($name);
+      if (not defined($syminfo)) {
+        print " Not found\n" if $debug > 1;
+        next unless ($warnings & WARN_SYM_NOT_FOUND);
+                next if $disable_warnings;
+                # Complain about missing symbols only for executables
+                # and public libraries
+                if ($obj->is_executable() or $obj->is_public_library()) {
+          my $print_name = $name;
+          # Drop the default suffix for readability
+          $print_name =~ s/\@Base$//;
+          unless ($sym->{weak}) {
+                        if ($debug or ($in_public_dir and $nb_warnings < 10)
+                or (not $in_public_dir and $nb_warnings < 1))
+            {
+              if ($in_public_dir) {
+                warning(_g('symbol %s used by %s found in none of the ' .
+                                           'libraries'), $print_name, $file);
+              } else {
+                warning(_g('%s contains an unresolvable reference to ' .
+                           "symbol %s: it's probably a plugin"),
+                        $file, $print_name);
+              }
+              $nb_warnings++;
+                        } else {
+              $nb_skipped_warnings++;
+                        }
+          }
+                }
+      } else {
+        print " Found in $syminfo->{soname} ($syminfo->{objid})\n" if $debug > 1;
+                if (exists $alt_soname{$syminfo->{soname}}) {
+          # Also count usage on alternate soname
+          $soname_used{$alt_soname{$syminfo->{soname}}}++;
+          $global_soname_used{$alt_soname{$syminfo->{soname}}}++;
+                }
+                $soname_used{$syminfo->{soname}}++;
+                $global_soname_used{$syminfo->{soname}}++;
+      }
+        }
+  }
+  warning(P_('%d similar warning has been skipped (use -v to see it)',
+             '%d other similar warnings have been skipped (use -v to see ' .
+             'them all)', $nb_skipped_warnings), $nb_skipped_warnings)
+    if $nb_skipped_warnings;
+  foreach my $soname (@sonames) {
+        # Adjust minimal version of dependencies with information
+        # extracted from build-dependencies
+        my $dev_pkg = $symfile->get_field($soname, 'Build-Depends-Package');
+        if (defined $dev_pkg) {
+      print "Updating dependencies of $soname with build-dependencies\n" if $debug;
+      my $minver = get_min_version_from_deps($build_deps, $dev_pkg);
+      if (defined $minver) {
+                foreach my $dep ($symfile->get_dependencies($soname)) {
+          update_dependency_version($dep, $minver, 1);
+          print " Minimal version of $dep updated with $minver\n" if $debug;
+                }
+      } else {
+        print " No minimal version found in $dev_pkg build-dependency\n" if $debug;
+      }
+        }
+
+        # Warn about un-NEEDED libraries
+        unless ($soname_notfound{$soname} or $soname_used{$soname}) {
+      # Ignore warning for libm.so.6 if also linked against libstdc++
+      next if ($soname =~ /^libm\.so\.\d+$/ and
+               any { m/^libstdc\+\+\.so\.\d+/ } @sonames);
+      next unless ($warnings & WARN_NOT_NEEDED);
+      warning(_g('%s should not be linked against %s (it uses none of ' .
+                 "the library's symbols)"), $file, $soname);
+        }
+  }
+}
+
+# Warn of unneeded libraries at the "package" level (i.e. over all
+# binaries that we have inspected)
+foreach my $soname (keys %global_soname_needed) {
+  unless ($global_soname_notfound{$soname} or $global_soname_used{$soname}) {
+    next if ($soname =~ /^libm\.so\.\d+$/ and
+             any { m/^libstdc\+\+\.so\.\d+/ } keys %global_soname_needed);
+    next unless ($warnings & WARN_DEP_AVOIDABLE);
+    warning(P_('package could avoid a useless dependency if %s was not ' .
+               "linked against %s (it uses none of the library's symbols)",
+               'package could avoid a useless dependency if %s were not ' .
+               "linked against %s (they use none of the library's symbols)",
+               scalar @{$global_soname_needed{$soname}}),
+            join(' ', @{$global_soname_needed{$soname}}), $soname);
+  }
+}
+
+# Quit now if any missing libraries
+if ($error_count >= 1) {
+  my $note = _g('Note: libraries are not searched in other binary packages ' .
+                "that do not have any shlibs or symbols file.\nTo help dpkg-shlibdeps " .
+                'find private libraries, you might need to use -l.');
+  error(P_('cannot continue due to the error above',
+           'cannot continue due to the errors listed above',
+           $error_count) . "\n" . $note);
+}
+
+# Open substvars file
+my $fh;
+if ($stdout) {
+  $fh = \*STDOUT;
+} else {
+  open(my $new_fh, '>', "$varlistfile.new")
+    or syserr(_g("open new substvars file \`%s'"), "$varlistfile.new");
+  if (-e $varlistfile) {
+        open(my $old_fh, '<', $varlistfile)
+      or syserr(_g("open old varlist file \`%s' for reading"), $varlistfile);
+        while (my $entry = <$old_fh>) {
+      next if $entry =~ m/^\Q$varnameprefix\E:/;
+      print { $new_fh } $entry
+        or syserr(_g("copy old entry to new varlist file \`%s'"),
+                  "$varlistfile.new");
+        }
+        close($old_fh);
+  }
+  $fh = $new_fh;
+}
+
+# Write out the shlibs substvars
+my %depseen;
+
+sub filter_deps {
+  my ($dep, $field) = @_;
+  # Skip dependencies on excluded packages
+  foreach my $exc (@exclude) {
+        return 0 if $dep =~ /^\s*\Q$exc\E\b/;
+  }
+  # Don't include dependencies if they are already
+  # mentionned in a higher priority field
+  if (not exists($depseen{$dep})) {
+        $depseen{$dep} = $dependencies{$field}{$dep};
+        return 1;
+  } else {
+        # Since dependencies can be versionned, we have to
+        # verify if the dependency is stronger than the
+        # previously seen one
+        my $stronger;
+        if ($depseen{$dep} eq $dependencies{$field}{$dep}) {
+      # If both versions are the same (possibly unversionned)
+      $stronger = 0;
+        } elsif ($dependencies{$field}{$dep} eq '') {
+      $stronger = 0; # If the dep is unversionned
+        } elsif ($depseen{$dep} eq '') {
+      $stronger = 1; # If the dep seen is unversionned
+        } elsif (version_compare_relation($depseen{$dep}, REL_GT,
+                                      $dependencies{$field}{$dep})) {
+      # The version of the dep seen is stronger...
+      $stronger = 0;
+        } else {
+      $stronger = 1;
+        }
+        $depseen{$dep} = $dependencies{$field}{$dep} if $stronger;
+        return $stronger;
+  }
+}
+
+foreach my $field (reverse @depfields) {
+  my $dep = '';
+  if (exists $dependencies{$field} and scalar keys %{$dependencies{$field}}) {
+        $dep = join ', ',
+      map {
+                # Translate dependency templates into real dependencies
+                if ($dependencies{$field}{$_}) {
+          s/#MINVER#/(>= $dependencies{$field}{$_})/g;
+                } else {
+          s/#MINVER#//g;
+                }
+                s/\s+/ /g;
+                $_;
+    } grep { filter_deps($_, $field) }
+    keys %{$dependencies{$field}};
+  }
+  if ($dep) {
+    my $obj = deps_parse($dep);
+    error(_g('invalid dependency got generated: %s'), $dep) unless defined $obj;
+    $obj->sort();
+        print { $fh } "$varnameprefix:$field=$obj\n";
+  }
+}
+
+# Replace old file by new one
+if (!$stdout) {
+  close($fh) or syserr(_g('cannot close %s'), "$varlistfile.new");
+  rename("$varlistfile.new",$varlistfile)
+    or syserr(_g("install new varlist file \`%s'"), $varlistfile);
+}
+
+##
+## Functions
+##
+
+sub version {
+  printf _g("Debian %s version %s.\n"), $Dpkg::PROGNAME, $Dpkg::PROGVERSION;
+
+  printf _g('
+            This is free software; see the GNU General Public License version 2 or
+            later for copying conditions. There is NO warranty.
+            ');
+}
+
+sub usage {
+  printf _g(
+    'Usage: %s [<option>...] <executable>|-e<executable> [<option>...]')
+    . "\n\n" . _g(
+    "Positional options (order is significant):
+    <executable>             include dependencies for <executable>,
+    -e<executable>           (use -e if <executable> starts with '-')
+    -d<dependency-field>     next executable(s) set shlibs:<dependency-field>.")
+    . "\n\n" . _g(
+    "Options:
+    -l<library-dir>          add directory to private shared library search list.
+    -p<varname-prefix>       set <varname-prefix>:* instead of shlibs:*.
+    -O[<file>]               write variable settings to stdout (or <file>).
+    -L<local-shlibs-file>    shlibs override file, not debian/shlibs.local.
+    -T<substvars-file>       update variables here, not debian/substvars.
+    -t<type>                 set package type (default is deb).
+    -x<package>              exclude package from the generated dependencies.
+    -S<package-build-dir>    search needed libraries in the given
+    package build directory first.
+    -v                       enable verbose mode (can be used multiple times).
+    --ignore-missing-info    don't fail if dependency information can't be found.
+    --warnings=<value>       define set of active warnings (see manual page).
+    --admindir=<directory>   change the administrative directory.
+    -?, --help               show this help message.
+    --version            show the version.")
+    . "\n\n" . _g(
+    'Dependency fields recognized are:
+    %s
+    '), $Dpkg::PROGNAME, join('/', @depfields);
+}
+
+sub get_min_version_from_deps {
+  my ($dep, $pkg) = @_;
+  if ($dep->isa('Dpkg::Deps::Simple')) {
+        if (($dep->{package} eq $pkg) &&
+            defined($dep->{relation}) &&
+            (($dep->{relation} eq REL_GE) ||
+             ($dep->{relation} eq REL_GT)))
+        {
+      return $dep->{version};
+        }
+        return;
+  } else {
+        my $res;
+        foreach my $subdep ($dep->get_deps()) {
+      my $minver = get_min_version_from_deps($subdep, $pkg);
+      next if not defined $minver;
+      if (defined $res) {
+                if (version_compare_relation($minver, REL_GT, $res)) {
+          $res = $minver;
+                }
+      } else {
+                $res = $minver;
+      }
+        }
+        return $res;
+  }
+}
+
+sub update_dependency_version {
+  my ($dep, $minver, $existing_only) = @_;
+  return if not defined($minver);
+  $minver = Dpkg::Version->new($minver);
+  foreach my $subdep (split /\s*,\s*/, $dep) {
+        if (exists $dependencies{$cur_field}{$subdep} and
+            defined($dependencies{$cur_field}{$subdep}))
+        {
+      if ($dependencies{$cur_field}{$subdep} eq '' or
+          version_compare_relation($minver, REL_GT,
+                                   $dependencies{$cur_field}{$subdep}))
+      {
+                $dependencies{$cur_field}{$subdep} = $minver;
+      }
+        } elsif (!$existing_only) {
+      $dependencies{$cur_field}{$subdep} = $minver;
+        }
+  }
+}
+
+sub add_shlibs_dep {
+  my ($soname, $pkg, $libfile) = @_;
+  my @shlibs = ($shlibslocal, $shlibsoverride);
+  if ($pkg eq '') {
+        # If the file is not packaged, try to find out the shlibs file in
+        # the package being built where the lib has been found
+        my $pkg_root = guess_pkg_root_dir($libfile);
+        if (defined $pkg_root) {
+      push @shlibs, "$pkg_root/DEBIAN/shlibs";
+        }
+        # Fallback to other shlibs files but it shouldn't be necessary
+        push @shlibs, @pkg_shlibs;
+  } else {
+        my $control_file = get_control_path($pkg, 'shlibs');
+        push @shlibs, $control_file if defined $control_file;
+  }
+  push @shlibs, $shlibsdefault;
+  print " Looking up shlibs dependency of $soname provided by '$pkg'\n" if $debug;
+  foreach my $file (@shlibs) {
+        next if not -e $file;
+        my $dep = extract_from_shlibs($soname, $file);
+        if (defined($dep)) {
+      print " Found $dep in $file\n" if $debug;
+      foreach (split(/,\s*/, $dep)) {
+                # Note: the value is empty for shlibs based dependency
+                # symbol based dependency will put a valid version as value
+                $dependencies{$cur_field}{$_} = Dpkg::Version->new('');
+      }
+      return 1;
+        }
+  }
+  print " Found nothing\n" if $debug;
+  return 0;
+}
+
+sub split_soname {
+  my $soname = shift;
+  if ($soname =~ /^(.*)\.so\.(.*)$/) {
+        return wantarray ? ($1, $2) : 1;
+  } elsif ($soname =~ /^(.*)-(\d.*)\.so$/) {
+        return wantarray ? ($1, $2) : 1;
+  } else {
+        return wantarray ? () : 0;
+  }
+}
+
+sub extract_from_shlibs {
+  my ($soname, $shlibfile) = @_;
+  # Split soname in name/version
+  my ($libname, $libversion) = split_soname($soname);
+  unless (defined $libname) {
+        warning(_g("can't extract name and version from library name '%s'"),
+                $soname);
+        return;
+  }
+  # Open shlibs file
+  open(my $shlibs_fh, '<', $shlibfile)
+    or syserr(_g("unable to open shared libs info file \`%s'"), $shlibfile);
+  my $dep;
+  while (<$shlibs_fh>) {
+        s/\s*\n$//;
+        next if m/^\#/;
+        if (!m/^\s*(?:(\S+):\s+)?(\S+)\s+(\S+)(?:\s+(\S.*\S))?\s*$/) {
+      warning(_g("shared libs info file \`%s' line %d: bad line \`%s'"),
+              $shlibfile, $., $_);
+      next;
+        }
+        my $depread = defined($4) ? $4 : '';
+        if (($libname eq $2) && ($libversion eq $3)) {
+      # Define dep and end here if the package type explicitly
+      # matches. Otherwise if the packagetype is not specified, use
+      # the dep only as a default that can be overriden by a later
+      # line
+      if (defined($1)) {
+                if ($1 eq $packagetype) {
+          $dep = $depread;
+          last;
+                }
+      } else {
+                $dep //= $depread;
+      }
+        }
+  }
+  close($shlibs_fh);
+  return $dep;
+}
+
+sub find_symbols_file {
+  my ($pkg, $soname, $libfile) = @_;
+  my @files;
+  if ($pkg eq '') {
+        # If the file is not packaged, try to find out the symbols file in
+        # the package being built where the lib has been found
+        my $pkg_root = guess_pkg_root_dir($libfile);
+        if (defined $pkg_root) {
+      push @files, "$pkg_root/DEBIAN/symbols";
+        }
+        # Fallback to other symbols files but it shouldn't be necessary
+        push @files, @pkg_symbols;
+  } else {
+        push @files, "$Dpkg::CONFDIR/symbols/$pkg.symbols.$host_arch",
+      "$Dpkg::CONFDIR/symbols/$pkg.symbols";
+        my $control_file = get_control_path($pkg, 'symbols');
+        push @files, $control_file if defined $control_file;
+  }
+
+  foreach my $file (@files) {
+        if (-e $file and symfile_has_soname($file, $soname)) {
+      return $file;
+        }
+  }
+  return;
+}
+
+sub symfile_has_soname {
+  my ($file, $soname) = @_;
+
+  if (exists $symfile_has_soname_cache{$file}{$soname}) {
+    return $symfile_has_soname_cache{$file}{$soname};
+  }
+
+  open(my $symfile_fh, '<', $file)
+    or syserr(_g('cannot open file %s'), $file);
+  my $result = 0;
+  while (<$symfile_fh>) {
+        if (/^\Q$soname\E /) {
+      $result = 1;
+      last;
+        }
+  }
+  close($symfile_fh);
+  $symfile_has_soname_cache{$file}{$soname} = $result;
+  return $result;
+}
+
+# find_library ($soname, \@rpath, $format)
+sub my_find_library {
+  my ($lib, $rpath, $format, $execfile) = @_;
+  my $file;
+
+  # Create real RPATH in case $ORIGIN is used
+  # Note: ld.so also supports $PLATFORM and $LIB but they are
+  # used in real case (yet)
+  my $libdir = relative_to_pkg_root($execfile);
+  my $origin;
+  if (defined $libdir) {
+        $origin = "/$libdir";
+        $origin =~ s{/+[^/]*$}{};
+  }
+  my @RPATH = ();
+  foreach my $path (@{$rpath}) {
+        if ($path =~ /\$ORIGIN|\$\{ORIGIN\}/) {
+      if (defined $origin) {
+                $path =~ s/\$ORIGIN/$origin/g;
+                $path =~ s/\$\{ORIGIN\}/$origin/g;
+      } else {
+                warning(_g('$ORIGIN is used in RPATH of %s and the corresponding ' .
+                   'directory could not be identified due to lack of DEBIAN ' .
+                   "sub-directory in the root of package's build tree"), $execfile);
+      }
+        }
+        push @RPATH, $path;
+  }
+
+  # Look into the packages we're currently building in the following
+  # order:
+  # - package build tree of the binary which is analyzed
+  # - package build tree given on the command line (option -S)
+  # - other package build trees that contain either a shlibs or a
+  # symbols file
+  my @builddirs;
+  my $pkg_root = guess_pkg_root_dir($execfile);
+  push @builddirs, $pkg_root if defined $pkg_root;
+  push @builddirs, @pkg_dir_to_search;
+  push @builddirs, @pkg_root_dirs;
+  my %dir_checked;
+  foreach my $builddir (@builddirs) {
+        next if defined($dir_checked{$builddir});
+        $file = find_library($lib, \@RPATH, $format, $builddir);
+        return $file if defined($file);
+        $dir_checked{$builddir} = 1;
+  }
+
+  # Fallback in the root directory if we have not found what we were
+  # looking for in the packages
+  $file = find_library($lib, \@RPATH, $format, '');
+  return $file if defined($file);
+
+  return;
+}
+
+my %cached_pkgmatch = ();
+
+sub find_packages {
+  my @files;
+  my $pkgmatch = {};
+
+  foreach (@_) {
+        if (exists $cached_pkgmatch{$_}) {
+      $pkgmatch->{$_} = $cached_pkgmatch{$_};
+        } else {
+      push @files, $_;
+      $cached_pkgmatch{$_} = ['']; # placeholder to cache misses too.
+      $pkgmatch->{$_} = [''];        # might be replaced later on
+        }
+  }
+  return $pkgmatch unless scalar(@files);
+
+  my $pid = open(my $dpkg_fh, '-|');
+  syserr(_g('cannot fork for %s'), 'dpkg --search') unless defined($pid);
+  if (!$pid) {
+        # Child process running dpkg --search and discarding errors
+        close STDERR;
+        open STDERR, '>', '/dev/null'
+      or syserr(_g('cannot open file %s'), '/dev/null');
+        $ENV{LC_ALL} = 'C';
+        exec('dpkg', '--search', '--', @files)
+      or syserr(_g('unable to execute %s'), 'dpkg');
+  }
+  while (defined($_ = <$dpkg_fh>)) {
+        chomp($_);
+        if (m/^local diversion |^diversion by/) {
+      warning(_g('diversions involved - output may be incorrect'));
+      print { *STDERR } " $_\n"
+                or syserr(_g('write diversion info to stderr'));
+        } elsif (m/^([-a-z0-9+.:, ]+): (\/.*)$/) {
+      $cached_pkgmatch{$2} = $pkgmatch->{$2} = [ split(/, /, $1) ];
+        } else {
+      warning(_g("unknown output from dpkg --search: '%s'"), $_);
+        }
+  }
+  close($dpkg_fh);
+  return $pkgmatch;
+}