Add tools and Debian packaging for parsing dlopen ELF notes

.github/workflows/tests.yml

@@ -0,0 +1,25 @@
+---
+# SPDX-License-Identifier: CC0-1.0
+# vi: ts=2 sw=2 et:
+
+name: Run tests
+on: [pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: ubuntu-22.04
+    concurrency:
+      group: ${{ github.workflow }}-${{ github.ref }}
+      cancel-in-progress: true
+    strategy:
+      fail-fast: false
+    steps:
+      - name: Repository checkout
+        uses: actions/checkout@v4
+      - name: Install dependencies
+        run: sudo apt -y update && sudo apt -y install python3-pyelftools python3-pytest
+      - name: Run tests
+        run: make check

.gitignore

@@ -1,6 +1,7 @@
 *.sw*
 /*.src.rpm
 /*.log
+/test/notes
 !/debian/changelog
 !/debian/control
 !/debian/copyright

Makefile

@@ -0,0 +1,10 @@
+all:
+
+install:
+	install -m 755 -D dlopen-notes.py $(DESTDIR)/usr/bin/dlopen-notes
+
+check:
+	make -C test check
+
+clean:
+	make -C test clean

debian/control

@@ -4,6 +4,9 @@ Priority: optional
 Rules-Requires-Root: no
 Maintainer: Luca Boccassi <[email protected]>
 Build-Depends: debhelper-compat (= 13),
+               python3:native <!nocheck>,
+               python3-pyelftools:native <!nocheck>,
+               python3-pytest:native <!nocheck>,
 Standards-Version: 4.6.1
 Homepage: https://systemd.io/ELF_PACKAGE_METADATA/
 Vcs-Git: https://github.com/systemd/package-notes.git
@@ -17,3 +20,17 @@ Depends: ${misc:Depends}, debhelper,
 Description: Debian Helper for adding package metadata to ELF binaries
  Provides a linker specs file to add package metadata to the ELF binaries being
  built. See: https://systemd.io/ELF_PACKAGE_METADATA/
+
+Package: dh-dlopenlibdeps
+Architecture: all
+Multi-Arch: foreign
+Enhances: debhelper
+Depends: ${misc:Depends},
+         ${perl:Depends},
+         debhelper,
+         python3,
+         python3-pyelftools,
+Provides: dh-sequence-dlopenlibdeps,
+Description: Debian Helper for parsing dlopen metadata from ELF binaries
+ Parses dlopen ELF note and generates dependencies from it that can be used
+ via ${dlopen:Depends|Recommends|Suggests}

debian/dh-dlopenlibdeps.install

@@ -0,0 +1,3 @@
+debian/dlopenlibdeps.pm usr/share/perl5/Debian/Debhelper/Sequence
+debian/dh_dlopenlibdeps usr/bin
+usr/bin/dlopen-notes

debian/dh-dlopenlibdeps.manpages

@@ -0,0 +1 @@
+debian/dh_dlopenlibdeps.1

debian/dh_dlopenlibdeps

@@ -0,0 +1,156 @@
+#!/usr/bin/perl
+# SPDX-License-Identifier: CC0-1.0
+
+=head1 NAME
+
+dh_dlopenlibdeps - parse dlopen library dependencies from ELF notes
+
+=cut
+
+use strict;
+use warnings;
+use Debian::Debhelper::Dh_Lib;
+
+our $VERSION = DH_BUILTIN_VERSION;
+
+=head1 SYNOPSIS
+
+B<dh_dlopenlibdeps> [S<I<debhelper options>>] [B<-X>I<item>]
+
+=head1 DESCRIPTION
+
+B<dh_dlopenlibdeps> is a debhelper program that is responsible for calculating
+dlopen library dependencies for packages.
+
+This program follows the dlopen notes metadata specification as defined at
+https://systemd.io/ELF_PACKAGE_METADATA/
+
+=head1 OPTIONS
+
+=over 4
+
+=item B<-X>I<item>, B<--exclude=>I<item>
+
+Exclude files that contain F<item> anywhere in their filename from being
+parsed. This will make their dependencies be ignored.
+This may be useful in some situations, but use it with caution. This option
+may be used more than once to exclude more than one thing.
+
+=back
+
+=cut
+
+init();
+
+on_pkgs_in_parallel {
+	my $is_elf_file = sub {
+		my ($file) = @_;
+		my @file_args = Debian::Debhelper::Dh_Lib::_internal_optional_file_args();
+		my $ff = qx_cmd('file', @file_args, '--brief', '-e', 'apptype', '-e', 'ascii',
+						'-e', 'encoding', '-e', 'cdf', '-e', 'compress', '-e', 'tar', '--', $file);
+		return 1 if $ff =~ m/ELF/;
+		return 0;
+	};
+
+	foreach my $package (@_) {
+		my $tmp = tmpdir($package);
+		my $ext = pkgext($package);
+		my (@filelist);
+		my %required_packages;
+		my %recommended_packages;
+		my %suggested_packages;
+
+		# Generate a list of ELF binaries in the package, ignoring any we were told to exclude.
+		my $find_options='';
+		if (defined($dh{EXCLUDE_FIND}) && $dh{EXCLUDE_FIND} ne '') {
+			$find_options="! \\( $dh{EXCLUDE_FIND} \\)";
+		}
+		next if not -d $tmp;
+		foreach my $file (split(/\n/, `find $tmp -type f \\( -perm /111 -or -name "*.so*" -or -name "*.cmxs" -or -name "*.node" \\) $find_options -print`)) {
+			# Prune directories that contain separated debug symbols.
+			# CAVEAT: There are files in /usr/lib/debug that are not detached debug symbols, which should be processed. (see #865982)
+			next if $file =~ m!^\Q$tmp\E/usr/lib/debug/(lib|lib64|usr|bin|sbin|opt|dev|emul|\.build-id)/!;
+			if ($is_elf_file->($file)) {
+				push @filelist, $file;
+			}
+		}
+
+		if (@filelist) {
+			my $required_sonames = '';
+			my $recommended_sonames = '';
+			my $suggested_sonames = '';
+
+			my $sonames = `dlopen-notes --sonames @filelist`;
+			foreach my $line (split(/\n/, $sonames)) {
+				my ($soname, $priority) = split(' ', $line, 2);
+
+				if ($priority eq 'required') {
+					$required_sonames .= " $soname";
+				} elsif ($priority eq 'recommended') {
+					$recommended_sonames .= " $soname";
+				} elsif ($priority eq 'suggested') {
+					$suggested_sonames .= " $soname";
+				} else {
+					warning("Unknown priority $priority for $soname");
+				}
+			}
+
+			if ($required_sonames) {
+				my $dpkg_query = `dpkg-query --search -- $required_sonames`;
+				foreach my $line (split(/\n/, $dpkg_query)) {
+					chomp $line;
+					if ($line =~ m/^local diversion |^diversion by/) {
+						next;
+					}
+					if ($line =~ m/^([-a-z0-9+]+):/) {
+						$required_packages{$1} = 1;
+					}
+				}
+			}
+
+			if ($recommended_sonames) {
+				my $dpkg_query = `dpkg-query --search -- $recommended_sonames`;
+				foreach my $line (split(/\n/, $dpkg_query)) {
+					chomp $line;
+					if ($line =~ m/^local diversion |^diversion by/) {
+						next;
+					}
+					if ($line =~ m/^([-a-z0-9+]+):/) {
+						$recommended_packages{$1} = 1;
+					}
+				}
+			}
+
+			if ($suggested_sonames) {
+				my $dpkg_query = `dpkg-query --search -- $suggested_sonames`;
+				foreach my $line (split(/\n/, $dpkg_query)) {
+					chomp $line;
+					if ($line =~ m/^local diversion |^diversion by/) {
+						next;
+					}
+					if ($line =~ m/^([-a-z0-9+]+):/) {
+						$suggested_packages{$1} = 1;
+					}
+				}
+			}
+		}
+
+		# Always write the substvars file, even if it's empty, so that the variables are defined and
+		# there are no warnings when using them in the control file.
+		open(SV, ">>debian/${ext}substvars") || error("open debian/${ext}substvars: $!");
+		print SV "dlopen:Depends=" . join(", ", sort keys %required_packages) . "\n";
+		print SV "dlopen:Recommends=" . join(", ", sort keys %recommended_packages) . "\n";
+		print SV "dlopen:Suggests=" . join(", ", sort keys %suggested_packages) . "\n";
+		close(SV);
+	}
+};
+
+=head1 SEE ALSO
+
+L<debhelper(7)>, L<dh_shlibsdeps(1)>
+
+=head1 AUTHOR
+
+Luca Boccassi <[email protected]>
+
+=cut

debian/dlopenlibdeps.pm

@@ -0,0 +1,7 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use Debian::Debhelper::Dh_Lib;
+
+insert_after("dh_shlibdeps", "dh_dlopenlibdeps");

debian/rules

@@ -2,3 +2,9 @@
 
 %:
 	dh $@
+
+execute_after_dh_auto_build:
+	pod2man --utf8 $(CURDIR)/debian/dh_dlopenlibdeps > $(CURDIR)/debian/dh_dlopenlibdeps.1
+
+execute_after_dh_auto_clean:
+	rm -f $(CURDIR)/debian/dh_dlopenlibdeps.1