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Filename : dpkg-gensymbols
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#!/usr/bin/perl
#
# dpkg-gensymbols
#
# Copyright © 2007 Raphaël Hertzog
# Copyright © 2007-2013 Guillem Jover <guillem@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 <https://www.gnu.org/licenses/>.

use strict;
use warnings;

use Dpkg ();
use Dpkg::Arch qw(get_host_arch);
use Dpkg::Package;
use Dpkg::Shlibs qw(get_library_paths);
use Dpkg::Shlibs::Objdump;
use Dpkg::Shlibs::SymbolFile;
use Dpkg::Gettext;
use Dpkg::ErrorHandling;
use Dpkg::Control::Info;
use Dpkg::Changelog::Parse;
use Dpkg::Path qw(check_files_are_the_same find_command);

textdomain('dpkg-dev');

my $packagebuilddir = 'debian/tmp';

my $sourceversion;
my $stdout;
my $oppackage;
my $compare = 1; # Bail on missing symbols by default
my $quiet = 0;
my $input;
my $output;
my $template_mode = 0; # non-template mode by default
my $verbose_output = 0;
my $debug = 0;
my $host_arch = get_host_arch();

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>...]')
    . "\n\n" . g_(
'Options:
  -l<library-path>         add directory to private shared library search list.
  -p<package>              generate symbols file for package.
  -P<package-build-dir>    temporary build directory instead of debian/tmp.
  -e<library>              explicitly list libraries to scan.
  -v<version>              version of the packages (defaults to
                           version extracted from debian/changelog).
  -c<level>                compare generated symbols file with the reference
                           template in the debian directory and fail if
                           difference is too important; level goes from 0 for
                           no check, to 4 for all checks (default level is 1).
  -q                       keep quiet and never emit any warnings or
                           generate a diff between generated symbols
                           file and the reference template.
  -I<file>                 force usage of <file> as reference symbols
                           file instead of the default file.
  -O[<file>]               write to stdout (or <file>), not .../DEBIAN/symbols.
  -t                       write in template mode (tags are not
                           processed and included in output).
  -V                       verbose output; write deprecated symbols and pattern
                           matching symbols as comments (in template mode only).
  -a<arch>                 assume <arch> as host architecture when processing
                           symbol files.
  -d                       display debug information during work.
  -?, --help               show this help message.
      --version            show the version.
'), $Dpkg::PROGNAME;
}

my @files;
while (@ARGV) {
    $_ = shift(@ARGV);
    if (m/^-p/p) {
	$oppackage = ${^POSTMATCH};
	my $err = pkg_name_is_illegal($oppackage);
	error(g_("illegal package name '%s': %s"), $oppackage, $err) if $err;
    } elsif (m/^-l(.*)$/) {
        Dpkg::Shlibs::add_library_dir($1);
    } elsif (m/^-c(\d)?$/) {
	$compare = $1 // 1;
    } elsif (m/^-q$/) {
	$quiet = 1;
    } elsif (m/^-d$/) {
	$debug = 1;
    } elsif (m/^-v(.+)$/) {
	$sourceversion = $1;
    } elsif (m/^-e(.+)$/) {
	my $file = $1;
	if (-e $file) {
	    push @files, $file;
	} else {
	    my @to_add = glob($file);
	    push @files, @to_add;
	    warning(g_("pattern '%s' did not match any file"), $file)
		unless scalar(@to_add);
	}
    } elsif (m/^-P(.+)$/) {
	$packagebuilddir = $1;
	$packagebuilddir =~ s{/+$}{};
    } elsif (m/^-O$/) {
	$stdout = 1;
    } elsif (m/^-I(.+)$/) {
	$input = $1;
    } elsif (m/^-O(.+)$/) {
	$output = $1;
    } elsif (m/^-t$/) {
	$template_mode = 1;
    } elsif (m/^-V$/) {
	$verbose_output = 1;
    } elsif (m/^-a(.+)$/) {
	$host_arch = $1;
    } elsif (m/^-(?:\?|-help)$/) {
	usage();
	exit(0);
    } elsif (m/^--version$/) {
	version();
	exit(0);
    } else {
	usageerr(g_("unknown option '%s'"), $_);
    }
}

report_options(debug_level => $debug);

umask 0022; # ensure sane default permissions for created files

if (exists $ENV{DPKG_GENSYMBOLS_CHECK_LEVEL}) {
    $compare = $ENV{DPKG_GENSYMBOLS_CHECK_LEVEL};
}

if (not defined($sourceversion)) {
    my $changelog = changelog_parse();
    $sourceversion = $changelog->{'Version'};
}
if (not defined($oppackage)) {
    my $control = Dpkg::Control::Info->new();
    my @packages = map { $_->{'Package'} } $control->get_packages();
    if (@packages == 0) {
	error(g_('no package stanza found in control info'));
    } elsif (@packages > 1) {
	error(g_('must specify package since control info has many (%s)'),
	      "@packages");
    }
    $oppackage = $packages[0];
}

my $symfile = Dpkg::Shlibs::SymbolFile->new(arch => $host_arch);
my $ref_symfile = Dpkg::Shlibs::SymbolFile->new(arch => $host_arch);
# Load source-provided symbol information
foreach my $file ($input, $output, "debian/$oppackage.symbols.$host_arch",
    "debian/symbols.$host_arch", "debian/$oppackage.symbols",
    'debian/symbols')
{
    if (defined $file and -e $file) {
	debug(1, "Using references symbols from $file");
	$symfile->load($file);
	$ref_symfile->load($file) if $compare || ! $quiet;
	last;
    }
}

# Scan package build dir looking for libraries
if (not scalar @files) {
    PATH: foreach my $path (get_library_paths()) {
	my $libdir = "$packagebuilddir$path";
	$libdir =~ s{/+}{/}g;
	lstat $libdir;
	next if not -d _;
	next if -l _; # Skip directories which are symlinks
        # Skip any directory _below_ a symlink as well
        my $updir = $libdir;
        while (($updir =~ s{/[^/]*$}{}) and
               not check_files_are_the_same($packagebuilddir, $updir)) {
            next PATH if -l $updir;
        }
	opendir(my $libdir_dh, "$libdir")
	    or syserr(g_("can't read directory %s: %s"), $libdir, $!);
	push @files, grep {
	    /(\.so\.|\.so$)/ && -f &&
	    Dpkg::Shlibs::Objdump::is_elf($_);
	} map { "$libdir/$_" } readdir($libdir_dh);
	closedir $libdir_dh;
    }
}

# Merge symbol information
my $od = Dpkg::Shlibs::Objdump->new();
foreach my $file (@files) {
    debug(1, "Scanning $file for symbol information");
    my $objid = $od->analyze($file);
    unless (defined($objid) && $objid) {
	warning(g_("Dpkg::Shlibs::Objdump couldn't parse %s\n"), $file);
	next;
    }
    my $object = $od->get_object($objid);
    if ($object->{SONAME}) { # Objects without soname are of no interest
	debug(1, "Merging symbols from $file as $object->{SONAME}");
	if (not $symfile->has_object($object->{SONAME})) {
	    $symfile->create_object($object->{SONAME}, "$oppackage #MINVER#");
	}
	$symfile->merge_symbols($object, $sourceversion);
    } else {
	debug(1, "File $file doesn't have a soname. Ignoring.");
    }
}
$symfile->clear_except(keys %{$od->{objects}});

# Write out symbols files
if ($stdout) {
    $output = g_('<standard output>');
    $symfile->output(\*STDOUT, package => $oppackage,
                     template_mode => $template_mode,
                     with_pattern_matches => $verbose_output,
                     with_deprecated => $verbose_output);
} else {
    unless (defined($output)) {
	unless ($symfile->is_empty()) {
	    $output = "$packagebuilddir/DEBIAN/symbols";
	    mkdir("$packagebuilddir/DEBIAN") if not -e "$packagebuilddir/DEBIAN";
	}
    }
    if (defined($output)) {
	debug(1, "Storing symbols in $output.");
	$symfile->save($output, package => $oppackage,
	               template_mode => $template_mode,
	               with_pattern_matches => $verbose_output,
	               with_deprecated => $verbose_output);
    } else {
	debug(1, 'No symbol information to store.');
    }
}

# Check if generated files differs from reference file
my $exitcode = 0;

sub compare_problem
{
    my ($level, $msg, @args) = @_;

    if ($compare >= $level) {
        errormsg($msg, @args);
        $exitcode = $level;
    } else {
        warning($msg, @args) unless $quiet;
    }
}

if ($compare || ! $quiet) {
    # Compare
    if (my @libs = $symfile->get_new_libs($ref_symfile)) {
        compare_problem(4, g_('new libraries appeared in the symbols file: %s'), "@libs");
    }
    if (my @libs = $symfile->get_lost_libs($ref_symfile)) {
        compare_problem(3, g_('some libraries disappeared in the symbols file: %s'), "@libs");
    }
    if ($symfile->get_new_symbols($ref_symfile)) {
        compare_problem(2, g_('some new symbols appeared in the symbols file: %s'),
                           g_('see diff output below'));
    }
    if ($symfile->get_lost_symbols($ref_symfile)) {
        compare_problem(1, g_('some symbols or patterns disappeared in the symbols file: %s'),
                           g_('see diff output below'))
    }
}

unless ($quiet) {
    require File::Temp;
    require Digest::MD5;

    my $file_label;

    # Compare template symbols files before and after
    my $before = File::Temp->new(TEMPLATE=>'dpkg-gensymbolsXXXXXX');
    my $after = File::Temp->new(TEMPLATE=>'dpkg-gensymbolsXXXXXX');
    if ($ref_symfile->{file}) {
        $file_label = $ref_symfile->{file};
    } else {
        $file_label = 'new_symbol_file';
    }
    $ref_symfile->output($before, package => $oppackage, template_mode => 1);
    $symfile->output($after, package => $oppackage, template_mode => 1);

    seek $before, 0, 0;
    seek $after, 0, 0;
    my ($md5_before, $md5_after) = (Digest::MD5->new(), Digest::MD5->new());
    $md5_before->addfile($before);
    $md5_after->addfile($after);

    # Output diffs between symbols files if any
    if ($md5_before->hexdigest() ne $md5_after->hexdigest()) {
	if (not defined($output)) {
	    warning(g_('the generated symbols file is empty'));
	} elsif (defined($ref_symfile->{file})) {
	    warning(g_("%s doesn't match completely %s"),
		    $output, $ref_symfile->{file});
	} else {
	    warning(g_('no debian/symbols file used as basis for generating %s'),
		    $output);
	}
	my ($a, $b) = ($before->filename, $after->filename);
	my $diff_label = sprintf('%s (%s_%s_%s)', $file_label, $oppackage,
	                         $sourceversion, $host_arch);
	system('diff', '-u', '-L', $diff_label, $a, $b) if find_command('diff');
    }
}
exit($exitcode);