dh_makeshlibs

#!/usr/bin/perl

=head1 NAME

dh_makeshlibs - automatically create shlibs file and call dpkg-gensymbols

=cut

use strict;
use warnings;
use Debian::Debhelper::Dh_Lib;

our $VERSION = DH_BUILTIN_VERSION;

=head1 SYNOPSIS

B<dh_makeshlibs> [S<I<debhelper options>>] [B<-m>I<major>] [B<-V>I<[dependencies]>] [B<-n>] [B<-X>I<item>] [S<B<--> I<params>>]

=head1 DESCRIPTION

B<dh_makeshlibs> is a debhelper program that automatically scans for shared
libraries, and generates a shlibs file for the libraries it finds.

It will also ensure that ldconfig is invoked during install and removal when
it finds shared libraries.  Since debhelper 9.20151004, this is done via a
dpkg trigger.  In older versions of debhelper, B<dh_makeshlibs> would
generate a maintainer script for this purpose.

Since debhelper 12.3, B<dh_makeshlibs> will by default add an additional
I<udeb> line for udebs in the shlibs file, when the udeb has the same
name as the deb followed by a "-udeb" suffix (e.g. if the deb is called
"libfoo1", then debhelper will auto-detect the udeb if it is named
"libfoo1-udeb"). Please use the B<--add-udeb> and B<--no-add-udeb> options
below when this auto-detection is insufficient.

If you previously used B<--add-udeb> and is considering to migrate to
using the new auto-detection feature in 12.3, then
please remember to test that the resulting F<DEBIAN/shlibs> files are
as expected.  There are some known corner cases, where the
auto-detection is insufficient.  These include when the udeb contains
library files from multiple regular deb packages or when the packages
do not follow the expected naming convention.

=head1 FILES

=over 4

=item debian/I<package>.shlibs

Installs this file, if present, into the package as DEBIAN/shlibs.  If
omitted, debhelper will generate a shlibs file automatically if it
detects any libraries.

Note in compat levels 9 and earlier, this file was installed by
L<dh_installdeb(1)> rather than B<dh_makeshlibs>.

=item debian/I<package>.symbols

=item debian/I<package>.symbols.I<arch>

These symbols files, if present, are passed to L<dpkg-gensymbols(1)> to
be processed and installed. Use the I<arch> specific names if you need
to provide different symbols files for different architectures.

=back

=head1 OPTIONS

=over 4

=item B<-m>I<major>, B<--major=>I<major>

Instead of trying to guess the major number of the library with objdump,
use the major number specified after the -m parameter. This is much less
useful than it used to be, back in the bad old days when this program
looked at library filenames rather than using objdump.

=item B<-V>, B<-V>I<dependencies>

=item B<--version-info>, B<--version-info=>I<dependencies>

If a shlibs file is generated by this program, this option controls
what version will be used in the dependency relation.

In compat 12 and later, B<dh_makeshlibs> defaults to B<-VUpstream-Version>.
In compat 11 and earlier the default behaved like B<-VNone>.

The B<dh_makeshlibs> tool can generate dependencies in three variants:

=over 4

=item B<-VUpstream-Version>

The dependency will be "I<packagename> B<(E<gt>>= I<packageversion>B<)>".
Note that I<Upstream-Version> is case-sensitive and must be written
exactly as shown here.

This is a conservative setting that always ensures that other packages'
shared library dependencies are at least as tight as they need to be
(unless the library is prone to changing ABI without updating the
upstream version number).

The flip side is that packages might end up with dependencies that are
too tight in some cases (note a symbols file can mitigate this issue).
This is often of minor temporary inconvenience and usually a lot
better than the fall out caused by forgetting to bump the dependency
information.

This explicit form was added in debhelper/11.3.  In previous versions,
a B<-V> without any dependency information was used instead (and that
form still works)

=item B<-VNone>

The dependency will be "I<packagename>".  Note that I<None> is
case-sensitive and must be written exactly as shown here.

This form is generally unsafe with the only exception being if upstream
does not extend the ABI in any way.  However, most upstreams improve their
interfaces over time and packagers are recommended to use
B<-VUpstream-Version> (or one of the other forms of B<-V>I<dependencies>).

Alternatively, this may be sufficient if (and only if) the package uses
symbol versioning (see L<dpkg-gensymbols(1)>) and does I<not> build any
udeb packages.  Note that symbols are not supported for udeb packages,
which solely relies on shlibs for dependency handling.

=item B<-V>I<package-relation>

In this case, the value passed to B<-V> will be used as a dependency
relation.  The I<package-relation> should generally be of the form
"I<some-package-name> B<(E<gt>>= I<some-package-version>B<)>".  Remember
to include the package name.

Note that debhelper will use the value I<as it is> with no sanity
checking or modification.  In I<rare special> cases, this is needed to
generate a dependency on a different package than the one containing
the library.

=back

When choosing a value for this option, please keep mind that if the
package provides a symbols file, then that this is generally preferred over
the shlibs file for regular .deb packages.  See L<dpkg-shlibdeps(1)>
for more information on this topic.

=item B<-n>, B<--no-scripts>

Do not add the "ldconfig" trigger even if it seems like the package
might need it.  The option is called B<--no-scripts> for historical
reasons as B<dh_makeshlibs> would previously generate maintainer
scripts that called B<ldconfig>.

=item B<-X>I<item>, B<--exclude=>I<item>

Exclude files that contain I<item> anywhere in their filename or directory 
from being treated as shared libraries.

=item B<--add-udeb=>I<udeb>

Create an additional line for udebs in the shlibs file and use I<udeb> as the
package name for udebs to depend on instead of the regular library package.

This option is only useful for special cases such as when debhelper
cannot auto-detect package name of the udeb package, when the udeb
will contain libraries from multiple deb packages, or when the udeb
contains libraries B<not> present in the deb package.

=item B<--no-add-udeb>

Do not add any udeb lines to the shlibs file.  This can be used to disable the
default auto-detection of udebs.

This may be useful in case you do not want a shlibs file at all for the udeb
because no package will depend on it.  E.g. because adding a udeb package
for the library was "overkill" and the library is embedded in a different
udeb package.

=item B<--> I<params>

Pass I<params> to L<dpkg-gensymbols(1)>.

=back

=head1 EXAMPLES

=over 4

=item B<dh_makeshlibs -VNone>

Assuming this is a package named F<libfoobar1>, generates a shlibs file that
looks something like:
 libfoobar 1 libfoobar1

=item B<dh_makeshlibs -VUpstream-Version>

Assuming the current version of the package is 1.1-3, generates a shlibs
file that looks something like:
 libfoobar 1 libfoobar1 (>= 1.1)

=item B<dh_makeshlibs -V 'libfoobar1 (E<gt>= 1.0)'>

Generates a shlibs file that looks something like:
  libfoobar 1 libfoobar1 (>= 1.0)

=back

=cut

my ($shlibs_udeb, %known_udeb_solibs);

init(options => {
	"m=s", => \$dh{M_PARAMS},
	"major=s" => \$dh{M_PARAMS},
	"version-info:s" => \$dh{V_FLAG},
	"add-udeb=s" => \$shlibs_udeb,
	"no-add-udeb" => sub { $shlibs_udeb = ''; },
});

my $ok=1;

sub _all_so_files {
	my ($package, $root_dir) = @_;
	return if not -d $root_dir;
	my (@all_so_files, @so_file_data);
	my $objdump = cross_command($package, "objdump");
	require File::Find;
	File::Find::find(sub {
		# Lazy loading of File::Find makes perl think that File::Find::dir is only used once
		# and we might have typo'ed something
		no warnings qw(once);
		# Only real/regular files
		-l && return;
		-f _ || return;
		my $path = "$File::Find::dir/$_";
		return if excludefile($path);
		return if not is_so_or_exec_elf_file($_);
		push(@all_so_files, $path);
	}, $root_dir);

	@all_so_files = sort(@all_so_files);
	for my $lib_file (@all_so_files) {
		my ($library, $major, $ret);
		if (compat(10)) {
			# In compat 10, we silently ignored failing exit codes
			# from objdump.  Its horrible, but such was compat 10.
			$ret = `$objdump -p "$lib_file"`;
			chomp($ret);
		} else {
			$ret = qx_cmd($objdump, '-p', $lib_file);
		}
		if ($ret=~m/\s+SONAME\s+(.*)\.so\.(.*)/) {
			# proper soname format
			$library=$1;
			$major=$2;
		} elsif ($ret=~m/\s+SONAME\s+(.*)-(\d.*)\.so/) {
			# idiotic crap soname format
			$library=$1;
			$major=$2;
		} elsif ($ret !~ m/\s+SONAME\s+(?:\S)/) {
			next;
		}
		push(@so_file_data, [$lib_file, $library, $major,]);
	};
	return @so_file_data;
}

foreach my $package (@{$dh{DOPACKAGES}}) {
	next if is_udeb($package);
	
	my $tmp=tmpdir($package);

	my (%seen, $unversioned_so);
	my $need_ldconfig = 0;
	# Note that since each package can have a shlibs file independently of
	# each other, we need to make these local.
	my $v_flag_set = $dh{V_FLAG_SET};
	my $v_flag = $dh{V_FLAG} // '';
	my $shlibs_file = pkgfile($package, 'shlibs');

	rm_files("$tmp/DEBIAN/shlibs");

	# So, we look for files or links to existing files with names that
	# match "*.so.*". And we only look at real files not
	# symlinks, so we don't accidentally add shlibs data to -dev
	# packages. This may have a few false positives, which is ok,
	# because only if we can get a library name and a major number from
	# objdump is anything actually added.
	my (@udeb_lines, @deb_lines, @lib_files, $udeb_name);
	if (defined($shlibs_udeb)) {
		$udeb_name = $shlibs_udeb if $shlibs_udeb ne '';
	} else {
		my $guessed_udeb = "${package}-udeb";
		$udeb_name = $guessed_udeb if is_known_package($guessed_udeb) and is_udeb($guessed_udeb);
	}
	# If there is a udeb (which we assume there never is under the "noudeb" build-profile)
	# then check it for libraries.
	if (defined($udeb_name) and not is_build_profile_active('noudeb')) {
		for my $so_data (_all_so_files($udeb_name, tmpdir($udeb_name))) {
			my (undef, $library, $major) = @{$so_data};
			$major = $dh{M_PARAMS} if defined($dh{M_PARAMS}) and $dh{M_PARAMS} ne '';
			next if not defined($library) or not defined($major);
			$known_udeb_solibs{$udeb_name}{"${library}\x1f${major}"} = 1;
		}
		# If the udeb contains no SO files but there was an explicit --add-udeb, then
		# something is wrong.
		error("The udeb $shlibs_udeb does not contain any shared libraries but --add-udeb=$shlibs_udeb was passed!?")
			if defined($shlibs_udeb) and not exists($known_udeb_solibs{$udeb_name});
	}
	for my $so_data (_all_so_files($package, $tmp)) {
		my ($lib_file, $library, $major) = @{$so_data};
		push(@lib_files, $lib_file) if compat(11);
		if (not defined($library)) {
			$unversioned_so = 1;
			push(@lib_files, $lib_file) if not compat(11);
		}

		if (defined($dh{M_PARAMS}) && $dh{M_PARAMS} ne '') {
			$major=$dh{M_PARAMS};
		}

		my $deps=$package;
		if ($v_flag_set) {
			if ($shlibs_file) {
				warning("The provided ${shlibs_file} file overwrites -V");
				# Clear the flag to avoid duplicate warnings.
				$v_flag_set = 0;
				$v_flag = '';
			} else {
				# Set the default "-V" (with no value) is passed.
				$v_flag = 'Upstream-Version' if $v_flag eq '';
			}
		} elsif ($v_flag eq '') {
			# Set the default if "-V" is omitted.
			$v_flag = compat(11) ? 'None' : 'Upstream-Version';
		}
		if ($v_flag ne '') {
			if ($v_flag eq 'Upstream-Version') {
				# Call isnative because it sets $dh{VERSION}
				# as a side effect.
				isnative($package);
				my $version = $dh{VERSION};
				# Old compatibility levels include the
				# debian revision, while new do not.
				# Remove debian version, if any.
				$version =~ s/-[^-]+$//;
				$deps = "$package (>= $version)";
			} elsif ($v_flag ne 'None') {
				$deps = $v_flag;
			}
		}
		if (defined($library) && defined($major) && defined($deps) &&
		      $library ne '' && $major ne '' && $deps ne '') {
			$need_ldconfig=1;
			push(@lib_files, $lib_file) if not compat(11);
			# Prevent duplicate lines from entering the file.
			my $line="$library $major $deps";
			if (! $seen{$line}) {
				$seen{$line}=1;
				push(@deb_lines, $line);
				if (defined($udeb_name)) {
					my $udeb_deps = $deps;
					$udeb_deps =~ s/\Q$package\E/$udeb_name/e;
					$line="udeb: $library $major $udeb_deps";
					push @udeb_lines, $line;
					# Track which libraries have been used in the udeb to ensure
					# we spot missing libraries.
					delete($known_udeb_solibs{$udeb_name}{"${library}\x1f${major}"})
						if defined($udeb_name);
				}
			}
		}
	}

	if (defined($udeb_name) and not $shlibs_udeb) {
		my $issues = 0;
		for my $lib_key (sort(keys(%{$known_udeb_solibs{$udeb_name}}))) {
			my ($library, $major) = split(qr/\x1f/, $lib_key);
			warning("$udeb_name contains SO library $library (version $major) but $package does not contain a similar library!?");
			$issues = 1;
		}
		if ($issues) {
			$ok = 0;
			warning("Rejecting the generated shlibs file for $udeb_name!");
			warning("Hint: Either add the missing libraries to $package, remove them from $udeb_name, or");
			warning("Hint: (if this difference is expected) pass \"--add-udeb=$udeb_name\" to dh_makeshlibs.");
			warning("Hint: In the latter case, you *may* also need to combine it with \"-p$package\"");
			warning("Hint: Alternatively, if you have merged the shared lib package into $udeb_name and it has no");
			warning("Hint: other packages need to know of this library, then use \"--no-add-udeb\"");
		}
	}

	if ($shlibs_file) {
		install_dir("$tmp/DEBIAN");
		install_file($shlibs_file, "$tmp/DEBIAN/shlibs");
	} elsif (@deb_lines or @udeb_lines) {
		install_dir("$tmp/DEBIAN");
		if ($dh{VERBOSE}) {
			verbose_print('echo ' . escape_shell($_) . ' >> ' . escape_shell("$tmp/DEBIAN/shlibs"))
				for @deb_lines, @udeb_lines;
		}
		if (not $dh{NO_ACT}) {
			open(my $shlibs_fd, '>', "$tmp/DEBIAN/shlibs") or error("open($tmp/DEBIAN/shlibs): $!");
			# Write the shlibs file with the udeb: lines last.
			print {$shlibs_fd} "$_\n" for @deb_lines, @udeb_lines;
			close($shlibs_fd) or error("close($tmp/DEBIAN/shlibs");
		}
	}

	if (-e "$tmp/DEBIAN/shlibs") {
		reset_perm_and_owner(0644, "$tmp/DEBIAN/shlibs");
	}

	# dpkg-gensymbols files
	my $symbols=pkgfile($package, "symbols");
	if (-e $symbols) {
		my @liblist;
		if (! compat(7)) {
			@liblist=map { "-e$_" } @lib_files;
		}
		# -I is used rather than using dpkg-gensymbols
		# own search for symbols files, since that search
		# is not 100% compatible with debhelper. (For example,
		# this supports --ignore being used.)
		$ok = doit_noerror(
				"dpkg-gensymbols",
				"-p$package",
				"-I$symbols",
				"-P$tmp",
				@liblist,
				@{$dh{U_PARAMS}}
			) && $ok;

		if (-f "$tmp/DEBIAN/symbols" and -s _ == 0) {
			rm_files("$tmp/DEBIAN/symbols");
		} elsif ($unversioned_so) {
			# There are a few "special" libraries (e.g. nss/nspr)
			# which do not have versioned SONAMES.  However the
			# maintainer provides a symbols file for them and we can
			# then use that to add an ldconfig trigger.
			$need_ldconfig = 1;
		}
	}

	# Historically, --no-scripts would disable the creation of
	# maintscripts for calling ldconfig.
	if (! $dh{NOSCRIPTS} && $need_ldconfig) {
		autotrigger($package, 'activate-noawait', 'ldconfig');
	}
}

unless ($ok) {
	error "failing due to earlier errors";
}

=head1 SEE ALSO

L<debhelper(7)>

This program is a part of debhelper.

=head1 AUTHOR

Joey Hess <joeyh@debian.org>

=cut