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File:Dpkg/Shlibs/Cppfilt.pm
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1# Copyright © 2009-2010 Modestas Vainius <modax@debian.org>
2# Copyright © 2010, 2012-2015 Guillem Jover <guillem@debian.org>
3#
4# This program is free software; you can redistribute it and/or modify
5# it under the terms of the GNU General Public License as published by
6# the Free Software Foundation; either version 2 of the License, or
7# (at your option) any later version.
8#
9# This program is distributed in the hope that it will be useful,
10# but WITHOUT ANY WARRANTY; without even the implied warranty of
11# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12# GNU General Public License for more details.
13#
14# You should have received a copy of the GNU General Public License
15# along with this program.  If not, see <https://www.gnu.org/licenses/>.
16
17=encoding utf8
18
19 - 30
=head1 NAME

Dpkg::Shlibs::Cppfilt - C++ symbol mangling support via c++filt

=head1 DESCRIPTION

This module provides functions that wrap over c++filt for its easy and
fast usage.

B<Note>: This is a private module, its API can change at any time.

=cut
31
32package Dpkg::Shlibs::Cppfilt 0.01;
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use strict;
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use warnings;
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37our @EXPORT = qw(
38    cppfilt_demangle_cpp
39);
40our @EXPORT_OK = qw(
41    cppfilt_demangle
42);
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use Exporter qw(import);
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use Dpkg::ErrorHandling;
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use Dpkg::IPC;
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49# A hash of 'objects' referring to preforked c++filt processes for the distinct
50# demangling types.
51my %cppfilts;
52
53sub get_cppfilt {
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    my $type = shift || 'auto';
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56    # Fork c++filt process for demangling $type unless it is forked already.
57    # Keeping c++filt running improves performance a lot.
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    my $filt;
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    if (exists $cppfilts{$type}) {
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        $filt = $cppfilts{$type};
61    } else {
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        $filt = {
63            from => undef,
64            to => undef,
65            last_symbol => '',
66            last_result => '',
67        };
68        $filt->{pid} = spawn(exec => [ 'c++filt', "--format=$type" ],
69                             from_pipe => \$filt->{from},
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                             to_pipe => \$filt->{to});
71        syserr(g_('unable to execute %s'), 'c++filt')
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            unless defined $filt->{from};
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        $filt->{from}->autoflush(1);
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        $cppfilts{$type} = $filt;
76    }
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    return $filt;
78}
79
80# Demangle the given $symbol using demangler for the specified $type (defaults
81# to 'auto') . Extraneous characters trailing after a mangled name are kept
82# intact. If neither whole $symbol nor portion of it could be demangled, undef
83# is returned.
84sub cppfilt_demangle {
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    my ($symbol, $type) = @_;
86
87    # Start or get c++filt 'object' for the requested type.
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    my $filt = get_cppfilt($type);
89
90    # Remember the last result. Such a local optimization is cheap and useful
91    # when sequential pattern matching is performed.
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    if ($filt->{last_symbol} ne $symbol) {
93        # This write/read operation should not deadlock because c++filt flushes
94        # output buffer on LF or each invalid character.
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        print { $filt->{from} } $symbol, "\n";
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        my $demangled = readline($filt->{to});
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        chop $demangled;
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99        # If the symbol was not demangled, return undef. Otherwise normalize
100        # it as llvm packs ending angle brackets with no intermediate spaces
101        # as allowed by C++11, contrary to GNU binutils.
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        if ($symbol eq $demangled) {
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            $demangled = undef;
104        } else {
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            $demangled =~ s{(?<=>)(?=>)}{ }g;
106        }
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108        # Remember the last result
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        $filt->{last_symbol} = $symbol;
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        $filt->{last_result} = $demangled;
111    }
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    return $filt->{last_result};
113}
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115sub cppfilt_demangle_cpp {
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    my $symbol = shift;
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    return cppfilt_demangle($symbol, 'auto');
118}
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120sub terminate_cppfilts {
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    foreach my $type (keys %cppfilts) {
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        next if not defined $cppfilts{$type}{pid};
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        close $cppfilts{$type}{from};
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        close $cppfilts{$type}{to};
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        wait_child($cppfilts{$type}{pid}, cmdline => 'c++filt',
126                                          nocheck => 1,
127                                          timeout => 5);
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        delete $cppfilts{$type};
129    }
130}
131
132# Close/terminate running c++filt process(es)
133END {
134    # Make sure exitcode is not changed (by wait_child)
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    my $exitcode = $?;
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    terminate_cppfilts();
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    $? = $exitcode;
138}
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=head1 CHANGES

=head2 Version 0.xx

This is a private module.

=cut
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1481;